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This article is about a paraphyletic group. For close extinct relatives, see Elephantidae. For other uses, see Elephant (disambiguation).
Elephants
Temporal range: Pliocene–Present
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From top left to right: the African bush elephant, the Asian elephant and African forest elephant.
From top left to right: the African bush elephant, the Asian elephant and African forest elephant.
Scientific classificationEdit this classification
Kingdom:Animalia
Phylum:Chordata
Class:Mammalia
Order:Proboscidea
Family:Elephantidae
Subfamily:Elephantinae
Groups included
Loxodonta Anonymous, 1827
Elephas Linnaeus, 1758
†Palaeoloxodon Matsumoto, 1925
Cladistically included but traditionally excluded taxa
†Mammuthus Brookes, 1828
†Primelephas Maglio, 1970
Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are an informal grouping within the proboscidean family Elephantidae. Elephantidae is the only surviving family of proboscideans; extinct members include the mastodons. Elephantidae also contains several extinct groups, including the mammoths and straight-tusked elephants. African elephants have larger ears and concave backs, whereas Asian elephants have smaller ears, and convex or level backs. Distinctive features of all elephants include a long proboscis called a trunk, tusks, large ear flaps, massive legs, and tough but sensitive skin. The trunk is used for breathing, bringing food and water to the mouth, and grasping objects. Tusks, which are derived from the incisor teeth, serve both as weapons and as tools for moving objects and digging. The large ear flaps assist in maintaining a constant body temperature as well as in communication. The pillar-like legs carry their great weight.
Elephants are scattered throughout sub-Saharan Africa, South Asia, and Southeast Asia and are found in different habitats, including savannahs, forests, deserts, and marshes. They are herbivorous, and they stay near water when it is accessible. They are considered to be keystone species, due to their impact on their environments. Elephants have a fission–fusion society, in which multiple family groups come together to socialise. Females (cows) tend to live in family groups, which can consist of one female with her calves or several related females with offspring. The groups, which do not include bulls, are usually led by the oldest cow, known as the matriarch.
Males (bulls) leave their family groups when they reach puberty and may live alone or with other males. Adult bulls mostly interact with family groups when looking for a mate. They enter a state of increased testosterone and aggression known as musth, which helps them gain dominance over other males as well as reproductive success. Calves are the centre of attention in their family groups and rely on their mothers for as long as three years. Elephants can live up to 70 years in the wild. They communicate by touch, sight, smell, and sound; elephants use infrasound, and seismic communication over long distances. Elephant intelligence has been compared with that of primates and cetaceans. They appear to have self-awareness, and appear to show empathy for dying and dead family members.
African bush elephants and Asian elephants are listed as endangered and African forest elephants as critically endangered by the International Union for Conservation of Nature (IUCN). One of the biggest threats to elephant populations is the ivory trade, as the animals are poached for their ivory tusks. Other threats to wild elephants include habitat destruction and conflicts with local people. Elephants are used as working animals in Asia. In the past, they were used in war; today, they are often controversially put on display in zoos, or exploited for entertainment in circuses. Elephants are highly recognisable and have been featured in art, folklore, religion, literature, and popular culture.
Etymology
The word "elephant" is based on the Latin elephas (genitive elephantis) ("elephant"), which is the Latinised form of the Greek ἐλέφας (elephas) (genitive ἐλέφαντος (elephantos[1]), probably from a non-Indo-European language, likely Phoenician.[2] It is attested in Mycenaean Greek as e-re-pa (genitive e-re-pa-to) in Linear B syllabic script.[3][4] As in Mycenaean Greek, Homer used the Greek word to mean ivory, but after the time of Herodotus, it also referred to the animal.[1] The word "elephant" appears in Middle English as olyfaunt (c.1300) and was borrowed from Old French oliphant (12th century).[2]
Taxonomy and phylogeny
Afrotheria
Afroinsectiphilia
Tubulidentata
Orycteropodidae Aardvark2 (PSF) colourised.png
Afroinsectivora
Macroscelidea
Macroscelididae Rhynchocyon chrysopygus-J Smit white background.jpg
Afrosoricida
Chrysochloridae The animal kingdom, arranged according to its organization, serving as a foundation for the natural history of animals (Pl. 18) (Chrysochloris asiatica).jpg
Tenrecidae Brehms Thierleben - Allgemeine Kunde des Thierreichs (1876) (Tenrec ecaudatus).jpg
Paenungulata
Hyracoidea
Procaviidae DendrohyraxEminiSmit white background.jpg
Tethytheria
Proboscidea
Elephantidae Elephas africanus - 1700-1880 - Print - Iconographia Zoologica - (white background).jpg
Sirenia
Dugongidae Dugong dugon Hardwicke white background.jpg
Trichechidae Manatee white background.jpg
A cladogram of the elephants within Afrotheria based on molecular evidence[5]
Proboscidea
early proboscideans, e.g. Moeritherium Moeritherium NT small.jpg
Deinotheriidae Deinotherium12.jpg
Elephantiformes
Mammutidae BlankMastodon.jpg
Gomphotheriidae Gomphotherium NT small.jpg
Stegodontidae Stegodon Siwalik Hills.jpg
Elephantidae
Loxodonta African Bush Elephant.jpg
Mammuthus Mammuthus trogontherii122DB.jpg
Elephas Elephas maximus (Bandipur).jpg
Proboscidea phylogeny based on upper molars.[6]
Elephantimorpha
Elephantidae
Mammuthus primigenius Woolly mammoth model Royal BC Museum in Victoria.jpg
Mammuthus columbi Archidiskodon imperator121.jpg
Elephas maximus Elephas maximus (Bandipur).jpg
Loxodonta cyclotis African Forest Elephant.jpg
Palaeoloxodon antiquus Elephas-antiquus.jpg
Loxodonta africana African Bush Elephant.jpg
Mammut americanum BlankMastodon.jpg
Phylogeny of modern elephants and close extinct relatives based on molecular evidence[7]
See also: List of elephant species
Elephants belong to the family Elephantidae, the sole remaining family within the order Proboscidea which belongs to the superorder Afrotheria. Their closest extant relatives are the sirenians (dugongs and manatees) and the hyraxes, with which they share the clade Paenungulata within the superorder Afrotheria.[8] Elephants and sirenians are further grouped in the clade Tethytheria.[9]
Three species of elephants are recognised; the African bush elephant (Loxodonta africana) and forest elephant (Loxodonta cyclotis) of sub-Saharan Africa, and the Asian elephant (Elephas maximus) of South and Southeast Asia.[10] African elephants have larger ears, a concave back, more wrinkled skin, a sloping abdomen, and two finger-like extensions at the tip of the trunk. Asian elephants have smaller ears, a convex or level back, smoother skin, a horizontal abdomen that occasionally sags in the middle and one extension at the tip of the trunk. The looped ridges on the molars are narrower in the Asian elephant while those of the African are more diamond-shaped. The Asian elephant also has dorsal bumps on its head and some patches of depigmentation on its skin.[11]
Among African elephants, forest elephants have smaller and more rounded ears and thinner and straighter tusks than bush elephants and are limited in range to the forested areas of western and Central Africa.[12] Both were traditionally considered a single species, Loxodonta africana, but molecular studies have affirmed their status as separate species.[13][14][15] In 2017, DNA sequence analysis showed that L. cyclotis is more closely related to the extinct Palaeoloxodon antiquus, than it is to L. africana, possibly undermining the genus Loxodonta as a whole.[16]
Evolution and extinct relatives
Over 180 extinct members and three major evolutionary radiations of the order Proboscidea have been recorded.[17] The earliest proboscids, the African Eritherium and Phosphatherium of the late Paleocene, heralded the first radiation.[18] The Eocene included Numidotherium, Moeritherium, and Barytherium from Africa. These animals were relatively small and aquatic. Later on, genera such as Phiomia and Palaeomastodon arose; the latter likely inhabited forests and open woodlands. Proboscidean diversity declined during the Oligocene.[19] One notable species of this epoch was Eritreum melakeghebrekristosi of the Horn of Africa, which may have been an ancestor to several later species.[20] The beginning of the Miocene saw the second diversification, with the appearance of the deinotheres and the mammutids. The former were related to Barytherium and lived in Africa and Eurasia,[21] while the latter may have descended from Eritreum[20] and spread to North America.[21]
The second radiation was represented by the emergence of the gomphotheres in the Miocene,[21] which likely evolved from Eritreum[20] and originated in Africa, spreading to every continent except Australia and Antarctica. Members of this group included Gomphotherium and Platybelodon.[21] The third radiation started in the late Miocene and led to the arrival of the elephantids, which descended from, and slowly replaced, the gomphotheres.[22] The African Primelephas gomphotheroides gave rise to Loxodonta, Mammuthus, and Elephas. Loxodonta branched off earliest around the Miocene and Pliocene boundary while Mammuthus and Elephas diverged later during the early Pliocene. Loxodonta remained in Africa while Mammuthus and Elephas spread to Eurasia, and the former reached North America. At the same time, the stegodontids, another proboscidean group descended from gomphotheres, spread throughout Asia, including the Indian subcontinent, China, southeast Asia, and Japan. Mammutids continued to evolve into new species, such as the American mastodon.[23]
At the beginning of the Pleistocene, elephantids experienced a high rate of speciation.[24] The Pleistocene also saw the arrival of Palaeoloxodon namadicus, the largest terrestrial mammal of all time.[25] Loxodonta atlantica became the most common species in northern and southern Africa but was replaced by Elephas iolensis later in the Pleistocene. Only when Elephas disappeared from Africa did Loxodonta become dominant once again, this time in the form of the modern species. Elephas diversified into new species in Asia, such as E. hysudricus and E. platycephus;[26] the latter the likely ancestor of the modern Asian elephant.[24] Mammuthus evolved into several species, including the well-known woolly mammoth.[26] Interbreeding appears to have been common among elephantid species, which in some cases led to species with three ancestral genetic components, such as the Palaeoloxodon antiquus.[7] In the Late Pleistocene, most proboscidean species vanished during the Quaternary glaciation which killed off 50% of genera weighing over 5 kg (11 lb) worldwide.[27]
Proboscideans experienced several evolutionary trends, such as an increase in size, which led to many giant species that stood up to 500 cm (16 ft 5 in) tall.[25] As with other megaherbivores, including the extinct sauropod dinosaurs, the large size of elephants likely developed to allow them to survive on vegetation with low nutritional value.[28] Their limbs grew longer and the feet shorter and broader.[6] The feet were originally plantigrade and developed into a digitigrade stance with cushion pads and the sesamoid bone providing support.[29] Early proboscideans developed longer mandibles and smaller craniums while more derived ones developed shorter mandibles, which shifted the head's centre of gravity. The skull grew larger, especially the cranium, while the neck shortened to provide better support for the skull. The increase in size led to the development and elongation of the mobile trunk to provide reach. The number of premolars, incisors and canines decreased.[6]
The cheek teeth (molars and premolars) of proboscideans became larger and more specialized, especially after elephants started to switch from C3-plants to C4-grasses, which caused their teeth to undergo a three-fold increase in teeth height as well as substantial multiplication of lamellae after about five million years ago. Only in the last million years or so did they return to a diet mainly consisting of C3 trees and shrubs.[30][31] The upper second incisors grew into tusks, which varied in shape from straight, to curved (either upward or downward), to spiralled, depending on the species. Some proboscideans developed tusks from their lower incisors.[6] Elephants retain certain features from their aquatic ancestry, such as their middle ear anatomy.[32]
