A rather large fairy wasp with feathered wings. The antennae are threadlike which indicates a male. I am not familiar with the family and would like confirmation. See en.wikipedia.org/wiki/Fairyfly for information quoted.

Katydids are nocturnal insects related to crickets and grasshoppers, noted for their loud mating calls. Katydids have large hind legs and are distinguished by their extremely long, threadlike antennae and the thick, upwardly curved ovipositor (egg-laying structure) of the females. Often large and green, many katydids have long wings. The United States has over 100 variety varieties if Katydids.

 

This particular Katydid was found in my front yard in some shrubbery. The Katydid has a leaf like appearance protecting it from predators. Easy to miss if you don't look closely.

  

Tradescantia virginiana, the type species of Tradescantia native to the eastern USA, is a very hardy North American native spring-blooming perennial with long, strappy leaves in a kind of messy, grass-like form punctuated with quarter-sized flowers that last ...only one day; cut stems release a viscous secretion which becomes threadlike and silky upon hardening (like a spider's web), hence the common name

 

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Landsford Canal State Park, SC – 2019JUN04 – Shoals Spider Lily:

 

I've long wanted to see the largest known stand of the rocky shoals spider lily in peak bloom on the Catawba River, Number One on the Landsford Canal State Park's Top 5 Things To Do.

 

Today we drove into South Carolina just to see those spider lilies!

 

We also explored the Canal Trail and read the interpretive text along the path to understand the incredible work done on the trail by 1820s standards. "Next time" we want to paddle the shoals and appreciate the power of a piedmont, fall line river.

 

Hope you enjoy the 14% of 144 photos we took here this day!

My Summer Garden (series)

This is Dill (Anethum graveolens), a familiar culinary herb in the carrot family (Apiaceae).

 

Identification

 

Flowers:

 

Bright yellow-green, tiny, clustered in flat-topped umbels (umbrella-like structures typical of the Apiaceae family).

 

Each umbel is composed of many small five-petaled flowers.

 

Stems:

 

Tall, slender, hollow, slightly ridged.

 

Can reach 2–4 feet tall,

often leaning under the weight of flowers.

 

Leaves (not as prominent in this photo, lower down):

 

Very fine, feathery, threadlike segments (similar to fennel but more delicate).

 

Aromatic, with the distinct dill scent.

 

Growth Habit

 

Annual herb.

 

Prefers full sun and well-drained soil.

 

Commonly self-seeds, often reappearing each year in gardens.

 

Seasonal Notes

 

Spring–early summer: Feathery foliage is harvested for fresh use in cooking and pickling.

 

Summer: Plants bolt, sending up tall flowering umbels (as in your photo).

 

Late summer–fall: Seeds mature, used whole in pickling or ground as a spice.

 

Uses

 

Culinary:

 

Leaves (dill weed) for flavoring soups, fish, potatoes, and salads.

 

Seeds used in pickling, rye bread, and spice mixes.

 

Pollinator plant: Attracts many beneficial insects, including parasitic wasps and hoverflies.

To view more in this series, please click "here" !

 

Nerine is a genus of flowering plants belonging to the Amaryllidaceae family, subfamily Amaryllidoideae. They are bulbous perennials, some evergreen, associated with rocky and arid habitats. They bear spherical umbels of lily-like flowers in shades from white through pink to crimson. In the case of deciduous species, the flowers may appear on naked stems before the leaves develop. Native to South Africa, there are about 30 species in the genus. Though described as lilies, they are not significantly related to the true lilies Lilium, but more closely resemble their relatives, Amaryllis and Lycoris. The genus was established by the cleric and Amaryllidaceae specialist William Herbert in 1820. Nerines have been widely cultivated and much hybridized worldwide, especially Nerine bowdenii, N. sarniensis and N. undulata (previously known as N. flexuosa). The hybrid cultivar 'Zeal Giant' has gained the Royal Horticultural Society's Award of Garden Merit. The other 20 species are rarely cultivated and very little is known regarding their biology. Many species are threatened with extinction due to the loss or degradation of their habitat. Species of Nerine are herbaceous flowering plants that grow from bulbs. Their leaves are linear, obviously flat in some species and appearing threadlike in others. Their flowers are borne in an umbel on a solid leafless stem (scape). Individual flowers are either radially symmetrical (actinomorphic) or have one plane of symmetry (zygomorphic). Each flower has six narrow red or pink tepals joined at the base to form a short extended or recurved tube. The free parts of the tepals are generally wavy. There are six stamens that are inserted in the base of the petals and frequently protrude from the flower. The stamens can be straight or curved with thin filaments and oblong anthers that attach to their filament at the back (dorsifixed). The inferior ovary has one to many ovules. The style is threadlike and has a three-lobed stigma. The fruit is a capsule. Many species of Nerine have petals with wavy edges, such as Nerine humilis. Profusion of flowers in Nerine filifolia, note the filiform leaves of this species.

Nerine species can be either evergreen or deciduous; the deciduous species can either grow during the winter or the summer. The growth cycle thus defines three groups. There is a strong association between a species' growth habit, the shape of its leaves and the amount of DNA in its cell nuclei. The largest group of 12 species contains the evergreen nerines that retain their leaves throughout the summer and winter (N. angustifolia, N. appendiculata, N. filamentosa, N. filifolia, N. frithii, N. gaberonensis, N. gibsonii, N. gracilis, N. masoniorum, N. pancratioides, N. platypetala and N. rehmannii). Their leaves are narrow and they have the smallest amount of DNA per nucleus (18.0â24.6 pg). Four deciduous species grow in the winter and do not have any leaves during the summer (N. humilis, N. pudica, N. ridleyi and N. sarniensis). They have wide leaves and more DNA per nucleus (25.3â26.2 pg). A final group of seven species only grow during the summer and have no leaves in the winter (N. bowdenii, N. duparquetiana, N. krigei, N. laticoma, N. marincowitzii, N. pusilla and N. undulata). They have wide leaves and the most DNA per nucleus (26.8â35.3 pg). The earliest published name for the genus was Imhofia, given by Lorenz Heister in 1755. The later name Nerine, published by William Herbert in 1820, was widely used, resulting in a decision to conserve the name Nerine and reject the name Imhofia. The genus name derives from the Nereids (sea-nymphs) of Greek mythology that protected sailors and their ships. When Herbert chose the name of these nymphs for the first species of the genus, Nerine sarniensis, he alluded to the story of how this South African species arrived on the island of Guernsey in the English Channel. It is said that a ship carrying boxes of the bulbs of this species destined for the Netherlands was shipwrecked on Guernsey. The boxes of bulbs were washed up on the island and the bulbs became established and multiplied around the coast.

 

From Wikipedia, the free encyclopedia

Kingdom Animalia (Animals)

Phylum Arthropoda (Arthropods)

Subphylum Hexapoda (Hexapods)

Class Insecta (Insects)

Order Lepidoptera (Butterflies and Moths)

 

Unfortunate by-catch from sweep netting for leafhoppers. I think it's a moth.

 

According to Jaret C. Danials in "Butterflies of Florida Field Guide,"

 

"Butterflies and moths are closely related and often difficult to quickly tell apart. Nonetheless, there are some basic differences that are easy to identify even in the field. Generally, butterflies fly during the day, have large colorful wings that are held vertically together over the back when at rest and bear distinctly clubbed antennae. In contrast, most moths are nocturnal. They are usually overall drabber in color and my often resemble dirty, hairy butterflies. At rest, the tend to hold their wings to the sides, and have feathery or threadlike antennae."

 

January 14, 2021; Aucilla Wildlife Management Area, Jefferson County, Florida.

 

Canon M6 MII; 3.7x/0.11 n.a. microscope objective (L); +/- 160mm extension tubes; Zerene Stacker (slabbing method).

 

210114_Moth_belly

White, threadlike algae coat the rocks in the pool below the sulfur spring.

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant native to Mexico. The species and its varieties and cultivars are popular as an ornamental plant in temperate climate gardens. It can also be found in natural areas in much of North America, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cosmos bipinnatus is considered a half-hardy annual, although plants may reappear via self-sowing for several years. The plant height varies from 2–4 ft (0.61–1.22 m). The cultivated varieties appear in shades of pink and purple as well as white. Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

The Huntington Library and Botanical Gardens. San Marino. California.

 

Leica APO-Macro-Elmarit-R 100mm f/2.8

 

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant native to Mexico. The species and its varieties and cultivars are popular as an ornamental plant in temperate climate gardens.

 

It naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cosmos bipinnatus is considered a half-hardy annual, although plants may reappear via self-sowing for several years. The plant height varies from 2–4 ft (0.61–1.22 m). The cultivated varieties appear in shades of pink and purple as well as white.

 

Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

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Thanks to every friend ! Greetings ! And wish you every lucky !

 

3/14

 

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant native to Mexico. The species and its varieties and cultivars are popular as an ornamental plant in temperate climate gardens.

 

It naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cosmos bipinnatus is considered a half-hardy annual, although plants may reappear via self-sowing for several years. The plant height varies from 2–4 ft (0.61–1.22 m). The cultivated varieties appear in shades of pink and purple as well as white.

 

Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

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Leave a message, add to the favorites or visit,

Thanks to every friend ! Greetings ! And wish you every lucky !

 

2019. 1. 6

6-prong crown setting rings. The parameters:

 

*copper band - no more than 1/2"wide (not sure what that is in centimeters)

*textured

*6-prong crown setting

*faceted stone - blue

*liver of sulpher

However you want to interpret this into a ring, can be technical, can be purely conceptual in some form.

 

So my stone is green, but if you mix blue with yellow you get green, so I'm sure that there is some blue in there somewhere.

 

Crown setting -- I don't know if difficult is the right word, but stressful is definitely in the running. Trying to get 6 equal prongs kept my brain and my compass busy for awhile. And sawing was interesting. So after all the figuring and sawing I had to solder it on and hope I didn't melt it or something.

 

The stone is a green spinel, more than I really wanted to spend for a stone in a ring I have never made before, but when I was at the rock shop searching for the perfect uncut stone, and I couldn't find one, this one just jumped into the setting and fit perfectly! It's mystical qualities are that it "refreshes the emotional, increasing compassion, love, forgiveness, self-esteem and the relaxed and easy affection for others."

 

The writing on the band is from "Lost Goddesses of Early Greece A collection of pre-Hellenic Myths" by Charlene Spretnak.

 

The part I used is from the myth of Athena and reads:

"...Long before there were palaces, the Goddess had appeared to a group of women gathering plants in a field. She broke open the stems of blue-flowered flax and showed them how the threadlike fibers could be spun and then woven. The woof and warp danced in Her fingers until a length of cloth was born before them. She told them which plants and roots would color the cloth, and then She led the mortal from the field to a pit of clay..."

 

Would I make another crown setting? Yes

Should we do this ring formula thing again? Definitely

Does someone have an idea for parameters for the next one?

Hesperaloe parviflora, also known as Red Yucca, Hummingbird Yucca, and Samandoque, is a plant which is native to Chihuahuan desert of west Texas east and south into central and south Texas and northeastern Mexico.

 

Hesperaloe parviflora has narrow evergreen leaves with a fringe along their edges of white threadlike hairs and grows in clumps 3–6 ft (0.91–1.8 m) high and wide. Red or yellow tubular flowers are held on branching flower stalks (inflorescences) up to 5 ft (1.5 m) tall from late spring to mid-summer.

 

This Hesperaloe species has become popular in xeriscape landscape design for public and private gardens in southern deserts of Arizona, California and New Mexico. The plant's qualities include drought tolerance, heat resistance, low maintenance needs, and hummingbird attracting flowers.

 

01085538-2080x1170+f0-AWS

Shot hand held with a D5000.

 

Please - no awards, photos, group invites or graphics!

Please do not use this image on a website without explicit permission from me. Thanks.

Are you ready to geek out with me? You had better hold on, then! This is lichen (pronounced like-in), and it's a really cool facet of the natural world. I've spoken briefly of symbiosis before, the interaction of two different organisms acting as one for mutual benefit. This is a clear example of symbiosis at work.

 

The green, threadlike filaments are actually fungal hyphae structures. That is fungus. Yes, it's not a mushroom, but we all know that fungi don't have to look like mushrooms, right?? Those are just reproductive structures. No, this is a fungus clinging to my mailbox post.

 

Here's the kicker, though, it's green coloration is where the symbiosis comes in. The green coloration comes from cyanobacteria or algae that lives within the fungus. The fungus gets some free energy from the photosynthetic bacteria or protist while the protist or bacteria get a nutrient rich, protected environment from the fungus.

 

It's beautiful . . . oh, and here's a photo of it.

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant in the daisy family Asteraceae, native to the Americas. The species and its varieties and cultivars are popular as ornamental plants in temperate climate gardens.

 

Description

In natural habitat

Cosmos bipinnatus is an annual that is often considered half-hardy, although plants may reappear via self-sowing for several years. The plant height varies from 2–6 ft to (rarely) 9 ft (0.61–1.83–2.74 m). The cultivated varieties appear in shades of pink and purple as well as white. The branched stem is usually densely to occasionally occupied by fine, split up, rough trichomes, some specimens are completely hairless. The petiole itself is inconspicuous, winged, 10 (rarely to 15) mm long, sometimes the leaves are almost sessile.

 

The partial leaves are linear-filiform to narrow linear with a width of 0.5 to 1 (rarely to 1.7) mm; the tips are pointed, hardened, but not particularly sharp. Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

The achenes become blackish, are smooth or short-bristly. Their shape is spindle-like. They are rounded off into a short, 0.5 to 1.7 mm long, but distinctly pronounced rostrum. The inner achenes are up to 18 mm long, their yellowish beaks are 4 to 5 (rarely to 10) mm long. A pappus is missing or it consists only of two to three awn-like, 1-3 mm large bristles.

 

Flowers

The very conspicuous cup-shaped inflorescences have a diameter of usually 5–7 cm (2.0–2.8 in) and contain tongue and tubular flowers, which are surrounded by bracts. There are usually 8 outer bracts, and they are ovate to lanceolate-tail-shaped, 7-15 mm long, 3-5 mm wide. The inner bracts are ovate-lanceolate and 8-12 mm long. They are translucent with many black stripes and a clear edge up to 1 mm wide, sometimes with yellowish or pink pigments, the tip is ciliate. The sprout leaves have gold-yellow, thread-like tips and protrude between the tubular flowers. The broadened base of these spreader leaves is translucent, provided with a yellow line. During flowering, the plant can sag under its weight. This problem can be solved by grouping the feet together so that the leaves hang together.

 

The mostly eight ray florets are pink to violet or white colored, at the base may show noticeable stains caused by anthocyanin. The tongues are reversely ovate shaped, have a length of usually 20-35 mm and a width of usually 12-20 mm. The tips are almost dull and have three broad, wavy teeth. Below that, they are greatly rejuvenated. In the center of the flower baskets is a large number of tubular flowers (also called disc florets), whose overgrown petals are yellow, turn white in the lower part and reach a length of 5-6 mm. The anthers are brownish-black and about 3 mm long, at the tips are short-triangular, translucent attachments with a length of 0.5-0.8 mm. The branches of the stylus are short and rather dull, with a length of .5 mm.

 

Distribution

This plant is native to Mexico, Guatemala and Costa Rica. Since it is used as an ornamental plant in many countries and prone to sedimentation, it is an invasive plant in many areas of the world. It has naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cultivars

Cultivars of Cosmos bipinnatus in cultivation today include:

 

Apollo Series

'Apollo Carmine' agm

'Apollo Pink' agm

'Apollo White' agm

'Daydream' features a pink inner ring on a white background

Double Click Series features semidouble to fully double flowers that resemble Japanese anemones (Anemone japonica)

'Double Click Cranberries'

'Double Click Rose Bonbon'

'Double Click Snow Puff'

'Double Click Vari Extra'

'Rubenza' agm

'Sensation', also known as 'Early Sensation', is a widely available mix of tall varieties

'Sensation Pinkie' agm

Sonata series

'Velouette'agm

'Versailles', developed for the cut flower trade, are shorter than the species, with heights remaining below three feet

'Versailles Dark Rose'

'Vesailles Tetra'

(those marked agm have gained the Royal Horticultural Society's Award of Garden Merit).

 

Cultivation

Germination takes between 7 and 10 days at the optimal temperature of 75 °F (24 °C); flowering begins between 60 and 90 days after germination

It prefers a soil pH between 6.0 and 8.5, reflecting its native habitat in the alkaline regions of Central America

Flowering is best in full sun, although partial shade is tolerated

Excessive rain can cause cultivation problems, due to the delicate nature of the stems. Heavy rain can cause breakage. Cosmos bipinnatus can tolerate heat as long as adequate moisture is provided, however, it does not handle droughts, strong winds or cold temperatures well. Snails, slugs and aphids have a taste for Cosmos bipinnatus. Successfully cultivated plants can mature 2 to 4 feet (0.61 to 1.22 m) x 12 to 18 inches (300 to 460 mm).

 

They are not tolerant of frost, but can be grown outdoors in a temperate climate with a warm to hot summer and are therefore called half-hardy in British gardening literature.

Pollinators

The flowers of Cosmos bipinnatus attract birds and butterflies, including the monarch butterfly. It can be part of butterfly gardening and pollinator/honey-bee habitat gardens.[

Jellyfish, also known sea jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria.

 

Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex life cycle. The medusa is normally the sexual phase, which produces planula larvae; these then disperse widely and enter a sedentary polyp phase, before reaching sexual maturity.

 

Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the "true jellyfish") are exclusively marine, but some hydrozoans with a similar appearance live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. The medusae of most species are fast-growing, and mature within a few months then die soon after breeding, but the polyp stage, attached to the seabed, may be much more long-lived. Jellyfish have been in existence for at least 500 million years, and possibly 700 million years or more, making them the oldest multi-organ animal group.

 

Jellyfish are eaten by humans in certain cultures. They are considered a delicacy in some Asian countries, where species in the Rhizostomeae order are pressed and salted to remove excess water. Australian researchers have described them as a "perfect food": sustainable and protein-rich but relatively low in food energy.

 

They are also used in research, where the green fluorescent protein used by some species to cause bioluminescence has been adapted as a fluorescent marker for genes inserted into other cells or organisms.

 

The stinging cells used by jellyfish to subdue their prey can injure humans. Thousands of swimmers worldwide are stung every year, with effects ranging from mild discomfort to serious injury or even death. When conditions are favourable, jellyfish can form vast swarms, which can be responsible for damage to fishing gear by filling fishing nets, and sometimes clog the cooling systems of power and desalination plants which draw their water from the sea.

  

Names

The name jellyfish, in use since 1796, has traditionally been applied to medusae and all similar animals including the comb jellies (ctenophores, another phylum). The term jellies or sea jellies is more recent, having been introduced by public aquaria in an effort to avoid use of the word "fish" with its modern connotation of an animal with a backbone, though shellfish, cuttlefish and starfish are not vertebrates either. In scientific literature, "jelly" and "jellyfish" have been used interchangeably. Many sources refer to only scyphozoans as "true jellyfish".

 

A group of jellyfish is called a "smack" or a "smuck".

 

Definition

The term jellyfish broadly corresponds to medusae, that is, a life-cycle stage in the Medusozoa. The American evolutionary biologist Paulyn Cartwright gives the following general definition:

 

Typically, medusozoan cnidarians have a pelagic, predatory jellyfish stage in their life cycle; staurozoans are the exceptions [as they are stalked].

 

The Merriam-Webster dictionary defines jellyfish as follows:

 

A free-swimming marine coelenterate that is the sexually reproducing form of a hydrozoan or scyphozoan and has a nearly transparent saucer-shaped body and extensible marginal tentacles studded with stinging cells.

 

Given that jellyfish is a common name, its mapping to biological groups is inexact. Some authorities have called the comb jellies and certain salps jellyfish, though other authorities state that neither of these are jellyfish, which they consider should be limited to certain groups within the medusozoa.

 

The non-medusozoan clades called jellyfish by some but not all authorities (both agreeing and disagreeing citations are given in each case) are indicated with on the following cladogram of the animal kingdom:

 

Jellyfish are not a clade, as they include most of the Medusozoa, barring some of the Hydrozoa. The medusozoan groups included by authorities are indicated on the following phylogenetic tree by the presence of citations. Names of included jellyfish, in English where possible, are shown in boldface; the presence of a named and cited example indicates that at least that species within its group has been called a jellyfish.

 

Taxonomy

The subphylum Medusozoa includes all cnidarians with a medusa stage in their life cycle. The basic cycle is egg, planula larva, polyp, medusa, with the medusa being the sexual stage. The polyp stage is sometimes secondarily lost. The subphylum include the major taxa, Scyphozoa (large jellyfish), Cubozoa (box jellyfish) and Hydrozoa (small jellyfish), and excludes Anthozoa (corals and sea anemones). This suggests that the medusa form evolved after the polyps. Medusozoans have tetramerous symmetry, with parts in fours or multiples of four.

 

The four major classes of medusozoan Cnidaria are:

Scyphozoa are sometimes called true jellyfish, though they are no more truly jellyfish than the others listed here. They have tetra-radial symmetry. Most have tentacles around the outer margin of the bowl-shaped bell, and long, oral arms around the mouth in the center of the subumbrella.

Cubozoa (box jellyfish) have a (rounded) box-shaped bell, and their velarium assists them to swim more quickly. Box jellyfish may be related more closely to scyphozoan jellyfish than either are to the Hydrozoa.

Hydrozoa medusae also have tetra-radial symmetry, nearly always have a velum (diaphragm used in swimming) attached just inside the bell margin, do not have oral arms, but a much smaller central stalk-like structure, the manubrium, with terminal mouth opening, and are distinguished by the absence of cells in the mesoglea. Hydrozoa show great diversity of lifestyle; some species maintain the polyp form for their entire life and do not form medusae at all (such as Hydra, which is hence not considered a jellyfish), and a few are entirely medusal and have no polyp form.

Staurozoa (stalked jellyfish) are characterized by a medusa form that is generally sessile, oriented upside down and with a stalk emerging from the apex of the "calyx" (bell), which attaches to the substrate. At least some Staurozoa also have a polyp form that alternates with the medusoid portion of the life cycle. Until recently, Staurozoa were classified within the Scyphozoa.

There are over 200 species of Scyphozoa, about 50 species of Staurozoa, about 50 species of Cubozoa, and the Hydrozoa includes about 1000–1500 species that produce medusae, but many more species that do not.

 

Fossil history

Since jellyfish have no hard parts, fossils are rare. The oldest unambiguous fossil of a free-swimming medusa is Burgessomedusa from the mid Cambrian Burgess Shale of Canada, which is likely either a stem group of box jellyfish (Cubozoa) or Acraspeda (the clade including Staurozoa, Cubozoa, and Scyphozoa). Other claimed records from the Cambrian of China and Utah in the United States are uncertain, and possibly represent ctenophores instead.

 

Anatomy

The main feature of a true jellyfish is the umbrella-shaped bell. This is a hollow structure consisting of a mass of transparent jelly-like matter known as mesoglea, which forms the hydrostatic skeleton of the animal. 95% or more of the mesogloea consists of water, but it also contains collagen and other fibrous proteins, as well as wandering amoebocytes which can engulf debris and bacteria. The mesogloea is bordered by the epidermis on the outside and the gastrodermis on the inside. The edge of the bell is often divided into rounded lobes known as lappets, which allow the bell to flex. In the gaps or niches between the lappets are dangling rudimentary sense organs known as rhopalia, and the margin of the bell often bears tentacles.

  

Anatomy of a scyphozoan jellyfish

On the underside of the bell is the manubrium, a stalk-like structure hanging down from the centre, with the mouth, which also functions as the anus, at its tip. There are often four oral arms connected to the manubrium, streaming away into the water below. The mouth opens into the gastrovascular cavity, where digestion takes place and nutrients are absorbed. This is subdivided by four thick septa into a central stomach and four gastric pockets. The four pairs of gonads are attached to the septa, and close to them four septal funnels open to the exterior, perhaps supplying good oxygenation to the gonads. Near the free edges of the septa, gastric filaments extend into the gastric cavity; these are armed with nematocysts and enzyme-producing cells and play a role in subduing and digesting the prey. In some scyphozoans, the gastric cavity is joined to radial canals which branch extensively and may join a marginal ring canal. Cilia in these canals circulate the fluid in a regular direction.

  

Discharge mechanism of a nematocyst

The box jellyfish is largely similar in structure. It has a squarish, box-like bell. A short pedalium or stalk hangs from each of the four lower corners. One or more long, slender tentacles are attached to each pedalium. The rim of the bell is folded inwards to form a shelf known as a velarium which restricts the bell's aperture and creates a powerful jet when the bell pulsates, allowing box jellyfish to swim faster than true jellyfish. Hydrozoans are also similar, usually with just four tentacles at the edge of the bell, although many hydrozoans are colonial and may not have a free-living medusal stage. In some species, a non-detachable bud known as a gonophore is formed that contains a gonad but is missing many other medusal features such as tentacles and rhopalia. Stalked jellyfish are attached to a solid surface by a basal disk, and resemble a polyp, the oral end of which has partially developed into a medusa with tentacle-bearing lobes and a central manubrium with four-sided mouth.

 

Most jellyfish do not have specialized systems for osmoregulation, respiration and circulation, and do not have a central nervous system. Nematocysts, which deliver the sting, are located mostly on the tentacles; true jellyfish also have them around the mouth and stomach. Jellyfish do not need a respiratory system because sufficient oxygen diffuses through the epidermis. They have limited control over their movement, but can navigate with the pulsations of the bell-like body; some species are active swimmers most of the time, while others largely drift. The rhopalia contain rudimentary sense organs which are able to detect light, water-borne vibrations, odour and orientation. A loose network of nerves called a "nerve net" is located in the epidermis. Although traditionally thought not to have a central nervous system, nerve net concentration and ganglion-like structures could be considered to constitute one in most species. A jellyfish detects stimuli, and transmits impulses both throughout the nerve net and around a circular nerve ring, to other nerve cells. The rhopalial ganglia contain pacemaker neurones which control swimming rate and direction.

 

In many species of jellyfish, the rhopalia include ocelli, light-sensitive organs able to tell light from dark. These are generally pigment spot ocelli, which have some of their cells pigmented. The rhopalia are suspended on stalks with heavy crystals at one end, acting like gyroscopes to orient the eyes skyward. Certain jellyfish look upward at the mangrove canopy while making a daily migration from mangrove swamps into the open lagoon, where they feed, and back again.

 

Box jellyfish have more advanced vision than the other groups. Each individual has 24 eyes, two of which are capable of seeing colour, and four parallel information processing areas that act in competition, supposedly making them one of the few kinds of animal to have a 360-degree view of its environment.

 

Box jellyfish eye

The study of jellyfish eye evolution is an intermediary to a better understanding of how visual systems evolved on Earth. Jellyfish exhibit immense variation in visual systems ranging from photoreceptive cell patches seen in simple photoreceptive systems to more derived complex eyes seen in box jellyfish. Major topics of jellyfish visual system research (with an emphasis on box jellyfish) include: the evolution of jellyfish vision from simple to complex visual systems), the eye morphology and molecular structures of box jellyfish (including comparisons to vertebrate eyes), and various uses of vision including task-guided behaviors and niche specialization.

 

Evolution

Experimental evidence for photosensitivity and photoreception in cnidarians antecedes the mid 1900s, and a rich body of research has since covered evolution of visual systems in jellyfish. Jellyfish visual systems range from simple photoreceptive cells to complex image-forming eyes. More ancestral visual systems incorporate extraocular vision (vision without eyes) that encompass numerous receptors dedicated to single-function behaviors. More derived visual systems comprise perception that is capable of multiple task-guided behaviors.

 

Although they lack a true brain, cnidarian jellyfish have a "ring" nervous system that plays a significant role in motor and sensory activity. This net of nerves is responsible for muscle contraction and movement and culminates the emergence of photosensitive structures. Across Cnidaria, there is large variation in the systems that underlie photosensitivity. Photosensitive structures range from non-specialized groups of cells, to more "conventional" eyes similar to those of vertebrates. The general evolutionary steps to develop complex vision include (from more ancestral to more derived states): non-directional photoreception, directional photoreception, low-resolution vision, and high-resolution vision. Increased habitat and task complexity has favored the high-resolution visual systems common in derived cnidarians such as box jellyfish.

 

Basal visual systems observed in various cnidarians exhibit photosensitivity representative of a single task or behavior. Extraocular photoreception (a form of non-directional photoreception), is the most basic form of light sensitivity and guides a variety of behaviors among cnidarians. It can function to regulate circadian rhythm (as seen in eyeless hydrozoans) and other light-guided behaviors responsive to the intensity and spectrum of light. Extraocular photoreception can function additionally in positive phototaxis (in planula larvae of hydrozoans), as well as in avoiding harmful amounts of UV radiation via negative phototaxis. Directional photoreception (the ability to perceive direction of incoming light) allows for more complex phototactic responses to light, and likely evolved by means of membrane stacking. The resulting behavioral responses can range from guided spawning events timed by moonlight to shadow responses for potential predator avoidance. Light-guided behaviors are observed in numerous scyphozoans including the common moon jelly, Aurelia aurita, which migrates in response to changes in ambient light and solar position even though they lack proper eyes.

 

The low-resolution visual system of box jellyfish is more derived than directional photoreception, and thus box jellyfish vision represents the most basic form of true vision in which multiple directional photoreceptors combine to create the first imaging and spatial resolution. This is different from the high-resolution vision that is observed in camera or compound eyes of vertebrates and cephalopods that rely on focusing optics. Critically, the visual systems of box jellyfish are responsible for guiding multiple tasks or behaviors in contrast to less derived visual systems in other jellyfish that guide single behavioral functions. These behaviors include phototaxis based on sunlight (positive) or shadows (negative), obstacle avoidance, and control of swim-pulse rate.

 

Box jellyfish possess "proper eyes" (similar to vertebrates) that allow them to inhabit environments that lesser derived medusae cannot. In fact, they are considered the only class in the clade Medusozoa that have behaviors necessitating spatial resolution and genuine vision. However, the lens in their eyes are more functionally similar to cup-eyes exhibited in low-resolution organisms, and have very little to no focusing capability. The lack of the ability to focus is due to the focal length exceeding the distance to the retina, thus generating unfocused images and limiting spatial resolution. The visual system is still sufficient for box jellyfish to produce an image to help with tasks such as object avoidance.

 

Utility as a model organism

Box jellyfish eyes are a visual system that is sophisticated in numerous ways. These intricacies include the considerable variation within the morphology of box jellyfishes' eyes (including their task/behavior specification), and the molecular makeup of their eyes including: photoreceptors, opsins, lenses, and synapses. The comparison of these attributes to more derived visual systems can allow for a further understanding of how the evolution of more derived visual systems may have occurred, and puts into perspective how box jellyfish can play the role as an evolutionary/developmental model for all visual systems.

 

Characteristics

Box jellyfish visual systems are both diverse and complex, comprising multiple photosystems. There is likely considerable variation in visual properties between species of box jellyfish given the significant inter-species morphological and physiological variation. Eyes tend to differ in size and shape, along with number of receptors (including opsins), and physiology across species of box jellyfish.

 

Box jellyfish have a series of intricate lensed eyes that are similar to those of more derived multicellular organisms such as vertebrates. Their 24 eyes fit into four different morphological categories. These categories consist of two large, morphologically different medial eyes (a lower and upper lensed eye) containing spherical lenses, a lateral pair of pigment slit eyes, and a lateral pair of pigment pit eyes. The eyes are situated on rhopalia (small sensory structures) which serve sensory functions of the box jellyfish and arise from the cavities of the exumbrella (the surface of the body) on the side of the bells of the jellyfish. The two large eyes are located on the mid-line of the club and are considered complex because they contain lenses. The four remaining eyes lie laterally on either side of each rhopalia and are considered simple. The simple eyes are observed as small invaginated cups of epithelium that have developed pigmentation. The larger of the complex eyes contains a cellular cornea created by a mono ciliated epithelium, cellular lens, homogenous capsule to the lens, vitreous body with prismatic elements, and a retina of pigmented cells. The smaller of the complex eyes is said to be slightly less complex given that it lacks a capsule but otherwise contains the same structure as the larger eye.

 

Box jellyfish have multiple photosystems that comprise different sets of eyes. Evidence includes immunocytochemical and molecular data that show photopigment differences among the different morphological eye types, and physiological experiments done on box jellyfish to suggest behavioral differences among photosystems. Each individual eye type constitutes photosystems that work collectively to control visually guided behaviors.

 

Box jellyfish eyes primarily use c-PRCs (ciliary photoreceptor cells) similar to that of vertebrate eyes. These cells undergo phototransduction cascades (process of light absorption by photoreceptors) that are triggered by c-opsins. Available opsin sequences suggest that there are two types of opsins possessed by all cnidarians including an ancient phylogenetic opsin, and a sister ciliary opsin to the c-opsins group. Box jellyfish could have both ciliary and cnidops (cnidarian opsins), which is something not previously believed to appear in the same retina. Nevertheless, it is not entirely evident whether cnidarians possess multiple opsins that are capable of having distinctive spectral sensitivities.

 

Comparison with other organisms

Comparative research on genetic and molecular makeup of box jellyfishes' eyes versus more derived eyes seen in vertebrates and cephalopods focuses on: lenses and crystallin composition, synapses, and Pax genes and their implied evidence for shared primordial (ancestral) genes in eye evolution.

 

Box jellyfish eyes are said to be an evolutionary/developmental model of all eyes based on their evolutionary recruitment of crystallins and Pax genes. Research done on box jellyfish including Tripedalia cystophora has suggested that they possess a single Pax gene, PaxB. PaxB functions by binding to crystallin promoters and activating them. PaxB in situ hybridization resulted in PaxB expression in the lens, retina, and statocysts. These results and the rejection of the prior hypothesis that Pax6 was an ancestral Pax gene in eyes has led to the conclusion that PaxB was a primordial gene in eye evolution, and that the eyes of all organisms likely share a common ancestor.

 

The lens structure of box jellyfish appears very similar to those of other organisms, but the crystallins are distinct in both function and appearance. Weak reactions were seen within the sera and there were very weak sequence similarities within the crystallins among vertebrate and invertebrate lenses. This is likely due to differences in lower molecular weight proteins and the subsequent lack of immunological reactions with antisera that other organisms' lenses exhibit.

 

All four of the visual systems of box jellyfish species investigated with detail (Carybdea marsupialis, Chiropsalmus quadrumanus, Tamoya haplonema and Tripedalia cystophora) have invaginated synapses, but only in the upper and lower lensed eyes. Different densities were found between the upper and lower lenses, and between species. Four types of chemical synapses have been discovered within the rhopalia which could help in understanding neural organization including: clear unidirectional, dense-core unidirectional, clear bidirectional, and clear and dense-core bidirectional. The synapses of the lensed eyes could be useful as markers to learn more about the neural circuit in box jellyfish retinal areas.

 

Evolution as a response to natural stimuli

The primary adaptive responses to environmental variation observed in box jellyfish eyes include pupillary constriction speeds in response to light environments, as well as photoreceptor tuning and lens adaptations to better respond to shifts between light environments and darkness. Interestingly, some box jellyfish species' eyes appear to have evolved more focused vision in response to their habitat.

 

Pupillary contraction appears to have evolved in response to variation in the light environment across ecological niches across three species of box jellyfish (Chironex fleckeri, Chiropsella bronzie, and Carukia barnesi). Behavioral studies suggest that faster pupil contraction rates allow for greater object avoidance, and in fact, species with more complex habitats exhibit faster rates. Ch. bronzie inhabit shallow beach fronts that have low visibility and very few obstacles, thus, faster pupil contraction in response to objects in their environment is not important. Ca. barnesi and Ch. fleckeri are found in more three-dimensionally complex environments like mangroves with an abundance of natural obstacles, where faster pupil contraction is more adaptive. Behavioral studies support the idea that faster pupillary contraction rates assist with obstacle avoidance as well as depth adjustments in response to differing light intensities.

 

Light/dark adaptation via pupillary light reflexes is an additional form of an evolutionary response to the light environment. This relates to the pupil's response to shifts between light intensity (generally from sunlight to darkness). In the process of light/dark adaptation, the upper and lower lens eyes of different box jellyfish species vary in specific function. The lower lens-eyes contain pigmented photoreceptors and long pigment cells with dark pigments that migrate on light/dark adaptation, while the upper-lens eyes play a concentrated role in light direction and phototaxis given that they face upward towards the water surface (towards the sun or moon). The upper lens of Ch. bronzie does not exhibit any considerable optical power while Tr. cystophora (a box jellyfish species that tends to live in mangroves) does. The ability to use light to visually guide behavior is not of as much importance to Ch. bronzie as it is to species in more obstacle-filled environments. Differences in visually guided behavior serve as evidence that species that share the same number and structure of eyes can exhibit differences in how they control behavior.

 

Largest and smallest

Jellyfish range from about one millimeter in bell height and diameter, to nearly 2 metres (6+1⁄2 ft) in bell height and diameter; the tentacles and mouth parts usually extend beyond this bell dimension.

 

The smallest jellyfish are the peculiar creeping jellyfish in the genera Staurocladia and Eleutheria, which have bell disks from 0.5 millimetres (1⁄32 in) to a few millimeters in diameter, with short tentacles that extend out beyond this, which these jellyfish use to move across the surface of seaweed or the bottoms of rocky pools; many of these tiny creeping jellyfish cannot be seen in the field without a hand lens or microscope. They can reproduce asexually by fission (splitting in half). Other very small jellyfish, which have bells about one millimeter, are the hydromedusae of many species that have just been released from their parent polyps; some of these live only a few minutes before shedding their gametes in the plankton and then dying, while others will grow in the plankton for weeks or months. The hydromedusae Cladonema radiatum and Cladonema californicum are also very small, living for months, yet never growing beyond a few mm in bell height and diameter.

 

The lion's mane jellyfish, Cyanea capillata, was long-cited as the largest jellyfish, and arguably the longest animal in the world, with fine, thread-like tentacles that may extend up to 36.5 m (119 ft 9 in) long (though most are nowhere near that large). They have a moderately painful, but rarely fatal, sting. The increasingly common giant Nomura's jellyfish, Nemopilema nomurai, found in some, but not all years in the waters of Japan, Korea and China in summer and autumn is another candidate for "largest jellyfish", in terms of diameter and weight, since the largest Nomura's jellyfish in late autumn can reach 2 m (6 ft 7 in) in bell (body) diameter and about 200 kg (440 lb) in weight, with average specimens frequently reaching 0.9 m (2 ft 11 in) in bell diameter and about 150 kg (330 lb) in weight. The large bell mass of the giant Nomura's jellyfish can dwarf a diver and is nearly always much greater than the Lion's Mane, whose bell diameter can reach 1 m (3 ft 3 in).

 

The rarely encountered deep-sea jellyfish Stygiomedusa gigantea is another candidate for "largest jellyfish", with its thick, massive bell up to 100 cm (3 ft 3 in) wide, and four thick, "strap-like" oral arms extending up to 6 m (19+1⁄2 ft) in length, very different from the typical fine, threadlike tentacles that rim the umbrella of more-typical-looking jellyfish, including the Lion's Mane.

 

Desmonema glaciale, which lives in the Antarctic region, can reach a very large size (several meters). Purple-striped jelly (Chrysaora colorata) can also be extremely long (up to 15 feet).

 

Life history and behavior

Life cycle

Jellyfish have a complex life cycle which includes both sexual and asexual phases, with the medusa being the sexual stage in most instances. Sperm fertilize eggs, which develop into larval planulae, become polyps, bud into ephyrae and then transform into adult medusae. In some species certain stages may be skipped.

 

Upon reaching adult size, jellyfish spawn regularly if there is a sufficient supply of food. In most species, spawning is controlled by light, with all individuals spawning at about the same time of day; in many instances this is at dawn or dusk. Jellyfish are usually either male or female (with occasional hermaphrodites). In most cases, adults release sperm and eggs into the surrounding water, where the unprotected eggs are fertilized and develop into larvae. In a few species, the sperm swim into the female's mouth, fertilizing the eggs within her body, where they remain during early development stages. In moon jellies, the eggs lodge in pits on the oral arms, which form a temporary brood chamber for the developing planula larvae.

 

The planula is a small larva covered with cilia. When sufficiently developed, it settles onto a firm surface and develops into a polyp. The polyp generally consists of a small stalk topped by a mouth that is ringed by upward-facing tentacles. The polyps resemble those of closely related anthozoans, such as sea anemones and corals. The jellyfish polyp may be sessile, living on the bottom, boat hulls or other substrates, or it may be free-floating or attached to tiny bits of free-living plankton or rarely, fish or other invertebrates. Polyps may be solitary or colonial. Most polyps are only millimetres in diameter and feed continuously. The polyp stage may last for years.

 

After an interval and stimulated by seasonal or hormonal changes, the polyp may begin reproducing asexually by budding and, in the Scyphozoa, is called a segmenting polyp, or a scyphistoma. Budding produces more scyphistomae and also ephyrae. Budding sites vary by species; from the tentacle bulbs, the manubrium (above the mouth), or the gonads of hydromedusae. In a process known as strobilation, the polyp's tentacles are reabsorbed and the body starts to narrow, forming transverse constrictions, in several places near the upper extremity of the polyp. These deepen as the constriction sites migrate down the body, and separate segments known as ephyra detach. These are free-swimming precursors of the adult medusa stage, which is the life stage that is typically identified as a jellyfish. The ephyrae, usually only a millimeter or two across initially, swim away from the polyp and grow. Limnomedusae polyps can asexually produce a creeping frustule larval form, which crawls away before developing into another polyp. A few species can produce new medusae by budding directly from the medusan stage. Some hydromedusae reproduce by fission.

 

Lifespan

Little is known of the life histories of many jellyfish as the places on the seabed where the benthic forms of those species live have not been found. However, an asexually reproducing strobila form can sometimes live for several years, producing new medusae (ephyra larvae) each year.

 

An unusual species, Turritopsis dohrnii, formerly classified as Turritopsis nutricula, might be effectively immortal because of its ability under certain circumstances to transform from medusa back to the polyp stage, thereby escaping the death that typically awaits medusae post-reproduction if they have not otherwise been eaten by some other organism. So far this reversal has been observed only in the laboratory.

 

Locomotion

Jellyfish locomotion is highly efficient. Muscles in the jellylike bell contract, setting up a start vortex and propelling the animal. When the contraction ends, the bell recoils elastically, creating a stop vortex with no extra energy input.

Using the moon jelly Aurelia aurita as an example, jellyfish have been shown to be the most energy-efficient swimmers of all animals. They move through the water by radially expanding and contracting their bell-shaped bodies to push water behind them. They pause between the contraction and expansion phases to create two vortex rings. Muscles are used for the contraction of the body, which creates the first vortex and pushes the animal forward, but the mesoglea is so elastic that the expansion is powered exclusively by relaxing the bell, which releases the energy stored from the contraction. Meanwhile, the second vortex ring starts to spin faster, sucking water into the bell and pushing against the centre of the body, giving a secondary and "free" boost forward. The mechanism, called passive energy recapture, only works in relatively small jellyfish moving at low speeds, allowing the animal to travel 30 percent farther on each swimming cycle. Jellyfish achieved a 48 percent lower cost of transport (food and oxygen intake versus energy spent in movement) than other animals in similar studies. One reason for this is that most of the gelatinous tissue of the bell is inactive, using no energy during swimming.

 

Ecology

Diet

Jellyfish are, like other cnidarians, generally carnivorous (or parasitic), feeding on planktonic organisms, crustaceans, small fish, fish eggs and larvae, and other jellyfish, ingesting food and voiding undigested waste through the mouth. They hunt passively using their tentacles as drift lines, or sink through the water with their tentacles spread widely; the tentacles, which contain nematocysts to stun or kill the prey, may then flex to help bring it to the mouth. Their swimming technique also helps them to capture prey; when their bell expands it sucks in water which brings more potential prey within reach of the tentacles.

 

A few species such as Aglaura hemistoma are omnivorous, feeding on microplankton which is a mixture of zooplankton and phytoplankton (microscopic plants) such as dinoflagellates. Others harbour mutualistic algae (Zooxanthellae) in their tissues; the spotted jellyfish (Mastigias papua) is typical of these, deriving part of its nutrition from the products of photosynthesis, and part from captured zooplankton. The upside-down jellyfish (Cassiopea andromeda) also has a symbiotic relationship with microalgae, but captures tiny animals to supplement their diet. This is done by releasing tiny balls of living cells composed of mesoglea. These use cilia to drive them through water and stinging cells which stun the prey. The blobs also seems to have digestive capabilities.

 

Predation

Other species of jellyfish are among the most common and important jellyfish predators. Sea anemones may eat jellyfish that drift into their range. Other predators include tunas, sharks, swordfish, sea turtles and penguins. Jellyfish washed up on the beach are consumed by foxes, other terrestrial mammals and birds. In general however, few animals prey on jellyfish; they can broadly be considered to be top predators in the food chain. Once jellyfish have become dominant in an ecosystem, for example through overfishing which removes predators of jellyfish larvae, there may be no obvious way for the previous balance to be restored: they eat fish eggs and juvenile fish, and compete with fish for food, preventing fish stocks from recovering.

 

Symbiosis

Some small fish are immune to the stings of the jellyfish and live among the tentacles, serving as bait in a fish trap; they are safe from potential predators and are able to share the fish caught by the jellyfish. The cannonball jellyfish has a symbiotic relationship with ten different species of fish, and with the longnose spider crab, which lives inside the bell, sharing the jellyfish's food and nibbling its tissues.

 

Main article: Jellyfish bloom

Jellyfish form large masses or blooms in certain environmental conditions of ocean currents, nutrients, sunshine, temperature, season, prey availability, reduced predation and oxygen concentration. Currents collect jellyfish together, especially in years with unusually high populations. Jellyfish can detect marine currents and swim against the current to congregate in blooms. Jellyfish are better able to survive in nutrient-rich, oxygen-poor water than competitors, and thus can feast on plankton without competition. Jellyfish may also benefit from saltier waters, as saltier waters contain more iodine, which is necessary for polyps to turn into jellyfish. Rising sea temperatures caused by climate change may also contribute to jellyfish blooms, because many species of jellyfish are able to survive in warmer waters. Increased nutrients from agricultural or urban runoff with nutrients including nitrogen and phosphorus compounds increase the growth of phytoplankton, causing eutrophication and algal blooms. When the phytoplankton die, they may create dead zones, so-called because they are hypoxic (low in oxygen). This in turn kills fish and other animals, but not jellyfish, allowing them to bloom. Jellyfish populations may be expanding globally as a result of land runoff and overfishing of their natural predators. Jellyfish are well placed to benefit from disturbance of marine ecosystems. They reproduce rapidly; they prey upon many species, while few species prey on them; and they feed via touch rather than visually, so they can feed effectively at night and in turbid waters. It may be difficult for fish stocks to re-establish themselves in marine ecosystems once they have become dominated by jellyfish, because jellyfish feed on plankton, which includes fish eggs and larvae.

 

As suspected at the turn of this century, jellyfish blooms are increasing in frequency. Between 2013 and 2020 the Mediterranean Science Commission monitored on a weekly basis the frequency of such outbreaks in coastal waters from Morocco to the Black Sea, revealing a relatively high frequency of these blooms nearly all year round, with peaks observed from March to July and often again in the autumn. The blooms are caused by different jellyfish species, depending on their localisation within the Basin: one observes a clear dominance of Pelagia noctiluca and Velella velella outbreaks in the western Mediterranean, of Rhizostoma pulmo and Rhopilema nomadica outbreaks in the eastern Mediterranean, and of Aurelia aurita and Mnemiopsis leidyi outbreaks in the Black Sea.

 

Some jellyfish populations that have shown clear increases in the past few decades are invasive species, newly arrived from other habitats: examples include the Black Sea, Caspian Sea, Baltic Sea, central and eastern Mediterranean, Hawaii, and tropical and subtropical parts of the West Atlantic (including the Caribbean, Gulf of Mexico and Brazil).

 

Jellyfish blooms can have significant impact on community structure. Some carnivorous jellyfish species prey on zooplankton while others graze on primary producers. Reductions in zooplankton and ichthyoplankton due to a jellyfish bloom can ripple through the trophic levels. High-density jellyfish populations can outcompete other predators and reduce fish recruitment. Increased grazing on primary producers by jellyfish can also interrupt energy transfer to higher trophic levels.

 

During blooms, jellyfish significantly alter the nutrient availability in their environment. Blooms require large amounts of available organic nutrients in the water column to grow, limiting availability for other organisms. Some jellyfish have a symbiotic relationship with single-celled dinoflagellates, allowing them to assimilate inorganic carbon, phosphorus, and nitrogen creating competition for phytoplankton. Their large biomass makes them an important source of dissolved and particulate organic matter for microbial communities through excretion, mucus production, and decomposition. The microbes break down the organic matter into inorganic ammonium and phosphate. However, the low carbon availability shifts the process from production to respiration creating low oxygen areas making the dissolved inorganic nitrogen and phosphorus largely unavailable for primary production.

 

These blooms have very real impacts on industries. Jellyfish can outcompete fish by utilizing open niches in over-fished fisheries. Catch of jellyfish can strain fishing gear and lead to expenses relating to damaged gear. Power plants have been shut down due to jellyfish blocking the flow of cooling water. Blooms have also been harmful for tourism, causing a rise in stings and sometimes the closure of beaches.

 

Jellyfish form a component of jelly-falls, events where gelatinous zooplankton fall to the seafloor, providing food for the benthic organisms there. In temperate and subpolar regions, jelly-falls usually follow immediately after a bloom.

 

Habitats

Most jellyfish are marine animals, although a few hydromedusae inhabit freshwater. The best known freshwater example is the cosmopolitan hydrozoan jellyfish, Craspedacusta sowerbii. It is less than an inch (2.5 cm) in diameter, colorless and does not sting. Some jellyfish populations have become restricted to coastal saltwater lakes, such as Jellyfish Lake in Palau. Jellyfish Lake is a marine lake where millions of golden jellyfish (Mastigias spp.) migrate horizontally across the lake daily.

 

Although most jellyfish live well off the ocean floor and form part of the plankton, a few species are closely associated with the bottom for much of their lives and can be considered benthic. The upside-down jellyfish in the genus Cassiopea typically lie on the bottom of shallow lagoons where they sometimes pulsate gently with their umbrella top facing down. Even some deep-sea species of hydromedusae and scyphomedusae are usually collected on or near the bottom. All of the stauromedusae are found attached to either seaweed or rocky or other firm material on the bottom.

 

Some species explicitly adapt to tidal flux. In Roscoe Bay, jellyfish ride the current at ebb tide until they hit a gravel bar, and then descend below the current. They remain in still waters until the tide rises, ascending and allowing it to sweep them back into the bay. They also actively avoid fresh water from mountain snowmelt, diving until they find enough salt.

  

Parasites

Jellyfish are hosts to a wide variety of parasitic organisms. They act as intermediate hosts of endoparasitic helminths, with the infection being transferred to the definitive host fish after predation. Some digenean trematodes, especially species in the family Lepocreadiidae, use jellyfish as their second intermediate hosts. Fish become infected by the trematodes when they feed on infected jellyfish.

 

Relation to humans

Jellyfish have long been eaten in some parts of the world. Fisheries have begun harvesting the American cannonball jellyfish, Stomolophus meleagris, along the southern Atlantic coast of the United States and in the Gulf of Mexico for export to Asia.

 

Jellyfish are also harvested for their collagen, which is being investigated for use in a variety of applications including the treatment of rheumatoid arthritis.

 

Aquaculture and fisheries of other species often suffer severe losses – and so losses of productivity – due to jellyfish.

 

Products

Main article: Jellyfish as food

In some countries, including China, Japan, and Korea, jellyfish are a delicacy. The jellyfish is dried to prevent spoiling. Only some 12 species of scyphozoan jellyfish belonging to the order Rhizostomeae are harvested for food, mostly in southeast Asia. Rhizostomes, especially Rhopilema esculentum in China (海蜇 hǎizhé, 'sea stingers') and Stomolophus meleagris (cannonball jellyfish) in the United States, are favored because of their larger and more rigid bodies and because their toxins are harmless to humans.

 

Traditional processing methods, carried out by a jellyfish master, involve a 20- to 40-day multi-phase procedure in which, after removing the gonads and mucous membranes, the umbrella and oral arms are treated with a mixture of table salt and alum, and compressed. Processing makes the jellyfish drier and more acidic, producing a crisp texture. Jellyfish prepared this way retain 7–10% of their original weight, and the processed product consists of approximately 94% water and 6% protein. Freshly processed jellyfish has a white, creamy color and turns yellow or brown during prolonged storage.

 

In China, processed jellyfish are desalted by soaking in water overnight and eaten cooked or raw. The dish is often served shredded with a dressing of oil, soy sauce, vinegar and sugar, or as a salad with vegetables. In Japan, cured jellyfish are rinsed, cut into strips and served with vinegar as an appetizer. Desalted, ready-to-eat products are also available.

 

Biotechnology

The hydromedusa Aequorea victoria was the source of green fluorescent protein, studied for its role in bioluminescence and later for use as a marker in genetic engineering.

Pliny the Elder reported in his Natural History that the slime of the jellyfish "Pulmo marinus" produced light when rubbed on a walking stick.

 

In 1961, Osamu Shimomura extracted green fluorescent protein (GFP) and another bioluminescent protein, called aequorin, from the large and abundant hydromedusa Aequorea victoria, while studying photoproteins that cause bioluminescence in this species. Three decades later, Douglas Prasher sequenced and cloned the gene for GFP. Martin Chalfie figured out how to use GFP as a fluorescent marker of genes inserted into other cells or organisms. Roger Tsien later chemically manipulated GFP to produce other fluorescent colors to use as markers. In 2008, Shimomura, Chalfie and Tsien won the Nobel Prize in Chemistry for their work with GFP. Man-made GFP became widely used as a fluorescent tag to show which cells or tissues express specific genes. The genetic engineering technique fuses the gene of interest to the GFP gene. The fused DNA is then put into a cell, to generate either a cell line or (via IVF techniques) an entire animal bearing the gene. In the cell or animal, the artificial gene turns on in the same tissues and the same time as the normal gene, making a fusion of the normal protein with GFP attached to the end, illuminating the animal or cell reveals what tissues express that protein—or at what stage of development. The fluorescence shows where the gene is expressed.

 

Aquarium display

Jellyfish are displayed in many public aquariums. Often the tank's background is blue and the animals are illuminated by side light, increasing the contrast between the animal and the background. In natural conditions, many jellies are so transparent that they are nearly invisible. Jellyfish are not adapted to closed spaces. They depend on currents to transport them from place to place. Professional exhibits as in the Monterey Bay Aquarium feature precise water flows, typically in circular tanks to avoid trapping specimens in corners. The outflow is spread out over a large surface area and the inflow enters as a sheet of water in front of the outflow, so the jellyfish do not get sucked into it. As of 2009, jellyfish were becoming popular in home aquariums, where they require similar equipment.

 

Stings

Jellyfish are armed with nematocysts, a type of specialized stinging cell. Contact with a jellyfish tentacle can trigger millions of nematocysts to pierce the skin and inject venom, but only some species' venom causes an adverse reaction in humans. In a study published in Communications Biology, researchers found a jellyfish species called Cassiopea xamachana which when triggered will release tiny balls of cells that swim around the jellyfish stinging everything in their path. Researchers described these as "self-propelling microscopic grenades" and named them cassiosomes.

 

The effects of stings range from mild discomfort to extreme pain and death. Most jellyfish stings are not deadly, but stings of some box jellyfish (Irukandji jellyfish), such as the sea wasp, can be deadly. Stings may cause anaphylaxis (a form of shock), which can be fatal. Jellyfish kill 20 to 40 people a year in the Philippines alone. In 2006 the Spanish Red Cross treated 19,000 stung swimmers along the Costa Brava.

 

Vinegar (3–10% aqueous acetic acid) may help with box jellyfish stings but not the stings of the Portuguese man o' war. Clearing the area of jelly and tentacles reduces nematocyst firing. Scraping the affected skin, such as with the edge of a credit card, may remove remaining nematocysts. Once the skin has been cleaned of nematocysts, hydrocortisone cream applied locally reduces pain and inflammation. Antihistamines may help to control itching. Immunobased antivenins are used for serious box jellyfish stings.

 

In Elba Island and Corsica dittrichia viscosa is now used by residents and tourists to heal stings from jellyfish, bees and wasps pressing fresh leaves on the skin with quick results.

 

Mechanical issues

Jellyfish in large quantities can fill and split fishing nets and crush captured fish. They can clog cooling equipment, having disabled power stations in several countries; jellyfish caused a cascading blackout in the Philippines in 1999, as well as damaging the Diablo Canyon Power Plant in California in 2008. They can also stop desalination plants and ships' engines.

 

Leica APO-Macro-Elmarit-R 100mm f/2.8

 

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant native to Mexico. The species and its varieties and cultivars are popular as an ornamental plant in temperate climate gardens.

 

It naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cosmos bipinnatus is considered a half-hardy annual, although plants may reappear via self-sowing for several years. The plant height varies from 2–4 ft (0.61–1.22 m). The cultivated varieties appear in shades of pink and purple as well as white.

 

Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

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2/24

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant in the daisy family Asteraceae, native to the Americas. The species and its varieties and cultivars are popular as ornamental plants in temperate climate gardens.

 

Description

In natural habitat

Cosmos bipinnatus is an annual that is often considered half-hardy, although plants may reappear via self-sowing for several years. The plant height varies from 2–6 ft to (rarely) 9 ft (0.61–1.83–2.74 m). The cultivated varieties appear in shades of pink and purple as well as white. The branched stem is usually densely to occasionally occupied by fine, split up, rough trichomes, some specimens are completely hairless. The petiole itself is inconspicuous, winged, 10 (rarely to 15) mm long, sometimes the leaves are almost sessile.

 

The partial leaves are linear-filiform to narrow linear with a width of 0.5 to 1 (rarely to 1.7) mm; the tips are pointed, hardened, but not particularly sharp. Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

The achenes become blackish, are smooth or short-bristly. Their shape is spindle-like. They are rounded off into a short, 0.5 to 1.7 mm long, but distinctly pronounced rostrum. The inner achenes are up to 18 mm long, their yellowish beaks are 4 to 5 (rarely to 10) mm long. A pappus is missing or it consists only of two to three awn-like, 1-3 mm large bristles.

 

Flowers

The very conspicuous cup-shaped inflorescences have a diameter of usually 5–7 cm (2.0–2.8 in) and contain tongue and tubular flowers, which are surrounded by bracts. There are usually 8 outer bracts, and they are ovate to lanceolate-tail-shaped, 7-15 mm long, 3-5 mm wide. The inner bracts are ovate-lanceolate and 8-12 mm long. They are translucent with many black stripes and a clear edge up to 1 mm wide, sometimes with yellowish or pink pigments, the tip is ciliate. The sprout leaves have gold-yellow, thread-like tips and protrude between the tubular flowers. The broadened base of these spreader leaves is translucent, provided with a yellow line. During flowering, the plant can sag under its weight. This problem can be solved by grouping the feet together so that the leaves hang together.

 

The mostly eight ray florets are pink to violet or white colored, at the base may show noticeable stains caused by anthocyanin. The tongues are reversely ovate shaped, have a length of usually 20-35 mm and a width of usually 12-20 mm. The tips are almost dull and have three broad, wavy teeth. Below that, they are greatly rejuvenated. In the center of the flower baskets is a large number of tubular flowers (also called disc florets), whose overgrown petals are yellow, turn white in the lower part and reach a length of 5-6 mm. The anthers are brownish-black and about 3 mm long, at the tips are short-triangular, translucent attachments with a length of 0.5-0.8 mm. The branches of the stylus are short and rather dull, with a length of .5 mm.

 

Distribution

This plant is native to Mexico, Guatemala and Costa Rica. Since it is used as an ornamental plant in many countries and prone to sedimentation, it is an invasive plant in many areas of the world. It has naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cultivars

Cultivars of Cosmos bipinnatus in cultivation today include:

Apollo Series

'Apollo Carmine' agm

'Apollo Pink' agm

'Apollo White' agm

'Daydream' features a pink inner ring on a white background

Double Click Series features semidouble to fully double flowers that resemble Japanese anemones (Anemone japonica)

'Double Click Cranberries'

'Double Click Rose Bonbon'

'Double Click Snow Puff'

'Double Click Vari Extra'

'Rubenza' agm

'Sensation', also known as 'Early Sensation', is a widely available mix of tall varieties

'Sensation Pinkie' agm

Sonata series

'Velouette'agm

'Versailles', developed for the cut flower trade, are shorter than the species, with heights remaining below three feet

'Versailles Dark Rose'

'Vesailles Tetra'

(those marked agm have gained the Royal Horticultural Society's Award of Garden Merit).

 

Cultivation

Germination takes between 7 and 10 days at the optimal temperature of 75 °F (24 °C); flowering begins between 60 and 90 days after germination

It prefers a soil pH between 6.0 and 8.5, reflecting its native habitat in the alkaline regions of Central America

Flowering is best in full sun, although partial shade is tolerated

Excessive rain can cause cultivation problems, due to the delicate nature of the stems. Heavy rain can cause breakage. Cosmos bipinnatus can tolerate heat as long as adequate moisture is provided, however, it does not handle droughts, strong winds or cold temperatures well. Snails, slugs and aphids have a taste for Cosmos bipinnatus. Successfully cultivated plants can mature 2 to 4 feet (0.61 to 1.22 m) x 12 to 18 inches (300 to 460 mm).

 

They are not tolerant of frost, but can be grown outdoors in a temperate climate with a warm to hot summer and are therefore called half-hardy in British gardening literature.

Pollinators

The flowers of Cosmos bipinnatus attract birds and butterflies, including the monarch butterfly. It can be part of butterfly gardening and pollinator/honey-bee habitat gardens.

Found camoflaged on some leaves in our backyard, Palmerston North, Aotearoa-New Zealand

 

'katydid, (family Tettigoniidae), any of about 8,000 predominantly nocturnal insects that are related to crickets (the two groups are in the suborder Ensifera, order Orthoptera) and are noted for their mating calls. Katydids are also known for their large hind legs and extremely long threadlike antennae as well as the thick, upwardly curved ovipositor (egg-laying structure) of the females.'

 

www.britannica.com/animal/long-horned-grasshopper

Ageratum houstonianum, also called Floss Flower or 'Pussyfoot', is a member of the Asteraceae family and is native to Mexico, where it is also known as the 'Mexican Paintbrush'. It is a summer annual with fluffy purple flowers. The flower heads are borne in dense corymbs. The ray flowers are threadlike and fluff-haired, leading to its common name. The Floss Flower is also naturalized in large parts of the tropics and in the southern United States. Its habitat is pastures, moist forest clearings and bushes up to altitudes of 3,300 ft.

Ageratum houstonianum, commonly known as flossflower, bluemink, blueweed, pussy foot or Mexican paintbrush, is a cool-season annual plant often grown as bedding in gardens.

This herbaceous annual or dwarf shrub grows to 0.3–1 m (1 ft 0 in–3 ft 3 in) high, with ovate to triangular leaves 2–7 cm (0.79–2.76 in) long, and blue flowerheads (sometimes white, pink, or purple). The flower heads are borne in dense corymbs. The ray flowers are threadlike and fluff-haired, leading to the common name. The narrow lanceolate bracts are pointed, denticulate only at the top and glandular hairy. The flowering period is from May to November in the northern hemisphere.

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant in the daisy family Asteraceae, native to the Americas. The species and its varieties and cultivars are popular as ornamental plants in temperate climate gardens.

 

Description

In natural habitat

Cosmos bipinnatus is an annual that is often considered half-hardy, although plants may reappear via self-sowing for several years. The plant height varies from 2–6 ft to (rarely) 9 ft (0.61–1.83–2.74 m). The cultivated varieties appear in shades of pink and purple as well as white. The branched stem is usually densely to occasionally occupied by fine, split up, rough trichomes, some specimens are completely hairless. The petiole itself is inconspicuous, winged, 10 (rarely to 15) mm long, sometimes the leaves are almost sessile.