Several species of proboscideans lived on islands and experienced insular dwarfism. This occurred primarily during the Pleistocene when some elephant populations became isolated by fluctuating sea levels, although dwarf elephants did exist earlier in the Pliocene. These elephants likely grew smaller on islands due to a lack of large or viable predator populations and limited resources. By contrast, small mammals such as rodents develop gigantism in these conditions. Dwarf elephants are known to have lived in Indonesia, the Channel Islands of California, and several islands of the Mediterranean.[33]
Anatomy and morphology
Size
African bush elephant skeleton
Elephants are the largest living terrestrial animals. African bush elephants are the largest species, with males being 304–336 cm (10 ft 0 in–11 ft 0 in) tall at the shoulder with a body mass of 5.2–6.9 t (5.7–7.6 short tons) and females standing 247–273 cm (8 ft 1 in–8 ft 11 in) tall at the shoulder with a body mass of 2.6–3.5 t (2.9–3.9 short tons). Male Asian elephants are usually about 261–289 cm (8 ft 7 in–9 ft 6 in) tall at the shoulder and 3.5–4.6 t (3.9–5.1 short tons) whereas females are 228–252 cm (7 ft 6 in–8 ft 3 in) tall at the shoulder and 2.3–3.1 t (2.5–3.4 short tons). African forest elephants are the smallest species, with males usually being around 209–231 cm (6 ft 10 in–7 ft 7 in) tall at the shoulder and 1.7–2.3 t (1.9–2.5 short tons). Male African bush elephants are typically 23% taller than females, whereas male Asian elephants are only around 15% taller than females.[25]
Bones
The skeleton of the elephant is made up of 326–351 bones.[34] The vertebrae are connected by tight joints, which limit the backbone's flexibility. African elephants have 21 pairs of ribs, while Asian elephants have 19 or 20 pairs.[35]
Head
An elephant's skull is resilient enough to withstand the forces generated by the leverage of the tusks and head-to-head collisions. The back of the skull is flattened and spread out, creating arches that protect the brain in every direction.[36] The skull contains air cavities (sinuses) that reduce the weight of the skull while maintaining overall strength. These cavities give the inside of the skull a honeycomb-like appearance. The cranium is particularly large and provides enough room for the attachment of muscles to support the entire head. The lower jaw is solid and heavy.[34] Because of the size of the head, the neck is relatively short to provide better support.[6] Lacking a lacrimal apparatus, the eye relies on the harderian gland to keep it moist. A durable nictitating membrane protects the eye globe. The animal's field of vision is compromised by the location and limited mobility of the eyes.[37] Elephants are considered dichromats[38] and they can see well in dim light but not in bright light.[39]
African bush elephant with ears spread in a threat or attentive position; note the visible blood vessels
Ears
Elephant ears have thick bases with thin tips. The ear flaps, or pinnae, contain numerous blood vessels called capillaries. Warm blood flows into the capillaries, helping to release excess body heat into the environment. This occurs when the pinnae are still, and the animal can enhance the effect by flapping them. Larger ear surfaces contain more capillaries, and more heat can be released. Of all the elephants, African bush elephants live in the hottest climates, and have the largest ear flaps.[40] Elephants are capable of hearing at low frequencies and are most sensitive at 1 kHz (in close proximity to the Soprano C).[41]
Trunk
African bush elephant with its trunk raised, a behaviour often adopted when trumpeting
Asian elephant drinking water with trunk
The trunk, or proboscis, is a fusion of the nose and upper lip, although in early fetal life, the upper lip and trunk are separated.[6] The trunk is elongated and specialised to become the elephant's most important and versatile appendage. It contains up to 150,000 separate muscle fascicles,[42] with no bone and little fat. These paired muscles consist of two major types: superficial (surface) and internal. The former are divided into dorsals, ventrals, and laterals while the latter are divided into transverse and radiating muscles. The muscles of the trunk connect to a bony opening in the skull. The nasal septum is composed of tiny muscle units that stretch horizontally between the nostrils. Cartilage divides the nostrils at the base.[43] As a muscular hydrostat, the trunk moves by precisely coordinated muscle contractions. The muscles work both with and against each other. A unique proboscis nerve – formed by the maxillary and facial nerves – runs along both sides of the trunk.[44]
Elephant trunks have multiple functions, including breathing, olfaction, touching, grasping, and sound production.[6] The animal's sense of smell may be four times as sensitive as that of a bloodhound.[45] The trunk's ability to make powerful twisting and coiling movements allows it to collect food, wrestle with other elephants,[46] and lift up to 350 kg (770 lb).[6] It can be used for delicate tasks, such as wiping an eye and checking an orifice,[46] and is capable of cracking a peanut shell without breaking the seed.[6] With its trunk, an elephant can reach items at heights of up to 7 m (23 ft) and dig for water under mud or sand.[46] Individuals may show lateral preference when grasping with their trunks: some prefer to twist them to the left, others to the right.[44] Elephants are capable of dilating their nostrils at a radius of nearly 30%, increasing the nasal volume by 64%, and can inhale at over 150 m/s (490 ft/s) which is around 30 times the speed of a human sneeze.[47] Elephants can suck up food and water both to spray in the mouth and, in the case of the later, to sprinkle on their bodies.[6][47] An adult Asian elephant is capable of holding 8.5 L (2.2 US gal) of water in its trunk.[43] They will also spray dust or grass on themselves.[6] When underwater, the elephant uses its trunk as a snorkel.[32]
The African elephant has two finger-like extensions at the tip of the trunk that allow it to grasp and bring food to its mouth. The Asian elephant has only one and relies more on wrapping around a food item and squeezing it into its mouth.[11] Asian elephants have more muscle coordination and can perform more complex tasks.[43] Losing the trunk would be detrimental to an elephant's survival,[6] although in rare cases, individuals have survived with shortened ones. One elephant has been observed to graze by kneeling on its front legs, raising on its hind legs and taking in grass with its lips.[43] Floppy trunk syndrome is a condition of trunk paralysis in African bush elephants caused by the degradation of the peripheral nerves and muscles beginning at the tip.[48]
Teeth
Closeup of the cheek teeth of a dead juvenile bush elephant
Asian elephant eating tree bark, using its tusks to peel it off.
Elephants usually have 26 teeth: the incisors, known as the tusks, 12 deciduous premolars, and 12 molars. Unlike most mammals, which grow baby teeth and then replace them with a single permanent set of adult teeth, elephants are polyphyodonts that have cycles of tooth rotation throughout their lives. The chewing teeth are replaced six times in a typical elephant's lifetime. Teeth are not replaced by new ones emerging from the jaws vertically as in most mammals. Instead, new teeth grow in at the back of the mouth and move forward to push out the old ones. The first chewing tooth on each side of the jaw falls out when the elephant is two to three years old. The second set of chewing teeth falls out at four to six years old. The third set falls out at 9–15 years of age and set four lasts until 18–28 years of age. The fifth set of teeth falls out at the early 40s. The sixth (and usually final) set must last the elephant the rest of its life. Elephant teeth have loop-shaped dental ridges, which are thicker and more diamond-shaped in African elephants.[49]
Tusks
The tusks of an elephant are modified second incisors in the upper jaw. They replace deciduous milk teeth at 6–12 months of age and grow continuously at about 17 cm (7 in) a year. A newly developed tusk has a smooth enamel cap that eventually wears off. The dentine is known as ivory and its cross-section consists of crisscrossing line patterns, known as "engine turning", which create diamond-shaped areas. As a piece of living tissue, a tusk is relatively soft; it is as hard as the mineral calcite. Much of the tusk can be seen outside; the rest is in a socket in the skull. At least one-third of the tusk contains the pulp and some have nerves stretching to the tip. Thus it would be difficult to remove it without harming the animal. When removed, ivory begins to dry up and crack if not kept cool and moist. Tusks serve multiple purposes. They are used for digging for water, salt, and roots; debarking or marking trees; and for moving trees and branches when clearing a path. When fighting, they are used to attack and defend, and to protect the trunk.[50]
Like humans, who are typically right- or left-handed, elephants are usually right- or left-tusked. The dominant tusk, called the master tusk, is generally more worn down, as it is shorter with a rounder tip. For the African elephants, tusks are present in both males and females, and are around the same length in both sexes, reaching up to 300 cm (9 ft 10 in),[50] but those of males tend to be thicker.[51] In earlier times, elephant tusks weighing over 200 pounds (more than 90 kg) were not uncommon, though it is rare today to see any over 100 pounds (45 kg).[52]
In the Asian species, only the males have large tusks. Female Asians have very small tusks, or none at all.[50] Tuskless males exist and are particularly common among Sri Lankan elephants.[53] Asian males can have tusks as long as Africans', but they are usually slimmer and lighter; the largest recorded was 302 cm (9 ft 11 in) long and weighed 39 kg (86 lb). Hunting for elephant ivory in Africa[54] and Asia[55] has led to natural selection for shorter tusks[56][57] and tusklessness.[58][59]
Skin
An African forest elephant covering its skin with mud
An elephant's skin is generally very tough, at 2.5 cm (1 in) thick on the back and parts of the head. The skin around the mouth, anus, and inside of the ear is considerably thinner. Elephants typically have grey skin, but African elephants look brown or reddish after wallowing in coloured mud. Asian elephants have some patches of depigmentation, particularly on the forehead and ears and the areas around them. Calves have brownish or reddish hair, especially on the head and back. As elephants mature, their hair darkens and becomes sparser, but dense concentrations of hair and bristles remain on the end of the tail as well as the chin, genitals and the areas around the eyes and ear openings. Normally the skin of an Asian elephant is covered with more hair than its African counterpart.[60] Their hair is thought to be for thermoregulation, helping them lose heat in their hot environments.[61]
An elephant uses mud as a sunscreen, protecting its skin from ultraviolet light. Although tough, an elephant's skin is very sensitive. Without regular mud baths to protect it from burning, insect bites and moisture loss, an elephant's skin suffers serious damage. After bathing, the elephant will usually use its trunk to blow dust onto its body and this dries into a protective crust. Elephants have difficulty releasing heat through the skin because of their low surface-area-to-volume ratio, which is many times smaller than that of a human. They have even been observed lifting up their legs, presumably in an effort to expose their soles to the air.[60]
Legs, locomotion, and posture
An Asian elephant walking
To support the animal's weight, an elephant's limbs are positioned more vertically under the body than in most other mammals. The long bones of the limbs have cancellous bone in place of medullary cavities. This strengthens the bones while still allowing haematopoiesis.[62] Both the front and hind limbs can support an elephant's weight, although 60% is borne by the front.[63] Since the limb bones are placed on top of each other and under the body, an elephant can stand still for long periods of time without using much energy. Elephants are incapable of rotating their front legs, as the ulna and radius are fixed in pronation; the "palm" of the manus faces backward.[62] The pronator quadratus and the pronator teres are either reduced or absent.[64] The circular feet of an elephant have soft tissues or "cushion pads" beneath the manus or pes, which distribute the weight of the animal.[63] They appear to have a sesamoid, an extra "toe" similar in placement to a giant panda's extra "thumb", that also helps in weight distribution.[65] As many as five toenails can be found on both the front and hind feet.[11]