 

The partial leaves are linear-filiform to narrow linear with a width of 0.5 to 1 (rarely to 1.7) mm; the tips are pointed, hardened, but not particularly sharp. Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

The achenes become blackish, are smooth or short-bristly. Their shape is spindle-like. They are rounded off into a short, 0.5 to 1.7 mm long, but distinctly pronounced rostrum. The inner achenes are up to 18 mm long, their yellowish beaks are 4 to 5 (rarely to 10) mm long. A pappus is missing or it consists only of two to three awn-like, 1-3 mm large bristles.

 

Flowers

The very conspicuous cup-shaped inflorescences have a diameter of usually 5–7 cm (2.0–2.8 in) and contain tongue and tubular flowers, which are surrounded by bracts. There are usually 8 outer bracts, and they are ovate to lanceolate-tail-shaped, 7-15 mm long, 3-5 mm wide. The inner bracts are ovate-lanceolate and 8-12 mm long. They are translucent with many black stripes and a clear edge up to 1 mm wide, sometimes with yellowish or pink pigments, the tip is ciliate. The sprout leaves have gold-yellow, thread-like tips and protrude between the tubular flowers. The broadened base of these spreader leaves is translucent, provided with a yellow line. During flowering, the plant can sag under its weight. This problem can be solved by grouping the feet together so that the leaves hang together.

 

The mostly eight ray florets are pink to violet or white colored, at the base may show noticeable stains caused by anthocyanin. The tongues are reversely ovate shaped, have a length of usually 20-35 mm and a width of usually 12-20 mm. The tips are almost dull and have three broad, wavy teeth. Below that, they are greatly rejuvenated. In the center of the flower baskets is a large number of tubular flowers (also called disc florets), whose overgrown petals are yellow, turn white in the lower part and reach a length of 5-6 mm. The anthers are brownish-black and about 3 mm long, at the tips are short-triangular, translucent attachments with a length of 0.5-0.8 mm. The branches of the stylus are short and rather dull, with a length of .5 mm.

 

Distribution

This plant is native to Mexico, Guatemala and Costa Rica. Since it is used as an ornamental plant in many countries and prone to sedimentation, it is an invasive plant in many areas of the world. It has naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cultivars

Cultivars of Cosmos bipinnatus in cultivation today include:

Apollo Series

'Apollo Carmine' agm

'Apollo Pink' agm

'Apollo White' agm

'Daydream' features a pink inner ring on a white background

Double Click Series features semidouble to fully double flowers that resemble Japanese anemones (Anemone japonica)

'Double Click Cranberries'

'Double Click Rose Bonbon'

'Double Click Snow Puff'

'Double Click Vari Extra'

'Rubenza' agm

'Sensation', also known as 'Early Sensation', is a widely available mix of tall varieties

'Sensation Pinkie' agm

Sonata series

'Velouette'agm

'Versailles', developed for the cut flower trade, are shorter than the species, with heights remaining below three feet

'Versailles Dark Rose'

'Vesailles Tetra'

(those marked agm have gained the Royal Horticultural Society's Award of Garden Merit).

 

Cultivation

Germination takes between 7 and 10 days at the optimal temperature of 75 °F (24 °C); flowering begins between 60 and 90 days after germination

It prefers a soil pH between 6.0 and 8.5, reflecting its native habitat in the alkaline regions of Central America

Flowering is best in full sun, although partial shade is tolerated

Excessive rain can cause cultivation problems, due to the delicate nature of the stems. Heavy rain can cause breakage. Cosmos bipinnatus can tolerate heat as long as adequate moisture is provided, however, it does not handle droughts, strong winds or cold temperatures well. Snails, slugs and aphids have a taste for Cosmos bipinnatus. Successfully cultivated plants can mature 2 to 4 feet (0.61 to 1.22 m) x 12 to 18 inches (300 to 460 mm).

 

They are not tolerant of frost, but can be grown outdoors in a temperate climate with a warm to hot summer and are therefore called half-hardy in British gardening literature.

Pollinators

The flowers of Cosmos bipinnatus attract birds and butterflies, including the monarch butterfly. It can be part of butterfly gardening and pollinator/honey-bee habitat gardens.

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant native to Mexico. The species and its varieties and cultivars are popular as an ornamental plant in temperate climate gardens.

 

It naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cosmos bipinnatus is considered a half-hardy annual, although plants may reappear via self-sowing for several years. The plant height varies from 2–4 ft (0.61–1.22 m). The cultivated varieties appear in shades of pink and purple as well as white.

 

Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

=========================================================

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2/13

I looked up Katydid after Marty Horowitz identified the katydid eggs that Sabino Canyon Volunteer Naturalist Ann Green found on a stick (that broke off the plant unexpectedly.)

 

www.britannica.com/animal/katydid

 

Katydid (family Tettigoniidae), also called long-horned grasshopper or bushcricket, also spelled bush cricket,

any of about 6,000 predominantly nocturnal insects that are related to crickets (the two groups are in the suborder Ensifera, order Orthoptera) and are noted for their mating calls. Katydids are also known for their large hind legs and extremely long threadlike antennae as well as the thick, upwardly curved ovipositor (egg-laying structure) of the females.

 

The common true katydid (Pterophylla camellifolia) produces the repetitive song for which katydids are named; the song is phoneticized as “katy-did, katy-didn’t.” However, each species of katydid has its own rasping song, produced by stridulation, whereby the forewings, one of which is ridged, are rubbed together. Although katydid songs are species-specific, different species are able to hear one another’s calls. Songs differ as to their purpose, being either reproductive, territorial, aggressive, or defensive in nature.

 

Physical characteristics

d’Orbigny’s round-eared bat [Credit: © Merlin D. Tuttle, Bat Conservation International/Photo Researchers, Inc.]Katydids are often large, with body lengths that range from about 1 to more than 6 cm (0.4 to more than 2.4 inches). An exception is the predatory bushcricket (Saga pedo; also called the matriarchal katydid), the body of which can grow to about 12 cm (4.7 inches) in length. Although many species are bright green, various colour morphs, including pink and yellow, occur naturally and have been reared in captivity.

 

Wing form varies widely among katydids. Many species have long wings that cover the body. Siliquofera grandis, for example, which is among the largest of the katydids, has a wingspan of more than 25 cm (9.8 inches). Other species, however, including some common ones, have short wings or are nearly wingless. As a group, katydids are poor flyers. Many species do not fly but only flutter their wings during leaps.

 

Katydids hear by using a structure called a tympanum, or tympanic organ, one of which is located on each foreleg. There also is a thoracic auditory structure, and some species can communicate through substrate vibration. Males are the primary sound producers, as the females of many species are silent. An important exception are species in the subfamily Phaneropterinae, where the sexes form duets, with females producing ticks in response to the males’ calls.

 

Distribution and habitat

katydid: pink katydid [Credit: Frank Oberle—Stone/Getty Images]Katydids are widespread, occurring in every region of the world with the exception of Antarctica. They are especially abundant in the tropics, particularly in the Amazon Rainforest, but are also found in cooler and drier regions, such as the heathlands of Australia, the deserts of the United States, and parts of Canada and northern Europe. They typically are found living on trees, bushes, or grasses, often matching the appearance of their surroundings.

 

Life cycle

Species of katydids that inhabit areas with distinct seasons typically live for less than a year and produce one generation of offspring, the eggs being the only life stage capable of surviving winter. Species in tropical climates can live for several years and may produce two generations annually, with overlap among various life stages. Depending on the species, eggs may be deposited in the soil or directly into plant tissue; some species lay their eggs on sticks or rocks. The young are similar to adults but have less-developed wings. Katydids feed chiefly on plant matter, though some species are predatory, feeding on other insects.

 

Defense adaptations

greater angle-wing katydid [Credit: Encyclopædia Britannica, Inc.]Katydids display remarkable adaptations for defense, a consequence in part of their generally poor flying ability, which leaves them highly vulnerable to predation. Cryptically coloured species, which blend in with the environment, rely primarily on the mimicry of vegetation. The peacock katydid (Pterochroza ocellata), for example, precisely mimics the discoloration of a dead leaf.

 

Some katydid species exhibit deimatic (startling) behaviour, in which they use vivid coloration or chemical defenses in their attempts to ward off attack by a predator. When threatened, the mountain katydid (Acripeza reticulata) lifts its wings to expose the bright colours on its abdomen. An otherwise cryptic species, the mountain katydid’s bright markings serve an aposematic function, warning predators of its noxious chemical secretions. Species in the genus Vestria flash brightly coloured markings by lifting their wings and arching their abdomens. Vestria also produce an unpleasant odour when threatened.

 

Katydids may employ unique communication strategies to avoid detection by predators. Males of the species Docidocercus gigliotosi, for example, may mask their nighttime mating signals from predatory bats by using tremulations, whereby vibrations are sent along plant substrates shared by females. Some katydid species supplement abbreviated songs with tremulations in order to avoid bat predation.

 

Kara Rogers

 

Jellyfish, also known sea jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria.

 

Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex life cycle. The medusa is normally the sexual phase, which produces planula larvae; these then disperse widely and enter a sedentary polyp phase, before reaching sexual maturity.

 

Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the "true jellyfish") are exclusively marine, but some hydrozoans with a similar appearance live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. The medusae of most species are fast-growing, and mature within a few months then die soon after breeding, but the polyp stage, attached to the seabed, may be much more long-lived. Jellyfish have been in existence for at least 500 million years, and possibly 700 million years or more, making them the oldest multi-organ animal group.

 

Jellyfish are eaten by humans in certain cultures. They are considered a delicacy in some Asian countries, where species in the Rhizostomeae order are pressed and salted to remove excess water. Australian researchers have described them as a "perfect food": sustainable and protein-rich but relatively low in food energy.

 

They are also used in research, where the green fluorescent protein used by some species to cause bioluminescence has been adapted as a fluorescent marker for genes inserted into other cells or organisms.

 

The stinging cells used by jellyfish to subdue their prey can injure humans. Thousands of swimmers worldwide are stung every year, with effects ranging from mild discomfort to serious injury or even death. When conditions are favourable, jellyfish can form vast swarms, which can be responsible for damage to fishing gear by filling fishing nets, and sometimes clog the cooling systems of power and desalination plants which draw their water from the sea.

  

Names

The name jellyfish, in use since 1796, has traditionally been applied to medusae and all similar animals including the comb jellies (ctenophores, another phylum). The term jellies or sea jellies is more recent, having been introduced by public aquaria in an effort to avoid use of the word "fish" with its modern connotation of an animal with a backbone, though shellfish, cuttlefish and starfish are not vertebrates either. In scientific literature, "jelly" and "jellyfish" have been used interchangeably. Many sources refer to only scyphozoans as "true jellyfish".

 

A group of jellyfish is called a "smack" or a "smuck".

 

Definition

The term jellyfish broadly corresponds to medusae, that is, a life-cycle stage in the Medusozoa. The American evolutionary biologist Paulyn Cartwright gives the following general definition:

 

Typically, medusozoan cnidarians have a pelagic, predatory jellyfish stage in their life cycle; staurozoans are the exceptions [as they are stalked].

 

The Merriam-Webster dictionary defines jellyfish as follows:

 

A free-swimming marine coelenterate that is the sexually reproducing form of a hydrozoan or scyphozoan and has a nearly transparent saucer-shaped body and extensible marginal tentacles studded with stinging cells.

 

Given that jellyfish is a common name, its mapping to biological groups is inexact. Some authorities have called the comb jellies and certain salps jellyfish, though other authorities state that neither of these are jellyfish, which they consider should be limited to certain groups within the medusozoa.

 

The non-medusozoan clades called jellyfish by some but not all authorities (both agreeing and disagreeing citations are given in each case) are indicated with on the following cladogram of the animal kingdom:

 

Jellyfish are not a clade, as they include most of the Medusozoa, barring some of the Hydrozoa. The medusozoan groups included by authorities are indicated on the following phylogenetic tree by the presence of citations. Names of included jellyfish, in English where possible, are shown in boldface; the presence of a named and cited example indicates that at least that species within its group has been called a jellyfish.

 

Taxonomy

The subphylum Medusozoa includes all cnidarians with a medusa stage in their life cycle. The basic cycle is egg, planula larva, polyp, medusa, with the medusa being the sexual stage. The polyp stage is sometimes secondarily lost. The subphylum include the major taxa, Scyphozoa (large jellyfish), Cubozoa (box jellyfish) and Hydrozoa (small jellyfish), and excludes Anthozoa (corals and sea anemones). This suggests that the medusa form evolved after the polyps. Medusozoans have tetramerous symmetry, with parts in fours or multiples of four.

 

The four major classes of medusozoan Cnidaria are:

Scyphozoa are sometimes called true jellyfish, though they are no more truly jellyfish than the others listed here. They have tetra-radial symmetry. Most have tentacles around the outer margin of the bowl-shaped bell, and long, oral arms around the mouth in the center of the subumbrella.

Cubozoa (box jellyfish) have a (rounded) box-shaped bell, and their velarium assists them to swim more quickly. Box jellyfish may be related more closely to scyphozoan jellyfish than either are to the Hydrozoa.

Hydrozoa medusae also have tetra-radial symmetry, nearly always have a velum (diaphragm used in swimming) attached just inside the bell margin, do not have oral arms, but a much smaller central stalk-like structure, the manubrium, with terminal mouth opening, and are distinguished by the absence of cells in the mesoglea. Hydrozoa show great diversity of lifestyle; some species maintain the polyp form for their entire life and do not form medusae at all (such as Hydra, which is hence not considered a jellyfish), and a few are entirely medusal and have no polyp form.

Staurozoa (stalked jellyfish) are characterized by a medusa form that is generally sessile, oriented upside down and with a stalk emerging from the apex of the "calyx" (bell), which attaches to the substrate. At least some Staurozoa also have a polyp form that alternates with the medusoid portion of the life cycle. Until recently, Staurozoa were classified within the Scyphozoa.

There are over 200 species of Scyphozoa, about 50 species of Staurozoa, about 50 species of Cubozoa, and the Hydrozoa includes about 1000–1500 species that produce medusae, but many more species that do not.

 

Fossil history

Since jellyfish have no hard parts, fossils are rare. The oldest unambiguous fossil of a free-swimming medusa is Burgessomedusa from the mid Cambrian Burgess Shale of Canada, which is likely either a stem group of box jellyfish (Cubozoa) or Acraspeda (the clade including Staurozoa, Cubozoa, and Scyphozoa). Other claimed records from the Cambrian of China and Utah in the United States are uncertain, and possibly represent ctenophores instead.

 

Anatomy

The main feature of a true jellyfish is the umbrella-shaped bell. This is a hollow structure consisting of a mass of transparent jelly-like matter known as mesoglea, which forms the hydrostatic skeleton of the animal. 95% or more of the mesogloea consists of water, but it also contains collagen and other fibrous proteins, as well as wandering amoebocytes which can engulf debris and bacteria. The mesogloea is bordered by the epidermis on the outside and the gastrodermis on the inside. The edge of the bell is often divided into rounded lobes known as lappets, which allow the bell to flex. In the gaps or niches between the lappets are dangling rudimentary sense organs known as rhopalia, and the margin of the bell often bears tentacles.

  

Anatomy of a scyphozoan jellyfish

On the underside of the bell is the manubrium, a stalk-like structure hanging down from the centre, with the mouth, which also functions as the anus, at its tip. There are often four oral arms connected to the manubrium, streaming away into the water below. The mouth opens into the gastrovascular cavity, where digestion takes place and nutrients are absorbed. This is subdivided by four thick septa into a central stomach and four gastric pockets. The four pairs of gonads are attached to the septa, and close to them four septal funnels open to the exterior, perhaps supplying good oxygenation to the gonads. Near the free edges of the septa, gastric filaments extend into the gastric cavity; these are armed with nematocysts and enzyme-producing cells and play a role in subduing and digesting the prey. In some scyphozoans, the gastric cavity is joined to radial canals which branch extensively and may join a marginal ring canal. Cilia in these canals circulate the fluid in a regular direction.

  

Discharge mechanism of a nematocyst

The box jellyfish is largely similar in structure. It has a squarish, box-like bell. A short pedalium or stalk hangs from each of the four lower corners. One or more long, slender tentacles are attached to each pedalium. The rim of the bell is folded inwards to form a shelf known as a velarium which restricts the bell's aperture and creates a powerful jet when the bell pulsates, allowing box jellyfish to swim faster than true jellyfish. Hydrozoans are also similar, usually with just four tentacles at the edge of the bell, although many hydrozoans are colonial and may not have a free-living medusal stage. In some species, a non-detachable bud known as a gonophore is formed that contains a gonad but is missing many other medusal features such as tentacles and rhopalia. Stalked jellyfish are attached to a solid surface by a basal disk, and resemble a polyp, the oral end of which has partially developed into a medusa with tentacle-bearing lobes and a central manubrium with four-sided mouth.

 

Most jellyfish do not have specialized systems for osmoregulation, respiration and circulation, and do not have a central nervous system. Nematocysts, which deliver the sting, are located mostly on the tentacles; true jellyfish also have them around the mouth and stomach. Jellyfish do not need a respiratory system because sufficient oxygen diffuses through the epidermis. They have limited control over their movement, but can navigate with the pulsations of the bell-like body; some species are active swimmers most of the time, while others largely drift. The rhopalia contain rudimentary sense organs which are able to detect light, water-borne vibrations, odour and orientation. A loose network of nerves called a "nerve net" is located in the epidermis. Although traditionally thought not to have a central nervous system, nerve net concentration and ganglion-like structures could be considered to constitute one in most species. A jellyfish detects stimuli, and transmits impulses both throughout the nerve net and around a circular nerve ring, to other nerve cells. The rhopalial ganglia contain pacemaker neurones which control swimming rate and direction.

 

In many species of jellyfish, the rhopalia include ocelli, light-sensitive organs able to tell light from dark. These are generally pigment spot ocelli, which have some of their cells pigmented. The rhopalia are suspended on stalks with heavy crystals at one end, acting like gyroscopes to orient the eyes skyward. Certain jellyfish look upward at the mangrove canopy while making a daily migration from mangrove swamps into the open lagoon, where they feed, and back again.

 

Box jellyfish have more advanced vision than the other groups. Each individual has 24 eyes, two of which are capable of seeing colour, and four parallel information processing areas that act in competition, supposedly making them one of the few kinds of animal to have a 360-degree view of its environment.

 

Box jellyfish eye

The study of jellyfish eye evolution is an intermediary to a better understanding of how visual systems evolved on Earth. Jellyfish exhibit immense variation in visual systems ranging from photoreceptive cell patches seen in simple photoreceptive systems to more derived complex eyes seen in box jellyfish. Major topics of jellyfish visual system research (with an emphasis on box jellyfish) include: the evolution of jellyfish vision from simple to complex visual systems), the eye morphology and molecular structures of box jellyfish (including comparisons to vertebrate eyes), and various uses of vision including task-guided behaviors and niche specialization.

 

Evolution

Experimental evidence for photosensitivity and photoreception in cnidarians antecedes the mid 1900s, and a rich body of research has since covered evolution of visual systems in jellyfish. Jellyfish visual systems range from simple photoreceptive cells to complex image-forming eyes. More ancestral visual systems incorporate extraocular vision (vision without eyes) that encompass numerous receptors dedicated to single-function behaviors. More derived visual systems comprise perception that is capable of multiple task-guided behaviors.

 

Although they lack a true brain, cnidarian jellyfish have a "ring" nervous system that plays a significant role in motor and sensory activity. This net of nerves is responsible for muscle contraction and movement and culminates the emergence of photosensitive structures. Across Cnidaria, there is large variation in the systems that underlie photosensitivity. Photosensitive structures range from non-specialized groups of cells, to more "conventional" eyes similar to those of vertebrates. The general evolutionary steps to develop complex vision include (from more ancestral to more derived states): non-directional photoreception, directional photoreception, low-resolution vision, and high-resolution vision. Increased habitat and task complexity has favored the high-resolution visual systems common in derived cnidarians such as box jellyfish.

 

Basal visual systems observed in various cnidarians exhibit photosensitivity representative of a single task or behavior. Extraocular photoreception (a form of non-directional photoreception), is the most basic form of light sensitivity and guides a variety of behaviors among cnidarians. It can function to regulate circadian rhythm (as seen in eyeless hydrozoans) and other light-guided behaviors responsive to the intensity and spectrum of light. Extraocular photoreception can function additionally in positive phototaxis (in planula larvae of hydrozoans), as well as in avoiding harmful amounts of UV radiation via negative phototaxis. Directional photoreception (the ability to perceive direction of incoming light) allows for more complex phototactic responses to light, and likely evolved by means of membrane stacking. The resulting behavioral responses can range from guided spawning events timed by moonlight to shadow responses for potential predator avoidance. Light-guided behaviors are observed in numerous scyphozoans including the common moon jelly, Aurelia aurita, which migrates in response to changes in ambient light and solar position even though they lack proper eyes.

 

The low-resolution visual system of box jellyfish is more derived than directional photoreception, and thus box jellyfish vision represents the most basic form of true vision in which multiple directional photoreceptors combine to create the first imaging and spatial resolution. This is different from the high-resolution vision that is observed in camera or compound eyes of vertebrates and cephalopods that rely on focusing optics. Critically, the visual systems of box jellyfish are responsible for guiding multiple tasks or behaviors in contrast to less derived visual systems in other jellyfish that guide single behavioral functions. These behaviors include phototaxis based on sunlight (positive) or shadows (negative), obstacle avoidance, and control of swim-pulse rate.

 

Box jellyfish possess "proper eyes" (similar to vertebrates) that allow them to inhabit environments that lesser derived medusae cannot. In fact, they are considered the only class in the clade Medusozoa that have behaviors necessitating spatial resolution and genuine vision. However, the lens in their eyes are more functionally similar to cup-eyes exhibited in low-resolution organisms, and have very little to no focusing capability. The lack of the ability to focus is due to the focal length exceeding the distance to the retina, thus generating unfocused images and limiting spatial resolution. The visual system is still sufficient for box jellyfish to produce an image to help with tasks such as object avoidance.

 

Utility as a model organism

Box jellyfish eyes are a visual system that is sophisticated in numerous ways. These intricacies include the considerable variation within the morphology of box jellyfishes' eyes (including their task/behavior specification), and the molecular makeup of their eyes including: photoreceptors, opsins, lenses, and synapses. The comparison of these attributes to more derived visual systems can allow for a further understanding of how the evolution of more derived visual systems may have occurred, and puts into perspective how box jellyfish can play the role as an evolutionary/developmental model for all visual systems.

 

Characteristics

Box jellyfish visual systems are both diverse and complex, comprising multiple photosystems. There is likely considerable variation in visual properties between species of box jellyfish given the significant inter-species morphological and physiological variation. Eyes tend to differ in size and shape, along with number of receptors (including opsins), and physiology across species of box jellyfish.

 

Box jellyfish have a series of intricate lensed eyes that are similar to those of more derived multicellular organisms such as vertebrates. Their 24 eyes fit into four different morphological categories. These categories consist of two large, morphologically different medial eyes (a lower and upper lensed eye) containing spherical lenses, a lateral pair of pigment slit eyes, and a lateral pair of pigment pit eyes. The eyes are situated on rhopalia (small sensory structures) which serve sensory functions of the box jellyfish and arise from the cavities of the exumbrella (the surface of the body) on the side of the bells of the jellyfish. The two large eyes are located on the mid-line of the club and are considered complex because they contain lenses. The four remaining eyes lie laterally on either side of each rhopalia and are considered simple. The simple eyes are observed as small invaginated cups of epithelium that have developed pigmentation. The larger of the complex eyes contains a cellular cornea created by a mono ciliated epithelium, cellular lens, homogenous capsule to the lens, vitreous body with prismatic elements, and a retina of pigmented cells. The smaller of the complex eyes is said to be slightly less complex given that it lacks a capsule but otherwise contains the same structure as the larger eye.

 

Box jellyfish have multiple photosystems that comprise different sets of eyes. Evidence includes immunocytochemical and molecular data that show photopigment differences among the different morphological eye types, and physiological experiments done on box jellyfish to suggest behavioral differences among photosystems. Each individual eye type constitutes photosystems that work collectively to control visually guided behaviors.

 

Box jellyfish eyes primarily use c-PRCs (ciliary photoreceptor cells) similar to that of vertebrate eyes. These cells undergo phototransduction cascades (process of light absorption by photoreceptors) that are triggered by c-opsins. Available opsin sequences suggest that there are two types of opsins possessed by all cnidarians including an ancient phylogenetic opsin, and a sister ciliary opsin to the c-opsins group. Box jellyfish could have both ciliary and cnidops (cnidarian opsins), which is something not previously believed to appear in the same retina. Nevertheless, it is not entirely evident whether cnidarians possess multiple opsins that are capable of having distinctive spectral sensitivities.

 

Comparison with other organisms

Comparative research on genetic and molecular makeup of box jellyfishes' eyes versus more derived eyes seen in vertebrates and cephalopods focuses on: lenses and crystallin composition, synapses, and Pax genes and their implied evidence for shared primordial (ancestral) genes in eye evolution.

 

Box jellyfish eyes are said to be an evolutionary/developmental model of all eyes based on their evolutionary recruitment of crystallins and Pax genes. Research done on box jellyfish including Tripedalia cystophora has suggested that they possess a single Pax gene, PaxB. PaxB functions by binding to crystallin promoters and activating them. PaxB in situ hybridization resulted in PaxB expression in the lens, retina, and statocysts. These results and the rejection of the prior hypothesis that Pax6 was an ancestral Pax gene in eyes has led to the conclusion that PaxB was a primordial gene in eye evolution, and that the eyes of all organisms likely share a common ancestor.

 

The lens structure of box jellyfish appears very similar to those of other organisms, but the crystallins are distinct in both function and appearance. Weak reactions were seen within the sera and there were very weak sequence similarities within the crystallins among vertebrate and invertebrate lenses. This is likely due to differences in lower molecular weight proteins and the subsequent lack of immunological reactions with antisera that other organisms' lenses exhibit.

 

All four of the visual systems of box jellyfish species investigated with detail (Carybdea marsupialis, Chiropsalmus quadrumanus, Tamoya haplonema and Tripedalia cystophora) have invaginated synapses, but only in the upper and lower lensed eyes. Different densities were found between the upper and lower lenses, and between species. Four types of chemical synapses have been discovered within the rhopalia which could help in understanding neural organization including: clear unidirectional, dense-core unidirectional, clear bidirectional, and clear and dense-core bidirectional. The synapses of the lensed eyes could be useful as markers to learn more about the neural circuit in box jellyfish retinal areas.

 

Evolution as a response to natural stimuli

The primary adaptive responses to environmental variation observed in box jellyfish eyes include pupillary constriction speeds in response to light environments, as well as photoreceptor tuning and lens adaptations to better respond to shifts between light environments and darkness. Interestingly, some box jellyfish species' eyes appear to have evolved more focused vision in response to their habitat.

 

Pupillary contraction appears to have evolved in response to variation in the light environment across ecological niches across three species of box jellyfish (Chironex fleckeri, Chiropsella bronzie, and Carukia barnesi). Behavioral studies suggest that faster pupil contraction rates allow for greater object avoidance, and in fact, species with more complex habitats exhibit faster rates. Ch. bronzie inhabit shallow beach fronts that have low visibility and very few obstacles, thus, faster pupil contraction in response to objects in their environment is not important. Ca. barnesi and Ch. fleckeri are found in more three-dimensionally complex environments like mangroves with an abundance of natural obstacles, where faster pupil contraction is more adaptive. Behavioral studies support the idea that faster pupillary contraction rates assist with obstacle avoidance as well as depth adjustments in response to differing light intensities.

 

Light/dark adaptation via pupillary light reflexes is an additional form of an evolutionary response to the light environment. This relates to the pupil's response to shifts between light intensity (generally from sunlight to darkness). In the process of light/dark adaptation, the upper and lower lens eyes of different box jellyfish species vary in specific function. The lower lens-eyes contain pigmented photoreceptors and long pigment cells with dark pigments that migrate on light/dark adaptation, while the upper-lens eyes play a concentrated role in light direction and phototaxis given that they face upward towards the water surface (towards the sun or moon). The upper lens of Ch. bronzie does not exhibit any considerable optical power while Tr. cystophora (a box jellyfish species that tends to live in mangroves) does. The ability to use light to visually guide behavior is not of as much importance to Ch. bronzie as it is to species in more obstacle-filled environments. Differences in visually guided behavior serve as evidence that species that share the same number and structure of eyes can exhibit differences in how they control behavior.

 

Largest and smallest

Jellyfish range from about one millimeter in bell height and diameter, to nearly 2 metres (6+1⁄2 ft) in bell height and diameter; the tentacles and mouth parts usually extend beyond this bell dimension.

 

The smallest jellyfish are the peculiar creeping jellyfish in the genera Staurocladia and Eleutheria, which have bell disks from 0.5 millimetres (1⁄32 in) to a few millimeters in diameter, with short tentacles that extend out beyond this, which these jellyfish use to move across the surface of seaweed or the bottoms of rocky pools; many of these tiny creeping jellyfish cannot be seen in the field without a hand lens or microscope. They can reproduce asexually by fission (splitting in half). Other very small jellyfish, which have bells about one millimeter, are the hydromedusae of many species that have just been released from their parent polyps; some of these live only a few minutes before shedding their gametes in the plankton and then dying, while others will grow in the plankton for weeks or months. The hydromedusae Cladonema radiatum and Cladonema californicum are also very small, living for months, yet never growing beyond a few mm in bell height and diameter.

 

The lion's mane jellyfish, Cyanea capillata, was long-cited as the largest jellyfish, and arguably the longest animal in the world, with fine, thread-like tentacles that may extend up to 36.5 m (119 ft 9 in) long (though most are nowhere near that large). They have a moderately painful, but rarely fatal, sting. The increasingly common giant Nomura's jellyfish, Nemopilema nomurai, found in some, but not all years in the waters of Japan, Korea and China in summer and autumn is another candidate for "largest jellyfish", in terms of diameter and weight, since the largest Nomura's jellyfish in late autumn can reach 2 m (6 ft 7 in) in bell (body) diameter and about 200 kg (440 lb) in weight, with average specimens frequently reaching 0.9 m (2 ft 11 in) in bell diameter and about 150 kg (330 lb) in weight. The large bell mass of the giant Nomura's jellyfish can dwarf a diver and is nearly always much greater than the Lion's Mane, whose bell diameter can reach 1 m (3 ft 3 in).

 

The rarely encountered deep-sea jellyfish Stygiomedusa gigantea is another candidate for "largest jellyfish", with its thick, massive bell up to 100 cm (3 ft 3 in) wide, and four thick, "strap-like" oral arms extending up to 6 m (19+1⁄2 ft) in length, very different from the typical fine, threadlike tentacles that rim the umbrella of more-typical-looking jellyfish, including the Lion's Mane.

 

Desmonema glaciale, which lives in the Antarctic region, can reach a very large size (several meters). Purple-striped jelly (Chrysaora colorata) can also be extremely long (up to 15 feet).

 

Life history and behavior

Life cycle

Jellyfish have a complex life cycle which includes both sexual and asexual phases, with the medusa being the sexual stage in most instances. Sperm fertilize eggs, which develop into larval planulae, become polyps, bud into ephyrae and then transform into adult medusae. In some species certain stages may be skipped.

 

Upon reaching adult size, jellyfish spawn regularly if there is a sufficient supply of food. In most species, spawning is controlled by light, with all individuals spawning at about the same time of day; in many instances this is at dawn or dusk. Jellyfish are usually either male or female (with occasional hermaphrodites). In most cases, adults release sperm and eggs into the surrounding water, where the unprotected eggs are fertilized and develop into larvae. In a few species, the sperm swim into the female's mouth, fertilizing the eggs within her body, where they remain during early development stages. In moon jellies, the eggs lodge in pits on the oral arms, which form a temporary brood chamber for the developing planula larvae.

 

The planula is a small larva covered with cilia. When sufficiently developed, it settles onto a firm surface and develops into a polyp. The polyp generally consists of a small stalk topped by a mouth that is ringed by upward-facing tentacles. The polyps resemble those of closely related anthozoans, such as sea anemones and corals. The jellyfish polyp may be sessile, living on the bottom, boat hulls or other substrates, or it may be free-floating or attached to tiny bits of free-living plankton or rarely, fish or other invertebrates. Polyps may be solitary or colonial. Most polyps are only millimetres in diameter and feed continuously. The polyp stage may last for years.

 

After an interval and stimulated by seasonal or hormonal changes, the polyp may begin reproducing asexually by budding and, in the Scyphozoa, is called a segmenting polyp, or a scyphistoma. Budding produces more scyphistomae and also ephyrae. Budding sites vary by species; from the tentacle bulbs, the manubrium (above the mouth), or the gonads of hydromedusae. In a process known as strobilation, the polyp's tentacles are reabsorbed and the body starts to narrow, forming transverse constrictions, in several places near the upper extremity of the polyp. These deepen as the constriction sites migrate down the body, and separate segments known as ephyra detach. These are free-swimming precursors of the adult medusa stage, which is the life stage that is typically identified as a jellyfish. The ephyrae, usually only a millimeter or two across initially, swim away from the polyp and grow. Limnomedusae polyps can asexually produce a creeping frustule larval form, which crawls away before developing into another polyp. A few species can produce new medusae by budding directly from the medusan stage. Some hydromedusae reproduce by fission.

 

Lifespan

Little is known of the life histories of many jellyfish as the places on the seabed where the benthic forms of those species live have not been found. However, an asexually reproducing strobila form can sometimes live for several years, producing new medusae (ephyra larvae) each year.

 

An unusual species, Turritopsis dohrnii, formerly classified as Turritopsis nutricula, might be effectively immortal because of its ability under certain circumstances to transform from medusa back to the polyp stage, thereby escaping the death that typically awaits medusae post-reproduction if they have not otherwise been eaten by some other organism. So far this reversal has been observed only in the laboratory.

 

Locomotion

Jellyfish locomotion is highly efficient. Muscles in the jellylike bell contract, setting up a start vortex and propelling the animal. When the contraction ends, the bell recoils elastically, creating a stop vortex with no extra energy input.

Using the moon jelly Aurelia aurita as an example, jellyfish have been shown to be the most energy-efficient swimmers of all animals. They move through the water by radially expanding and contracting their bell-shaped bodies to push water behind them. They pause between the contraction and expansion phases to create two vortex rings. Muscles are used for the contraction of the body, which creates the first vortex and pushes the animal forward, but the mesoglea is so elastic that the expansion is powered exclusively by relaxing the bell, which releases the energy stored from the contraction. Meanwhile, the second vortex ring starts to spin faster, sucking water into the bell and pushing against the centre of the body, giving a secondary and "free" boost forward. The mechanism, called passive energy recapture, only works in relatively small jellyfish moving at low speeds, allowing the animal to travel 30 percent farther on each swimming cycle. Jellyfish achieved a 48 percent lower cost of transport (food and oxygen intake versus energy spent in movement) than other animals in similar studies. One reason for this is that most of the gelatinous tissue of the bell is inactive, using no energy during swimming.

 

Ecology

Diet

Jellyfish are, like other cnidarians, generally carnivorous (or parasitic), feeding on planktonic organisms, crustaceans, small fish, fish eggs and larvae, and other jellyfish, ingesting food and voiding undigested waste through the mouth. They hunt passively using their tentacles as drift lines, or sink through the water with their tentacles spread widely; the tentacles, which contain nematocysts to stun or kill the prey, may then flex to help bring it to the mouth. Their swimming technique also helps them to capture prey; when their bell expands it sucks in water which brings more potential prey within reach of the tentacles.

 

A few species such as Aglaura hemistoma are omnivorous, feeding on microplankton which is a mixture of zooplankton and phytoplankton (microscopic plants) such as dinoflagellates. Others harbour mutualistic algae (Zooxanthellae) in their tissues; the spotted jellyfish (Mastigias papua) is typical of these, deriving part of its nutrition from the products of photosynthesis, and part from captured zooplankton. The upside-down jellyfish (Cassiopea andromeda) also has a symbiotic relationship with microalgae, but captures tiny animals to supplement their diet. This is done by releasing tiny balls of living cells composed of mesoglea. These use cilia to drive them through water and stinging cells which stun the prey. The blobs also seems to have digestive capabilities.

 

Predation

Other species of jellyfish are among the most common and important jellyfish predators. Sea anemones may eat jellyfish that drift into their range. Other predators include tunas, sharks, swordfish, sea turtles and penguins. Jellyfish washed up on the beach are consumed by foxes, other terrestrial mammals and birds. In general however, few animals prey on jellyfish; they can broadly be considered to be top predators in the food chain. Once jellyfish have become dominant in an ecosystem, for example through overfishing which removes predators of jellyfish larvae, there may be no obvious way for the previous balance to be restored: they eat fish eggs and juvenile fish, and compete with fish for food, preventing fish stocks from recovering.

 

Symbiosis

Some small fish are immune to the stings of the jellyfish and live among the tentacles, serving as bait in a fish trap; they are safe from potential predators and are able to share the fish caught by the jellyfish. The cannonball jellyfish has a symbiotic relationship with ten different species of fish, and with the longnose spider crab, which lives inside the bell, sharing the jellyfish's food and nibbling its tissues.

 

Main article: Jellyfish bloom

Jellyfish form large masses or blooms in certain environmental conditions of ocean currents, nutrients, sunshine, temperature, season, prey availability, reduced predation and oxygen concentration. Currents collect jellyfish together, especially in years with unusually high populations. Jellyfish can detect marine currents and swim against the current to congregate in blooms. Jellyfish are better able to survive in nutrient-rich, oxygen-poor water than competitors, and thus can feast on plankton without competition. Jellyfish may also benefit from saltier waters, as saltier waters contain more iodine, which is necessary for polyps to turn into jellyfish. Rising sea temperatures caused by climate change may also contribute to jellyfish blooms, because many species of jellyfish are able to survive in warmer waters. Increased nutrients from agricultural or urban runoff with nutrients including nitrogen and phosphorus compounds increase the growth of phytoplankton, causing eutrophication and algal blooms. When the phytoplankton die, they may create dead zones, so-called because they are hypoxic (low in oxygen). This in turn kills fish and other animals, but not jellyfish, allowing them to bloom. Jellyfish populations may be expanding globally as a result of land runoff and overfishing of their natural predators. Jellyfish are well placed to benefit from disturbance of marine ecosystems. They reproduce rapidly; they prey upon many species, while few species prey on them; and they feed via touch rather than visually, so they can feed effectively at night and in turbid waters. It may be difficult for fish stocks to re-establish themselves in marine ecosystems once they have become dominated by jellyfish, because jellyfish feed on plankton, which includes fish eggs and larvae.

 

As suspected at the turn of this century, jellyfish blooms are increasing in frequency. Between 2013 and 2020 the Mediterranean Science Commission monitored on a weekly basis the frequency of such outbreaks in coastal waters from Morocco to the Black Sea, revealing a relatively high frequency of these blooms nearly all year round, with peaks observed from March to July and often again in the autumn. The blooms are caused by different jellyfish species, depending on their localisation within the Basin: one observes a clear dominance of Pelagia noctiluca and Velella velella outbreaks in the western Mediterranean, of Rhizostoma pulmo and Rhopilema nomadica outbreaks in the eastern Mediterranean, and of Aurelia aurita and Mnemiopsis leidyi outbreaks in the Black Sea.

 

Some jellyfish populations that have shown clear increases in the past few decades are invasive species, newly arrived from other habitats: examples include the Black Sea, Caspian Sea, Baltic Sea, central and eastern Mediterranean, Hawaii, and tropical and subtropical parts of the West Atlantic (including the Caribbean, Gulf of Mexico and Brazil).

 

Jellyfish blooms can have significant impact on community structure. Some carnivorous jellyfish species prey on zooplankton while others graze on primary producers. Reductions in zooplankton and ichthyoplankton due to a jellyfish bloom can ripple through the trophic levels. High-density jellyfish populations can outcompete other predators and reduce fish recruitment. Increased grazing on primary producers by jellyfish can also interrupt energy transfer to higher trophic levels.

 

During blooms, jellyfish significantly alter the nutrient availability in their environment. Blooms require large amounts of available organic nutrients in the water column to grow, limiting availability for other organisms. Some jellyfish have a symbiotic relationship with single-celled dinoflagellates, allowing them to assimilate inorganic carbon, phosphorus, and nitrogen creating competition for phytoplankton. Their large biomass makes them an important source of dissolved and particulate organic matter for microbial communities through excretion, mucus production, and decomposition. The microbes break down the organic matter into inorganic ammonium and phosphate. However, the low carbon availability shifts the process from production to respiration creating low oxygen areas making the dissolved inorganic nitrogen and phosphorus largely unavailable for primary production.

 

These blooms have very real impacts on industries. Jellyfish can outcompete fish by utilizing open niches in over-fished fisheries. Catch of jellyfish can strain fishing gear and lead to expenses relating to damaged gear. Power plants have been shut down due to jellyfish blocking the flow of cooling water. Blooms have also been harmful for tourism, causing a rise in stings and sometimes the closure of beaches.

 

Jellyfish form a component of jelly-falls, events where gelatinous zooplankton fall to the seafloor, providing food for the benthic organisms there. In temperate and subpolar regions, jelly-falls usually follow immediately after a bloom.

 

Habitats

Most jellyfish are marine animals, although a few hydromedusae inhabit freshwater. The best known freshwater example is the cosmopolitan hydrozoan jellyfish, Craspedacusta sowerbii. It is less than an inch (2.5 cm) in diameter, colorless and does not sting. Some jellyfish populations have become restricted to coastal saltwater lakes, such as Jellyfish Lake in Palau. Jellyfish Lake is a marine lake where millions of golden jellyfish (Mastigias spp.) migrate horizontally across the lake daily.

 

Although most jellyfish live well off the ocean floor and form part of the plankton, a few species are closely associated with the bottom for much of their lives and can be considered benthic. The upside-down jellyfish in the genus Cassiopea typically lie on the bottom of shallow lagoons where they sometimes pulsate gently with their umbrella top facing down. Even some deep-sea species of hydromedusae and scyphomedusae are usually collected on or near the bottom. All of the stauromedusae are found attached to either seaweed or rocky or other firm material on the bottom.

 

Some species explicitly adapt to tidal flux. In Roscoe Bay, jellyfish ride the current at ebb tide until they hit a gravel bar, and then descend below the current. They remain in still waters until the tide rises, ascending and allowing it to sweep them back into the bay. They also actively avoid fresh water from mountain snowmelt, diving until they find enough salt.

  

Parasites

Jellyfish are hosts to a wide variety of parasitic organisms. They act as intermediate hosts of endoparasitic helminths, with the infection being transferred to the definitive host fish after predation. Some digenean trematodes, especially species in the family Lepocreadiidae, use jellyfish as their second intermediate hosts. Fish become infected by the trematodes when they feed on infected jellyfish.

 

Relation to humans

Jellyfish have long been eaten in some parts of the world. Fisheries have begun harvesting the American cannonball jellyfish, Stomolophus meleagris, along the southern Atlantic coast of the United States and in the Gulf of Mexico for export to Asia.

 

Jellyfish are also harvested for their collagen, which is being investigated for use in a variety of applications including the treatment of rheumatoid arthritis.

 

Aquaculture and fisheries of other species often suffer severe losses – and so losses of productivity – due to jellyfish.

 

Products

Main article: Jellyfish as food

In some countries, including China, Japan, and Korea, jellyfish are a delicacy. The jellyfish is dried to prevent spoiling. Only some 12 species of scyphozoan jellyfish belonging to the order Rhizostomeae are harvested for food, mostly in southeast Asia. Rhizostomes, especially Rhopilema esculentum in China (海蜇 hǎizhé, 'sea stingers') and Stomolophus meleagris (cannonball jellyfish) in the United States, are favored because of their larger and more rigid bodies and because their toxins are harmless to humans.

 

Traditional processing methods, carried out by a jellyfish master, involve a 20- to 40-day multi-phase procedure in which, after removing the gonads and mucous membranes, the umbrella and oral arms are treated with a mixture of table salt and alum, and compressed. Processing makes the jellyfish drier and more acidic, producing a crisp texture. Jellyfish prepared this way retain 7–10% of their original weight, and the processed product consists of approximately 94% water and 6% protein. Freshly processed jellyfish has a white, creamy color and turns yellow or brown during prolonged storage.

 

In China, processed jellyfish are desalted by soaking in water overnight and eaten cooked or raw. The dish is often served shredded with a dressing of oil, soy sauce, vinegar and sugar, or as a salad with vegetables. In Japan, cured jellyfish are rinsed, cut into strips and served with vinegar as an appetizer. Desalted, ready-to-eat products are also available.

 

Biotechnology

The hydromedusa Aequorea victoria was the source of green fluorescent protein, studied for its role in bioluminescence and later for use as a marker in genetic engineering.

Pliny the Elder reported in his Natural History that the slime of the jellyfish "Pulmo marinus" produced light when rubbed on a walking stick.

 

In 1961, Osamu Shimomura extracted green fluorescent protein (GFP) and another bioluminescent protein, called aequorin, from the large and abundant hydromedusa Aequorea victoria, while studying photoproteins that cause bioluminescence in this species. Three decades later, Douglas Prasher sequenced and cloned the gene for GFP. Martin Chalfie figured out how to use GFP as a fluorescent marker of genes inserted into other cells or organisms. Roger Tsien later chemically manipulated GFP to produce other fluorescent colors to use as markers. In 2008, Shimomura, Chalfie and Tsien won the Nobel Prize in Chemistry for their work with GFP. Man-made GFP became widely used as a fluorescent tag to show which cells or tissues express specific genes. The genetic engineering technique fuses the gene of interest to the GFP gene. The fused DNA is then put into a cell, to generate either a cell line or (via IVF techniques) an entire animal bearing the gene. In the cell or animal, the artificial gene turns on in the same tissues and the same time as the normal gene, making a fusion of the normal protein with GFP attached to the end, illuminating the animal or cell reveals what tissues express that protein—or at what stage of development. The fluorescence shows where the gene is expressed.

 

Aquarium display

Jellyfish are displayed in many public aquariums. Often the tank's background is blue and the animals are illuminated by side light, increasing the contrast between the animal and the background. In natural conditions, many jellies are so transparent that they are nearly invisible. Jellyfish are not adapted to closed spaces. They depend on currents to transport them from place to place. Professional exhibits as in the Monterey Bay Aquarium feature precise water flows, typically in circular tanks to avoid trapping specimens in corners. The outflow is spread out over a large surface area and the inflow enters as a sheet of water in front of the outflow, so the jellyfish do not get sucked into it. As of 2009, jellyfish were becoming popular in home aquariums, where they require similar equipment.

 

Stings

Jellyfish are armed with nematocysts, a type of specialized stinging cell. Contact with a jellyfish tentacle can trigger millions of nematocysts to pierce the skin and inject venom, but only some species' venom causes an adverse reaction in humans. In a study published in Communications Biology, researchers found a jellyfish species called Cassiopea xamachana which when triggered will release tiny balls of cells that swim around the jellyfish stinging everything in their path. Researchers described these as "self-propelling microscopic grenades" and named them cassiosomes.

 

The effects of stings range from mild discomfort to extreme pain and death. Most jellyfish stings are not deadly, but stings of some box jellyfish (Irukandji jellyfish), such as the sea wasp, can be deadly. Stings may cause anaphylaxis (a form of shock), which can be fatal. Jellyfish kill 20 to 40 people a year in the Philippines alone. In 2006 the Spanish Red Cross treated 19,000 stung swimmers along the Costa Brava.

 

Vinegar (3–10% aqueous acetic acid) may help with box jellyfish stings but not the stings of the Portuguese man o' war. Clearing the area of jelly and tentacles reduces nematocyst firing. Scraping the affected skin, such as with the edge of a credit card, may remove remaining nematocysts. Once the skin has been cleaned of nematocysts, hydrocortisone cream applied locally reduces pain and inflammation. Antihistamines may help to control itching. Immunobased antivenins are used for serious box jellyfish stings.

 

In Elba Island and Corsica dittrichia viscosa is now used by residents and tourists to heal stings from jellyfish, bees and wasps pressing fresh leaves on the skin with quick results.

 

Mechanical issues

Jellyfish in large quantities can fill and split fishing nets and crush captured fish. They can clog cooling equipment, having disabled power stations in several countries; jellyfish caused a cascading blackout in the Philippines in 1999, as well as damaging the Diablo Canyon Power Plant in California in 2008. They can also stop desalination plants and ships' engines.

I looked up Katydid after Marty Horowitz identified the katydid eggs that Sabino Canyon Volunteer Naturalist Ann Green found on a stick (that broke off the plant unexpectedly.)

 

www.britannica.com/animal/katydid

 

Katydid (family Tettigoniidae), also called long-horned grasshopper or bushcricket, also spelled bush cricket,

any of about 6,000 predominantly nocturnal insects that are related to crickets (the two groups are in the suborder Ensifera, order Orthoptera) and are noted for their mating calls. Katydids are also known for their large hind legs and extremely long threadlike antennae as well as the thick, upwardly curved ovipositor (egg-laying structure) of the females.

 

The common true katydid (Pterophylla camellifolia) produces the repetitive song for which katydids are named; the song is phoneticized as “katy-did, katy-didn’t.” However, each species of katydid has its own rasping song, produced by stridulation, whereby the forewings, one of which is ridged, are rubbed together. Although katydid songs are species-specific, different species are able to hear one another’s calls. Songs differ as to their purpose, being either reproductive, territorial, aggressive, or defensive in nature.

 

Physical characteristics

d’Orbigny’s round-eared bat [Credit: © Merlin D. Tuttle, Bat Conservation International/Photo Researchers, Inc.]Katydids are often large, with body lengths that range from about 1 to more than 6 cm (0.4 to more than 2.4 inches). An exception is the predatory bushcricket (Saga pedo; also called the matriarchal katydid), the body of which can grow to about 12 cm (4.7 inches) in length. Although many species are bright green, various colour morphs, including pink and yellow, occur naturally and have been reared in captivity.

 

Wing form varies widely among katydids. Many species have long wings that cover the body. Siliquofera grandis, for example, which is among the largest of the katydids, has a wingspan of more than 25 cm (9.8 inches). Other species, however, including some common ones, have short wings or are nearly wingless. As a group, katydids are poor flyers. Many species do not fly but only flutter their wings during leaps.

 

Katydids hear by using a structure called a tympanum, or tympanic organ, one of which is located on each foreleg. There also is a thoracic auditory structure, and some species can communicate through substrate vibration. Males are the primary sound producers, as the females of many species are silent. An important exception are species in the subfamily Phaneropterinae, where the sexes form duets, with females producing ticks in response to the males’ calls.

 

Distribution and habitat

katydid: pink katydid [Credit: Frank Oberle—Stone/Getty Images]Katydids are widespread, occurring in every region of the world with the exception of Antarctica. They are especially abundant in the tropics, particularly in the Amazon Rainforest, but are also found in cooler and drier regions, such as the heathlands of Australia, the deserts of the United States, and parts of Canada and northern Europe. They typically are found living on trees, bushes, or grasses, often matching the appearance of their surroundings.

 

Life cycle

Species of katydids that inhabit areas with distinct seasons typically live for less than a year and produce one generation of offspring, the eggs being the only life stage capable of surviving winter. Species in tropical climates can live for several years and may produce two generations annually, with overlap among various life stages. Depending on the species, eggs may be deposited in the soil or directly into plant tissue; some species lay their eggs on sticks or rocks. The young are similar to adults but have less-developed wings. Katydids feed chiefly on plant matter, though some species are predatory, feeding on other insects.

 

Defense adaptations

greater angle-wing katydid [Credit: Encyclopædia Britannica, Inc.]Katydids display remarkable adaptations for defense, a consequence in part of their generally poor flying ability, which leaves them highly vulnerable to predation. Cryptically coloured species, which blend in with the environment, rely primarily on the mimicry of vegetation. The peacock katydid (Pterochroza ocellata), for example, precisely mimics the discoloration of a dead leaf.

 

Some katydid species exhibit deimatic (startling) behaviour, in which they use vivid coloration or chemical defenses in their attempts to ward off attack by a predator. When threatened, the mountain katydid (Acripeza reticulata) lifts its wings to expose the bright colours on its abdomen. An otherwise cryptic species, the mountain katydid’s bright markings serve an aposematic function, warning predators of its noxious chemical secretions. Species in the genus Vestria flash brightly coloured markings by lifting their wings and arching their abdomens. Vestria also produce an unpleasant odour when threatened.

 

Katydids may employ unique communication strategies to avoid detection by predators. Males of the species Docidocercus gigliotosi, for example, may mask their nighttime mating signals from predatory bats by using tremulations, whereby vibrations are sent along plant substrates shared by females. Some katydid species supplement abbreviated songs with tremulations in order to avoid bat predation.

 

Kara Rogers

 

 

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant native to Mexico. The species and its varieties and cultivars are popular as an ornamental plant in temperate climate gardens.

 

It naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cosmos bipinnatus is considered a half-hardy annual, although plants may reappear via self-sowing for several years. The plant height varies from 2–4 ft (0.61–1.22 m). The cultivated varieties appear in shades of pink and purple as well as white.

 

Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

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Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant native to Mexico. The species and its varieties and cultivars are popular as an ornamental plant in temperate climate gardens.

 

It naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cosmos bipinnatus is considered a half-hardy annual, although plants may reappear via self-sowing for several years. The plant height varies from 2–4 ft (0.61–1.22 m). The cultivated varieties appear in shades of pink and purple as well as white.

 

Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

=========================================================

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Incredible camouflage of a neotropical epiphyll-mimicking katydid (Clepsydronotus deciduus). Ephiphylls are tiny plants and lichens that grow on the surfaces of leaves in tropical rainforests, usually being detrimental to their host because they block light to the leaves. Having selected such an epiphyll-ridden leaf, the katydid is able to blend with the mottled colors and rough texture to conceal itself despite being completely exposed on the upper surface. Notice also how the katydid has carefully folded its long threadlike antennae under itself – if they were to stick out then the insect could be much more easily discovered by sharp-eyed birds. Choco, Colombia.

axon |ˈaksɒn|

noun

the long threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells.

DERIVATIVES

axonal adjective

ORIGIN mid 19th cent. (denoting the body axis): from Greek axōn ‘axis.’

Edited Public Domain Review image of of the Bakemono Zukushi, a scroll describing various monsters and demons. The second image source discusses each monster in detail.

 

Image source: www.flickr.com/photos/publicdomainreview/42579644741/

 

and

 

Image source: publicdomainreview.org/collections/the-bakemono-zukushi-m...

 

Original caption: These wonderful images featured here are from a Japanese painted scroll known as the Bakemono zukushi. The artist and date is unknown, though its thought to hail from the Edo-period, sometime from the 18th or 19th century. Across it’s length are depicted a ghoulish array of “yokai” from Japanese folklore. In his The Book of Yokai, Michael Dylan Foster describes a yokai as:

 

a weird or mysterious creature, a monster or fantastic being, a spirit or a sprite … creatures of the borderlands, living on the edge of town, or in the mountains between villages, or in the eddies of a river running between two rice fields. They often appear at twilight, that gray time when the familiar seems strange and faces become indistinguishable. They haunt bridges and tunnels, entranceways and thresholds. They lurk at crossroads.

 

The class of yokai characterised by an ability to shapeshift, and that featured in this scroll, is the bakemono (or obake), a word literally meaning “changing thing” or “thing that changes”. The founding father of minzokugaku (Japanese folklore studies), Yanagita Kuno (1875–1962), drew a distinction between yurei (ghosts) and bakemono: the former haunt people and are associated with the depth of night, whereas the latter haunt places and are seen by the dim light of dusk or dawn.

 

Amongst the bakemono monsters depicted in the scroll is the rokurokubi (ろくろくび), a long-necked woman whose name literally means “pulley neck”. Whether shown with a completely detachable head (more common in Chinese versions), or with head upon the end of a long threadlike neck as shown here, the head of the rokurokubi has the ability to fly about independently of the body. In his 1904 collection Kwaidan, Lafcadio Hearn provides the first extended discussion of this yokai in English, telling of a samurai-turned-travelling-priest who finds himself staying the night in a household of rokurokubi intent on eating their guest.

 

Yuki-onna (“snow woman” – 雪女) appears on snowy nights as a beautiful woman with long hair. Details vary from region to region — in some parts a sighting would mean your spirit being drawn from your body, in other parts she asks you to hold her baby. Explanations for her vary too, for some she is the spirit of the snow, for others the ghost of a woman who perished in the snow, or even as a moon princess expelled from the sky-world. Yuki-onna again appears in Hearn’s Kwaidan, where she visits two woodcutters caught in a snowstorm, killing the older by blowing in his face, and promising to kill the younger if he ever tells of what happened (which, many years later, he does).

 

Kami-kiri (“hair cutter” – 髪切) is a yokai known for sneaking up on people and cutting off their hair. The phenomenon of people’s hair being mysteriously chopped appeared in many urban legends, in the Edo period in particular. Sometimes the chop would be attributed to a “demon wind”, but often to a creature doing the cutting, such as the kamikiri-mushi (a “hair cutting- insect”, likely in reference to the praying mantis, with its scythelike front limbs, and named a very similar-sounding kamakiri in Japanese). In the Bakemono zukushi, it appears with a bird like face and huge pincer hand brandishing the severed crop.

 

Below we’ve featured our highlights from the scroll (see the whole thing complete here), the digitisation of which appears to have come from the International Research Center for Japanese Studies – Yokai Database. Many thanks to Pink Tentacle, from whom we’ve taken the image descriptions. If you want to learn more about yokai in general then do check out Michael Dylan Foster’s fascinating The Book of Yokai.

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant in the daisy family Asteraceae, native to the Americas. The species and its varieties and cultivars are popular as ornamental plants in temperate climate gardens.

 

Description

In natural habitat

Cosmos bipinnatus is an annual that is often considered half-hardy, although plants may reappear via self-sowing for several years. The plant height varies from 2–6 ft to (rarely) 9 ft (0.61–1.83–2.74 m). The cultivated varieties appear in shades of pink and purple as well as white. The branched stem is usually densely to occasionally occupied by fine, split up, rough trichomes, some specimens are completely hairless. The petiole itself is inconspicuous, winged, 10 (rarely to 15) mm long, sometimes the leaves are almost sessile.

 

The partial leaves are linear-filiform to narrow linear with a width of 0.5 to 1 (rarely to 1.7) mm; the tips are pointed, hardened, but not particularly sharp. Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

The achenes become blackish, are smooth or short-bristly. Their shape is spindle-like. They are rounded off into a short, 0.5 to 1.7 mm long, but distinctly pronounced rostrum. The inner achenes are up to 18 mm long, their yellowish beaks are 4 to 5 (rarely to 10) mm long. A pappus is missing or it consists only of two to three awn-like, 1-3 mm large bristles.

 

Flowers

The very conspicuous cup-shaped inflorescences have a diameter of usually 5–7 cm (2.0–2.8 in) and contain tongue and tubular flowers, which are surrounded by bracts. There are usually 8 outer bracts, and they are ovate to lanceolate-tail-shaped, 7-15 mm long, 3-5 mm wide. The inner bracts are ovate-lanceolate and 8-12 mm long. They are translucent with many black stripes and a clear edge up to 1 mm wide, sometimes with yellowish or pink pigments, the tip is ciliate. The sprout leaves have gold-yellow, thread-like tips and protrude between the tubular flowers. The broadened base of these spreader leaves is translucent, provided with a yellow line. During flowering, the plant can sag under its weight. This problem can be solved by grouping the feet together so that the leaves hang together.

 

The mostly eight ray florets are pink to violet or white colored, at the base may show noticeable stains caused by anthocyanin. The tongues are reversely ovate shaped, have a length of usually 20-35 mm and a width of usually 12-20 mm. The tips are almost dull and have three broad, wavy teeth. Below that, they are greatly rejuvenated. In the center of the flower baskets is a large number of tubular flowers (also called disc florets), whose overgrown petals are yellow, turn white in the lower part and reach a length of 5-6 mm. The anthers are brownish-black and about 3 mm long, at the tips are short-triangular, translucent attachments with a length of 0.5-0.8 mm. The branches of the stylus are short and rather dull, with a length of .5 mm.

 

Distribution

This plant is native to Mexico, Guatemala and Costa Rica. Since it is used as an ornamental plant in many countries and prone to sedimentation, it is an invasive plant in many areas of the world. It has naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cultivars

Cultivars of Cosmos bipinnatus in cultivation today include:

Apollo Series

'Apollo Carmine' agm

'Apollo Pink' agm

'Apollo White' agm

'Daydream' features a pink inner ring on a white background

Double Click Series features semidouble to fully double flowers that resemble Japanese anemones (Anemone japonica)

'Double Click Cranberries'

'Double Click Rose Bonbon'

'Double Click Snow Puff'

'Double Click Vari Extra'

'Rubenza' agm

'Sensation', also known as 'Early Sensation', is a widely available mix of tall varieties

'Sensation Pinkie' agm

Sonata series

'Velouette'agm

'Versailles', developed for the cut flower trade, are shorter than the species, with heights remaining below three feet

'Versailles Dark Rose'

'Vesailles Tetra'

(those marked agm have gained the Royal Horticultural Society's Award of Garden Merit).

 

Cultivation

Germination takes between 7 and 10 days at the optimal temperature of 75 °F (24 °C); flowering begins between 60 and 90 days after germination

It prefers a soil pH between 6.0 and 8.5, reflecting its native habitat in the alkaline regions of Central America

Flowering is best in full sun, although partial shade is tolerated

Excessive rain can cause cultivation problems, due to the delicate nature of the stems. Heavy rain can cause breakage. Cosmos bipinnatus can tolerate heat as long as adequate moisture is provided, however, it does not handle droughts, strong winds or cold temperatures well. Snails, slugs and aphids have a taste for Cosmos bipinnatus. Successfully cultivated plants can mature 2 to 4 feet (0.61 to 1.22 m) x 12 to 18 inches (300 to 460 mm).

 

They are not tolerant of frost, but can be grown outdoors in a temperate climate with a warm to hot summer and are therefore called half-hardy in British gardening literature.

Pollinators

The flowers of Cosmos bipinnatus attract birds and butterflies, including the monarch butterfly. It can be part of butterfly gardening and pollinator/honey-bee habitat gardens.

For anyone who is interested .. the way to tell the difference between butterflies, moths and skippers is the antennae....

> Butterflies have knobs (or clubs) on the end of their antennae

> Moths have either feathery or threadlike antennae

> Skippers have hooked antennae

LEICA R 100mm f2.8 APO MACRO

 

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant native to Mexico. The species and its varieties and cultivars are popular as an ornamental plant in temperate climate gardens. It can also be found in natural areas in much of North America, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cosmos bipinnatus is considered a half-hardy annual, although plants may reappear via self-sowing for several years. The plant height varies from 2–4 ft (0.61–1.22 m). The cultivated varieties appear in shades of pink and purple as well as white. Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

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Because of personal reasons,

I am unable to respond to all every one, apologize!

 

2/10re

If you zoom into the middle of the photograph you can see the mist trail winding up the mountainside towards vernal falls. The threadlike trail and the minuscule hikers put the majesty of these mountains in perspective. Shot from glacier point on a sunny day.

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant in the daisy family Asteraceae, native to the Americas. The species and its varieties and cultivars are popular as ornamental plants in temperate climate gardens.

 

Cosmos bipinnatus is an annual that is often considered half-hardy, although plants may reappear via self-sowing for several years. The plant height varies from 2–6 ft to (rarely) 9 ft (0.61–1.83–2.74 m). The cultivated varieties appear in shades of pink and purple as well as white. The branched stem is usually densely to occasionally occupied by fine, split up, rough trichomes, some specimens are completely hairless. The petiole itself is inconspicuous, winged, 10 (rarely to 15) mm long, sometimes the leaves are almost sessile.

 

The partial leaves are linear-filiform to narrow linear with a width of 0.5 to 1 (rarely to 1.7) mm; the tips are pointed, hardened, but not particularly sharp. Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

The achenes become blackish, are smooth or short-bristly. Their shape is spindle-like. They are rounded off into a short, 0.5 to 1.7 mm long, but distinctly pronounced rostrum. The inner achenes are up to 18 mm long, their yellowish beaks are 4 to 5 (rarely to 10) mm long. A pappus is missing or it consists only of two to three awn-like, 1-3 mm large bristles.