Elephants can move both forwards and backwards, but cannot trot, jump, or gallop. They use only two gaits when moving on land: the walk and a faster gait similar to running.[62] In walking, the legs act as pendulums, with the hips and shoulders rising and falling while the foot is planted on the ground. With no "aerial phase", the fast gait does not meet all the criteria of running, although the elephant uses its legs much like other running animals, with the hips and shoulders falling and then rising while the feet are on the ground.[66] Fast-moving elephants appear to 'run' with their front legs, but 'walk' with their hind legs and can reach a top speed of 25 km/h (16 mph).[67] At this speed, most other quadrupeds are well into a gallop, even accounting for leg length. Spring-like kinetics could explain the difference between the motion of elephants and other animals.[67] During locomotion, the cushion pads expand and contract, and reduce both the pain and noise that would come from a very heavy animal moving.[63] Elephants are capable swimmers. They have been recorded swimming for up to six hours without touching the bottom, and have travelled as far as 48 km (30 mi) at a stretch and at speeds of up to 2.1 km/h (1 mph).[68]
Organs
African elephant heart in a jar
The brain of an elephant weighs 4.5–5.5 kg (10–12 lb) compared to 1.6 kg (4 lb) for a human brain. While the elephant brain is larger overall, it is proportionally smaller. At birth, an elephant's brain already weighs 30–40% of its adult weight. The cerebrum and cerebellum are well developed, and the temporal lobes are so large that they bulge out laterally.[69] The throat of an elephant appears to contain a pouch where it can store water for later use.[6] The larynx of the elephant is the largest known among mammals. The vocal folds are long and are attached close to the epiglottis base. When comparing an elephant's vocal folds to those of a human, an elephant's are longer, thicker, and have a larger cross-sectional area. In addition, they are tilted at 45 degrees and positioned more anteriorly than a human's vocal folds.[70]
The heart of an elephant weighs 12–21 kg (26–46 lb). It has a double-pointed apex, an unusual trait among mammals.[69] In addition, the ventricles separate near the top of the heart, a trait they share with sirenians.[71] When standing, the elephant's heart beats approximately 30 times per minute. Unlike many other animals, the heart rate speeds up by 8 to 10 beats per minute when the elephant is lying down.[72] The blood vessels in most of the body are wide and thick and can withstand high blood pressures.[71] The lungs are attached to the diaphragm, and breathing relies mainly on the diaphragm rather than the expansion of the ribcage.[69] Connective tissue exists in place of the pleural cavity. This may allow the animal to deal with the pressure differences when its body is underwater and its trunk is breaking the surface for air,[32] although this explanation has been questioned.[73] Another possible function for this adaptation is that it helps the animal suck up water through the trunk.[32] Elephants inhale mostly through the trunk, although some air goes through the mouth. They have a hindgut fermentation system, and their large and small intestines together reach 35 m (115 ft) in length. The majority of an elephant's food intake goes undigested despite the process lasting up to a day.[69]
A male elephant's testes are located internally near the kidneys.[74] The elephant's penis can reach a length of 100 cm (39 in) and a diameter of 16 cm (6 in) at the base. It is S-shaped when fully erect and has a Y-shaped orifice. The female has a well-developed clitoris at up to 40 cm (16 in). The vulva is located between the hind legs instead of near the tail as in most mammals. Determining pregnancy status can be difficult due to the animal's large abdominal cavity. The female's mammary glands occupy the space between the front legs, which puts the suckling calf within reach of the female's trunk.[69] Elephants have a unique organ, the temporal gland, located in both sides of the head. This organ is associated with sexual behaviour, and males secrete a fluid from it when in musth.[75] Females have also been observed with secretions from the temporal glands.[45]
Body temperature
Elephants are homeotherms, and maintain their average body temperature at ~ 36 °C, with minimum 35.2 °C during cool season, and maximum 38.0 °C during hot dry season.[76] Sweat glands are absent in the elephant's skin, but water diffuses through the skin, allowing cooling by evaporative loss.[77][78][79] Other physiological or behavioral features may assist with thermoregulation such as flapping ears,[80] mud bathing, spraying water on the skin, seeking shade,[76][81] and adopting different walking patterns.[82] In addition, the interconnected crevices in the elephant's skin is thought to impede dehydration and improve thermal regulation over a long period of time.[83]
This vintage and highly stylish convex shaped enamel cap badge would have been worn in the 1950s/60s by a regional truck driver distributing Coca Cola from a bottling plant/s throughout the State of Queensland, Australia. The abbreviation QLD located at the bottom of this badge codes the piece to Queensland - identical badges from other Australian States used the following abbreviations: (NSW) New South Wales, (SA) South Australia, (VIC) Victoria, (WA) Western Australia and (TAS) Tasmania.
The badge was made by the Melbourne maker, Swann & Hudson, a company that along with other Melbourne makers such as KG Lukes, Brim Medallions and Wheelen's Castings made the majority of badges/pins, medallions and key chains between the 1900s and the 1980s. All these companies were, at different stages, amalgamated under the name 'JJ Cash' in the late 1980s which has since become Cash's Awards and Promotions Solutions.
Coca Cola debuted in Australia in 1938 and by 1939 numerous plants had opened all over the country. Indeed, the plants served both American and Australian Forces covering both urban bases and 'jungle units' stationed in the Pacific theatre. After the immediate post-war period, Coca Cola began granting franchises across the country. This grew rapidly and at one stage the Coca Cola drink was bottled in thirty different locations throughout Australia from small single-town bottlers e.g. Inverell and Cairns, to large conglomerate bottlers spanning regional States. Over the years these operations were rationalised and consolidated into one overarching territiory that is still held by Coca Cola Amatil today.
The Coca Cola beverage originated in the 19th Century and was invented in the USA by Dr John S Pemberton in 1886. His friend and business partner, Frank M Robinson, named the beverage 'Coca Cola' and created the familiar scripted logotype that was handwritten using classic letterforms from the Spencerian Script of the day. The logotype is one of the world's unique and instantly recognisable trademarks, evidenced by its longevity - bridging the 19th, 20th and 21st Centuries.
Photography, layout and design: Argy58
(This image also exists as a high resolution jpeg and tiff - ideal for a
variety of print sizes e.g. A4, A3, A2 and A1. The current uploaded
format is for screen based viewing only: 72pi)
No retouch but only pushed the shutter button.
This art work was designed by Ikemath.
Do you want to know the secret?
convex and concave is the title of M. C. Escher's work.
2007-10-02 Kakamigahara, Gifu, Japan
Pentax *istDS2
Valencia, la splendida facciata concavo-convessa della Cattedrale (1703). A sinistra la celebre torre campanaria medievale del Micalet.
Valencia, the splendid concave-convex façade of the Cathedral (1703). To the left the famous medieval bell tower of the Micalet.
Shot for Active Assignment Weekly, theme "Faceless Selfie".
WIT
Self portrait using a convex mirror. In post noise reduction, BW conversion and heavy cropping
They are so pretty, that they are best viewed large.
I think we all know by now that I am a bit of a magpie and I have several collections within my glass/crystal collection.
I have quite a lot of depression ware (and TEN large boxes still not unpacked - do I hear a sigh of relief !!!!) and in particular quite a lot of depression ware candleholders.
I actually spent five hours yesterday photographing my depression ware for a friends new web site and I thought over the next week or so I would pop up a few of my favourites that haven't been seen yet.
Now I BELIEVE these are Fostoria, one of the biggest makers of Depression ware in America. I have scoured the Internet and other makers and I cannot seem to confirm it. Bill Barber can you??
These are my favourite's as they are so unusual. Matching pair, flared curves at the top (very Fostoria), etched pedestals and in the centre it is actually convex glass.
I have not seen another pair like it in 8 years of collecting.
If anyone can identify them I would be so grateful!!
Taken from the sidewalk, reflected in a restaurant window, with a convex mirror inside.
I posted a version of this photo about a year ago, and it took a few months to get its first comment (thanks, Nino!) and almost a year to get its first fave (thanks, Zita!)
I think it deserves another look, not because I'm a great subject, but as a photograph.
In this version I cropped it square, desaturated a bit, did some cloning, and tried to find a better balance between sharpness and blur.
Convex and concave buddles on the floor of the buddle house, below the frue vanner house.
For more photographs of the Basset Mines click here: www.jhluxton.com/Industrial-Archaeology/Mines-of-Devon-Co...
[One of 7 images on the Heck-Andrews House] This is a creative commons image, which you may freely use by linking to this page. Please respect the photographer and his work.
“Among the first grand residences built in Raleigh after the Civil War, the Heck-Andrews House set the tone for the subsequent development of North Blount Street as an enclave of the well-to-do.” [www.nps.gov/nr/travel/raleigh/hec.htm] Contracted in 1869 by Jonathan Heck and finished in 1870, the house was designed by George S. H. Applegate (1831-1880) and constructed by John A. Waddell (1826-1883) of the firm of Wilson & Waddell. Heck, a Confederate officer in the Civil War, had been captured but paroled. His consequent fortune was made by manufacturing armaments for the Confederacy. “Life at the house was opulent and active. Photographs show the interior lavishly decorated in the style of the day, with heavy draperies, lace curtains, mahogany furniture and plush carpets.” [www.nps.gov/nr/travel/raleigh/hec.htm]
Jonathan Heck died in 1894 and his wife Mattie deeded the house to a daughter in 1916. In 1921 Raleigh attorney A. N. Andrews, Jr. acquired the property. After his death in 1946, the house went through a time of deterioration. In 1987 the state of North Carolina acquired majority interest in the building, completely refurbishing the exterior. Adaptive use had been planned for the interior, and I assume these plans have been realized.
A classic wood Second Empire-style mansion with blue and red trim, the Heck-Andrews House is marked by a tall 4-story front tower with convex mansard roof, 4 circular windows with decorated molding, and a balustrade at the top. Slate alternating rectangular with fish-scale shapes covers the tower. Dormers are the dominant feature of the structure’s concave mansard roof, the arched windows separated by exaggerated brackets and capped with wide pedimented hoods. Throughout the facade, the windows are slightly arched and have ornamental surrounds. A pediment is located just above the second level. Pairs of thick millwork brackets distinguish the overhang. The windows on the first level are taller than elsewhere, all with decorative surrounds of pale blue.
The bracketed porch roof mimics the concave aspect of the mansard roof, momentarily presenting an almost Oriental appearance. It uses the rectangular and fish-scale slate pattern of the main roof. Four steps lead upward to the porch leading to the entry with wooden door and heavily ornamented glass. A low porch railing of millwork is broken up by elaborately detailed posts set on decorated bases. Bay windows are prominent on the sides. At the rear right side is another porch and entry, utilizing the same patterns as the front porch but not as elaborately done.
The house was placed on the National Register of Historic Places 20 January 1972, NRHP #72001000.
Sources
1) National Register— www.nps.gov/nr/travel/raleigh/hec.htm
2) George S. H. Appleget— ncarchitects.lib.ncsu.edu/people/P000005
3) John A. Waddell— ncarchitects.lib.ncsu.edu/people/P000007
4) WRAL-TV (1999)— www.wral.com/news/local/story/137795/
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
A simple wireframe design with a convex hull of a truncated tetrahedron.
It is the sketch of something bigger and more sophisticated... Four Interlocking Hexagonal Prisms.
Designer: Me.
Paper: Kami.
Unit count: 24.
Paper's size: 1:3 rectangle.
Various views from the 19th floor of our hotel on Hornby Street, Vancouver - convex mirror windows make for interesting reflections - must be a selfie in there somewhere
2012 Hong Kong Bodybuilding Championships & 3rd South China Invitational Championships
2012 全港健美錦標賽 暨 華南地區健美邀請賽
I have a ton more pictures from the HK Bodybuilding Campionships, so if you competed, get in touch with me as I may have taken your picture.
The mirror was part of a security mirror package, I guess it won't mind that it will be watching our house now instead of catching people stealing sodas.