 

The very conspicuous cup-shaped inflorescences have a diameter of usually 5–7 cm (2.0–2.8 in) and contain tongue and tubular flowers, which are surrounded by bracts. There are usually 8 outer bracts, and they are ovate to lanceolate-tail-shaped, 7-15 mm long, 3-5 mm wide. The inner bracts are ovate-lanceolate and 8-12 mm long. They are translucent with many black stripes and a clear edge up to 1 mm wide, sometimes with yellowish or pink pigments, the tip is ciliate. The sprout leaves have gold-yellow, thread-like tips and protrude between the tubular flowers. The broadened base of these spreader leaves is translucent, provided with a yellow line. During flowering, the plant can sag under its weight. This problem can be solved by grouping the feet together so that the leaves hang together.

 

The mostly eight ray florets are pink to violet or white colored, at the base may show noticeable stains caused by anthocyanin. The tongues are reversely ovate shaped, have a length of usually 20-35 mm and a width of usually 12-20 mm. The tips are almost dull and have three broad, wavy teeth. Below that, they are greatly rejuvenated. In the center of the flower baskets is a large number of tubular flowers (also called disc florets), whose overgrown petals are yellow, turn white in the lower part and reach a length of 5-6 mm. The anthers are brownish-black and about 3 mm long, at the tips are short-triangular, translucent attachments with a length of 0.5-0.8 mm. The branches of the stylus are short and rather dull, with a length of .5 mm.

 

This plant is native to Mexico, Guatemala and Costa Rica. Since it is used as an ornamental plant in many countries and prone to sedimentation, it is an invasive plant in many areas of the world. It has naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cultivars of Cosmos bipinnatus in cultivation today include:

Apollo Series

'Apollo Carmine' agm

'Apollo Pink' agm

'Apollo White' agm

'Daydream' features a pink inner ring on a white background

Double Click Series features semidouble to fully double flowers that resemble Japanese anemones (Anemone japonica)

'Double Click Cranberries'

'Double Click Rose Bonbon'

'Double Click Snow Puff'

'Double Click Vari Extra'

'Rubenza' agm

'Sensation', also known as 'Early Sensation', is a widely available mix of tall varieties

'Sensation Pinkie' agm

Sonata series

'Velouette'agm

'Versailles', developed for the cut flower trade, are shorter than the species, with heights remaining below three feet

'Versailles Dark Rose'

'Vesailles Tetra'

(those marked agm have gained the Royal Horticultural Society's Award of Garden Merit).

 

Germination takes between 7 and 10 days at the optimal temperature of 75 °F (24 °C); flowering begins between 60 and 90 days after germination

It prefers a soil pH between 6.0 and 8.5, reflecting its native habitat in the alkaline regions of Central America

Flowering is best in full sun, although partial shade is tolerated

Excessive rain can cause cultivation problems, due to the delicate nature of the stems. Heavy rain can cause breakage. Cosmos bipinnatus can tolerate heat as long as adequate moisture is provided, however, it does not handle droughts, strong winds or cold temperatures well. Snails, slugs and aphids have a taste for Cosmos bipinnatus. Successfully cultivated plants can mature 2 to 4 feet (0.61 to 1.22 m) x 12 to 18 inches (300 to 460 mm).

 

They are not tolerant of frost, but can be grown outdoors in a temperate climate with a warm to hot summer and are therefore called half-hardy in British gardening literature.

Pollinators

The flowers of Cosmos bipinnatus attract birds and butterflies, including the monarch butterfly. It can be part of butterfly gardening and pollinator/honey-bee habitat gardens.

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant in the daisy family Asteraceae, native to the Americas. The species and its varieties and cultivars are popular as ornamental plants in temperate climate gardens.

 

Description

In natural habitat

Cosmos bipinnatus is an annual that is often considered half-hardy, although plants may reappear via self-sowing for several years. The plant height varies from 2–6 ft to (rarely) 9 ft (0.61–1.83–2.74 m). The cultivated varieties appear in shades of pink and purple as well as white. The branched stem is usually densely to occasionally occupied by fine, split up, rough trichomes, some specimens are completely hairless. The petiole itself is inconspicuous, winged, 10 (rarely to 15) mm long, sometimes the leaves are almost sessile.

 

The partial leaves are linear-filiform to narrow linear with a width of 0.5 to 1 (rarely to 1.7) mm; the tips are pointed, hardened, but not particularly sharp. Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

The achenes become blackish, are smooth or short-bristly. Their shape is spindle-like. They are rounded off into a short, 0.5 to 1.7 mm long, but distinctly pronounced rostrum. The inner achenes are up to 18 mm long, their yellowish beaks are 4 to 5 (rarely to 10) mm long. A pappus is missing or it consists only of two to three awn-like, 1-3 mm large bristles.

 

Flowers

The very conspicuous cup-shaped inflorescences have a diameter of usually 5–7 cm (2.0–2.8 in) and contain tongue and tubular flowers, which are surrounded by bracts. There are usually 8 outer bracts, and they are ovate to lanceolate-tail-shaped, 7-15 mm long, 3-5 mm wide. The inner bracts are ovate-lanceolate and 8-12 mm long. They are translucent with many black stripes and a clear edge up to 1 mm wide, sometimes with yellowish or pink pigments, the tip is ciliate. The sprout leaves have gold-yellow, thread-like tips and protrude between the tubular flowers. The broadened base of these spreader leaves is translucent, provided with a yellow line. During flowering, the plant can sag under its weight. This problem can be solved by grouping the feet together so that the leaves hang together.

 

The mostly eight ray florets are pink to violet or white colored, at the base may show noticeable stains caused by anthocyanin. The tongues are reversely ovate shaped, have a length of usually 20-35 mm and a width of usually 12-20 mm. The tips are almost dull and have three broad, wavy teeth. Below that, they are greatly rejuvenated. In the center of the flower baskets is a large number of tubular flowers (also called disc florets), whose overgrown petals are yellow, turn white in the lower part and reach a length of 5-6 mm. The anthers are brownish-black and about 3 mm long, at the tips are short-triangular, translucent attachments with a length of 0.5-0.8 mm. The branches of the stylus are short and rather dull, with a length of .5 mm.

 

Distribution

This plant is native to Mexico, Guatemala and Costa Rica. Since it is used as an ornamental plant in many countries and prone to sedimentation, it is an invasive plant in many areas of the world. It has naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cultivars

Cultivars of Cosmos bipinnatus in cultivation today include:

Apollo Series

'Apollo Carmine' agm

'Apollo Pink' agm

'Apollo White' agm

'Daydream' features a pink inner ring on a white background

Double Click Series features semidouble to fully double flowers that resemble Japanese anemones (Anemone japonica)

'Double Click Cranberries'

'Double Click Rose Bonbon'

'Double Click Snow Puff'

'Double Click Vari Extra'

'Rubenza' agm

'Sensation', also known as 'Early Sensation', is a widely available mix of tall varieties

'Sensation Pinkie' agm

Sonata series

'Velouette'agm

'Versailles', developed for the cut flower trade, are shorter than the species, with heights remaining below three feet

'Versailles Dark Rose'

'Vesailles Tetra'

(those marked agm have gained the Royal Horticultural Society's Award of Garden Merit).

 

Cultivation

Germination takes between 7 and 10 days at the optimal temperature of 75 °F (24 °C); flowering begins between 60 and 90 days after germination

It prefers a soil pH between 6.0 and 8.5, reflecting its native habitat in the alkaline regions of Central America

Flowering is best in full sun, although partial shade is tolerated

Excessive rain can cause cultivation problems, due to the delicate nature of the stems. Heavy rain can cause breakage. Cosmos bipinnatus can tolerate heat as long as adequate moisture is provided, however, it does not handle droughts, strong winds or cold temperatures well. Snails, slugs and aphids have a taste for Cosmos bipinnatus. Successfully cultivated plants can mature 2 to 4 feet (0.61 to 1.22 m) x 12 to 18 inches (300 to 460 mm).

 

They are not tolerant of frost, but can be grown outdoors in a temperate climate with a warm to hot summer and are therefore called half-hardy in British gardening literature.

Pollinators

The flowers of Cosmos bipinnatus attract birds and butterflies, including the monarch butterfly. It can be part of butterfly gardening and pollinator/honey-bee habitat gardens.

I had never seen this cloud formation before. After searching the Web, I found that it was a terrific example of Vertical Cirrus Clouds. These are fibrous, threadlike, and white feather clouds of ice crystals, whose form resembles hair curls. Taken in my backyard over a year ago.

 

View Large On Black

 

Please do not use this image on websites, blogs or any other media without my explicit permission. © All rights reserved

Mosses are truly strange beings. To really grasp how strange, please follow this primitive explanation:

Have you ever wondered how mosses can grow on solid, bare rock? Sure! It's because they have no roots - only threadlike structures that anchor them. They absorb all water and nutrients directly through their leaves...

Humans and animals (and plants) have double sets of chromosomes in all cells (diploid cells). ONLY sex cells (sperms and eggs) have reduced the DNA through meiosis to single chromosomes (hapliod cells).

The "adult" moss plants are sort of like our sex cells, with half set of chromosomes (haploid). Male plants produce sperm-like cells that swim to the female plants in rain water and combine with the eggs, inside the female plant.

Now this embryo has double chromosome set (diploid). It grows a stalk from within the female, still diploid, and on top of this a sporangium with spores. This stalk/sporangium is the only part, ever, of a moss that has complete set of chromosomes!

NOW the moss reduce the chromosome number in the spores (by meiosis), not like other creatures that perform meiosis exclusively to produce sex cells.

Spores germinate, produce tiny threadlike structures from which male and female plants (haploid) grow......

Still confused? =)

There are mysteries down there in Miniature Land.

Anomodon tristis, one of a number of green ragged threadlike mosses growing on bark. 2020 DEC23 MD:PG Co.:Laurel: Patuxent Research Refuge South Tract about 1m high on mature oak (18" dbh) in wet woodland. GPS: 39.029335, -76.800970, Laurel Quad. Ref# 2020DEC23-004

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant in the daisy family Asteraceae, native to the Americas. The species and its varieties and cultivars are popular as ornamental plants in temperate climate gardens.

 

Description

In natural habitat

Cosmos bipinnatus is an annual that is often considered half-hardy, although plants may reappear via self-sowing for several years. The plant height varies from 2–6 ft to (rarely) 9 ft (0.61–1.83–2.74 m). The cultivated varieties appear in shades of pink and purple as well as white. The branched stem is usually densely to occasionally occupied by fine, split up, rough trichomes, some specimens are completely hairless. The petiole itself is inconspicuous, winged, 10 (rarely to 15) mm long, sometimes the leaves are almost sessile.

 

The partial leaves are linear-filiform to narrow linear with a width of 0.5 to 1 (rarely to 1.7) mm; the tips are pointed, hardened, but not particularly sharp. Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

The achenes become blackish, are smooth or short-bristly. Their shape is spindle-like. They are rounded off into a short, 0.5 to 1.7 mm long, but distinctly pronounced rostrum. The inner achenes are up to 18 mm long, their yellowish beaks are 4 to 5 (rarely to 10) mm long. A pappus is missing or it consists only of two to three awn-like, 1-3 mm large bristles.

 

Flowers

The very conspicuous cup-shaped inflorescences have a diameter of usually 5–7 cm (2.0–2.8 in) and contain tongue and tubular flowers, which are surrounded by bracts. There are usually 8 outer bracts, and they are ovate to lanceolate-tail-shaped, 7-15 mm long, 3-5 mm wide. The inner bracts are ovate-lanceolate and 8-12 mm long. They are translucent with many black stripes and a clear edge up to 1 mm wide, sometimes with yellowish or pink pigments, the tip is ciliate. The sprout leaves have gold-yellow, thread-like tips and protrude between the tubular flowers. The broadened base of these spreader leaves is translucent, provided with a yellow line. During flowering, the plant can sag under its weight. This problem can be solved by grouping the feet together so that the leaves hang together.

 

The mostly eight ray florets are pink to violet or white colored, at the base may show noticeable stains caused by anthocyanin. The tongues are reversely ovate shaped, have a length of usually 20-35 mm and a width of usually 12-20 mm. The tips are almost dull and have three broad, wavy teeth. Below that, they are greatly rejuvenated. In the center of the flower baskets is a large number of tubular flowers (also called disc florets), whose overgrown petals are yellow, turn white in the lower part and reach a length of 5-6 mm. The anthers are brownish-black and about 3 mm long, at the tips are short-triangular, translucent attachments with a length of 0.5-0.8 mm. The branches of the stylus are short and rather dull, with a length of .5 mm.

 

Distribution

This plant is native to Mexico, Guatemala and Costa Rica. Since it is used as an ornamental plant in many countries and prone to sedimentation, it is an invasive plant in many areas of the world. It has naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cultivars

Cultivars of Cosmos bipinnatus in cultivation today include:

Apollo Series

'Apollo Carmine' agm

'Apollo Pink' agm

'Apollo White' agm

'Daydream' features a pink inner ring on a white background

Double Click Series features semidouble to fully double flowers that resemble Japanese anemones (Anemone japonica)

'Double Click Cranberries'

'Double Click Rose Bonbon'

'Double Click Snow Puff'

'Double Click Vari Extra'

'Rubenza' agm

'Sensation', also known as 'Early Sensation', is a widely available mix of tall varieties

'Sensation Pinkie' agm

Sonata series

'Velouette'agm

'Versailles', developed for the cut flower trade, are shorter than the species, with heights remaining below three feet

'Versailles Dark Rose'

'Vesailles Tetra'

(those marked agm have gained the Royal Horticultural Society's Award of Garden Merit).

 

Cultivation

Germination takes between 7 and 10 days at the optimal temperature of 75 °F (24 °C); flowering begins between 60 and 90 days after germination

It prefers a soil pH between 6.0 and 8.5, reflecting its native habitat in the alkaline regions of Central America

Flowering is best in full sun, although partial shade is tolerated

Excessive rain can cause cultivation problems, due to the delicate nature of the stems. Heavy rain can cause breakage. Cosmos bipinnatus can tolerate heat as long as adequate moisture is provided, however, it does not handle droughts, strong winds or cold temperatures well. Snails, slugs and aphids have a taste for Cosmos bipinnatus. Successfully cultivated plants can mature 2 to 4 feet (0.61 to 1.22 m) x 12 to 18 inches (300 to 460 mm).

 

They are not tolerant of frost, but can be grown outdoors in a temperate climate with a warm to hot summer and are therefore called half-hardy in British gardening literature.

Pollinators

The flowers of Cosmos bipinnatus attract birds and butterflies, including the monarch butterfly. It can be part of butterfly gardening and pollinator/honey-bee habitat gardens.

Viola is a genus of flowering plants in the violet family Violaceae. It is the largest genus in the family, containing over 680 species. Most species are found in the temperate Northern Hemisphere; however, some are also found in widely divergent areas such as Hawaii, Australasia, and the Andes.

 

Some Viola species are perennial plants, some are annual plants, and a few are small shrubs. Many species, varieties and cultivars are grown in gardens for their ornamental flowers. In horticulture, the term pansy is normally used for those multi-colored, large-flowered cultivars which are raised annually or biennially from seed and used extensively in bedding. The terms viola and violet are normally reserved for small-flowered annuals or perennials, including the wild species.

 

Description

Annual or perennial caulescent or acaulescent (with or without a visible plant stem above the ground) herbs, shrubs or very rarely treelets. In acaulescent taxa the foliage and flowers appear to rise from the ground. The remainder have short stems with foliage and flowers produced in the axils of the leaves (axillary).

 

Viola typically have heart-shaped or reniform (kidney-shaped), scalloped leaves, though a number have linear or palmate leaves. The simple leaves of plants with either habit are arranged alternately; the acaulescent species produce basal rosettes. Plants always have leaves with stipules that are often leaf-like.

 

The flowers of the vast majority of the species are strongly zygomorphic with bilateral symmetry and solitary, but occasionally form cymes. The flowers are formed from five petals; four are upswept or fan-shaped with two per side, and there is one, broad, lobed lower petal pointing downward. This petal may be slightly or much shorter than the others and is weakly differentiated. The shape of the petals and placement defines many species, for example, some species have a "spur" on the end of each petal while most have a spur on the lower petal. The spur may vary from scarcely exserted (projecting) to very long, such as in Viola rostrata.

 

Solitary flowers end long stalks with a pair of bracteoles. The flowers have five sepals that persist after blooming, and in some species the sepals enlarge after blooming. The corolla ranges from white to yellow, orange or various shades of blue and violet or multicolored, often blue and yellow, with or without a yellow throat.

 

The flowers have five free stamens with short free filaments that are oppressed against the ovary, with a dorsal connective appendage that is large, entire and oblong to ovate. Only the lower two stamens are calcarate (possessing nectary spurs that are inserted on the lowest petal into the spur or a pouch). The styles are filiform (threadlike) or clavate (clubshaped), thickened at their tip, being globose to rostellate (beaked). The stigmas are head-like, narrowed or often beaked. The flowers have a superior ovary with one cell, which has three placentae, containing many ovules.

 

After flowering, fruit capsules are produced that are thick walled, with few to many seeds per carpel, and dehisce (split open) by way of three valves. On drying, the capsules may eject seeds with considerable force to distances of several meters. The nutlike seeds, which are obovoid to globose, are typically arillate (with a specialized outgrowth) and have straight embryos, flat cotyledons, and soft fleshy endosperm that is oily.

 

Phytochemistry

One characteristic of some Viola is the elusive scent of their flowers; along with terpenes, a major component of the scent is a ketone compound called ionone, which temporarily desensitizes the receptors of the nose, thus preventing any further scent being detected from the flower until the nerves recover.

 

Taxonomy

First page of Linnaeus' 1753 description of Viola

Linnaeus' original description (1753)

 

History

First formally described by Carl Linnaeus in 1753[7] with 19 species, the genus Viola bears his botanical authority, L. When Jussieu established the hierarchical system of families (1789), he placed Viola in the Cisti (rock roses), though by 1811 he suggested Viola be separated from these. However, in 1802 Batsch had already established a separate family, which he called Violariae based on Viola as the type genus, with seven other genera. Although Violariae continued to be used by some authors, such as Bentham and Hooker in 1862 (as Violarieae), most authors adopted the alternative name Violaceae, first proposed by de Lamarck and de Candolle in 1805, and Gingins (1823) and Saint-Hilaire (1824). However de Candolle also used Violarieae in his 1824 Prodromus.

 

Phylogeny

Viola is one of about 25 genera and about 600 species in the large eudicot family Violaceae, divided into subfamilies and tribes. While most genera are monotypic, Viola is a very large genus, variously circumscribed as having between 500 and 600 species. Historically it was placed in subfamily Violoideae, tribe Violeae. But these divisions have been shown to be artificial and not monophyletic. Molecular phylogenetic studies show that Viola occurs in Clade I of the family, as Viola, Schweiggeria, Noisettia and Allexis, in which Schweiggeria and Noisettia are monotypic and form a sister group to Viola.

 

Subdivision

Viola is a large genus that has traditionally been treated in sections. One of these was that of Gingins (1823), based on stigma morphology, with five sections (Nomimium, Dischidium, Chamaemelanium, Melanium, Leptidium). The extensive taxonomic studies of Wilhelm Becker, culminating in his 1925 conspectus, resulted in 14 sections and many infrasectional groups. The largest and most diverse, being section Viola, with 17 subsections. In addition to subsections, series were also described. Alternatively, some authors have preferred to subdivide the genus into subgenera. Subsequent treatments were by Gershoy (1934) and Clausen (1964), using subsections and series. These were all based on morphological characteristics. Subsequent studies using molecular phylogenetic methods, such as that of Ballard et al. (1998) have shown that many of these traditional divisions are not monophyletic, the problem being related to a high degree of hybridization. In particular section Nomimium was dismembered into several new sections and transferring part of it to section Viola. Section Viola s. lat. is represented by four sections, Viola sensu stricto, Plagiostigma s. str., Nosphinium sensu lato. and the V. spathulata group. In that analysis, the S American sections appear to be the basal groups, starting with Rubellium, then Leptidium. However, the exact phylogenetic relationships remain unresolved, as a consequence many different taxonomic nomenclatures are in use, including groupings referred to as Grex. Marcussen et al. place the five S American sections, Andinium, Leptidium, Tridens, Rubellium and Chilenium at the base of the phylogenetic tree, in that order. These are followed by the single Australian section, Erpetion, as sister group to Chilenium, the northern hemisphere sections and finally the single African section, V. abyssinica. These sections are morphologically, chromosomally, and geographically distinct.

 

Sections

Seventeen sections are recognized, listed alphabetically (approximate no. species);

 

Sect. Andinium W.Becker (113) S America

Sect. Chamaemelanium Ging. s.lat. (61) N America, northeast Asia (includes Dischidium, Orbiculares)

Subsect. Chamaemelanium

Subsect. Nudicaules

Subsect. Nuttalianae

Sect. Chilenium W.Becker (8) southern S America

Sect. Danxiaviola W. B. Liao et Q. Fan (1) China

Sect. Delphiniopsis W.Becker (3) western Eurasia: southern Spain; Balkans

Sect. Erpetion (Banks) W.Becker (11–18) eastern Australia; Tasmania

Sect. Leptidium Ging. (19) S America

Sect. Melanium Ging. (125) western Eurasia (pansies)

Sect. Nosphinium W.Becker s.lat. (31–50) N, C and northern S America; Beringia; Hawaii

Sect. nov. A (V. abyssinica group) (1–3) Africa: equatorial high mountains

Sect. nov. B (V. spathulata group) (7–9) western and central Asia: northern Iraq to Mongolia

Sect. Plagiostigma Godr. (120) northern hemisphere (includes Diffusae)

Grex Primulifolia

Sect. Rubellium W.Becker (3–6) S America: Chile

Sect. Sclerosium W.Becker (1–4) northeastern Africa to southwestern Asia

Sect. Tridens W.Becker (2) southern S America

Sect. Viola  s.str. (Rostellatae nom. illeg.) (75) northern hemisphere (violets) (includes Repentes)

Subsect. Rostratae Kupffer (W.Becker)

Subsect. Viola

Sect. Xylinosium W.Becker (3–4) Mediterranean region

 

Species

The genus includes dog violets, a group of scentless species which are the most common Viola in many areas, sweet violet (Viola odorata) (named from its sweet scent), and many other species whose common name includes the word "violet". But not other "violets": Neither Streptocarpus sect. Saintpaulia ("African violets", Gesneriaceae) nor Erythronium dens-canis ("dogtooth violets", Liliaceae) are related to Viola.

 

List of selected species

Viola canina flower and leaves

Viola canina

 

Section Andinium

With about 113 species, the South American section Andinium is the largest of the Viola sections. It is one of the four sections distributed primarily or exclusively in South America, and the basal group of Viola. New species continue to be identified. Species include;

Viola escarapela

Viola lilliputana

Viola biflora flower and leaves

Viola biflora

 

Section Chamaemelanium

Chamaemelanium was one of a number of sections originally classified on the basis of the shape of the stigma, in this case one that was facial shaped, had an absent beak and had lateral beards. But this section has subsequently been shown to be paraphyletic, requiring revision. It occurs at high altitudes (above 600 m) in both N America and northeast Asia, including Siberia and Korea, and the species are perennial, caulous and herbaceous. With about 61 species including;

 

Viola biflora – yellow wood violet, twoflower violet

Viola glabella – stream violet

Viola pedunculata – yellow pansy

Viola praemorsa – canary violet

Viola pubescens – downy yellow violet

Viola reichei

Viola reichei

 

Section Chilenium

A small S American section with about 8 species, as sister group to Erpetion, including;

Viola reichei

 

Section Danxiaviola

Viola hybanthoides

 

Section Delphiniopsis

Viola Cazorlensis

Viola Cazorlensis

Viola cazorlensis

Viola delphinantha

Viola kosaninii

 

Section Erpetion

Viola banksii

Viola banksii

Viola banksii – Australian native violet, ivy-leaved violet

Viola hederacea – Australian native violet, ivy-leaved violet

 

Section Leptidium

Viola stipularis

Viola stipularis

Viola stipularis

Section Melanium (pansies)

 

Flowers of Viola tricolor

Viola tricolor

Viola arvensis – field pansy

Viola bicolor

Viola pedunculata – yellow pansy, Pacific coast.

Viola bertolonii

Viola calcarata

Viola cheiranthifolia – Teide violet

Viola cornuta

Viola lutea

Viola tricolor – wild pansy, heartsease

Section Nosphinium

 

Flowers of Viola pedata

Viola pedata

Viola pedata

Section A (V. abyssinica group)

 

Flower of Viola abyssinica

Viola abyssinica

Viola abyssinica

Section B (V. spathulata group)

 

Viola spathulata

Section Plagiostigma

 

Flower of Viola epipsila

Viola epipsila

Viola epipsila

 

Section Rubellium

Viola capillaris

Viola portalesia

Viola rubella

 

Section Sclerosium

Viola cinerea

 

Section Tridens

Flowers of Viola tridentata

Viola tridentata

Viola tridentata – mountain violet

Section Viola (violets)

 

Flowers of Viola sororia

Viola sororia

Viola canina – heath dog violet

Viola hirta – hairy violet

Viola labradorica – alpine violet

Viola odorata – sweet violet

Viola persicifolia – fen violet

Viola riviniana – common dog violet

Viola rostrata – long-spurred violet

Viola sororia – common blue violet, hooded violet

Viola decumbens

Viola decumbens

 

Evolution and biogeography

One fossil seed of †Viola rimosa has been extracted from borehole samples of the Middle Miocene fresh water deposits in Nowy Sacz Basin, West Carpathians, Poland. The genus is thought to have arisen in S America, most likely the Andes.

 

Genetics

Habitat fragmentation has been shown to have minimal effect on the genetic diversity and gene flow of the North American woodland violet Viola pubescens. This may be partially attributed to the ability of Viola pubescens to continue to persist within a largely agricultural matrix. This trend of unexpectedly high genetic diversity is also observed in Viola palmensis, a Canary Island endemic known only from a 15 square kilometer range on La palma island. High levels of genetic diversity within these species indicate that these plants are outcrossing, even though many violet species can produce many clonal offspring throughout the year via cleistogamous flowers. Plants that produce copious amounts of clonal seeds from cleistogamous flowers often experience increased levels of inbreeding. These reportedly high rates of outcrossing and genetic diversity indicate that these violets are strong competitors for pollinators during the early spring when they are in bloom and that those pollinators can travel considerable distances between often fragmented populations.

 

Distribution and habitat

The worldwide northern temperate distribution of the genus distinguishes it from the remaining largely tropical Violaceae genera, restricted to either Old World or New World species, while in the tropics the distribution is primarily in high mountainous areas. Centres of diversity occur mainly in the northern hemisphere, in mountainous regions of eastern Asia, Melanesia, and southern Europe, but also occur in the Andes and the southern Patagonian cone of South America. One of the highest species concentrations is in the former USSR. Australia is home to a number of Viola species, including Viola hederacea, Viola betonicifolia and Viola banksii, first collected by Joseph Banks and Daniel Solander on the Cook voyage to Botany Bay.

 

Ecology

Viola species are used as food plants by the larvae of some Lepidoptera species, including the giant leopard moth, large yellow underwing, lesser broad-bordered yellow underwing, high brown fritillary, small pearl-bordered fritillary, pearl-bordered fritillary, regal fritillary, cardinal, and Setaceous Hebrew character. The larvae of many fritilary butterfly species use violets as an obligate host plant, although these butterflies do not always ovaposit directly onto violets. While the ecology of this genera is extremely diverse, violets are mainly pollinated by members within the orders Diptera and Hymenoptera. Showy flowers are produced in early spring, and clonal cleistogamous flowers are produced from late spring until the end of the growing season under favorable conditions. Cleistogamy allows plants to produce offspring year round and have more chances for establishment. This system is especially important in violets, as these plants are often weak competitors for pollination due to their small size.

 

Many violet species exhibit two modes of seed dispersal. Once seed capsules have matured, seeds are dispelled around the plant through explosive dehiscence. Viola pedata seeds have been reported being dispersed distances of up to 5 meters away from the parent plant. Often, seeds are then further dispersed by ants through a process called myrmecochory. Violets whose seeds are dispersed this way have specialized structures on the exterior of the seeds called elaiosomes. This interaction allows violet seed to germinate and establish in a protected, stable environment.

 

Many violet seeds exhibit physiological dormancy and require some period of cold stratification to induce germination under ex situ conditions. Rates of germination are often quite poor, especially when seeds are stored for extended periods of time. In North American habitat restoration, native violets are in high demand due to their relationship with the aforementioned fritillary butterflies.

 

Violet species occupy a diverse array of habitats, from bogs (Viola lanceolata) to dry hill prairies (V. pedata) to woodland understories (V. labradorica). While many of these species are indicators of high quality habitat, some violets are capable of thriving in a human altered landscape. Two species of zinc violet (V. calaminaria and V. guestphalica) are capable of living in soils severely contaminated with heavy metals. Many violets form relationships with arbuscular mycorrhizal fungi, and in the case of the zinc violets, this allows them to tolerate such highly contaminated soils.

 

Flowering is often profuse, and may last for much of the spring and summer. Viola are most often spring-blooming with chasmogamous flowers that have well developed petals pollinated by insects. Many species also produce self-pollinated cleistogamous flowers in summer and autumn that do not open and lack petals. In some species the showy chasmogamous flowers are infertile (e.g.,Viola sororia).

 

Horticultural uses

The international registration authority for the genus is the American Violet Society, where growers register new Viola cultivars. A coding system is used for cultivar description of ten horticultural divisions, such as Violet (Vt) and Violetta (Vtta). Examples include Viola 'Little David' (Vtta) and Viola 'Königin Charlotte' (Vt).

 

In this system violets (Vt) are defined as "stoloniferous perennials with small, highly fragrant, self-coloured purple, blue or white flowers in late winter and early spring".

 

Species and cultivars

Many species, varieties and cultivars are grown in gardens for their ornamental flowers. In horticulture the term pansy is normally used for those multi-colored, large-flowered cultivars which are raised annually or biennially from seed and used extensively in bedding. The terms viola and violet are normally reserved for small-flowered annuals or perennials, including the wild species.

 

Cultivars of Viola cornuta, Viola cucullata, and Viola odorata, are commonly grown from seed. Other species often grown include Viola labradorica, Viola pedata, and Viola rotundifolia.

 

The modern garden pansy (V. × wittrockiana) is a plant of complex hybrid origin involving at least three species, V. tricolor (wild pansy or heartsease), V. altaica, and V. lutea (mountain pansy). The hybrid horned pansy (V. × williamsii) originates from hybridization involving garden pansy and Viola cornuta.

 

Bedding plants

In 2005 in the United States, Viola cultivars (including pansies) were one of the top three bedding plant crops and 111 million dollars worth of flats of Viola were produced for the bedding flower market. Pansies and violas used for bedding are generally raised from seed, and F1 hybrid seed strains have been developed which produce compact plants of reasonably consistent flower coloring and appearance. Bedding plants are usually discarded after one growing season.

 

Perennial cultivars

There are hundreds of perennial viola and violetta cultivars; many of these do not breed true from seed and therefore have to be propagated from cuttings. Violettas can be distinguished from violas by the lack of ray markings on their petals. The following cultivars, of mixed or uncertain parentage, have gained the Royal Horticultural Society's

 

Award of Garden Merit:

'Aspasia'

'Clementina'

'Huntercombe Purple'

'Jackanapes'

'Molly Sanderson'

'Moonlight'

'Nellie Britton'

 

Other popular examples include:

Ardross Gem' (viola)

'Blackjack'

'Buttercup' (violetta)

'Columbine' (viola)

'Dawn' (violetta)

'Etain' (viola)

'Irish Molly' (viola)

'Maggie Mott' (viola)

'Martin' (viola)

'Rebecca' (violetta)

'Vita' (viola)

'Zoe' (violetta)

 

Other uses

Culinary

When newly opened, Viola flowers may be used to decorate salads or in stuffings for poultry or fish. Soufflés, cream, and similar desserts can be flavoured with essence of Viola flowers. The young leaves are edible raw or cooked as a mild-tasting leaf vegetable. The flowers and leaves of the cultivar 'Rebecca', one of the Violetta violets, have a distinct vanilla flavor with hints of wintergreen. The pungent perfume of some varieties of V. odorata adds inimitable sweetness to desserts, fruit salads, and teas while the mild pea flavor of V. tricolor combines equally well with sweet or savory foods, like grilled meats and steamed vegetables. The heart-shaped leaves of V. odorata provide a free source of greens throughout a long growing season, while the petals are used for fragrant flavoring in milk puddings and ice cream or in salads and as garnishes.

 

A candied violet or crystallized violet is a flower, usually of Viola odorata, preserved by a coating of egg white and crystallised sugar. Alternatively, hot syrup is poured over the fresh flower (or the flower is immersed in the syrup) and stirred until the sugar recrystallizes and has dried. This method is still used for rose petals and was applied to orange flowers in the past (when almonds or orange peel are treated this way they are called pralines). Candied violets are still made commercially in Toulouse, France, where they are known as violettes de Toulouse. They are used as decorating cakes or trifles or included in aromatic desserts.

 

The French are also known for their violet syrup, most commonly made from an extract of violets. In the United States, this French violet syrup is used to make violet scones and marshmallows. Viola essence flavours the liqueurs Creme Yvette, Creme de Violette, and Parfait d'Amour. It is also used in confectionery, such as Parma Violets and C. Howard's Violet candies.

 

Medicinal

Many Viola species contain antioxidants called anthocyanins. Fourteen anthocyanins from V. yedoensis and V. prionantha have been identified. Some anthocyanins show strong antioxidant activities. Most violas tested and many other plants of the family Violaceae contain cyclotides, which have a diverse range of in vitro biological activities when isolated from the plant, including uterotonic, anti-HIV, antimicrobial, and insecticidal activities. Viola canescens, a species from India, exhibited in vitro activity against Trypanosoma cruzi.

 

Viola has been evaluated in different clinical indications in human studies. A double blind clinical trial showed that the adjuvant use of Viola odorata syrup with short-acting β-agonists can improve the cough suppression in children with asthma. In another study intranasal administration of Viola odorata extract oil showed to be effective in patients with insomnia. Topical use of an herbal formulation containing Viola tricolor extract also showed promising effects in patients with mild-to-moderate atopic dermatitis.

 

Perfume

Viola odorata is used as a source for scents in the perfume industry. Violet is known to have a 'flirty' scent as its fragrance comes and goes. Ionone is present in the flowers, which turns off the ability for humans to smell the fragrant compound for moments at a time.

 

Cultural associations

Birth

Violet is the traditional birth flower for February in English tradition.

 

Geographical territories

In the United States, the common blue violet Viola sororia is the state flower of Illinois, Rhode Island, New Jersey and Wisconsin, In Canada, the Viola cucullata is the provincial flower of New Brunswick adopted in 1936 In the United Kingdom, Viola riviniana is the county flower of Lincolnshire.

 

Lesbian and bisexual culture

Violets became symbolically associated with romantic love between women. This connection originates from fragments of a poem by Sappho about a lost love, in which she describes her as "Close by my side you put around yourself [many wreaths] of violets and roses." In another poem, Sappho describes her lost love as wearing "violet tiaras, braided rosebuds, dill and crocus twined around" her neck. In 1926, one of the first plays to involve a lesbian relationship, La Prisonnière by Édouard Bourdet, used a bouquet of violets to signify lesbian love.

 

Tributes

Violets, and badges depicting them, were sold in fund-raising efforts in Australia and New Zealand on and around Violet Day in commemoration of the lost soldiers of World War I.

Jellyfish, also known sea jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria.

 

Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex life cycle. The medusa is normally the sexual phase, which produces planula larvae; these then disperse widely and enter a sedentary polyp phase, before reaching sexual maturity.

 

Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the "true jellyfish") are exclusively marine, but some hydrozoans with a similar appearance live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. The medusae of most species are fast-growing, and mature within a few months then die soon after breeding, but the polyp stage, attached to the seabed, may be much more long-lived. Jellyfish have been in existence for at least 500 million years,[1] and possibly 700 million years or more, making them the oldest multi-organ animal group.[2]

 

Jellyfish are eaten by humans in certain cultures. They are considered a delicacy in some Asian countries, where species in the Rhizostomeae order are pressed and salted to remove excess water. Australian researchers have described them as a "perfect food": sustainable and protein-rich but relatively low in food energy.[3]

 

They are also used in research, where the green fluorescent protein used by some species to cause bioluminescence has been adapted as a fluorescent marker for genes inserted into other cells or organisms.

 

The stinging cells used by jellyfish to subdue their prey can injure humans. Thousands of swimmers worldwide are stung every year, with effects ranging from mild discomfort to serious injury or even death. When conditions are favourable, jellyfish can form vast swarms, which can be responsible for damage to fishing gear by filling fishing nets, and sometimes clog the cooling systems of power and desalination plants which draw their water from the sea.

  

Names

The name jellyfish, in use since 1796,[4] has traditionally been applied to medusae and all similar animals including the comb jellies (ctenophores, another phylum).[5][6] The term jellies or sea jellies is more recent, having been introduced by public aquaria in an effort to avoid use of the word "fish" with its modern connotation of an animal with a backbone, though shellfish, cuttlefish and starfish are not vertebrates either.[7][8] In scientific literature, "jelly" and "jellyfish" have been used interchangeably.[9][10] Many sources refer to only scyphozoans as "true jellyfish".[11]

 

A group of jellyfish is called a "smack"[12] or a "smuck".[13]

 

Mapping to taxonomic groups

 

A purple-striped jellyfish at the Monterey Bay Aquarium

Phylogeny

Definition

The term jellyfish broadly corresponds to medusae,[4] that is, a life-cycle stage in the Medusozoa. The American evolutionary biologist Paulyn Cartwright gives the following general definition:

 

Typically, medusozoan cnidarians have a pelagic, predatory jellyfish stage in their life cycle; staurozoans are the exceptions [as they are stalked].[14]

 

The Merriam-Webster dictionary defines jellyfish as follows:

 

A free-swimming marine coelenterate that is the sexually reproducing form of a hydrozoan or scyphozoan and has a nearly transparent saucer-shaped body and extensible marginal tentacles studded with stinging cells.[15]

 

Given that jellyfish is a common name, its mapping to biological groups is inexact. Some authorities have called the comb jellies[16] and certain salps[16] jellyfish, though other authorities state that neither of these are jellyfish, which they consider should be limited to certain groups within the medusozoa.[17][18]

 

The non-medusozoan clades called jellyfish by some but not all authorities (both agreeing and disagreeing citations are given in each case) are indicated with "???" on the following cladogram of the animal kingdom:

 

Animalia

Porifera

 

Ctenophora (comb jellies)[16] ???[17]

 

Cnidaria (includes jellyfish and other jellies)

 

Bilateria

Protostomia

 

Deuterostomia

Ambulacraria

 

Chordata

Tunicata (includes salps)[16] ???[18]

 

Vertebrata

 

Medusozoan jellyfish

Jellyfish are not a clade, as they include most of the Medusozoa, barring some of the Hydrozoa.[19][20] The medusozoan groups included by authorities are indicated on the following phylogenetic tree by the presence of citations. Names of included jellyfish, in English where possible, are shown in boldface; the presence of a named and cited example indicates that at least that species within its group has been called a jellyfish.

 

Cnidaria

Anthozoa (corals)

 

Polypodiozoa and Myxozoa (parasitic cnidarians)

 

Medusozoa

Acraspeda

Staurozoa (stalked jellyfish)[21]

 

Rhopaliophora

Cubozoa (box jellyfish)[16]

 

Scyphozoa

Discomedusae[16]

 

Coronatae (crown jellyfish)[22]

 

(true jellyfish[19])

Hydrozoa

Aplanulata

 

Siphonophorae

 

Some Leptothecata[16] e.g. crystal jelly

 

Filifera[16] e.g. red paper lantern jellyfish[23]

 

Trachylinae

Limnomedusae, e.g. flower hat jelly[16]

 

Narcomedusae, e.g. cosmic jellyfish[24]

 

Taxonomy

The subphylum Medusozoa includes all cnidarians with a medusa stage in their life cycle. The basic cycle is egg, planula larva, polyp, medusa, with the medusa being the sexual stage. The polyp stage is sometimes secondarily lost. The subphylum include the major taxa, Scyphozoa (large jellyfish), Cubozoa (box jellyfish) and Hydrozoa (small jellyfish), and excludes Anthozoa (corals and sea anemones).[25] This suggests that the medusa form evolved after the polyps.[26] Medusozoans have tetramerous symmetry, with parts in fours or multiples of four.[25]

 

The four major classes of medusozoan Cnidaria are:

 

Scyphozoa are sometimes called true jellyfish, though they are no more truly jellyfish than the others listed here. They have tetra-radial symmetry. Most have tentacles around the outer margin of the bowl-shaped bell, and long, oral arms around the mouth in the center of the subumbrella.[25]

Cubozoa (box jellyfish) have a (rounded) box-shaped bell, and their velarium assists them to swim more quickly. Box jellyfish may be related more closely to scyphozoan jellyfish than either are to the Hydrozoa.[26]

Hydrozoa medusae also have tetra-radial symmetry, nearly always have a velum (diaphragm used in swimming) attached just inside the bell margin, do not have oral arms, but a much smaller central stalk-like structure, the manubrium, with terminal mouth opening, and are distinguished by the absence of cells in the mesoglea. Hydrozoa show great diversity of lifestyle; some species maintain the polyp form for their entire life and do not form medusae at all (such as Hydra, which is hence not considered a jellyfish), and a few are entirely medusal and have no polyp form.[25]

Staurozoa (stalked jellyfish) are characterized by a medusa form that is generally sessile, oriented upside down and with a stalk emerging from the apex of the "calyx" (bell), which attaches to the substrate. At least some Staurozoa also have a polyp form that alternates with the medusoid portion of the life cycle. Until recently, Staurozoa were classified within the Scyphozoa.[25]

There are over 200 species of Scyphozoa, about 50 species of Staurozoa, about 50 species of Cubozoa, and the Hydrozoa includes about 1000–1500 species that produce medusae, but many more species that do not.[27][28]

 

Fossil history

 

Fossil jellyfish, Rhizostomites lithographicus, one of the Scypho-medusae, from the Kimmeridgian (late Jurassic, 157 to 152 mya) of Solnhofen, Germany

 

Stranded scyphozoans on a Cambrian tidal flat at Blackberry Hill, Wisconsin

 

The conulariid Conularia milwaukeensis from the Middle Devonian of Wisconsin

Since jellyfish have no hard parts, fossils are rare. The oldest unambiguous fossil of a free-swimming medusa is Burgessomedusa from the mid Cambrian Burgess Shale of Canada, which is likely either a stem group of box jellyfish (Cubozoa) or Acraspeda (the clade including Staurozoa, Cubozoa, and Scyphozoa). Other claimed records from the Cambrian of China and Utah in the United States are uncertain, and possibly represent ctenophores instead.[29]

 

Anatomy

 

Labelled cross section of a jellyfish

The main feature of a true jellyfish is the umbrella-shaped bell. This is a hollow structure consisting of a mass of transparent jelly-like matter known as mesoglea, which forms the hydrostatic skeleton of the animal.[25] 95% or more of the mesogloea consists of water,[30] but it also contains collagen and other fibrous proteins, as well as wandering amoebocytes which can engulf debris and bacteria. The mesogloea is bordered by the epidermis on the outside and the gastrodermis on the inside. The edge of the bell is often divided into rounded lobes known as lappets, which allow the bell to flex. In the gaps or niches between the lappets are dangling rudimentary sense organs known as rhopalia, and the margin of the bell often bears tentacles.[25]

  

Anatomy of a scyphozoan jellyfish

On the underside of the bell is the manubrium, a stalk-like structure hanging down from the centre, with the mouth, which also functions as the anus, at its tip. There are often four oral arms connected to the manubrium, streaming away into the water below.[31] The mouth opens into the gastrovascular cavity, where digestion takes place and nutrients are absorbed. This is subdivided by four thick septa into a central stomach and four gastric pockets. The four pairs of gonads are attached to the septa, and close to them four septal funnels open to the exterior, perhaps supplying good oxygenation to the gonads. Near the free edges of the septa, gastric filaments extend into the gastric cavity; these are armed with nematocysts and enzyme-producing cells and play a role in subduing and digesting the prey. In some scyphozoans, the gastric cavity is joined to radial canals which branch extensively and may join a marginal ring canal. Cilia in these canals circulate the fluid in a regular direction.[25]

  

Discharge mechanism of a nematocyst

The box jellyfish is largely similar in structure. It has a squarish, box-like bell. A short pedalium or stalk hangs from each of the four lower corners. One or more long, slender tentacles are attached to each pedalium.[32] The rim of the bell is folded inwards to form a shelf known as a velarium which restricts the bell's aperture and creates a powerful jet when the bell pulsates, allowing box jellyfish to swim faster than true jellyfish.[25] Hydrozoans are also similar, usually with just four tentacles at the edge of the bell, although many hydrozoans are colonial and may not have a free-living medusal stage. In some species, a non-detachable bud known as a gonophore is formed that contains a gonad but is missing many other medusal features such as tentacles and rhopalia.[25] Stalked jellyfish are attached to a solid surface by a basal disk, and resemble a polyp, the oral end of which has partially developed into a medusa with tentacle-bearing lobes and a central manubrium with four-sided mouth.[25]

 

Most jellyfish do not have specialized systems for osmoregulation, respiration and circulation, and do not have a central nervous system. Nematocysts, which deliver the sting, are located mostly on the tentacles; true jellyfish also have them around the mouth and stomach.[33] Jellyfish do not need a respiratory system because sufficient oxygen diffuses through the epidermis. They have limited control over their movement, but can navigate with the pulsations of the bell-like body; some species are active swimmers most of the time, while others largely drift.[34] The rhopalia contain rudimentary sense organs which are able to detect light, water-borne vibrations, odour and orientation.[25] A loose network of nerves called a "nerve net" is located in the epidermis.[35][36] Although traditionally thought not to have a central nervous system, nerve net concentration and ganglion-like structures could be considered to constitute one in most species.[37] A jellyfish detects stimuli, and transmits impulses both throughout the nerve net and around a circular nerve ring, to other nerve cells. The rhopalial ganglia contain pacemaker neurones which control swimming rate and direction.[25]

 

In many species of jellyfish, the rhopalia include ocelli, light-sensitive organs able to tell light from dark. These are generally pigment spot ocelli, which have some of their cells pigmented. The rhopalia are suspended on stalks with heavy crystals at one end, acting like gyroscopes to orient the eyes skyward. Certain jellyfish look upward at the mangrove canopy while making a daily migration from mangrove swamps into the open lagoon, where they feed, and back again.[2]

 

Box jellyfish have more advanced vision than the other groups. Each individual has 24 eyes, two of which are capable of seeing colour, and four parallel information processing areas that act in competition,[38] supposedly making them one of the few kinds of animal to have a 360-degree view of its environment.[39]

 

Box jellyfish eye

The study of jellyfish eye evolution is an intermediary to a better understanding of how visual systems evolved on Earth.[40] Jellyfish exhibit immense variation in visual systems ranging from photoreceptive cell patches seen in simple photoreceptive systems to more derived complex eyes seen in box jellyfish.[40] Major topics of jellyfish visual system research (with an emphasis on box jellyfish) include: the evolution of jellyfish vision from simple to complex visual systems), the eye morphology and molecular structures of box jellyfish (including comparisons to vertebrate eyes), and various uses of vision including task-guided behaviors and niche specialization.

 

Evolution

Experimental evidence for photosensitivity and photoreception in cnidarians antecedes the mid 1900s, and a rich body of research has since covered evolution of visual systems in jellyfish.[41] Jellyfish visual systems range from simple photoreceptive cells to complex image-forming eyes. More ancestral visual systems incorporate extraocular vision (vision without eyes) that encompass numerous receptors dedicated to single-function behaviors. More derived visual systems comprise perception that is capable of multiple task-guided behaviors.

 

Although they lack a true brain, cnidarian jellyfish have a "ring" nervous system that plays a significant role in motor and sensory activity. This net of nerves is responsible for muscle contraction and movement and culminates the emergence of photosensitive structures.[40] Across Cnidaria, there is large variation in the systems that underlie photosensitivity. Photosensitive structures range from non-specialized groups of cells, to more "conventional" eyes similar to those of vertebrates.[41] The general evolutionary steps to develop complex vision include (from more ancestral to more derived states): non-directional photoreception, directional photoreception, low-resolution vision, and high-resolution vision.[40] Increased habitat and task complexity has favored the high-resolution visual systems common in derived cnidarians such as box jellyfish.[40]

 

Basal visual systems observed in various cnidarians exhibit photosensitivity representative of a single task or behavior. Extraocular photoreception (a form of non-directional photoreception), is the most basic form of light sensitivity and guides a variety of behaviors among cnidarians. It can function to regulate circadian rhythm (as seen in eyeless hydrozoans) and other light-guided behaviors responsive to the intensity and spectrum of light. Extraocular photoreception can function additionally in positive phototaxis (in planula larvae of hydrozoans),[41] as well as in avoiding harmful amounts of UV radiation via negative phototaxis. Directional photoreception (the ability to perceive direction of incoming light) allows for more complex phototactic responses to light, and likely evolved by means of membrane stacking.[40] The resulting behavioral responses can range from guided spawning events timed by moonlight to shadow responses for potential predator avoidance.[41][42] Light-guided behaviors are observed in numerous scyphozoans including the common moon jelly, Aurelia aurita, which migrates in response to changes in ambient light and solar position even though they lack proper eyes.[41]

 

The low-resolution visual system of box jellyfish is more derived than directional photoreception, and thus box jellyfish vision represents the most basic form of true vision in which multiple directional photoreceptors combine to create the first imaging and spatial resolution. This is different from the high-resolution vision that is observed in camera or compound eyes of vertebrates and cephalopods that rely on focusing optics.[41] Critically, the visual systems of box jellyfish are responsible for guiding multiple tasks or behaviors in contrast to less derived visual systems in other jellyfish that guide single behavioral functions. These behaviors include phototaxis based on sunlight (positive) or shadows (negative), obstacle avoidance, and control of swim-pulse rate.[43]

 

Box jellyfish possess "proper eyes" (similar to vertebrates) that allow them to inhabit environments that lesser derived medusae cannot. In fact, they are considered the only class in the clade Medusozoa that have behaviors necessitating spatial resolution and genuine vision.[41] However, the lens in their eyes are more functionally similar to cup-eyes exhibited in low-resolution organisms, and have very little to no focusing capability.[44][43] The lack of the ability to focus is due to the focal length exceeding the distance to the retina, thus generating unfocused images and limiting spatial resolution.[41] The visual system is still sufficient for box jellyfish to produce an image to help with tasks such as object avoidance.

 

Utility as a model organism

Box jellyfish eyes are a visual system that is sophisticated in numerous ways. These intricacies include the considerable variation within the morphology of box jellyfishes' eyes (including their task/behavior specification), and the molecular makeup of their eyes including: photoreceptors, opsins, lenses, and synapses.[41] The comparison of these attributes to more derived visual systems can allow for a further understanding of how the evolution of more derived visual systems may have occurred, and puts into perspective how box jellyfish can play the role as an evolutionary/developmental model for all visual systems.[45]

 

Characteristics

Box jellyfish visual systems are both diverse and complex, comprising multiple photosystems.[41] There is likely considerable variation in visual properties between species of box jellyfish given the significant inter-species morphological and physiological variation. Eyes tend to differ in size and shape, along with number of receptors (including opsins), and physiology across species of box jellyfish.[41]

 

Box jellyfish have a series of intricate lensed eyes that are similar to those of more derived multicellular organisms such as vertebrates. Their 24 eyes fit into four different morphological categories.[46] These categories consist of two large, morphologically different medial eyes (a lower and upper lensed eye) containing spherical lenses, a lateral pair of pigment slit eyes, and a lateral pair of pigment pit eyes.[43] The eyes are situated on rhopalia (small sensory structures) which serve sensory functions of the box jellyfish and arise from the cavities of the exumbrella (the surface of the body) on the side of the bells of the jellyfish.[41] The two large eyes are located on the mid-line of the club and are considered complex because they contain lenses. The four remaining eyes lie laterally on either side of each rhopalia and are considered simple. The simple eyes are observed as small invaginated cups of epithelium that have developed pigmentation.[47] The larger of the complex eyes contains a cellular cornea created by a mono ciliated epithelium, cellular lens, homogenous capsule to the lens, vitreous body with prismatic elements, and a retina of pigmented cells. The smaller of the complex eyes is said to be slightly less complex given that it lacks a capsule but otherwise contains the same structure as the larger eye.[47]

 

Box jellyfish have multiple photosystems that comprise different sets of eyes.[41] Evidence includes immunocytochemical and molecular data that show photopigment differences among the different morphological eye types, and physiological experiments done on box jellyfish to suggest behavioral differences among photosystems. Each individual eye type constitutes photosystems that work collectively to control visually guided behaviors.[41]

 

Box jellyfish eyes primarily use c-PRCs (ciliary photoreceptor cells) similar to that of vertebrate eyes. These cells undergo phototransduction cascades (process of light absorption by photoreceptors) that are triggered by c-opsins.[48] Available opsin sequences suggest that there are two types of opsins possessed by all cnidarians including an ancient phylogenetic opsin, and a sister ciliary opsin to the c-opsins group. Box jellyfish could have both ciliary and cnidops (cnidarian opsins), which is something not previously believed to appear in the same retina.[41] Nevertheless, it is not entirely evident whether cnidarians possess multiple opsins that are capable of having distinctive spectral sensitivities.[41]

 

Comparison with other organisms

Comparative research on genetic and molecular makeup of box jellyfishes' eyes versus more derived eyes seen in vertebrates and cephalopods focuses on: lenses and crystallin composition, synapses, and Pax genes and their implied evidence for shared primordial (ancestral) genes in eye evolution.[49]

 

Box jellyfish eyes are said to be an evolutionary/developmental model of all eyes based on their evolutionary recruitment of crystallins and Pax genes.[45] Research done on box jellyfish including Tripedalia cystophora has suggested that they possess a single Pax gene, PaxB. PaxB functions by binding to crystallin promoters and activating them. PaxB in situ hybridization resulted in PaxB expression in the lens, retina, and statocysts.[45] These results and the rejection of the prior hypothesis that Pax6 was an ancestral Pax gene in eyes has led to the conclusion that PaxB was a primordial gene in eye evolution, and that the eyes of all organisms likely share a common ancestor.[45]

 

The lens structure of box jellyfish appears very similar to those of other organisms, but the crystallins are distinct in both function and appearance.[49] Weak reactions were seen within the sera and there were very weak sequence similarities within the crystallins among vertebrate and invertebrate lenses.[49] This is likely due to differences in lower molecular weight proteins and the subsequent lack of immunological reactions with antisera that other organisms' lenses exhibit.[49]

 

All four of the visual systems of box jellyfish species investigated with detail (Carybdea marsupialis, Chiropsalmus quadrumanus, Tamoya haplonema and Tripedalia cystophora) have invaginated synapses, but only in the upper and lower lensed eyes. Different densities were found between the upper and lower lenses, and between species.[46] Four types of chemical synapses have been discovered within the rhopalia which could help in understanding neural organization including: clear unidirectional, dense-core unidirectional, clear bidirectional, and clear and dense-core bidirectional. The synapses of the lensed eyes could be useful as markers to learn more about the neural circuit in box jellyfish retinal areas.[46]

 

Evolution as a response to natural stimuli

The primary adaptive responses to environmental variation observed in box jellyfish eyes include pupillary constriction speeds in response to light environments, as well as photoreceptor tuning and lens adaptations to better respond to shifts between light environments and darkness. Interestingly, some box jellyfish species' eyes appear to have evolved more focused vision in response to their habitat.[50]

 

Pupillary contraction appears to have evolved in response to variation in the light environment across ecological niches across three species of box jellyfish (Chironex fleckeri, Chiropsella bronzie, and Carukia barnesi). Behavioral studies suggest that faster pupil contraction rates allow for greater object avoidance,[50] and in fact, species with more complex habitats exhibit faster rates. Ch. bronzie inhabit shallow beach fronts that have low visibility and very few obstacles, thus, faster pupil contraction in response to objects in their environment is not important. Ca. barnesi and Ch. fleckeri are found in more three-dimensionally complex environments like mangroves with an abundance of natural obstacles, where faster pupil contraction is more adaptive.[50] Behavioral studies support the idea that faster pupillary contraction rates assist with obstacle avoidance as well as depth adjustments in response to differing light intensities.

 

Light/dark adaptation via pupillary light reflexes is an additional form of an evolutionary response to the light environment. This relates to the pupil's response to shifts between light intensity (generally from sunlight to darkness). In the process of light/dark adaptation, the upper and lower lens eyes of different box jellyfish species vary in specific function.[43] The lower lens-eyes contain pigmented photoreceptors and long pigment cells with dark pigments that migrate on light/dark adaptation, while the upper-lens eyes play a concentrated role in light direction and phototaxis given that they face upward towards the water surface (towards the sun or moon).[43] The upper lens of Ch. bronzie does not exhibit any considerable optical power while Tr. cystophora (a box jellyfish species that tends to live in mangroves) does. The ability to use light to visually guide behavior is not of as much importance to Ch. bronzie as it is to species in more obstacle-filled environments.[43] Differences in visually guided behavior serve as evidence that species that share the same number and structure of eyes can exhibit differences in how they control behavior.

 

Largest and smallest

Jellyfish range from about one millimeter in bell height and diameter,[51] to nearly 2 metres (6+1⁄2 ft) in bell height and diameter; the tentacles and mouth parts usually extend beyond this bell dimension.[25]

 

The smallest jellyfish are the peculiar creeping jellyfish in the genera Staurocladia and Eleutheria, which have bell disks from 0.5 millimetres (1⁄32 in) to a few millimeters in diameter, with short tentacles that extend out beyond this, which these jellyfish use to move across the surface of seaweed or the bottoms of rocky pools;[51] many of these tiny creeping jellyfish cannot be seen in the field without a hand lens or microscope. They can reproduce asexually by fission (splitting in half). Other very small jellyfish, which have bells about one millimeter, are the hydromedusae of many species that have just been released from their parent polyps;[52] some of these live only a few minutes before shedding their gametes in the plankton and then dying, while others will grow in the plankton for weeks or months. The hydromedusae Cladonema radiatum and Cladonema californicum are also very small, living for months, yet never growing beyond a few mm in bell height and diameter.[53]

  

The lion's mane jellyfish (Cyanea capillata) is one of the largest species.

The lion's mane jellyfish, Cyanea capillata, was long-cited as the largest jellyfish, and arguably the longest animal in the world, with fine, thread-like tentacles that may extend up to 36.5 m (119 ft 9 in) long (though most are nowhere near that large).[54][55] They have a moderately painful, but rarely fatal, sting.[56] The increasingly common giant Nomura's jellyfish, Nemopilema nomurai, found in some, but not all years in the waters of Japan, Korea and China in summer and autumn is another candidate for "largest jellyfish", in terms of diameter and weight, since the largest Nomura's jellyfish in late autumn can reach 2 m (6 ft 7 in) in bell (body) diameter and about 200 kg (440 lb) in weight, with average specimens frequently reaching 0.9 m (2 ft 11 in) in bell diameter and about 150 kg (330 lb) in weight.[57][58] The large bell mass of the giant Nomura's jellyfish[59] can dwarf a diver and is nearly always much greater than the Lion's Mane, whose bell diameter can reach 1 m (3 ft 3 in).[60]

 

The rarely encountered deep-sea jellyfish Stygiomedusa gigantea is another candidate for "largest jellyfish", with its thick, massive bell up to 100 cm (3 ft 3 in) wide, and four thick, "strap-like" oral arms extending up to 6 m (19+1⁄2 ft) in length, very different from the typical fine, threadlike tentacles that rim the umbrella of more-typical-looking jellyfish, including the Lion's Mane.[61]

 

Desmonema glaciale, which lives in the Antarctic region, can reach a very large size (several meters).[62][63] Purple-striped jelly (Chrysaora colorata) can also be extremely long (up to 15 feet).[64]

 

Life history and behavior

See also: Biological life cycle and Developmental biology

Illustration of two life stages of seven jelly species

The developmental stages of scyphozoan jellyfish's life cycle:

1–3 Larva searches for site

4–8 Polyp grows

9–11 Polyp strobilates

12–14 Medusa grows

Life cycle

Jellyfish have a complex life cycle which includes both sexual and asexual phases, with the medusa being the sexual stage in most instances. Sperm fertilize eggs, which develop into larval planulae, become polyps, bud into ephyrae and then transform into adult medusae. In some species certain stages may be skipped.[65]

 

Upon reaching adult size, jellyfish spawn regularly if there is a sufficient supply of food. In most species, spawning is controlled by light, with all individuals spawning at about the same time of day; in many instances this is at dawn or dusk.[66] Jellyfish are usually either male or female (with occasional hermaphrodites). In most cases, adults release sperm and eggs into the surrounding water, where the unprotected eggs are fertilized and develop into larvae. In a few species, the sperm swim into the female's mouth, fertilizing the eggs within her body, where they remain during early development stages. In moon jellies, the eggs lodge in pits on the oral arms, which form a temporary brood chamber for the developing planula larvae.[67]

 

The planula is a small larva covered with cilia. When sufficiently developed, it settles onto a firm surface and develops into a polyp. The polyp generally consists of a small stalk topped by a mouth that is ringed by upward-facing tentacles. The polyps resemble those of closely related anthozoans, such as sea anemones and corals. The jellyfish polyp may be sessile, living on the bottom, boat hulls or other substrates, or it may be free-floating or attached to tiny bits of free-living plankton[68] or rarely, fish[69][70] or other invertebrates. Polyps may be solitary or colonial.[71] Most polyps are only millimetres in diameter and feed continuously. The polyp stage may last for years.[25]

 

After an interval and stimulated by seasonal or hormonal changes, the polyp may begin reproducing asexually by budding and, in the Scyphozoa, is called a segmenting polyp, or a scyphistoma. Budding produces more scyphistomae and also ephyrae.[25] Budding sites vary by species; from the tentacle bulbs, the manubrium (above the mouth), or the gonads of hydromedusae.[68] In a process known as strobilation, the polyp's tentacles are reabsorbed and the body starts to narrow, forming transverse constrictions, in several places near the upper extremity of the polyp. These deepen as the constriction sites migrate down the body, and separate segments known as ephyra detach. These are free-swimming precursors of the adult medusa stage, which is the life stage that is typically identified as a jellyfish.[25][72] The ephyrae, usually only a millimeter or two across initially, swim away from the polyp and grow. Limnomedusae polyps can asexually produce a creeping frustule larval form, which crawls away before developing into another polyp.[25] A few species can produce new medusae by budding directly from the medusan stage. Some hydromedusae reproduce by fission.[68]

 

Lifespan

Little is known of the life histories of many jellyfish as the places on the seabed where the benthic forms of those species live have not been found. However, an asexually reproducing strobila form can sometimes live for several years, producing new medusae (ephyra larvae) each year.[73]

 

An unusual species, Turritopsis dohrnii, formerly classified as Turritopsis nutricula,[74] might be effectively immortal because of its ability under certain circumstances to transform from medusa back to the polyp stage, thereby escaping the death that typically awaits medusae post-reproduction if they have not otherwise been eaten by some other organism. So far this reversal has been observed only in the laboratory.[75]

 

Locomotion

 

Jellyfish locomotion is highly efficient. Muscles in the jellylike bell contract, setting up a start vortex and propelling the animal. When the contraction ends, the bell recoils elastically, creating a stop vortex with no extra energy input.