The now convex reflector is glued inside the top cap.
A 4" convex mirror could also be used but I had these steel dishes around from another project.
Vacant shells in water. Colour variation from reddish-brown to purple brown depends partly on lighting and colour of substrate and whether shell is vacant or occupied, and in water or air.
1: whorls distinctly convex, but in profile shell is a depressed dome.
2 : debris lodged in suture.
Shell length 2.3 mm. North Yorkshire, September 2014. (leg. Jan Light.)
Illustrated pdf of this account available at
www.researchgate.net/profile/Ian_Smith19/contributions
Otina ovata (Brown, 1827)
Full SPECIES DESCRIPTION BELOW
Sets of OTHER SPECIES at: www.flickr.com/photos/56388191@N08/collections/.
Synonyms: Helix otis Turton, 1819; Otina otis (Turton, 1819); Gallericulum ovatum Brown, 1827.
Vernacular: Little ear-shell.
GLOSSARY BELOW
Shell Description
Usually up to 2.5mm long, maximum 3mm. Thin, semi-translucent. Very large body-whorl and single tiny bulbous spire-whorl forming lateral, inwardly-twisted apex; resembles tiny limpet or Haliotis shell 1Oo flic.kr/p/qfV1Vb . Whorls distinctly convex, but in profile shell is a depressed dome 2Oo flic.kr/p/qi2ddH . Aperture ear-shape, very extensive but does not expose interior of spire. Interior glossy. Inner and outer lips together form uninterrupted rim. Outer (palatal) lip smoothly-curved and thin; paler band within rim is area outside of foot-muscle attachment. Inner (columellar & parietal) lip forms almost transparent whitish shelf; no umbilicus 3Oo flic.kr/p/q1Dh3A . Exterior of shell superficially smooth, but magnification reveals sculpture of distinct growth lines and fine, regularly-spaced, parallel spiral striae forming lattice of oblongs 1Oo flic.kr/p/qfV1Vb ; growth lines sometimes emphasized by debris lodged against them 4Oo flic.kr/p/q1MiYR . Colour various shades of brown 2Oo flic.kr/p/qi2ddH , often darkened to dark chestnut-brown or purple-brown by closely adhering periostracum; groups of white specimens sometimes found (Killeen & Light, 1990), and newly hatched young are transparent showing yellow yolk in viscera. No operculum.
Body Description
Flesh white, slightly translucent. Head has large oral veil of two oral lappets and no protruding snout 5Oo flic.kr/p/qi8MYs . Mouth a ventral slit between lappets 9Oo flic.kr/p/q1CBfJ . Internal black sclerotized jaw near mouth shows as grey mark near junction of head and veil. Other blackish internal organs show grey through translucent head and body 6Oo flic.kr/p/q1CBwf . Strong short wide radula covers entire free surface of odontophore; up to 100 lateral teeth plus marginal teeth per row. Rudimentary cephalic tentacles consist of mound bearing large black eye 7Oo flic.kr/p/q1Dgzb . Mantle white; thin and transparent over mantle cavity; reflected as white rim at edge of shell-aperture 7Oo flic.kr/p/q1Dgzb . Mantle cavity has no special respiratory capillaries (usually present in less primitive pulmonates). Pneumostome near posterior of right mantle_rim 8Oo flic.kr/p/q1Dgum . Anus adjacent and anterior to pneumostome. Female and male genital openings on right side under posterior of oral lappet; penis a simple introverted tube. Foot white; sole oval, divided transversely at a third of way from anterior edge 9Oo flic.kr/p/q1CBfJ .
Internal anatomy
Image 10Oo flic.kr/p/qi2cfF shows features visible in specimen extracted from shell; includes jaw, transparent mantle skirt over mantle cavity containing no ctenidium or special respiratory capillaries, horseshoe-shaped loop of intestine, digestive gland surrounding intestine, stomach, ovotestis and very small kidney.
Key identification features
·Otina ovata
·Minute (2mm long) limpet-form shell with tiny spire.
·Lives near HW mark in humid chasms and caves, and in crevices.
Similar species
Several species of small limpet in NW Europe might have juveniles around 2mm with small spire, but none lives at HW mark.
Habits and ecology
In humid shaded positions on clean rock from splash zone of MHWN down to EHWN, including moist walls of caves 11Oo flic.kr/p/pmrqyZ , north facing walls of chasms and outer parts of not-heavily-silted crevices on north faces of reefs of slate, shale, chalk etc. Favours fissured rock, but not unstable rapidly-eroding outcrops. Unlikely to occur where turbid water deposits film of mud over rock surfaces.
Obligatory hygrophile, unable to survive constant immersion of entire 12-hour tidal cycle so not below EHWN, but needs air humidity near 100%, becoming shrivelled and inert after twelve hours at 90%. Negatively geotactic when submerged, promptly moving up to escape total immersion when possible 6Oo flic.kr/p/q1CBwf . If exposed to non-humid air, moves promptly to humid shelter if possible, or clamps down onto substrate if none accessible.
Often associated in crevices with Melarhaphe neritoides, Littorina saxatilis, Cingula trifasciata, Auriculinella bidentata, Lasaea adansoni, Spirorbis borealis (tube worm), and Chthamalus spp. (barnacles). On open surfaces, active during periods of wave-splash, and at other times may venture out in very humid weather, especially if can shelter in dead barnacle shell, tuft of Lichina pygmaea or byssus of small Mytilus edulis. Positively thigmotactic, so often found in packed groups of about ten that conserve moisture.
Respiration is with atmospheric air admitted to the mantle cavity through a pneumostome 8Oo flic.kr/p/q1Dgum , but, unlike most pulmonates, O. ovata lacks special respiratory capillaries in the mantle cavity 10Oo flic.kr/p/qi2cfF . Broad lateral tracts of foot-surface 5Oo flic.kr/p/qi8MYs may have accessory respiratory function as blood comes here to body-surface under very thin epithelium through which respiratory interchange might easily be possible (Morton, 1955); probably sufficient respiration for slow-moving animal with small volume.
Feeds by scraping wave-lodged diatoms and filamentous algae from rock surface with radula while jaw grips on substrate. Food particles compacted at mouth with copious mucus from suprapedal gland on upper surface of anterior lobe of foot. Stomach with rotating protostyle of mucus and faeces, similar to that of bivalves, is most primitive yet described in a pulmonate (Morton, 1955) 10Oo flic.kr/p/qi2cfF . Faecal string never compressed into pellets, much more loosely compacted than in prosobranchs 9Oo flic.kr/p/q1CBfJ ; unlike them, has no ctenidium to be fouled and anus does not discharge into pallial cavity. Small kidney in front of looped intestine opens into pallial cavity with no water current to carry discharges out of cavity 10Oo flic.kr/p/qi2cfF ; probably assisted by accessory excretion from amoebocytes in broad lateral tracts of foot (Morton, 1955).
Travels by advancing anterior third of foot, fixing it to substrate and then bringing up the rest of the foot. Foot moved by muscles and disposition of blood in pedal sinus.
Breeding: protandrous hermaphrodite with no clear cut separation of male and female phases, each animal produces sperm in September – December, followed by an egg-producing phase December - June. Copulation with simple penis occurs before late March. Spawns in late May/ early June. Loose clusters of 20-30 eggs in tough, yellow/straw-coloured mucal secretion, 4-5mm across, loosely attached to substrate in humid conditions where adults live. Operculum, but no velum, present in embryos. Young hatch as crawlers with transparent shell revealing viscera yellow with egg-yolk in apical bulb. Uncertain if annual life cycle, but presence of all sizes simultaneously suggests biennial or longer.
Search technique “if properly searched for it would doubtless be found in every suitable locality” (Jeffreys, 1869).
Take a torch and large hand lens to help detect the tiny white glistening blobs of flesh, or, in late May and early June, the larger (4 or 5mm across) yellowish egg masses. Choose a humid misty day, if possible, as O. ovata is then more likely to emerge from cover, and visit as soon after high tide as access is possible; wellingtons or waders may help early access to caves with entrances still awash. Seek, in fissured rock, a cave or chasm that is narrow, so likely to retain humid air and exclude direct sun 11Oo flic.kr/p/pmrqyZ . Search wet and damp rock faces around high water mark; sometimes different coloured algal films indicate differences of moisture. Shaded, north-facing faces of fissured reefs may have some within crevices, but splitting them open is destructive of the habitat and should be done very sparingly, if at all. If you take specimens for study, transport them in a wet air-tight box that preserves 100% humidity. At home keep box in a fridge between 6°C and 10°C. Examination and photography can be of animal in seawater to save from dehydration, but it will become inactive and drown if kept submerged for more than a few hours.
Also, see 12Oo flic.kr/p/q1CALh & 13Oo flic.kr/p/qicbXR .
Distribution and status
Sparse scattered records, but can be locally common. Probably overlooked because of its small size and specialized habitat requiring targeted searching, and unfamiliarity of recorders with it as often omitted from id guides of both terrestrial and marine molluscs. Known distribution: Britain, Ireland, Normandy and Brittany. Isolated records of beached dead shells from N.W. Spain, S. Portugal and Sardinia. GBIF map www.gbif.org/species/5189862 . NBN UK map species.nbnatlas.org/species/NBNSYS0000041447 has records on S. and W. coasts of Britain from Isle of Wight to Mull, but there were 19th Century east-coast finds in Northumberland and Yorkshire (Forbes & Hanley, 1853), and Jan Light found live specimens in N. Yorkshire in September 2014.
Acknowledgements
I am indebted to Dr Jan Light for providing specimens and sharing her expertise at the visit by the Conchological Society of G.B. & Ireland to N. Yorkshire in September 2014. I gratefully acknowledge Dr C.M. Cunha and Dr G. Rosenberg for help with sources and their interpretation.
Links and references
Eales, N.B. 1967. The Littoral fauna of the British Isles 4th ed. Cambridge, Cambridge University Press.
Forbes, E. & Hanley S. 1849-53. A history of the British mollusca and their shells. vol. 3 (1853) London, van Voorst. (As Otina otis; Free pdf at archive.org/details/historyofbritish03forb Use slide at base of page to select pp.320-323.)
Hayward, P.J. & Ryland, J.S. 1995. Handbook of the marine fauna of north-west Europe. Oxford, Oxford University Press.
Jeffreys, J.G. 1862-69. British conchology. vol. 5 (1869). London, van Voorst. (As Otina otis; Free pdf at archive.org/stream/britishconcholog05jeffr#page/108/mode/2up . Use slide at base of page to select pp.109-111.)
Killeen, I. & Light, J.M. 1990. Observations on Otina ovata (Brown): a little known pulmonate. J. Conch., Lond 33: 317 – 318.
McMillan, N.F. 1968. British shells. London, Warne.
Marshall, J.C. 1913. Additions to British conchology. Part 7. J. Conch., Lond. 14: 65-77. 12Oo flic.kr/p/q1CALh
Melville, J.C. 1918. Otina otis Turton at St Mary’s, Scilly. J. Conch., Lond. 15: 261. 13Oo flic.kr/p/qicbXR
Morton, J.E. 1954. The crevice faunas of the upper intertidal zone at Wembury. J. Mar. biol. Ass. U.K. 33: 187 – 224. plymsea.ac.uk/view/year/1954.html#group_M
Morton, J.E. 1955. The functional morphology of Otina otis, a primitive marine pulmonate. J. Mar. biol. Ass. U.K. 34: 113 – 150.