Using the moon jelly Aurelia aurita as an example, jellyfish have been shown to be the most energy-efficient swimmers of all animals.[76] They move through the water by radially expanding and contracting their bell-shaped bodies to push water behind them. They pause between the contraction and expansion phases to create two vortex rings. Muscles are used for the contraction of the body, which creates the first vortex and pushes the animal forward, but the mesoglea is so elastic that the expansion is powered exclusively by relaxing the bell, which releases the energy stored from the contraction. Meanwhile, the second vortex ring starts to spin faster, sucking water into the bell and pushing against the centre of the body, giving a secondary and "free" boost forward. The mechanism, called passive energy recapture, only works in relatively small jellyfish moving at low speeds, allowing the animal to travel 30 percent farther on each swimming cycle. Jellyfish achieved a 48 percent lower cost of transport (food and oxygen intake versus energy spent in movement) than other animals in similar studies. One reason for this is that most of the gelatinous tissue of the bell is inactive, using no energy during swimming.[77]

 

Ecology

Diet

Jellyfish are, like other cnidarians, generally carnivorous (or parasitic),[78] feeding on planktonic organisms, crustaceans, small fish, fish eggs and larvae, and other jellyfish, ingesting food and voiding undigested waste through the mouth. They hunt passively using their tentacles as drift lines, or sink through the water with their tentacles spread widely; the tentacles, which contain nematocysts to stun or kill the prey, may then flex to help bring it to the mouth.[25] Their swimming technique also helps them to capture prey; when their bell expands it sucks in water which brings more potential prey within reach of the tentacles.[79]

 

A few species such as Aglaura hemistoma are omnivorous, feeding on microplankton which is a mixture of zooplankton and phytoplankton (microscopic plants) such as dinoflagellates.[80] Others harbour mutualistic algae (Zooxanthellae) in their tissues;[25] the spotted jellyfish (Mastigias papua) is typical of these, deriving part of its nutrition from the products of photosynthesis, and part from captured zooplankton.[81][82] The upside-down jellyfish (Cassiopea andromeda) also has a symbiotic relationship with microalgae, but captures tiny animals to supplement their diet. This is done by releasing tiny balls of living cells composed of mesoglea. These use cilia to drive them through water and stinging cells which stun the prey. The blobs also seems to have digestive capabilities.[83]

 

Predation

Other species of jellyfish are among the most common and important jellyfish predators. Sea anemones may eat jellyfish that drift into their range. Other predators include tunas, sharks, swordfish, sea turtles and penguins.[84][85] Jellyfish washed up on the beach are consumed by foxes, other terrestrial mammals and birds.[86] In general however, few animals prey on jellyfish; they can broadly be considered to be top predators in the food chain. Once jellyfish have become dominant in an ecosystem, for example through overfishing which removes predators of jellyfish larvae, there may be no obvious way for the previous balance to be restored: they eat fish eggs and juvenile fish, and compete with fish for food, preventing fish stocks from recovering.[87]

 

Symbiosis

Some small fish are immune to the stings of the jellyfish and live among the tentacles, serving as bait in a fish trap; they are safe from potential predators and are able to share the fish caught by the jellyfish.[88] The cannonball jellyfish has a symbiotic relationship with ten different species of fish, and with the longnose spider crab, which lives inside the bell, sharing the jellyfish's food and nibbling its tissues.[89]

 

Blooms

Main article: Jellyfish bloom

 

Map of population trends of native and invasive jellyfish.[90]

Circles represent data records; larger circles denote higher certainty of findings.

Increase (high certainty)

Increase (low certainty)

Stable/variable

Decrease

No data

Jellyfish form large masses or blooms in certain environmental conditions of ocean currents, nutrients, sunshine, temperature, season, prey availability, reduced predation and oxygen concentration. Currents collect jellyfish together, especially in years with unusually high populations. Jellyfish can detect marine currents and swim against the current to congregate in blooms.[91][92] Jellyfish are better able to survive in nutrient-rich, oxygen-poor water than competitors, and thus can feast on plankton without competition. Jellyfish may also benefit from saltier waters, as saltier waters contain more iodine, which is necessary for polyps to turn into jellyfish. Rising sea temperatures caused by climate change may also contribute to jellyfish blooms, because many species of jellyfish are able to survive in warmer waters.[93] Increased nutrients from agricultural or urban runoff with nutrients including nitrogen and phosphorus compounds increase the growth of phytoplankton, causing eutrophication and algal blooms. When the phytoplankton die, they may create dead zones, so-called because they are hypoxic (low in oxygen). This in turn kills fish and other animals, but not jellyfish,[94] allowing them to bloom.[95][96] Jellyfish populations may be expanding globally as a result of land runoff and overfishing of their natural predators.[97][98] Jellyfish are well placed to benefit from disturbance of marine ecosystems. They reproduce rapidly; they prey upon many species, while few species prey on them; and they feed via touch rather than visually, so they can feed effectively at night and in turbid waters.[99][100] It may be difficult for fish stocks to re-establish themselves in marine ecosystems once they have become dominated by jellyfish, because jellyfish feed on plankton, which includes fish eggs and larvae.[101][102][96]

  

Moon jellyfishes can live in northern hemisphere seas,[103][104] such as the Baltic Sea.[105][106]

As suspected at the turn of this century, [107][108] jellyfish blooms are increasing in frequency. Between 2013 and 2020 the Mediterranean Science Commission monitored on a weekly basis the frequency of such outbreaks in coastal waters from Morocco to the Black Sea, revealing a relatively high frequency of these blooms nearly all year round, with peaks observed from March to July and often again in the autumn. The blooms are caused by different jellyfish species, depending on their localisation within the Basin: one observes a clear dominance of Pelagia noctiluca and Velella velella outbreaks in the western Mediterranean, of Rhizostoma pulmo and Rhopilema nomadica outbreaks in the eastern Mediterranean, and of Aurelia aurita and Mnemiopsis leidyi outbreaks in the Black Sea.[109]

 

Some jellyfish populations that have shown clear increases in the past few decades are invasive species, newly arrived from other habitats: examples include the Black Sea, Caspian Sea, Baltic Sea, central and eastern Mediterranean, Hawaii, and tropical and subtropical parts of the West Atlantic (including the Caribbean, Gulf of Mexico and Brazil).[105][106]

 

Jellyfish blooms can have significant impact on community structure. Some carnivorous jellyfish species prey on zooplankton while others graze on primary producers.[110] Reductions in zooplankton and ichthyoplankton due to a jellyfish bloom can ripple through the trophic levels. High-density jellyfish populations can outcompete other predators and reduce fish recruitment.[111] Increased grazing on primary producers by jellyfish can also interrupt energy transfer to higher trophic levels.[112]

 

During blooms, jellyfish significantly alter the nutrient availability in their environment. Blooms require large amounts of available organic nutrients in the water column to grow, limiting availability for other organisms.[113] Some jellyfish have a symbiotic relationship with single-celled dinoflagellates, allowing them to assimilate inorganic carbon, phosphorus, and nitrogen creating competition for phytoplankton.[113] Their large biomass makes them an important source of dissolved and particulate organic matter for microbial communities through excretion, mucus production, and decomposition.[90][114] The microbes break down the organic matter into inorganic ammonium and phosphate. However, the low carbon availability shifts the process from production to respiration creating low oxygen areas making the dissolved inorganic nitrogen and phosphorus largely unavailable for primary production.

 

These blooms have very real impacts on industries. Jellyfish can outcompete fish by utilizing open niches in over-fished fisheries.[115] Catch of jellyfish can strain fishing gear and lead to expenses relating to damaged gear. Power plants have been shut down due to jellyfish blocking the flow of cooling water.[116] Blooms have also been harmful for tourism, causing a rise in stings and sometimes the closure of beaches.[117]

 

Jellyfish form a component of jelly-falls, events where gelatinous zooplankton fall to the seafloor, providing food for the benthic organisms there.[118] In temperate and subpolar regions, jelly-falls usually follow immediately after a bloom.[119]

 

Habitats

 

A common Scyphozoan jellyfish seen near beaches in the Florida Panhandle

Most jellyfish are marine animals, although a few hydromedusae inhabit freshwater. The best known freshwater example is the cosmopolitan hydrozoan jellyfish, Craspedacusta sowerbii. It is less than an inch (2.5 cm) in diameter, colorless and does not sting.[120] Some jellyfish populations have become restricted to coastal saltwater lakes, such as Jellyfish Lake in Palau.[121] Jellyfish Lake is a marine lake where millions of golden jellyfish (Mastigias spp.) migrate horizontally across the lake daily.[82]

 

Although most jellyfish live well off the ocean floor and form part of the plankton, a few species are closely associated with the bottom for much of their lives and can be considered benthic. The upside-down jellyfish in the genus Cassiopea typically lie on the bottom of shallow lagoons where they sometimes pulsate gently with their umbrella top facing down. Even some deep-sea species of hydromedusae and scyphomedusae are usually collected on or near the bottom. All of the stauromedusae are found attached to either seaweed or rocky or other firm material on the bottom.[122]

 

Some species explicitly adapt to tidal flux. In Roscoe Bay, jellyfish ride the current at ebb tide until they hit a gravel bar, and then descend below the current. They remain in still waters until the tide rises, ascending and allowing it to sweep them back into the bay. They also actively avoid fresh water from mountain snowmelt, diving until they find enough salt.

  

Parasites

Jellyfish are hosts to a wide variety of parasitic organisms. They act as intermediate hosts of endoparasitic helminths, with the infection being transferred to the definitive host fish after predation. Some digenean trematodes, especially species in the family Lepocreadiidae, use jellyfish as their second intermediate hosts. Fish become infected by the trematodes when they feed on infected jellyfish.

 

Relation to humans

Jellyfish have long been eaten in some parts of the world. Fisheries have begun harvesting the American cannonball jellyfish, Stomolophus meleagris, along the southern Atlantic coast of the United States and in the Gulf of Mexico for export to Asia.

 

Jellyfish are also harvested for their collagen, which is being investigated for use in a variety of applications including the treatment of rheumatoid arthritis.

 

Aquaculture and fisheries of other species often suffer severe losses – and so losses of productivity – due to jellyfish.

 

Products

Main article: Jellyfish as food

In some countries, including China, Japan, and Korea, jellyfish are a delicacy. The jellyfish is dried to prevent spoiling. Only some 12 species of scyphozoan jellyfish belonging to the order Rhizostomeae are harvested for food, mostly in southeast Asia. Rhizostomes, especially Rhopilema esculentum in China (海蜇 hǎizhé, 'sea stingers') and Stomolophus meleagris (cannonball jellyfish) in the United States, are favored because of their larger and more rigid bodies and because their toxins are harmless to humans.

 

Traditional processing methods, carried out by a jellyfish master, involve a 20- to 40-day multi-phase procedure in which, after removing the gonads and mucous membranes, the umbrella and oral arms are treated with a mixture of table salt and alum, and compressed. Processing makes the jellyfish drier and more acidic, producing a crisp texture. Jellyfish prepared this way retain 7–10% of their original weight, and the processed product consists of approximately 94% water and 6% protein. Freshly processed jellyfish has a white, creamy color and turns yellow or brown during prolonged storage.

 

In China, processed jellyfish are desalted by soaking in water overnight and eaten cooked or raw. The dish is often served shredded with a dressing of oil, soy sauce, vinegar and sugar, or as a salad with vegetables. In Japan, cured jellyfish are rinsed, cut into strips and served with vinegar as an appetizer. Desalted, ready-to-eat products are also available.

 

Biotechnology

The hydromedusa Aequorea victoria was the source of green fluorescent protein, studied for its role in bioluminescence and later for use as a marker in genetic engineering.

Pliny the Elder reported in his Natural History that the slime of the jellyfish "Pulmo marinus" produced light when rubbed on a walking stick.

 

In 1961, Osamu Shimomura extracted green fluorescent protein (GFP) and another bioluminescent protein, called aequorin, from the large and abundant hydromedusa Aequorea victoria, while studying photoproteins that cause bioluminescence in this species. Three decades later, Douglas Prasher sequenced and cloned the gene for GFP. Martin Chalfie figured out how to use GFP as a fluorescent marker of genes inserted into other cells or organisms. Roger Tsien later chemically manipulated GFP to produce other fluorescent colors to use as markers. In 2008, Shimomura, Chalfie and Tsien won the Nobel Prize in Chemistry for their work with GFP. Man-made GFP became widely used as a fluorescent tag to show which cells or tissues express specific genes. The genetic engineering technique fuses the gene of interest to the GFP gene. The fused DNA is then put into a cell, to generate either a cell line or (via IVF techniques) an entire animal bearing the gene. In the cell or animal, the artificial gene turns on in the same tissues and the same time as the normal gene, making a fusion of the normal protein with GFP attached to the end, illuminating the animal or cell reveals what tissues express that protein—or at what stage of development. The fluorescence shows where the gene is expressed.

 

Aquarium display

Jellyfish are displayed in many public aquariums. Often the tank's background is blue and the animals are illuminated by side light, increasing the contrast between the animal and the background. In natural conditions, many jellies are so transparent that they are nearly invisible. Jellyfish are not adapted to closed spaces. They depend on currents to transport them from place to place. Professional exhibits as in the Monterey Bay Aquarium feature precise water flows, typically in circular tanks to avoid trapping specimens in corners. The outflow is spread out over a large surface area and the inflow enters as a sheet of water in front of the outflow, so the jellyfish do not get sucked into it. As of 2009, jellyfish were becoming popular in home aquariums, where they require similar equipment.

 

Stings

Jellyfish are armed with nematocysts, a type of specialized stinging cell. Contact with a jellyfish tentacle can trigger millions of nematocysts to pierce the skin and inject venom, but only some species' venom causes an adverse reaction in humans. In a study published in Communications Biology, researchers found a jellyfish species called Cassiopea xamachana which when triggered will release tiny balls of cells that swim around the jellyfish stinging everything in their path. Researchers described these as "self-propelling microscopic grenades" and named them cassiosomes.

 

The effects of stings range from mild discomfort to extreme pain and death. Most jellyfish stings are not deadly, but stings of some box jellyfish (Irukandji jellyfish), such as the sea wasp, can be deadly. Stings may cause anaphylaxis (a form of shock), which can be fatal. Jellyfish kill 20 to 40 people a year in the Philippines alone. In 2006 the Spanish Red Cross treated 19,000 stung swimmers along the Costa Brava.

 

Vinegar (3–10% aqueous acetic acid) may help with box jellyfish stings but not the stings of the Portuguese man o' war. Clearing the area of jelly and tentacles reduces nematocyst firing. Scraping the affected skin, such as with the edge of a credit card, may remove remaining nematocysts. Once the skin has been cleaned of nematocysts, hydrocortisone cream applied locally reduces pain and inflammation. Antihistamines may help to control itching. Immunobased antivenins are used for serious box jellyfish stings.

 

In Elba Island and Corsica dittrichia viscosa is now used by residents and tourists to heal stings from jellyfish, bees and wasps pressing fresh leaves on the skin with quick results.

 

Mechanical issues

Jellyfish in large quantities can fill and split fishing nets and crush captured fish. They can clog cooling equipment, having disabled power stations in several countries; jellyfish caused a cascading blackout in the Philippines in 1999, as well as damaging the Diablo Canyon Power Plant in California in 2008. They can also stop desalination plants and ships' engines.

Cosmos bipinnatus, commonly called the garden cosmos or Mexican aster, is a medium-sized flowering herbaceous plant in the daisy family Asteraceae, native to the Americas. The species and its varieties and cultivars are popular as ornamental plants in temperate climate gardens.

 

Description

In natural habitat

Cosmos bipinnatus is an annual that is often considered half-hardy, although plants may reappear via self-sowing for several years. The plant height varies from 2–6 ft to (rarely) 9 ft (0.61–1.83–2.74 m). The cultivated varieties appear in shades of pink and purple as well as white. The branched stem is usually densely to occasionally occupied by fine, split up, rough trichomes, some specimens are completely hairless. The petiole itself is inconspicuous, winged, 10 (rarely to 15) mm long, sometimes the leaves are almost sessile.

 

The partial leaves are linear-filiform to narrow linear with a width of 0.5 to 1 (rarely to 1.7) mm; the tips are pointed, hardened, but not particularly sharp. Its foliage is finely cut into threadlike segments. When flowering, the plant can become top heavy. This problem is alleviated when grown in groups, as the bipinnate leaves interlock, and the colony supports itself.

 

The achenes become blackish, are smooth or short-bristly. Their shape is spindle-like. They are rounded off into a short, 0.5 to 1.7 mm long, but distinctly pronounced rostrum. The inner achenes are up to 18 mm long, their yellowish beaks are 4 to 5 (rarely to 10) mm long. A pappus is missing or it consists only of two to three awn-like, 1-3 mm large bristles.

 

Flowers

The very conspicuous cup-shaped inflorescences have a diameter of usually 5–7 cm (2.0–2.8 in) and contain tongue and tubular flowers, which are surrounded by bracts. There are usually 8 outer bracts, and they are ovate to lanceolate-tail-shaped, 7-15 mm long, 3-5 mm wide. The inner bracts are ovate-lanceolate and 8-12 mm long. They are translucent with many black stripes and a clear edge up to 1 mm wide, sometimes with yellowish or pink pigments, the tip is ciliate. The sprout leaves have gold-yellow, thread-like tips and protrude between the tubular flowers. The broadened base of these spreader leaves is translucent, provided with a yellow line. During flowering, the plant can sag under its weight. This problem can be solved by grouping the feet together so that the leaves hang together.

 

The mostly eight ray florets are pink to violet or white colored, at the base may show noticeable stains caused by anthocyanin. The tongues are reversely ovate shaped, have a length of usually 20-35 mm and a width of usually 12-20 mm. The tips are almost dull and have three broad, wavy teeth. Below that, they are greatly rejuvenated. In the center of the flower baskets is a large number of tubular flowers (also called disc florets), whose overgrown petals are yellow, turn white in the lower part and reach a length of 5-6 mm. The anthers are brownish-black and about 3 mm long, at the tips are short-triangular, translucent attachments with a length of 0.5-0.8 mm. The branches of the stylus are short and rather dull, with a length of .5 mm.

 

Distribution

This plant is native to Mexico, Guatemala and Costa Rica. Since it is used as an ornamental plant in many countries and prone to sedimentation, it is an invasive plant in many areas of the world. It has naturalized in scattered locations across North America, South America, the West Indies, Italy, Australia, and Asia, where it is a garden escape (introduced species) and in some habitats becoming a weed.

 

Cultivars

Cultivars of Cosmos bipinnatus in cultivation today include:

Apollo Series

'Apollo Carmine' agm

'Apollo Pink' agm

'Apollo White' agm

'Daydream' features a pink inner ring on a white background

Double Click Series features semidouble to fully double flowers that resemble Japanese anemones (Anemone japonica)

'Double Click Cranberries'

'Double Click Rose Bonbon'

'Double Click Snow Puff'

'Double Click Vari Extra'

'Rubenza' agm

'Sensation', also known as 'Early Sensation', is a widely available mix of tall varieties

'Sensation Pinkie' agm

Sonata series

'Velouette'agm

'Versailles', developed for the cut flower trade, are shorter than the species, with heights remaining below three feet

'Versailles Dark Rose'

'Vesailles Tetra'

(those marked agm have gained the Royal Horticultural Society's Award of Garden Merit).

 

Cultivation

Germination takes between 7 and 10 days at the optimal temperature of 75 °F (24 °C); flowering begins between 60 and 90 days after germination

It prefers a soil pH between 6.0 and 8.5, reflecting its native habitat in the alkaline regions of Central America

Flowering is best in full sun, although partial shade is tolerated

Excessive rain can cause cultivation problems, due to the delicate nature of the stems. Heavy rain can cause breakage. Cosmos bipinnatus can tolerate heat as long as adequate moisture is provided, however, it does not handle droughts, strong winds or cold temperatures well. Snails, slugs and aphids have a taste for Cosmos bipinnatus. Successfully cultivated plants can mature 2 to 4 feet (0.61 to 1.22 m) x 12 to 18 inches (300 to 460 mm).

 

They are not tolerant of frost, but can be grown outdoors in a temperate climate with a warm to hot summer and are therefore called half-hardy in British gardening literature.

Pollinators

The flowers of Cosmos bipinnatus attract birds and butterflies, including the monarch butterfly. It can be part of butterfly gardening and pollinator/honey-bee habitat gardens.

I didn't see the silk spider's strand when i took the photo...

 

Article 1:

Hesperaloe parviflora

From Wikipedia, the free encyclopedia

 

Scientific Classification

Kingdom:Plantae

Clade:Angiosperms

Clade:Monocots

Order:Asparagales

Family:Asparagaceae

Subfamily:Agavoideae

Genus:Hesperaloe

Species:H. parviflora

Binomial name

Hesperaloe parviflora

(Torr.) J.M.Coult.

Synonyms

Yucca parviflora Torr.[1]

  

Hesperaloe parviflora flowers

Hesperaloe parviflora, also known as red yucca, hummingbird yucca, redflower false yucca and samandoque, is a plant that is native to Chihuahuan desert of west Texas east and south into central and south Texas and northeastern Mexico around Coahuila.[2]

 

Hesperaloe parviflora has narrow evergreen leaves with a fringe of white threadlike hairs along their edges and grows in clumps 3–6 ft (0.91–1.83 m) high and wide. Red or yellow tubular flowers are borne on branching flower stalks (inflorescences) up to 5 ft (1.5 m) tall from late spring to mid-summer.[3]

 

This species has become popular in xeriscape landscape design for public and private gardens in California and the Southwestern United States. The plant's qualities include drought tolerance, heat resistance, low maintenance needs, hummingbird attracting flowers,[4] and an architectural form. It also is a spineless alternative to Agave and Yucca horticultural species.[5]

_______________________________________________

Article 2:

ag.arizona.edu/yavapai/anr/hort/byg/archive/hesperaloe.html

 

Red Yucca: Drought Tolerant and Colorful - July 24, 2002

Jeff Schalau, County Director, Agent, Agriculture & Natural Resources

Arizona Cooperative Extension, Yavapai County

 

From time to time, I write about a particularly interesting and locally suitable landscape plant. Red yucca (Hesperaloe parviflora) is a no-brainer for north central Arizona. Red yucca is native to southwestern Texas and Coahuila, Mexico making it very fit to our local climate/environment. Better yet, once established, they are virtually maintenance free.

 

Red yucca somewhat resembles true yucca with linear leaves arising from the base and flower stalks rising above the leaves. Red yucca, however, produces several pups (new plants formed adjacent to the parent plant) and has finer leaves than true yucca giving it a more grass-like appearance. The serrated leaves are about 1 ½ to 2 feet long and a mature plant can be about 3 feet across.

 

The "red" in red yucca refers to the flower color. This is misleading because there is also a yellow flowered variety available. Both are well suited. Red yucca produces several flower stalks each year, having abundant tubular flowers that bloom in spring and extend well into summer. The flower stalks can grow up to 9 feet high, but most I've seen are 3- 5 feet high. Hummingbirds are also attracted to the flowers.

 

After flowering, do not remove the flower stalks. Rather, leave them be to produce fruit. After opening, seeds are a food source for birds or can be used to start new plants. New plants can also be started by dividing established clumps or removing individual pups.

 

Red yucca loves the heat and is ideally suited to the Verde Valley. It can tolerate cold temperatures down to 10 degrees F. I have seen it doing well in Prescott, so it must tolerate the cold fairly well.

 

Plant red yucca in full sun where it has room to grow without needing to be trimmed back. Nothing is worse than seeing one of these plants mowed, or worse yet, shredded by a weed eater. So, place the plants 2 to 3 feet away from sidewalks, walkways, or driveways. After planting from a nursery container, provide ample irrigation for the first year taking care not to over water. After the first year, they should do nicely on native rainfall or with infrequent irrigation during extended droughts.

 

Maintenance is easy. On established plants, the older leaves eventually will die and lay on the ground. These can be cut off individually to create a neater appearance. This and removing dead flower stalks are the only maintenance practices needed.

 

Red yuccas are drought adapted plants and should be planted in conjunction with plant having similar irrigation requirements. They are equally attractive when planted with cacti and succulents or with leafy plants such as Mexican primrose, brittlebush, Penstemon, or annual wildflowers.

 

As usual, now it is time to provide you with some trivial, little known, and possibly useless factoid. A close relative of red yucca (Hesperaloe funifera) is being tested as a crop plant by University of Arizona researchers. H. funifera is quite a bit larger than red yucca and in the leaves, it produces long, thin fibers that can be used to produce paper with exceptional strength. It has been experimentally grown at the University of Arizona Maricopa Agricultural Center since 1995 to learn its cultural requirements. Maybe this plant will replace cotton someday? Meanwhile, plant red yucca in your landscape. You won't be disappointed.

 

The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@verdeonline.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: ag.arizona.edu/yavapai/anr/hort/byg/.

 

Arizona Cooperative Extension

Yavapai County

840 Rodeo Dr. #C

Prescott, AZ 86305

(928) 445-6590

ag.arizona.edu/yavapai/anr/hort/byg/archive/hesperaloe.html

Last Updated: July 16, 2002

Content Questions/Comments: jschalau@ag.arizona.edu

 

IMG_5150 - Version 2

Jellyfish, also known sea jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria.

 

Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex life cycle. The medusa is normally the sexual phase, which produces planula larvae; these then disperse widely and enter a sedentary polyp phase, before reaching sexual maturity.

 

Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the "true jellyfish") are exclusively marine, but some hydrozoans with a similar appearance live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. The medusae of most species are fast-growing, and mature within a few months then die soon after breeding, but the polyp stage, attached to the seabed, may be much more long-lived. Jellyfish have been in existence for at least 500 million years, and possibly 700 million years or more, making them the oldest multi-organ animal group.

 

Jellyfish are eaten by humans in certain cultures. They are considered a delicacy in some Asian countries, where species in the Rhizostomeae order are pressed and salted to remove excess water. Australian researchers have described them as a "perfect food": sustainable and protein-rich but relatively low in food energy.

 

They are also used in research, where the green fluorescent protein used by some species to cause bioluminescence has been adapted as a fluorescent marker for genes inserted into other cells or organisms.

 

The stinging cells used by jellyfish to subdue their prey can injure humans. Thousands of swimmers worldwide are stung every year, with effects ranging from mild discomfort to serious injury or even death. When conditions are favourable, jellyfish can form vast swarms, which can be responsible for damage to fishing gear by filling fishing nets, and sometimes clog the cooling systems of power and desalination plants which draw their water from the sea.

  

Names

The name jellyfish, in use since 1796, has traditionally been applied to medusae and all similar animals including the comb jellies (ctenophores, another phylum). The term jellies or sea jellies is more recent, having been introduced by public aquaria in an effort to avoid use of the word "fish" with its modern connotation of an animal with a backbone, though shellfish, cuttlefish and starfish are not vertebrates either. In scientific literature, "jelly" and "jellyfish" have been used interchangeably. Many sources refer to only scyphozoans as "true jellyfish".

 

A group of jellyfish is called a "smack" or a "smuck".

 

Definition

The term jellyfish broadly corresponds to medusae, that is, a life-cycle stage in the Medusozoa. The American evolutionary biologist Paulyn Cartwright gives the following general definition:

 

Typically, medusozoan cnidarians have a pelagic, predatory jellyfish stage in their life cycle; staurozoans are the exceptions [as they are stalked].

 

The Merriam-Webster dictionary defines jellyfish as follows:

 

A free-swimming marine coelenterate that is the sexually reproducing form of a hydrozoan or scyphozoan and has a nearly transparent saucer-shaped body and extensible marginal tentacles studded with stinging cells.

 

Given that jellyfish is a common name, its mapping to biological groups is inexact. Some authorities have called the comb jellies and certain salps jellyfish, though other authorities state that neither of these are jellyfish, which they consider should be limited to certain groups within the medusozoa.

 

The non-medusozoan clades called jellyfish by some but not all authorities (both agreeing and disagreeing citations are given in each case) are indicated with on the following cladogram of the animal kingdom:

 

Jellyfish are not a clade, as they include most of the Medusozoa, barring some of the Hydrozoa. The medusozoan groups included by authorities are indicated on the following phylogenetic tree by the presence of citations. Names of included jellyfish, in English where possible, are shown in boldface; the presence of a named and cited example indicates that at least that species within its group has been called a jellyfish.

 

Taxonomy

The subphylum Medusozoa includes all cnidarians with a medusa stage in their life cycle. The basic cycle is egg, planula larva, polyp, medusa, with the medusa being the sexual stage. The polyp stage is sometimes secondarily lost. The subphylum include the major taxa, Scyphozoa (large jellyfish), Cubozoa (box jellyfish) and Hydrozoa (small jellyfish), and excludes Anthozoa (corals and sea anemones). This suggests that the medusa form evolved after the polyps. Medusozoans have tetramerous symmetry, with parts in fours or multiples of four.

 

The four major classes of medusozoan Cnidaria are:

Scyphozoa are sometimes called true jellyfish, though they are no more truly jellyfish than the others listed here. They have tetra-radial symmetry. Most have tentacles around the outer margin of the bowl-shaped bell, and long, oral arms around the mouth in the center of the subumbrella.

Cubozoa (box jellyfish) have a (rounded) box-shaped bell, and their velarium assists them to swim more quickly. Box jellyfish may be related more closely to scyphozoan jellyfish than either are to the Hydrozoa.

Hydrozoa medusae also have tetra-radial symmetry, nearly always have a velum (diaphragm used in swimming) attached just inside the bell margin, do not have oral arms, but a much smaller central stalk-like structure, the manubrium, with terminal mouth opening, and are distinguished by the absence of cells in the mesoglea. Hydrozoa show great diversity of lifestyle; some species maintain the polyp form for their entire life and do not form medusae at all (such as Hydra, which is hence not considered a jellyfish), and a few are entirely medusal and have no polyp form.

Staurozoa (stalked jellyfish) are characterized by a medusa form that is generally sessile, oriented upside down and with a stalk emerging from the apex of the "calyx" (bell), which attaches to the substrate. At least some Staurozoa also have a polyp form that alternates with the medusoid portion of the life cycle. Until recently, Staurozoa were classified within the Scyphozoa.

There are over 200 species of Scyphozoa, about 50 species of Staurozoa, about 50 species of Cubozoa, and the Hydrozoa includes about 1000–1500 species that produce medusae, but many more species that do not.

 

Fossil history

Since jellyfish have no hard parts, fossils are rare. The oldest unambiguous fossil of a free-swimming medusa is Burgessomedusa from the mid Cambrian Burgess Shale of Canada, which is likely either a stem group of box jellyfish (Cubozoa) or Acraspeda (the clade including Staurozoa, Cubozoa, and Scyphozoa). Other claimed records from the Cambrian of China and Utah in the United States are uncertain, and possibly represent ctenophores instead.

 

Anatomy

The main feature of a true jellyfish is the umbrella-shaped bell. This is a hollow structure consisting of a mass of transparent jelly-like matter known as mesoglea, which forms the hydrostatic skeleton of the animal. 95% or more of the mesogloea consists of water, but it also contains collagen and other fibrous proteins, as well as wandering amoebocytes which can engulf debris and bacteria. The mesogloea is bordered by the epidermis on the outside and the gastrodermis on the inside. The edge of the bell is often divided into rounded lobes known as lappets, which allow the bell to flex. In the gaps or niches between the lappets are dangling rudimentary sense organs known as rhopalia, and the margin of the bell often bears tentacles.

  

Anatomy of a scyphozoan jellyfish

On the underside of the bell is the manubrium, a stalk-like structure hanging down from the centre, with the mouth, which also functions as the anus, at its tip. There are often four oral arms connected to the manubrium, streaming away into the water below. The mouth opens into the gastrovascular cavity, where digestion takes place and nutrients are absorbed. This is subdivided by four thick septa into a central stomach and four gastric pockets. The four pairs of gonads are attached to the septa, and close to them four septal funnels open to the exterior, perhaps supplying good oxygenation to the gonads. Near the free edges of the septa, gastric filaments extend into the gastric cavity; these are armed with nematocysts and enzyme-producing cells and play a role in subduing and digesting the prey. In some scyphozoans, the gastric cavity is joined to radial canals which branch extensively and may join a marginal ring canal. Cilia in these canals circulate the fluid in a regular direction.

  

Discharge mechanism of a nematocyst

The box jellyfish is largely similar in structure. It has a squarish, box-like bell. A short pedalium or stalk hangs from each of the four lower corners. One or more long, slender tentacles are attached to each pedalium. The rim of the bell is folded inwards to form a shelf known as a velarium which restricts the bell's aperture and creates a powerful jet when the bell pulsates, allowing box jellyfish to swim faster than true jellyfish. Hydrozoans are also similar, usually with just four tentacles at the edge of the bell, although many hydrozoans are colonial and may not have a free-living medusal stage. In some species, a non-detachable bud known as a gonophore is formed that contains a gonad but is missing many other medusal features such as tentacles and rhopalia. Stalked jellyfish are attached to a solid surface by a basal disk, and resemble a polyp, the oral end of which has partially developed into a medusa with tentacle-bearing lobes and a central manubrium with four-sided mouth.