(Free pdf at core.kmi.open.ac.uk/download/pdf/6185241.pdf . pp144 - 145 missing from pdf). Also plymsea.ac.uk/view/year/1955.html#group_M
Sosso, M. & Dell’Angelo, B. 2010. Prima segnalazione di Otina ovata (Brown, 1827) (Systellomatophora: Otinidae) in Mediterraneo Boll. Malacol. 46: 1-3.
Current taxonomy: World Register of Marine Species (WoRMS) www.marinespecies.org/aphia.php?p=taxdetails&id=140661
Glossary
amoebocytes – mobile cells (moving by pseudopodia like amoeba) in invertebrate bodies that variously digest food, dispose of waste, fight infection etc.
aperture – mouth of gastropod shell; outlet for head and foot.
apical - at the apex.
cephalic – (adj.) of or on the head.
columella - solid or hollow axial “little column” around which gastropod shell spirals; hidden inside shell, except on final whorl next to lower part of inner lip of aperture where hollow ones may end in an umbilicus or siphonal canal.
columellar – (adj.) of or near central axis of spiral gastropod.
columellar lip - lower (abapical) part of inner lip of aperture.
coll. – in the collection of (named person or institution) (cf. legit).
ctenidium – comb-like molluscan gill; usually an axis with a row of filaments either side.
epithelium – tissue forming outer layer of body surface, “skin”.
EHWN – extreme high water neap tide (the weakest high tides of the year i.e. those that rise the least, usually near June and December solstices)
geotactic – (adj.) of species that moves towards pull of gravity (positively geotactic) or away from it (negatively geotactic). (Synonyms: gravitaxic, ? geotaxic.)
hygrophile – species that prefers moist conditions; often at water’s edge, but not permanently submerged. obligatory hygrophile – unable to survive out of moist conditions.
introverted – turned in on itself.
legit – (abbreviation; leg. or lgt.) collected/ found by (compare with coll.)
mantle – sheet of tissue that secretes the shell and forms a cavity for the gill in most marine molluscs (but not in adult nudibranchs), part or all of dorsal body surface when shell absent or internal.
MLWN – mean low water neap tide level (mean level reached by weakest low tides for a few days every fortnight. i.e. those that fall the least).
MHWN – mean high water neap tide level (mean level reached by weakest high tides for a few days every fortnight. i.e. those that rise the least).
odontophore – firm, approximately ellipsoid, structure of cartilage supporting radula. Protruded like a tongue to operate radula.
operculum – plate of horny conchiolin, rarely calcareous, used to close shell aperture.
oral lappets – flaps of flesh by mouth.
oral veil – flat anterior extension of head (may consist of lappets).
ovotestis – hermaphrodite organ serving as both ovary and testis.
palatal lip - outer lip of gastropod aperture.
pallial – (adj.) of the mantle.
parietal lip – (=parietal wall) part of inner lip of gastropod aperture, adapical of columellar lip.
pedal – (adj.) of the foot.
periostracum – thin horny layer of proteinaceous material often coating shells.
plankton – animals and plants that drift in pelagic zone (main body of water).
pneumostome - breathing pore in mantle of pulmonate molluscs.
protandrous hermaphrodite – each individual starts mature life as a functioning male, later changing to female function.
pulmonate – (adj.) of terrestrial and freshwater, air-breathing, slugs and snails.
radula – ribbon of chitinous teeth extruded on a tongue-like structure (odontophore) to rasp food.
rec. – recorded by (person who submitted record, may be different from leg. and coll. persons/institution).
sensu lato – (abbreviation s.l.) in the wide sense.
sensu stricto – (abbreviation s.s.) in the strict sense, excluding species that have been confused with it.
stria – very narrow spiral groove or ridge (plural: striae)
taxis – directional locomotary response to external stimuli such as light, gravity, temperature or chemicals.
thigmotactic – (adj.) of animal that moves towards (positively thigmotactic) or away (negatively thigmotactic) from physical contact with others.
umbilicus – cavity up axis of some gastropods, open as a hole or chink on base of shell, often sealed over.
velum – bilobed flap on veliger larva, with beating cilia for swimming.
Chapeau convexe mon spécimen jusqu’au 10cm.brun pale sec relevé ver la marge avec l’âge
Pied brun orange égal atténue ver le bas pointu
Pores blanc puis rosâtre par ses spores rond anguleux ver le pied.
Croissance avec pins .
reversible / squashable (nearly) sphere shape
lattice of equilateral convex hexagon rings.
Diameter about 15cm.
© Seb Alessandroni | All rights reserved.
All photos they may not be used or reproduced without my permission. If you would like to use one of my images for commercial purposes or other reason, please contact me. Depending on the situation may have to assign the work as specified by the author.
Squat, extremely exposed-shore form with short spire height (1) c. 24% of shell height. Large aperture 76% of height. Fourteen well developed, flattened, spiral ridges on body-whorl. Shell height 25 mm, breadth 17.4 mm. West coast of Hoy, Orkney (Atlantic fetch over 3000km). July 1973.
SPECIES DESCRIPTION PART A BELOW
Key id. features: flic.kr/p/oErLAb
SPECIES DESCRIPTION PART B at flic.kr/p/oGiBxM
Sets of OTHER SPECIES:
www.flickr.com/photos/56388191@N08/collections/
Illustrated pdf of account available at
www.researchgate.net/profile/Ian_Smith19/contributions
Nucella lapillus (Linnaeus, 1758)
Synonyms: Purpura lapillus (Linnaeus, 1758); Thais lapillus (Linnaeus, 1758); Polytropa lapillus (Linnaeus, 1758);
Vernacular: Dog whelk; Dog winkle; Purple; Rock whelk; Horse winkle (English); Gwichiad/Chwalcen y cŵn; Cragen foch felen (Welsh); Purpursnegl (Danish & Norwegian); purperslak (Dutch); Pourpre petit pierre; pourpre (French); Nordische Steinchenschneke/Purpurschneke (German); Purpur snäcke (Swedish);
GLOSSARY BELOW
Shell Description
Adults usually 17 to 30mm high, up to 45mm littorally 1Nl flic.kr/p/oErLAb and over 60mm sublittorally. Shape varies from long and slender (spire c. 55%, of shell height) 5Nl flic.kr/p/oCvYLG to short and squat (spire c. 24%, of shell-height) 2Nl flic.kr/p/oEkeZW . Apex slightly twisted, sharp if uneroded. Whorls moderately convex. Sutures usually slight, may be deeper near apex 3Nl flic.kr/p/oGiBxM , can be almost obliterated by erosion 4Nl flic.kr/p/oGiAZH . Aperture height varies greatly, about 45% 5Nl flic.kr/p/oCvYLG to 80% 2Nl flic.kr/p/oEkeZW of shell height. Juveniles and sub-adults (less than c17mm high) have thin shell- walls with sharp outer lip 6Nl flic.kr/p/oo3ZVh . Adults (when 17mm or more high) usually cease longitudinal growth and develop thick shell-walls and line of blunt bosses within outer lip of aperture 7Nl flic.kr/p/oCvWwm . Sometimes more than one row of bosses if growth arrested prematurely. Outer lip smooth, interior slightly shiny, not sharp, but tapers from bosses to edge. Aperture rapidly constricts into throat 8Nl flic.kr/p/oExH2t . Adapical angle acute when young 6Nl flic.kr/p/oo3ZVh , rounded as shell thickens 9Nl flic.kr/p/oEh5nn . Short, straight, open siphonal canal at base of aperture. Columellar and parietal lips are wide, smooth and slightly shiny 10Nl flic.kr/p/oCvTfw ; columellar lip overhangs siphonal canal slightly; parietal lip continuous with outer lip through the adapical angle. Siphonal fasciole pronounced on some 11Nl flic.kr/p/ooe2CW . Sculpture of flattened, spiral ridges (about 12 on body-whorl) 12Nl flic.kr/p/ooeM9v & 2Nl flic.kr/p/oEkeZW , often indistinct or absent 9Nl flic.kr/p/oEh5nn . Growth lines usually indistinct. Newly hatched young have globular, smooth, glossy shell (protoconch) of 2½ whorls about 1mm high. Early growth to c.3mm very often has prominent imbricate sculpture 13Nl flic.kr/p/ooeKHK which, with the protoconch, may persist on early whorls of uneroded adults 3Nl flic.kr/p/oGiBxM and occasionally continue on later whorls 14Nl flic.kr/p/oEHJRv & 15Nl flic.kr/p/oEvg6d . Ground colour white 7Nl flic.kr/p/oCvWwm , whitish-grey 4Nl flic.kr/p/oGiAZH , yellow 12Nl flic.kr/p/ooeM9v , orange 16Nl flic.kr/p/oCFXZ1 , brown to black 17Nl flic.kr/p/oGtyn8 , or mauve to pink 3Nl flic.kr/p/oGiBxM . Interior of aperture shows exterior colours on thin translucent young shells 6Nl flic.kr/p/oo3ZVh , and thickened adult shells are often coloured internally 9Nl flic.kr/p/oEh5nn , 10Nl flic.kr/p/oCvTfw & 12Nl flic.kr/p/ooeM9v . Sometimes exterior colours combined in spiral bands; narrow and confined to grooves between spiral ridges 18Nl flic.kr/p/ooe7M2 , or broad 6Nl flic.kr/p/oo3ZVh . Growths 7Nl flic.kr/p/oCvWwm , encrustations 19Nl flic.kr/p/oEFXeY and erosion 4Nl flic.kr/p/oGiAZH can affect colour. Light-horn coloured periostracum often on small juveniles 13Nl flic.kr/p/ooeKHK , absent or insignificant on adults. Broad, angular, mahogany, non-spiral operculum 20Nl flic.kr/p/ooeFck ; thin outer face extruded from transverse groove at anterior of opercular disc has many fine, gently-curving growth lines increasing in length away from nucleus on posterior (labial) edge; thick inner face made of stack of annual growth plates (adventitious layers extruded from circles of glands on opercular disc) with excentric nucleus and matt surface where opercular disc attached (termination of columellar muscle). Posterior (labial) margin beyond disc attachment (c.25% of total operculum surface) covered by shiny varnish from transverse groove across posterior of opercular disc. Operculum nearly opaque on old adults, but younger ones have translucent operculum through which adventitious plates show as strong concentric rings that obscure fine exterior growth lines 21Nl flic.kr/p/oojcrR .
Body Description
Flesh, apart from mantle, entirely pure-white or yellowish-white, variably translucent 22Nl flic.kr/p/oGy5Jx , sometimes opaque white freckles visible on surface of more translucent parts 23Nl flic.kr/p/oENedn . Head consists of transverse ridge at juncture of cephalic tentacles. No snout visible, except, when feeding, a short, thin proboscis 39bNl flic.kr/p/DAshoD is everted like a sock turned inside-out from opening at base of head’s anterior 24Nl flic.kr/p/oENe6Z . Pink buccal mass 22Nl flic.kr/p/oGy5Jx with narrow, short radula, about 30% of shell length; only three teeth per row 25Nl flic.kr/p/ooiMib . Long, tapering, rounded cephalic tentacles; translucent white, sometimes with opaque white flecks 23Nl flic.kr/p/oENedn . Basal two thirds of cephalic tentacle thickened by fusion with eye peduncle; black eye on summit of outer face of thickened section 26Nl flic.kr/p/ooiQC7 ; divided ventrally on one examined specimen 27Nl flic.kr/p/oojdTP . Mantle edge thickened, usually yellowish even on pure white animals 28Nl flic.kr/p/oGy3si , occasionally with a little brown. Mantle folded into white inhalent siphon on left of body, continues as channel to osphradium and substantial buff ctenidium within mantle cavity; siphon extends only slightly beyond end of siphonal canal of shell 29Nl flic.kr/p/oEwBUT . Faint pink of myoglobin-rich buccal mass, white salivary glands and other internal organs sometimes visible behind head of well-extended animal 22Nl flic.kr/p/oGy5Jx . Flat, strap-like (when live) penis attached sub-dorsally behind right tentacle; recurved up to 360° 24Nl flic.kr/p/oENe6Z , may be pulled straighter during emergence of body from shell 30Nl flic.kr/p/oEwA7p . Foot can change between oblong 31Nl flic.kr/p/ooMS7c and bluntly oval 32Nl flic.kr/p/ooMja8 , often constricted behind propodium. Anterior edge bilaminate 33Nl flic.kr/p/ooMRLT , sole and dorsum coloured as body. Small opercular disc does not extend beyond or overlap edge of operculum 24Nl flic.kr/p/oENe6Z , apart from anterior edge of operculum being exuded from opercular groove 27Nl flic.kr/p/oojdTP . Strong white columellar muscle attaches opercular disc to columella of shell 34Nl flic.kr/p/oFgVyD . Sole of foot divided along midline; most obvious when foot folds along it 23Nl flic.kr/p/oENedn . Sucker-like accessory boring organ (ABO) in sac within foot on midline near anterior; when everted swells into a large proboscis-like projection. Female has ventral pedal gland for moulding egg capsules, anterior to centre of sole.
Internal anatomy
When extracted from shell, organs in place but indistinctly seen through translucent mantle on anterior half of body. When mantle cut along pallial inhalent channel and opened out to the right of the animal like a page of a book, organs attached to its inner face are displaced but more clearly visible.
KEY to items on images 35aNl flic.kr/p/oF4opC & 35bNl flic.kr/p/oF4o3W (extracted male), 36Nl flic.kr/p/ooMch1 (opened male) 37Nl flic.kr/p/oF1kCZ (extracted female) 38Nl flic.kr/p/oFfdey (opened female). If key is read in order, the functions and inter-relationship of the organs may be understood.
Mantle
1: mantle edge - substantial, opaque, yellowish, slightly flounced, anterior border of mantle skirt. Only part that produces exterior layers of shell. Sometimes flounces exaggerated and make protruding shell-growth that forms imbricate sculpture. (Images 35a&b, 36, 37)
2: mantle skirt - forms roof of mantle cavity and, when uncut, partially obscures organs within. (Images 35a&b, 37)
Respiratory features
3: siphon – white, folded extension of mantle that rests in shell’s siphonal canal and draws in inhalent current of water when animal extended. (Images 35a, 36, 37)
4: pallial inhalent channel – distinct, white fold in mantle forming a channel from siphon to osphradium. (Images 35a, 36, 37)
5: osphradium - dark, bipectinate chemo-receptor at inner end of inhalent channel that tests water approaching ctenidium for quality and scents of food, prey, predators and/or mates. So highly developed on Nucella that Jeffreys (1867) thought it was second ctenidium. (Images 35a, 36, 37, 38)
6: ctenidium - substantial, buff-white gill with many fine leaflets that receive oxygen from inhalent water, and oxygenate blood passing through them. (Images 35a&b, 36, 37, 38)
7: hypobranchial gland – puckered gland that produces mucous to trap particles from inhalent water before reaches ctenidium, and to transport particles out of mantle cavity. Other functions might be attraction of mates by scent, and acrid smell/taste to discourage predators. Initially cream-white, changing to yellow, green, purple etc when exposed to light and air. (Images 35a&b, 36,37)
Vascular features
8: kidney – de-oxygenated blood has urea etc. removed and excreted by kidney before passing to efferent renal vein [9]. (Images 35a&b)
9: efferent renal vein – carries blood away from kidney. (Image 35b)
10: Hypobrachial vessels – carry blood from efferent renal vein through hypobranchial gland to afferent vessel of ctenidium [11]. (Image 35b)
11: afferent vessel of ctenidium – receives blood from hypobranchial vessels and passes it into leaflets of adjacent ctenidium for oxygenation. (Image 35b)
12: rectal gland - long, linear gland; dark brown to purple-black in adults. Function uncertain, perhaps produces substances that supplement the excretory activity of the kidney. (Images 35a&b, 37, 38)
Alimentary features
13: buccal mass – pink as rich in myoglobin; contains odontophore and anterior of radula used in rasping prey. (Image 36)
14: acinous salivary gland - compound gland of many small rounded sacs that secrete enzymes for external pre-digestion/ liquefaction of prey. (Image 36)
15: gland of Leiblein - secretes enzymes for internal digestion of ingested liquefied prey. (Image 36)
16: digestive gland – mass of branching tubules and ducts occupying majority of visceral mass (spiral ‘tail’ of body); most visible feature, except in breeding season when much may be covered by ovary or testis. Receives solution of digested food from stomach into tubules where taken up by absorbing digestive cells and passed into blood bathing the tubules. (Images 35a&b, 36, 37, 38)
Reproductive features
17: ovary- gland that produces eggs. (Image 37)
18: albumen gland - translucent whitish gland that secretes albumen for nutrition of developing eggs. (Images 37, 38)
19: sperm ingesting gland - dark brown blind tubules in female where sperm excess to requirements is engulfed and digested by cells; gland is used to establish sex of specimens as penis can occur on females affected by imposex. (Image 37, 38)
20: capsule gland - secretes fibrous wall of capsule containing ova, but does not give it its final shape. (Images 37, 38)
21: testis - gland that produces spermatozoa. (Images 35a&b, 36)
22: prostate – pink gland that secretes fluid which, with spermatozoa and seminal vesicle fluid, forms the semen. (Images 35b, 36)
23: penis - on males, and on females affected by imposex caused by tributyltin pollution. (Image 36)
SPECIES DESCRIPTION PART B at flic.kr/p/oGiBxM
Glossary
abapertural = away from aperture.
acinous salivary gland = compound gland of many small rounded sacs that secrete enzymes for external predigestion/ liquefaction of prey.
adapertural = towards aperture.
adapical = towards the apex of the shell.
afferent = carrying towards. (e.g. of vessel carrying blood, see efferent.)
aperture = mouth of gastropod shell; outlet for head and foot.
Ballantine scale = biologically-defined wave exposure scale (see references).
bipectinate = feather-like, with narrow filaments either side of central stalk.
capsule gland = secretes fibrous wall of capsule containing ova.
cephalic = (adj.) of or on the head.
chelae = (singular chela) pincers of crabs and other crustacea.
cilia = (pl.) vibrating linear extensions of membrane used in feeding or locomotion. (“cilium” singular).
ciliated = (adj.) coated with cilia.
columella = solid or hollow axial “little column” around which gastropod shell spirals; hidden inside shell, except on final whorl next to lower part of inner lip of aperture where hollow ones may end in an umbilicus or siphonal canal.
columellar = (adj.) of or near central axis of spiral gastropod.
columellar lip = lower (abapical) part of inner lip of aperture.
columellar muscle = attaches body, including opercular disc, to columella of shell; contraction of muscle withdraws body within shell, and pulls operculum to seal aperture.
commensal = (adj.) obtaining nutrients, shelter, support, or locomotion from a host species, without causing it significant detriment.
conchiolin = horny flexible protein that forms the matrix for the deposition of calcium carbonate to create a mollusc’s shell.
ctenidium = comb-like molluscan gill; usually an axis with a row of filaments either side.
ditaxic = (of locomotion waves on foot) double series of waves, out of phase with each other, one series on each side of central furrow on sole.
direct = (of locomotion waves on foot) waves travel from posterior to anterior.
efferent = carrying away from. (e.g. of vessel carrying blood from ctenidium).
fasciole = (see siphonal fasciole)
gland of Leiblein = secretes enzymes for internal digestion.
height = (of gastropod shells) distance from apex of spire to base of aperture.
hypobranchial gland = thickened, sometimes puckered, tissue on roof of mantle cavity of many gastropods. Emits mucous to trap particles from
inhalent water before it reaches ctenidium. Often other biologically active compounds produced. Gland occurs also in some bivalves and cephalopods (ink sac).
imbricate = shell sculpture of growth-line ornament overlapping like roof tiles.
MHWN = mean high water neap tide level (mean level reached by weakest high tides for a few days every fortnight).
MHWS = mean high water spring tide level (mean level reached by highest tides for a few days every fortnight; Pelvetia zone on rocky coasts).
MLWN = mean low water neap tide level (mean level reached by weakest low tides for a few days every fortnight. i.e. those that fall the least).
mantle = sheet of tissue that secretes the shell and forms a cavity for the gill in most marine molluscs.
mesopodium = middle section of gastropod foot. (see propodium & metapodium).
metapodium = rear section of gastropod foot. (see mesopodium & propodium).
myoglobin – red oxygen-binding protein in muscle tissue; often in buccal-mass muscles of gastropods. Similar to red haemoglobin in vertebrate blood, but green haemocyanin is usual oxygen-carrier in mollusc blood. See www.researchgate.net/publication/251227038_Radular_myoglo...
N = (See Newton).
Newton = (abbreviation N) force exerted by Earth’s gravity on approx. 100g.
odontophore = cartilaginous “tongue” that supports and protracts /retracts the radula.
opercular = (adj.) of the operculum.
opercular disc = part of foot attached to inner face of operculum.
opercular lobe = extension of opercular disc round edge of part of operculum.
operculum = plate of horny conchiolin, rarely calcareous, used to close shell aperture.
osphradium = chemo-receptor organ in molluscs that tests inhalent water flow approaching ctenidium (gill) for “smell” of food, prey, predators, mates and/or water quality.
penes = (plural of penis) male copulatory organs.
periostracum = thin horny layer of chitinous material often coating shells.
plankton = animals and plants that drift in pelagic zone (main body of water).
propodium = front section of gastropod foot. (Cf. mesopodium & metapodium).
prosobranchia = 20th Century term for subclass of Gastropoda that included most marine snails with ctenidia. Now distributed between several subclasses. See note at www.marinespecies.org/aphia.php?p=taxdetails&id=102
rectal gland = (a.k.a. anal gland) Function uncertain, perhaps produces substances that supplement the excretory activity of the kidney.
retrograde = (of locomotion waves on foot) waves travel from anterior to posterior.
sessile = (of organism) fixed in one place, e.g. barnacles.
siphon = extension of mantle to form a channel for inhalent respiratory water current.
siphonal canal = grooved or tubular extension of outer lip of the shell aperture on some snails to support the siphon.
siphonal fasciole = raised rib, ridge or band along abapertural side of siphonal canal, formed by successive edges of canal.
sperm ingesting gland = (in female Nucella lapillus) group of dark brown blind-ended tubules at posterior of capsule gland where excess sperm unrequired by female are trapped, engulfed by cells and digested.
suture = groove or line where whorls of gastropod shell adjoin.
vas deferens = tube carrying sperm to male’s penis.
veliger = shelled larva of marine gastropod or bivalve mollusc which swims by beating cilia of a velum (bilobed flap).
Light mauve-pink shell with slight flattened spiral ribs. Sharp uneroded spire retaining smooth apical protoconch and some imbrication on earl whorls. Whorls moderately convex with shallow sutures, deeper near apex. Menai Strait, Wales. February 2013.