 

Most jellyfish do not have specialized systems for osmoregulation, respiration and circulation, and do not have a central nervous system. Nematocysts, which deliver the sting, are located mostly on the tentacles; true jellyfish also have them around the mouth and stomach. Jellyfish do not need a respiratory system because sufficient oxygen diffuses through the epidermis. They have limited control over their movement, but can navigate with the pulsations of the bell-like body; some species are active swimmers most of the time, while others largely drift. The rhopalia contain rudimentary sense organs which are able to detect light, water-borne vibrations, odour and orientation. A loose network of nerves called a "nerve net" is located in the epidermis. Although traditionally thought not to have a central nervous system, nerve net concentration and ganglion-like structures could be considered to constitute one in most species. A jellyfish detects stimuli, and transmits impulses both throughout the nerve net and around a circular nerve ring, to other nerve cells. The rhopalial ganglia contain pacemaker neurones which control swimming rate and direction.

 

In many species of jellyfish, the rhopalia include ocelli, light-sensitive organs able to tell light from dark. These are generally pigment spot ocelli, which have some of their cells pigmented. The rhopalia are suspended on stalks with heavy crystals at one end, acting like gyroscopes to orient the eyes skyward. Certain jellyfish look upward at the mangrove canopy while making a daily migration from mangrove swamps into the open lagoon, where they feed, and back again.

 

Box jellyfish have more advanced vision than the other groups. Each individual has 24 eyes, two of which are capable of seeing colour, and four parallel information processing areas that act in competition, supposedly making them one of the few kinds of animal to have a 360-degree view of its environment.

 

Box jellyfish eye

The study of jellyfish eye evolution is an intermediary to a better understanding of how visual systems evolved on Earth. Jellyfish exhibit immense variation in visual systems ranging from photoreceptive cell patches seen in simple photoreceptive systems to more derived complex eyes seen in box jellyfish. Major topics of jellyfish visual system research (with an emphasis on box jellyfish) include: the evolution of jellyfish vision from simple to complex visual systems), the eye morphology and molecular structures of box jellyfish (including comparisons to vertebrate eyes), and various uses of vision including task-guided behaviors and niche specialization.

 

Evolution

Experimental evidence for photosensitivity and photoreception in cnidarians antecedes the mid 1900s, and a rich body of research has since covered evolution of visual systems in jellyfish. Jellyfish visual systems range from simple photoreceptive cells to complex image-forming eyes. More ancestral visual systems incorporate extraocular vision (vision without eyes) that encompass numerous receptors dedicated to single-function behaviors. More derived visual systems comprise perception that is capable of multiple task-guided behaviors.

 

Although they lack a true brain, cnidarian jellyfish have a "ring" nervous system that plays a significant role in motor and sensory activity. This net of nerves is responsible for muscle contraction and movement and culminates the emergence of photosensitive structures. Across Cnidaria, there is large variation in the systems that underlie photosensitivity. Photosensitive structures range from non-specialized groups of cells, to more "conventional" eyes similar to those of vertebrates. The general evolutionary steps to develop complex vision include (from more ancestral to more derived states): non-directional photoreception, directional photoreception, low-resolution vision, and high-resolution vision. Increased habitat and task complexity has favored the high-resolution visual systems common in derived cnidarians such as box jellyfish.

 

Basal visual systems observed in various cnidarians exhibit photosensitivity representative of a single task or behavior. Extraocular photoreception (a form of non-directional photoreception), is the most basic form of light sensitivity and guides a variety of behaviors among cnidarians. It can function to regulate circadian rhythm (as seen in eyeless hydrozoans) and other light-guided behaviors responsive to the intensity and spectrum of light. Extraocular photoreception can function additionally in positive phototaxis (in planula larvae of hydrozoans), as well as in avoiding harmful amounts of UV radiation via negative phototaxis. Directional photoreception (the ability to perceive direction of incoming light) allows for more complex phototactic responses to light, and likely evolved by means of membrane stacking. The resulting behavioral responses can range from guided spawning events timed by moonlight to shadow responses for potential predator avoidance. Light-guided behaviors are observed in numerous scyphozoans including the common moon jelly, Aurelia aurita, which migrates in response to changes in ambient light and solar position even though they lack proper eyes.

 

The low-resolution visual system of box jellyfish is more derived than directional photoreception, and thus box jellyfish vision represents the most basic form of true vision in which multiple directional photoreceptors combine to create the first imaging and spatial resolution. This is different from the high-resolution vision that is observed in camera or compound eyes of vertebrates and cephalopods that rely on focusing optics. Critically, the visual systems of box jellyfish are responsible for guiding multiple tasks or behaviors in contrast to less derived visual systems in other jellyfish that guide single behavioral functions. These behaviors include phototaxis based on sunlight (positive) or shadows (negative), obstacle avoidance, and control of swim-pulse rate.

 

Box jellyfish possess "proper eyes" (similar to vertebrates) that allow them to inhabit environments that lesser derived medusae cannot. In fact, they are considered the only class in the clade Medusozoa that have behaviors necessitating spatial resolution and genuine vision. However, the lens in their eyes are more functionally similar to cup-eyes exhibited in low-resolution organisms, and have very little to no focusing capability. The lack of the ability to focus is due to the focal length exceeding the distance to the retina, thus generating unfocused images and limiting spatial resolution. The visual system is still sufficient for box jellyfish to produce an image to help with tasks such as object avoidance.

 

Utility as a model organism

Box jellyfish eyes are a visual system that is sophisticated in numerous ways. These intricacies include the considerable variation within the morphology of box jellyfishes' eyes (including their task/behavior specification), and the molecular makeup of their eyes including: photoreceptors, opsins, lenses, and synapses. The comparison of these attributes to more derived visual systems can allow for a further understanding of how the evolution of more derived visual systems may have occurred, and puts into perspective how box jellyfish can play the role as an evolutionary/developmental model for all visual systems.

 

Characteristics

Box jellyfish visual systems are both diverse and complex, comprising multiple photosystems. There is likely considerable variation in visual properties between species of box jellyfish given the significant inter-species morphological and physiological variation. Eyes tend to differ in size and shape, along with number of receptors (including opsins), and physiology across species of box jellyfish.

 

Box jellyfish have a series of intricate lensed eyes that are similar to those of more derived multicellular organisms such as vertebrates. Their 24 eyes fit into four different morphological categories. These categories consist of two large, morphologically different medial eyes (a lower and upper lensed eye) containing spherical lenses, a lateral pair of pigment slit eyes, and a lateral pair of pigment pit eyes. The eyes are situated on rhopalia (small sensory structures) which serve sensory functions of the box jellyfish and arise from the cavities of the exumbrella (the surface of the body) on the side of the bells of the jellyfish. The two large eyes are located on the mid-line of the club and are considered complex because they contain lenses. The four remaining eyes lie laterally on either side of each rhopalia and are considered simple. The simple eyes are observed as small invaginated cups of epithelium that have developed pigmentation. The larger of the complex eyes contains a cellular cornea created by a mono ciliated epithelium, cellular lens, homogenous capsule to the lens, vitreous body with prismatic elements, and a retina of pigmented cells. The smaller of the complex eyes is said to be slightly less complex given that it lacks a capsule but otherwise contains the same structure as the larger eye.

 

Box jellyfish have multiple photosystems that comprise different sets of eyes. Evidence includes immunocytochemical and molecular data that show photopigment differences among the different morphological eye types, and physiological experiments done on box jellyfish to suggest behavioral differences among photosystems. Each individual eye type constitutes photosystems that work collectively to control visually guided behaviors.

 

Box jellyfish eyes primarily use c-PRCs (ciliary photoreceptor cells) similar to that of vertebrate eyes. These cells undergo phototransduction cascades (process of light absorption by photoreceptors) that are triggered by c-opsins. Available opsin sequences suggest that there are two types of opsins possessed by all cnidarians including an ancient phylogenetic opsin, and a sister ciliary opsin to the c-opsins group. Box jellyfish could have both ciliary and cnidops (cnidarian opsins), which is something not previously believed to appear in the same retina. Nevertheless, it is not entirely evident whether cnidarians possess multiple opsins that are capable of having distinctive spectral sensitivities.

 

Comparison with other organisms

Comparative research on genetic and molecular makeup of box jellyfishes' eyes versus more derived eyes seen in vertebrates and cephalopods focuses on: lenses and crystallin composition, synapses, and Pax genes and their implied evidence for shared primordial (ancestral) genes in eye evolution.

 

Box jellyfish eyes are said to be an evolutionary/developmental model of all eyes based on their evolutionary recruitment of crystallins and Pax genes. Research done on box jellyfish including Tripedalia cystophora has suggested that they possess a single Pax gene, PaxB. PaxB functions by binding to crystallin promoters and activating them. PaxB in situ hybridization resulted in PaxB expression in the lens, retina, and statocysts. These results and the rejection of the prior hypothesis that Pax6 was an ancestral Pax gene in eyes has led to the conclusion that PaxB was a primordial gene in eye evolution, and that the eyes of all organisms likely share a common ancestor.

 

The lens structure of box jellyfish appears very similar to those of other organisms, but the crystallins are distinct in both function and appearance. Weak reactions were seen within the sera and there were very weak sequence similarities within the crystallins among vertebrate and invertebrate lenses. This is likely due to differences in lower molecular weight proteins and the subsequent lack of immunological reactions with antisera that other organisms' lenses exhibit.

 

All four of the visual systems of box jellyfish species investigated with detail (Carybdea marsupialis, Chiropsalmus quadrumanus, Tamoya haplonema and Tripedalia cystophora) have invaginated synapses, but only in the upper and lower lensed eyes. Different densities were found between the upper and lower lenses, and between species. Four types of chemical synapses have been discovered within the rhopalia which could help in understanding neural organization including: clear unidirectional, dense-core unidirectional, clear bidirectional, and clear and dense-core bidirectional. The synapses of the lensed eyes could be useful as markers to learn more about the neural circuit in box jellyfish retinal areas.

 

Evolution as a response to natural stimuli

The primary adaptive responses to environmental variation observed in box jellyfish eyes include pupillary constriction speeds in response to light environments, as well as photoreceptor tuning and lens adaptations to better respond to shifts between light environments and darkness. Interestingly, some box jellyfish species' eyes appear to have evolved more focused vision in response to their habitat.

 

Pupillary contraction appears to have evolved in response to variation in the light environment across ecological niches across three species of box jellyfish (Chironex fleckeri, Chiropsella bronzie, and Carukia barnesi). Behavioral studies suggest that faster pupil contraction rates allow for greater object avoidance, and in fact, species with more complex habitats exhibit faster rates. Ch. bronzie inhabit shallow beach fronts that have low visibility and very few obstacles, thus, faster pupil contraction in response to objects in their environment is not important. Ca. barnesi and Ch. fleckeri are found in more three-dimensionally complex environments like mangroves with an abundance of natural obstacles, where faster pupil contraction is more adaptive. Behavioral studies support the idea that faster pupillary contraction rates assist with obstacle avoidance as well as depth adjustments in response to differing light intensities.

 

Light/dark adaptation via pupillary light reflexes is an additional form of an evolutionary response to the light environment. This relates to the pupil's response to shifts between light intensity (generally from sunlight to darkness). In the process of light/dark adaptation, the upper and lower lens eyes of different box jellyfish species vary in specific function. The lower lens-eyes contain pigmented photoreceptors and long pigment cells with dark pigments that migrate on light/dark adaptation, while the upper-lens eyes play a concentrated role in light direction and phototaxis given that they face upward towards the water surface (towards the sun or moon). The upper lens of Ch. bronzie does not exhibit any considerable optical power while Tr. cystophora (a box jellyfish species that tends to live in mangroves) does. The ability to use light to visually guide behavior is not of as much importance to Ch. bronzie as it is to species in more obstacle-filled environments. Differences in visually guided behavior serve as evidence that species that share the same number and structure of eyes can exhibit differences in how they control behavior.

 

Largest and smallest

Jellyfish range from about one millimeter in bell height and diameter, to nearly 2 metres (6+1⁄2 ft) in bell height and diameter; the tentacles and mouth parts usually extend beyond this bell dimension.

 

The smallest jellyfish are the peculiar creeping jellyfish in the genera Staurocladia and Eleutheria, which have bell disks from 0.5 millimetres (1⁄32 in) to a few millimeters in diameter, with short tentacles that extend out beyond this, which these jellyfish use to move across the surface of seaweed or the bottoms of rocky pools; many of these tiny creeping jellyfish cannot be seen in the field without a hand lens or microscope. They can reproduce asexually by fission (splitting in half). Other very small jellyfish, which have bells about one millimeter, are the hydromedusae of many species that have just been released from their parent polyps; some of these live only a few minutes before shedding their gametes in the plankton and then dying, while others will grow in the plankton for weeks or months. The hydromedusae Cladonema radiatum and Cladonema californicum are also very small, living for months, yet never growing beyond a few mm in bell height and diameter.

 

The lion's mane jellyfish, Cyanea capillata, was long-cited as the largest jellyfish, and arguably the longest animal in the world, with fine, thread-like tentacles that may extend up to 36.5 m (119 ft 9 in) long (though most are nowhere near that large). They have a moderately painful, but rarely fatal, sting. The increasingly common giant Nomura's jellyfish, Nemopilema nomurai, found in some, but not all years in the waters of Japan, Korea and China in summer and autumn is another candidate for "largest jellyfish", in terms of diameter and weight, since the largest Nomura's jellyfish in late autumn can reach 2 m (6 ft 7 in) in bell (body) diameter and about 200 kg (440 lb) in weight, with average specimens frequently reaching 0.9 m (2 ft 11 in) in bell diameter and about 150 kg (330 lb) in weight. The large bell mass of the giant Nomura's jellyfish can dwarf a diver and is nearly always much greater than the Lion's Mane, whose bell diameter can reach 1 m (3 ft 3 in).

 

The rarely encountered deep-sea jellyfish Stygiomedusa gigantea is another candidate for "largest jellyfish", with its thick, massive bell up to 100 cm (3 ft 3 in) wide, and four thick, "strap-like" oral arms extending up to 6 m (19+1⁄2 ft) in length, very different from the typical fine, threadlike tentacles that rim the umbrella of more-typical-looking jellyfish, including the Lion's Mane.

 

Desmonema glaciale, which lives in the Antarctic region, can reach a very large size (several meters). Purple-striped jelly (Chrysaora colorata) can also be extremely long (up to 15 feet).

 

Life history and behavior

Life cycle

Jellyfish have a complex life cycle which includes both sexual and asexual phases, with the medusa being the sexual stage in most instances. Sperm fertilize eggs, which develop into larval planulae, become polyps, bud into ephyrae and then transform into adult medusae. In some species certain stages may be skipped.

 

Upon reaching adult size, jellyfish spawn regularly if there is a sufficient supply of food. In most species, spawning is controlled by light, with all individuals spawning at about the same time of day; in many instances this is at dawn or dusk. Jellyfish are usually either male or female (with occasional hermaphrodites). In most cases, adults release sperm and eggs into the surrounding water, where the unprotected eggs are fertilized and develop into larvae. In a few species, the sperm swim into the female's mouth, fertilizing the eggs within her body, where they remain during early development stages. In moon jellies, the eggs lodge in pits on the oral arms, which form a temporary brood chamber for the developing planula larvae.

 

The planula is a small larva covered with cilia. When sufficiently developed, it settles onto a firm surface and develops into a polyp. The polyp generally consists of a small stalk topped by a mouth that is ringed by upward-facing tentacles. The polyps resemble those of closely related anthozoans, such as sea anemones and corals. The jellyfish polyp may be sessile, living on the bottom, boat hulls or other substrates, or it may be free-floating or attached to tiny bits of free-living plankton or rarely, fish or other invertebrates. Polyps may be solitary or colonial. Most polyps are only millimetres in diameter and feed continuously. The polyp stage may last for years.

 

After an interval and stimulated by seasonal or hormonal changes, the polyp may begin reproducing asexually by budding and, in the Scyphozoa, is called a segmenting polyp, or a scyphistoma. Budding produces more scyphistomae and also ephyrae. Budding sites vary by species; from the tentacle bulbs, the manubrium (above the mouth), or the gonads of hydromedusae. In a process known as strobilation, the polyp's tentacles are reabsorbed and the body starts to narrow, forming transverse constrictions, in several places near the upper extremity of the polyp. These deepen as the constriction sites migrate down the body, and separate segments known as ephyra detach. These are free-swimming precursors of the adult medusa stage, which is the life stage that is typically identified as a jellyfish. The ephyrae, usually only a millimeter or two across initially, swim away from the polyp and grow. Limnomedusae polyps can asexually produce a creeping frustule larval form, which crawls away before developing into another polyp. A few species can produce new medusae by budding directly from the medusan stage. Some hydromedusae reproduce by fission.

 

Lifespan

Little is known of the life histories of many jellyfish as the places on the seabed where the benthic forms of those species live have not been found. However, an asexually reproducing strobila form can sometimes live for several years, producing new medusae (ephyra larvae) each year.

 

An unusual species, Turritopsis dohrnii, formerly classified as Turritopsis nutricula, might be effectively immortal because of its ability under certain circumstances to transform from medusa back to the polyp stage, thereby escaping the death that typically awaits medusae post-reproduction if they have not otherwise been eaten by some other organism. So far this reversal has been observed only in the laboratory.

 

Locomotion

Jellyfish locomotion is highly efficient. Muscles in the jellylike bell contract, setting up a start vortex and propelling the animal. When the contraction ends, the bell recoils elastically, creating a stop vortex with no extra energy input.

Using the moon jelly Aurelia aurita as an example, jellyfish have been shown to be the most energy-efficient swimmers of all animals. They move through the water by radially expanding and contracting their bell-shaped bodies to push water behind them. They pause between the contraction and expansion phases to create two vortex rings. Muscles are used for the contraction of the body, which creates the first vortex and pushes the animal forward, but the mesoglea is so elastic that the expansion is powered exclusively by relaxing the bell, which releases the energy stored from the contraction. Meanwhile, the second vortex ring starts to spin faster, sucking water into the bell and pushing against the centre of the body, giving a secondary and "free" boost forward. The mechanism, called passive energy recapture, only works in relatively small jellyfish moving at low speeds, allowing the animal to travel 30 percent farther on each swimming cycle. Jellyfish achieved a 48 percent lower cost of transport (food and oxygen intake versus energy spent in movement) than other animals in similar studies. One reason for this is that most of the gelatinous tissue of the bell is inactive, using no energy during swimming.

 

Ecology

Diet

Jellyfish are, like other cnidarians, generally carnivorous (or parasitic), feeding on planktonic organisms, crustaceans, small fish, fish eggs and larvae, and other jellyfish, ingesting food and voiding undigested waste through the mouth. They hunt passively using their tentacles as drift lines, or sink through the water with their tentacles spread widely; the tentacles, which contain nematocysts to stun or kill the prey, may then flex to help bring it to the mouth. Their swimming technique also helps them to capture prey; when their bell expands it sucks in water which brings more potential prey within reach of the tentacles.

 

A few species such as Aglaura hemistoma are omnivorous, feeding on microplankton which is a mixture of zooplankton and phytoplankton (microscopic plants) such as dinoflagellates. Others harbour mutualistic algae (Zooxanthellae) in their tissues; the spotted jellyfish (Mastigias papua) is typical of these, deriving part of its nutrition from the products of photosynthesis, and part from captured zooplankton. The upside-down jellyfish (Cassiopea andromeda) also has a symbiotic relationship with microalgae, but captures tiny animals to supplement their diet. This is done by releasing tiny balls of living cells composed of mesoglea. These use cilia to drive them through water and stinging cells which stun the prey. The blobs also seems to have digestive capabilities.

 

Predation

Other species of jellyfish are among the most common and important jellyfish predators. Sea anemones may eat jellyfish that drift into their range. Other predators include tunas, sharks, swordfish, sea turtles and penguins. Jellyfish washed up on the beach are consumed by foxes, other terrestrial mammals and birds. In general however, few animals prey on jellyfish; they can broadly be considered to be top predators in the food chain. Once jellyfish have become dominant in an ecosystem, for example through overfishing which removes predators of jellyfish larvae, there may be no obvious way for the previous balance to be restored: they eat fish eggs and juvenile fish, and compete with fish for food, preventing fish stocks from recovering.

 

Symbiosis

Some small fish are immune to the stings of the jellyfish and live among the tentacles, serving as bait in a fish trap; they are safe from potential predators and are able to share the fish caught by the jellyfish. The cannonball jellyfish has a symbiotic relationship with ten different species of fish, and with the longnose spider crab, which lives inside the bell, sharing the jellyfish's food and nibbling its tissues.

 

Main article: Jellyfish bloom

Jellyfish form large masses or blooms in certain environmental conditions of ocean currents, nutrients, sunshine, temperature, season, prey availability, reduced predation and oxygen concentration. Currents collect jellyfish together, especially in years with unusually high populations. Jellyfish can detect marine currents and swim against the current to congregate in blooms. Jellyfish are better able to survive in nutrient-rich, oxygen-poor water than competitors, and thus can feast on plankton without competition. Jellyfish may also benefit from saltier waters, as saltier waters contain more iodine, which is necessary for polyps to turn into jellyfish. Rising sea temperatures caused by climate change may also contribute to jellyfish blooms, because many species of jellyfish are able to survive in warmer waters. Increased nutrients from agricultural or urban runoff with nutrients including nitrogen and phosphorus compounds increase the growth of phytoplankton, causing eutrophication and algal blooms. When the phytoplankton die, they may create dead zones, so-called because they are hypoxic (low in oxygen). This in turn kills fish and other animals, but not jellyfish, allowing them to bloom. Jellyfish populations may be expanding globally as a result of land runoff and overfishing of their natural predators. Jellyfish are well placed to benefit from disturbance of marine ecosystems. They reproduce rapidly; they prey upon many species, while few species prey on them; and they feed via touch rather than visually, so they can feed effectively at night and in turbid waters. It may be difficult for fish stocks to re-establish themselves in marine ecosystems once they have become dominated by jellyfish, because jellyfish feed on plankton, which includes fish eggs and larvae.

 

As suspected at the turn of this century, jellyfish blooms are increasing in frequency. Between 2013 and 2020 the Mediterranean Science Commission monitored on a weekly basis the frequency of such outbreaks in coastal waters from Morocco to the Black Sea, revealing a relatively high frequency of these blooms nearly all year round, with peaks observed from March to July and often again in the autumn. The blooms are caused by different jellyfish species, depending on their localisation within the Basin: one observes a clear dominance of Pelagia noctiluca and Velella velella outbreaks in the western Mediterranean, of Rhizostoma pulmo and Rhopilema nomadica outbreaks in the eastern Mediterranean, and of Aurelia aurita and Mnemiopsis leidyi outbreaks in the Black Sea.

 

Some jellyfish populations that have shown clear increases in the past few decades are invasive species, newly arrived from other habitats: examples include the Black Sea, Caspian Sea, Baltic Sea, central and eastern Mediterranean, Hawaii, and tropical and subtropical parts of the West Atlantic (including the Caribbean, Gulf of Mexico and Brazil).

 

Jellyfish blooms can have significant impact on community structure. Some carnivorous jellyfish species prey on zooplankton while others graze on primary producers. Reductions in zooplankton and ichthyoplankton due to a jellyfish bloom can ripple through the trophic levels. High-density jellyfish populations can outcompete other predators and reduce fish recruitment. Increased grazing on primary producers by jellyfish can also interrupt energy transfer to higher trophic levels.

 

During blooms, jellyfish significantly alter the nutrient availability in their environment. Blooms require large amounts of available organic nutrients in the water column to grow, limiting availability for other organisms. Some jellyfish have a symbiotic relationship with single-celled dinoflagellates, allowing them to assimilate inorganic carbon, phosphorus, and nitrogen creating competition for phytoplankton. Their large biomass makes them an important source of dissolved and particulate organic matter for microbial communities through excretion, mucus production, and decomposition. The microbes break down the organic matter into inorganic ammonium and phosphate. However, the low carbon availability shifts the process from production to respiration creating low oxygen areas making the dissolved inorganic nitrogen and phosphorus largely unavailable for primary production.

 

These blooms have very real impacts on industries. Jellyfish can outcompete fish by utilizing open niches in over-fished fisheries. Catch of jellyfish can strain fishing gear and lead to expenses relating to damaged gear. Power plants have been shut down due to jellyfish blocking the flow of cooling water. Blooms have also been harmful for tourism, causing a rise in stings and sometimes the closure of beaches.

 

Jellyfish form a component of jelly-falls, events where gelatinous zooplankton fall to the seafloor, providing food for the benthic organisms there. In temperate and subpolar regions, jelly-falls usually follow immediately after a bloom.

 

Habitats

Most jellyfish are marine animals, although a few hydromedusae inhabit freshwater. The best known freshwater example is the cosmopolitan hydrozoan jellyfish, Craspedacusta sowerbii. It is less than an inch (2.5 cm) in diameter, colorless and does not sting. Some jellyfish populations have become restricted to coastal saltwater lakes, such as Jellyfish Lake in Palau. Jellyfish Lake is a marine lake where millions of golden jellyfish (Mastigias spp.) migrate horizontally across the lake daily.

 

Although most jellyfish live well off the ocean floor and form part of the plankton, a few species are closely associated with the bottom for much of their lives and can be considered benthic. The upside-down jellyfish in the genus Cassiopea typically lie on the bottom of shallow lagoons where they sometimes pulsate gently with their umbrella top facing down. Even some deep-sea species of hydromedusae and scyphomedusae are usually collected on or near the bottom. All of the stauromedusae are found attached to either seaweed or rocky or other firm material on the bottom.

 

Some species explicitly adapt to tidal flux. In Roscoe Bay, jellyfish ride the current at ebb tide until they hit a gravel bar, and then descend below the current. They remain in still waters until the tide rises, ascending and allowing it to sweep them back into the bay. They also actively avoid fresh water from mountain snowmelt, diving until they find enough salt.

  

Parasites

Jellyfish are hosts to a wide variety of parasitic organisms. They act as intermediate hosts of endoparasitic helminths, with the infection being transferred to the definitive host fish after predation. Some digenean trematodes, especially species in the family Lepocreadiidae, use jellyfish as their second intermediate hosts. Fish become infected by the trematodes when they feed on infected jellyfish.

 

Relation to humans

Jellyfish have long been eaten in some parts of the world. Fisheries have begun harvesting the American cannonball jellyfish, Stomolophus meleagris, along the southern Atlantic coast of the United States and in the Gulf of Mexico for export to Asia.

 

Jellyfish are also harvested for their collagen, which is being investigated for use in a variety of applications including the treatment of rheumatoid arthritis.

 

Aquaculture and fisheries of other species often suffer severe losses – and so losses of productivity – due to jellyfish.

 

Products

Main article: Jellyfish as food

In some countries, including China, Japan, and Korea, jellyfish are a delicacy. The jellyfish is dried to prevent spoiling. Only some 12 species of scyphozoan jellyfish belonging to the order Rhizostomeae are harvested for food, mostly in southeast Asia. Rhizostomes, especially Rhopilema esculentum in China (海蜇 hǎizhé, 'sea stingers') and Stomolophus meleagris (cannonball jellyfish) in the United States, are favored because of their larger and more rigid bodies and because their toxins are harmless to humans.

 

Traditional processing methods, carried out by a jellyfish master, involve a 20- to 40-day multi-phase procedure in which, after removing the gonads and mucous membranes, the umbrella and oral arms are treated with a mixture of table salt and alum, and compressed. Processing makes the jellyfish drier and more acidic, producing a crisp texture. Jellyfish prepared this way retain 7–10% of their original weight, and the processed product consists of approximately 94% water and 6% protein. Freshly processed jellyfish has a white, creamy color and turns yellow or brown during prolonged storage.

 

In China, processed jellyfish are desalted by soaking in water overnight and eaten cooked or raw. The dish is often served shredded with a dressing of oil, soy sauce, vinegar and sugar, or as a salad with vegetables. In Japan, cured jellyfish are rinsed, cut into strips and served with vinegar as an appetizer. Desalted, ready-to-eat products are also available.

 

Biotechnology

The hydromedusa Aequorea victoria was the source of green fluorescent protein, studied for its role in bioluminescence and later for use as a marker in genetic engineering.

Pliny the Elder reported in his Natural History that the slime of the jellyfish "Pulmo marinus" produced light when rubbed on a walking stick.

 

In 1961, Osamu Shimomura extracted green fluorescent protein (GFP) and another bioluminescent protein, called aequorin, from the large and abundant hydromedusa Aequorea victoria, while studying photoproteins that cause bioluminescence in this species. Three decades later, Douglas Prasher sequenced and cloned the gene for GFP. Martin Chalfie figured out how to use GFP as a fluorescent marker of genes inserted into other cells or organisms. Roger Tsien later chemically manipulated GFP to produce other fluorescent colors to use as markers. In 2008, Shimomura, Chalfie and Tsien won the Nobel Prize in Chemistry for their work with GFP. Man-made GFP became widely used as a fluorescent tag to show which cells or tissues express specific genes. The genetic engineering technique fuses the gene of interest to the GFP gene. The fused DNA is then put into a cell, to generate either a cell line or (via IVF techniques) an entire animal bearing the gene. In the cell or animal, the artificial gene turns on in the same tissues and the same time as the normal gene, making a fusion of the normal protein with GFP attached to the end, illuminating the animal or cell reveals what tissues express that protein—or at what stage of development. The fluorescence shows where the gene is expressed.

 

Aquarium display

Jellyfish are displayed in many public aquariums. Often the tank's background is blue and the animals are illuminated by side light, increasing the contrast between the animal and the background. In natural conditions, many jellies are so transparent that they are nearly invisible. Jellyfish are not adapted to closed spaces. They depend on currents to transport them from place to place. Professional exhibits as in the Monterey Bay Aquarium feature precise water flows, typically in circular tanks to avoid trapping specimens in corners. The outflow is spread out over a large surface area and the inflow enters as a sheet of water in front of the outflow, so the jellyfish do not get sucked into it. As of 2009, jellyfish were becoming popular in home aquariums, where they require similar equipment.

 

Stings

Jellyfish are armed with nematocysts, a type of specialized stinging cell. Contact with a jellyfish tentacle can trigger millions of nematocysts to pierce the skin and inject venom, but only some species' venom causes an adverse reaction in humans. In a study published in Communications Biology, researchers found a jellyfish species called Cassiopea xamachana which when triggered will release tiny balls of cells that swim around the jellyfish stinging everything in their path. Researchers described these as "self-propelling microscopic grenades" and named them cassiosomes.

 

The effects of stings range from mild discomfort to extreme pain and death. Most jellyfish stings are not deadly, but stings of some box jellyfish (Irukandji jellyfish), such as the sea wasp, can be deadly. Stings may cause anaphylaxis (a form of shock), which can be fatal. Jellyfish kill 20 to 40 people a year in the Philippines alone. In 2006 the Spanish Red Cross treated 19,000 stung swimmers along the Costa Brava.

 

Vinegar (3–10% aqueous acetic acid) may help with box jellyfish stings but not the stings of the Portuguese man o' war. Clearing the area of jelly and tentacles reduces nematocyst firing. Scraping the affected skin, such as with the edge of a credit card, may remove remaining nematocysts. Once the skin has been cleaned of nematocysts, hydrocortisone cream applied locally reduces pain and inflammation. Antihistamines may help to control itching. Immunobased antivenins are used for serious box jellyfish stings.

 

In Elba Island and Corsica dittrichia viscosa is now used by residents and tourists to heal stings from jellyfish, bees and wasps pressing fresh leaves on the skin with quick results.

 

Mechanical issues

Jellyfish in large quantities can fill and split fishing nets and crush captured fish. They can clog cooling equipment, having disabled power stations in several countries; jellyfish caused a cascading blackout in the Philippines in 1999, as well as damaging the Diablo Canyon Power Plant in California in 2008. They can also stop desalination plants and ships' engines.