SPECIES DESCRIPTION PART B BELOW
Key id. features: flic.kr/p/oErLAb
SPECIES DESCRIPTION PART A at flic.kr/p/oEkeZW
Sets of OTHER SPECIES:
www.flickr.com/photos/56388191@N08/collections/
Habits and ecology
Commonest carnivorous prosobranch on rocky shores in Britain and Ireland. Usually most numerous between MHWN (75% time exposed to air) and MLWN, but up to MHWS if sheltered crevices, and to 20 metres depth in some places. Lives on shores ranging from extremely wave-exposed (Ballantine scale grade1) to extremely sheltered (grade 8), adjusting its low tide behaviour thus: on exposed shores shelters in crevices during storms and active in calm weather, even bright sun; on sheltered shores active at night and in daytime cloudy weather, sheltering in crevices and under rocks from sun. Lower limit of salinity tolerance varies with locality, in Britain usually down to 20 or 25 p.p.t. ; can survive short periods of lower salinity, but not where it is norm. Temperature limits (isotherms of neighbouring oceanic water) up to 19°C in summer, down to 0°C in winter; wider extremes on shore, upper lethal temperature 35°C. Some Swedish populations retreat to sublittoral to avoid winter ice on shore, and in Arctic Russia they retreat under stones on the lower shore. Abundance governed by prey availability; often >10/m² on semi-exposed (grade 4) shores where Semibalanus balanoides (barnacle) abundant, but few on extremely sheltered shores where dense weed-cover inhibits barnacle establishment apart from on occasional steep surfaces 40Nl flic.kr/p/oFfbtQ .
Respiratory water drawn in on left side through inhalent siphon by beat of cilia on robust ctenidium in the mantle cavity. Siphon and pallial channel allow water to be inhaled away from contamination of food, and, with osphradium at inner end of channel, to test water quality and the scents of prey and mates.
Locomotion by ditaxic retrograde waves on centrally divided sole of foot. Slow moving shambling gait. Sedentary as sessile prey usually abundant and unable to flee. Travels about 10cm in a tidal cycle, with days immobile while digests meals. No planktonic stage; dispersal relies on slow crawling; consequent low gene exchange contributes to local differences in appearance and behaviour; chromosome number of races varies.
Eats, in order of usual preference (Crothers, 1985):
Semibalanus balanoides (barnacle) flic.kr/s/aHsjzKXTEt (Flickr album);
Mytilus edulis (mussel, usually under 40mm long) 39a flic.kr/p/DAskNz ;
Elminius modestus (barnacle) flic.kr/s/aHsjyVXcr4 (Flickr album);
and less than full-grown Perforatus perforatus (barnacle) flic.kr/s/aHsjzsQKto (Flickr album).
Adults usually ignore small barnacle species such as Chthamalus flic.kr/s/aHsjzknk9h & flic.kr/s/aHsjzon3f1 (Flickr albums) [Some sources contradict Crothers; cause may be geographical variation in genetics or habit, or frequent misidentification by humans of barnacle spp. - examination of tergoscutal flaps required flic.kr/s/aHsjDCN2nY Flickr album].
When preferred-prey reduced or absent, feed on Patella spp. 40aNl flic.kr/p/CmkBu4 , Littorina spp. or other mollusca. Juveniles up to 8mm high eat tiny Mytilus, Spirorbis (worm) and, in Arctic Russia (Matveeva, 1955), Onoba aculeus (gastropod) in preference to barnacles. In extreme S.W. England, where S. balanoides is rare or absent (settlement and survival vary greatly with weather from year to year, Lewis, 1964, pp.250-251), Mytilus edulis is most frequent prey 39bNl flic.kr/p/DAshoD , and Patella spp. 40aNl flic.kr/p/CmkBu4 ,Littorina spp. and Gibbula spp. are frequently attacked (Crothers, 1985). Switching to Patella also occurs in areas, such as North Wales and Orkney, where S. balanoides breeds and survives consistently. In Guernsey 31 of 100 vacant Patella shells examined from sheltered shore (Ballantine scale 6-7; near-continuous fucoid cover) had completed Nucella-boreholes (Flint, 2001), suggesting high rate of predation, especially as Patella less than 35mm long can be forced off without boring. On sheltered shores sweep of dense fucoids often hinders settlement of barnacles 40Nl flic.kr/p/oFfbtQ , so reducing favoured prey and causing switch to Mytilus. But no Mytilus observed on this Guernsey shore so Patella the next best thing available. On a very exposed Guernsey shore (Ballantine scale 2; no fucoid cover, barnacles abundant) only 2 of 99 examined vacant Patella shells had completed Nucella-boreholes (Flint, 2001), suggesting less switching to Patella where plentiful barnacles. Oyster spat eaten in Essex. When a prey species exhausted, often delayed transfer, even to 'preferred' species, from what locally accustomed to while learns how to handle new prey.
Adults force way between opercular valves of barnacles with proboscis. Paralysing narcotic and digestive enzymes from salivary glands 22Nl flic.kr/p/oGy5Jx injected to liquefy flesh that is ingested through proboscis. Only small shells of M. edulis can be forced apart 39aNl flic.kr/p/DAskNz , and small N. lapillus cannot force way into barnacles. In these cases, and on other large prey, N. lapillus bores neat hole through shell 40bNI flic.kr/p/DbrK5H by alternating rasping by radula with application by accessory boring organ of enzymes and acid that soften conchiolin and lime in prey’s shell. Angle of radula constantly changed to give smooth round hole; straight rasp-marks show that no rotary action involved 40bNl flic.kr/p/DbrK5H . Diameter of hole constant; rim not bevelled and no raised boss at base of unfinished hole 40cNI flic.kr/p/CRBdSm (bevel and boss found in unfinished holes made by Euspira spp. mainly in bivalves) . On limpets, Nucella usually bore into pedal-retractor muscle 40dNl flic.kr/p/Cmkt7H , or central area enclosed by it 40eNl flic.kr/p/E8iHfS , where radula can reach nutritious viscera; of 73 vacant bored shells in Guernsey only 7% of holes were into viscera-free periphery distal of the muscle, though periphery was 52% of area of shells (Flint, 2001). Boring and feeding take between a day and over a week, depending on temperature and size of prey, followed by resting in sheltered position for day or two after barnacle meal to about five days after a mussel. Boring causes much wear on anterior teeth of radula. Liquid diet results in small amounts of small faecal pellets. Neighbours of assaulted Mytilus can counter-attack by attaching byssus threads to attacker and tightening them to pull it off victim and turn it over so foot is unable to grip substrate to escape 41Nl flic.kr/p/oFaR7o . This may be targeted, rather than accidental, as non-predatory Littorina littorea on mussel beds rarely so ensnared. N. lapillus seem aware of risk as small mussels without close neighbours preferred to dense beds, and boring usually near posterior adductor muscle away from mussel’s foot and byssus 41aMe flic.kr/p/oFmGPh . Possible alternative explanation: Littorina littorea more active than N. lapillus so moves and snaps attached byssus threads before numerous and set enough to restrain it. Many free N. lapillus have snapped byssus threads on shell from when moved in time to escape 26Nl flic.kr/p/ooiQC7 .
Consumption of N. lapillus by humans discouraged by acrid smell and taste, but several known predators; list in Crothers (1985) p. 302. Main enemies are Carcina maenas and Necora puber (crabs) and Larus spp. (gulls), and it is one of the hosts parasitized in sequence with Cerastoderma edule and Larus spp. by Parorchis acanthus (trematode worm). Thick shell can sustain considerable abrasion/erosion, but Polydora worms, initially commensal, may eventually cause its decay with multiple borings 1Nl flic.kr/p/oErLAb .
Variations in shell colour have been attributed to diet (barnacles :white, Mytilus : dark), but environmental selection and genetics seem more likely. Colour of individual’s new growth can change in response to impact of move from shore to aquarium; can confuse laboratory colour: diet experiment results. Populations with large proportions of coloured and banded shells are most frequent in S. Wales and S.W. England, including, but not only, the area where Mytilus consumption predominates. In most populations, old specimens are predominately plain whitish or greyish as outer pattern-bearing layer is eroded away 4Nl flic.kr/p/oGiAZH .
Variations in shell shape, size, strength and sculpture are related to combinations of environmental pressures and genetic factors. Adults from sheltered shores, when compared with those from neighbouring exposed shores, on average, have longer spires, smaller apertures, and stronger shells 42Nl flic.kr/p/oF7Nct . These features help resist attack of crabs (common on sheltered shores) by giving space to withdraw into spire, less space for crabs to insert their chelae and harder-to-crack shells (in N. Wales, average force of 580 Newtons to break adult shells on very sheltered shores, 240N on exposed shores). The small aperture also reduces evaporation and the risk of desiccation during low water, and imbrication is more common as there is less erosion to wear it away where there is little wave action. Adults from exposed sites have shorter spires, larger apertures and weaker shells. Here crabs are scarce, and frequent spray reduces the risk of desiccation so the weaker shell and larger aperture are less of a risk, and the larger foot accommodated gives a firmer grip against wave impact. Withdrawal from crabs is less important than the more compact wave-resistant shape formed by the small spire. The exposure related shell differences hold within local areas, but genetic differences affect absolute measurements. In both Pembroke (S. Wales) and the Great Orme (N. Wales) the above relationships hold locally, but on shores of equal exposure (high or low) the Pembroke shells are shorter spired than the Great Orme shells. It seems that the gene pool available in Pembroke lacks the genes needed for very long spires and the pool at the Orme lack those needed for very short spires. This difference is found round Britain; those in the North Sea, north coast of Scotland, Severn Estuary, Liverpool Bay and Kent to Portland being like those on the Orme, and elsewhere shells are like those in Pembroke (map on p.337 in Crothers, 1985).
Breeding occurs all year with a peak in winter or spring (April-May in Yorkshire when water 9°C). Thirty or more congregate in a pool or sheltered crevice for females to be repeatedly inseminated by the males’ long recurved penes, interspersed with periods of laying. An egg capsule passes from the female’s oviduct, along a temporary groove in the foot, to the sole which manoeuvres it into the ventral pedal gland just in front of the centre of the sole. The capsule is held with the plugged opening innermost and the base protruding while the gland squeezes and moulds the capsule into a smooth stalked vase-shape 8-10mm high, 2-4mm wide with a longitudinal seam down two sides. The base of the stalk is pressed into a disc and cemented onto the substrate 43Nl flic.kr/p/oFom7e . When foot and gland are lifted off, the conchiolin walls of the capsule harden on contact with sea water. Capsules usually yellow, sometimes mauve or brownish. Female can produce about ten capsules in 24 hours; a breeding congregation may deposit hundreds together. Central mass of capsule made of about 600 agglutinated “nurse” eggs that cease developing at early stage. Ten to thirty unarrested eggs hatch into non-planktonic veliger larvae; small velum with no food-collecting groove; larvae attach to central mass with sucking lips to feed. Temperature controls development time within capsule; four months on S. coast England, five months in Yorkshire, seven months in the White Sea. No free-swimming veliger stage; young emerge from the unplugged apical opening of capsule as crawling snails with globular, smooth, glossy shell (protoconch) of 2½ whorls about 1mm high. Hatching success varies; about 100% of capsules continuously immersed in sea water, about 25% if in cleft or rock pool that receives freshwater run off, 0% to about 60% if at MLWN and dry out at low tide. Hatchlings often shelter in empty barnacle shells. Growth, March-October; rate varies, slower in north than south, in England usually 10-16mm high at 1yr old, 12-26mm at 2yrs, growth usually ceases (but shell thickens) in third year at shell height 20-30mm (more on sheltered shores), but may continue for those castrated by parasites. Some live to over 6yrs old, but mortality heavy before thick shell and mouth bosses develop; about 10% of each cohort survive to 1 year old, 5% to 2yrs, 1.25% to 3yrs.
Reproduction of N. lapillus was greatly reduced in parts of Britain and Europe by imposex where females develop male features including penes that block oviducts and prevent escape of ova. In Plymouth, 5% of females affected in 1970, 67% in 1985; some populations near marinas entirely destroyed. Recognised c.1970, caused by tributyltin in anti-fouling paints on shipping and other marine structures. Tributyltin paint banned on small boats 1987 (UK) and 1991 (EU). Worldwide total ban agreed 2008, ratified by countries accounting for 80% of world shipping by 2012. Recovery of some populations slow; imposex still prevalent where much international shipping. Many other spp. affected world wide; N. lapillus very sensitive to minute amounts so used as indicator sp. for imposex incidence.
Primary function of hypobranchial gland of gastropods generally thought to be trapping in mucus of particles from inhalent water before reach ctenidium, and transporting particles out of mantle cavity. In N. lapillus additional suggested functions of hypobranchial gland have included attraction of mates by scent, and acrid smell/taste to discourage predators. When exposed to light and air, white hypobranchial mucus turns yellow 36Nl flic.kr/p/ooMch1 and, eventually, purple 44Nl flic.kr/p/ooUnjZ . Exact sequence varies; may include green, reddish, blue and brown 45Nl flic.kr/p/oH9duz & 46Nl flic.kr/p/ooTXqN and sometimes changes little from yellow. Similar mucus from Mediterranean Murex used in Ancient Roman times to dye emperors’ robes purple. Reports of small scale use of N. lapillus to dye cloth in Ireland in 17th Century and, perhaps, Anglo-Saxon England. Several vernacular names derive from ‘purple’. Crushed egg capsules can produce same colours, so probably contain same chemicals; may be cause of capsule colour varying from yellow to mauve or brown.
Distribution and status
White Sea to Gibraltar, not Baltic (low salinity), absent or scarce in Denmark, Germany and Netherlands (soft substrate) . GBIF map www.gbif.org/species/5193449 . Common on hard substrate all around Ireland and Britain, avoiding low salinity of inner estuaries. Apparently absent or scarce in Lincolnshire and Suffolk (soft substrate); many records exist around Ireland and E. Scotland (McKay & Smith, 1979) that have not been entered on NBN. U.K. map NBN species.nbnatlas.org/species/NBNSYS0000188539
Some local gaps difficult to explain; some perhaps due to imposex near international ports where tributyltin still present.
Images of Nucella lapillus by other Flickr users:
flic.kr/p/fjaKrE (Arctic Russia)
flic.kr/p/i7Pmg8 (Germany)
flic.kr/p/oBGyCv & flic.kr/p/bqcXVF (Atlantic France)
flic.kr/p/noKnKa (Galicia, N.W. Spain. Various colours, incl. black)
flic.kr/p/aq43TK & flic.kr/p/d9Rfpw (Massachusetts, USA)
flic.kr/p/9f2nxA (New Brunswick, Canada. Various colour forms)
Acknowledgements
For help and advice about anatomy I would like to thank Dr Gregorio Bigatti, Dr Alfredo Castro-Vazquez, Dr Sami Ibidli, Dr Ivan Nekhaev and Dr Yu I Kantor. Many thanks to Dr Jan Light for the loan of specimens, to Dominic Flint for access to data in his unpublished study and to Paul Challinor and Neil Ward for use of their images. Special thanks for correspondence and patient help are due to Dr Alexandra Richter. Any remaining inaccuracies are attributable to me.
Links and references
The most used sources for this account were Crothers (1985) and Fretter & Graham (1962). Fretter & Graham (1994) contains updated information, but lacks the systematic index of the 1962 edition that enables the finding of N. lapillus details scattered through 800 pages.
Andrews, E.B. & Thorogood, K.E. 2005. An ultrastructural study of the gland of Leiblein of muricid and nassariid neogastropods in relation to function, with a discussion on its homologies to other caenogastropods. J. Mollus. Stud. 71: 269-300. Malacological Society, London. Free pdf at: mollus.oxfordjournals.org/content/71/3/269.full.pdf
Ballantine, W.J. 1961. A biologically-defined exposure scale for comparative description of rocky shores. Field studies 1(3): 1-19. Free pdf at: fsj.field-studies-council.org/media/344345/vol1.3_17.pdf
[Ballantine, pp.16- 18, recognised that his use of indicator species lists was area specific. See Zettler, 2013 for further consideration of this topic.]
Biggam, C.P. 2006. Knowledge of whelk dyes and pigments in Anglo-Saxon England. Anglo-Saxon England 35: 23- 55. Abstract at: journals.cambridge.org/action/displayIssue?iid=1182236
Caldwell, M. Marine pollution and sexual confusion in dog whelks. Free pdf of University College of London poster about imposex, but note that illustrations of “Dog whelks” (N. lapillus) are of Buccinum undatum. www.ucl.ac.uk/~ucbpmbc/downloads/poster.pdf
Carefoot, T. 2016 (date viewed by IFS) A snail's odyssey; learn about whelks and relatives. [Web-page with detailed information on shell boring by Nucella]
www.asnailsodyssey.com/LEARNABOUT/WHELK/whelFeed.php
Crisp, M., Fine structure of some Prosobranch osphradia. Marine Biology 22: 231-242 Abstract at link.springer.com/article/10.1007%2FBF00389177#page-2
Crothers, J.H. 1985. Dog whelks: an introduction to the biology of Nucella lapillus. Field Studies, 6, 291-360. Free pdf at
fsj.field-studies-council.org/media/342851/vol6.2_171_col...
Flint, D. 2001. Unpublished study of Nucella predation on Patella spp. in Guernsey.
Forbes, E. & Hanley S. 1849-53. A history of the British mollusca and their shells. vol. 3 (1853), van Voorst, London. (As Purpura lapillus; Free pdf at archive.org/details/historyofbritish03forb Use slide at base of page to select pp.379-387.)
Fretter, V. and Graham, A. 1962. British prosobranch molluscs. Ray Society, London.
Fretter, V. and Graham, A. 1994. British prosobranch molluscs. Revised and updated edition. Ray Society, London.
Graham, A. 1988. Prosobranch and pyramidellid gastropods. Linnean Society of London.
Hughes, R.N. and Dunkin, S. de B. 1984. Behavioural components of prey selection by dogwhelks, Nucella lapillus (L.), feeding on mussels, Mytilus edulis L., in the laboratory. J. Exp. Mar. Biol. Ecol. 77(1-2) : 45-68. Abstract at www.sciencedirect.com/science/article/pii/0022098184900509
Jeffreys, J.G. 1862-69. British conchology. vol. 4 (1867). Van Voorst, London. (As Purpura lapillus; Free pdf at archive.org/details/britishconcholog04jeffr . Use slide at base of page to select pp.275-289.)
McKay, D.W. & Smith, S.M. 1979 Marine mollusca of east Scotland Royal Scottish Museum, Edinburgh.
Lewis, J.R. 1964. The ecology of rocky shores. London, Hodder & Stoughton.
Mallon, P. & Manga, N. 2007. The use of imposex in Nucella lapillus to assess tributyltin pollution in Carlingford Lough. J.E.H.R. vol.6 issue 2
www.cieh.org/jehr/imposex_nucella_lapillus.html
Matveeva T.A. 1955. Biology of Purpura lapillus (L.) on West Murman. In: Kamshilov M.M., ed. Trudy Murmanskoy Biologicheskoy Stanysii, 2: 48-61 [In Russian].
Medeiros, R., Serpa L. , Brito, C., De Wolf H. , Jordaens, K. , Winnepenninckx, B. & Backeljau T. 1998. Radular myoglobin and protein variation within and among some littorinid species (Mollusca: Gastropoda). Hydrobiologia 378: 43-51.
Richter, A., Amor, M.J. & Durfort, M. 2010. The anatomy and ultrastructure of the gland of Leiblein of Bolinus brandis and Coralliophila meyendorfii, two neogastropod species with different ecology and feeding strategies. Poster for Soc. for Environmental Biology, annual meeting, Prague 2010.
Santillo, D., Johnston, P. & Langston, W.J. 2001. Tributyltin (TBT) antifoulants: a tale of ships, snails and imposex. European Environment Agency, environmental issue report 22, part 13.
13. Tributyltin (TBT) antifoulants: a tale of ships, snails and imposex
Sarramégna, R. 1965. Poisonous gastropods of the Conidae family found in New Caledonia. Technical paper 144, S. Pacific Commission, New Caledonia.
www.spc.int/DigitalLibrary/Doc/FAME/Reports/Sarramegna_65...
European Environment Agency. Several articles on imposex and its effects on various species. glossary.eea.europa.eu//terminology/sitesearch?term=imposex
Yonge, C.M. and Thompson, T.E. 1976. Living marine molluscs. Collins, London.
Zettler, M.L. et al. 2013. On the myths of indicator species: issues and further consideration in the use of static concepts for ecological applications Plos One Vol 8, Issue 10 [Ref. is not specific to N. lapillus, see note under Ballantine, above.] Free pdf at
www.ncbi.nlm.nih.gov/pmc/articles/PMC3797757/pdf/pone.007...
Current taxonomy: World Register of Marine Species (WoRMS)
www.marinespecies.org/aphia.php?p=taxdetails&id=140403
Glossary
abapertural = away from aperture.
acinous salivary gland = compound gland of many small rounded sacs that secrete enzymes for external predigestion/ liquefaction of prey.
adapertural = towards aperture.
adapical = towards the apex of the shell.
afferent = carrying towards. (e.g. of vessel carrying blood, see efferent.)
aperture = mouth of gastropod shell; outlet for head and foot.
Ballantine scale = biologically-defined wave exposure scale (see references).
bipectinate = feather-like, with narrow filaments either side of central stalk.
capsule gland = secretes fibrous wall of capsule containing ova.
cephalic = (adj.) of or on the head.
chelae = (singular chela) pincers of crabs and other crustacea.
cilia = (pl.) vibrating linear extensions of membrane used in feeding or locomotion. (“cilium” singular).
ciliated = (adj.) coated with cilia.
columella = solid or hollow axial “little column” around which gastropod shell spirals; hidden inside shell, except on final whorl next to lower part of inner lip of aperture where hollow ones may end in an umbilicus or siphonal canal.
columellar = (adj.) of or near central axis of spiral gastropod.
columellar lip = lower (abapical) part of inner lip of aperture.
columellar muscle = attaches body, including opercular disc, to columella of shell; contraction of muscle withdraws body within shell, and pulls operculum to seal aperture.
commensal = (adj.) obtaining nutrients, shelter, support, or locomotion from a host species, without causing it significant detriment.
conchiolin = horny flexible protein that forms the matrix for the deposition of calcium carbonate to create a mollusc’s shell.
ctenidium = comb-like molluscan gill; usually an axis with a row of filaments either side.
ditaxic = (of locomotion waves on foot) double series of waves, out of phase with each other, one series on each side of central furrow on sole.
direct = (of locomotion waves on foot) waves travel from posterior to anterior.
efferent = carrying away from. (e.g. of vessel carrying blood from ctenidium).
fasciole = (see siphonal fasciole)
gland of Leiblein = secretes enzymes for internal digestion.
height = (of gastropod shells) distance from apex of spire to base of aperture.
hypobranchial gland = thickened, sometimes puckered, tissue on roof of mantle cavity of many gastropods. Emits mucous to trap particles from
inhalent water before it reaches ctenidium. Often other biologically active compounds produced. Gland occurs also in some bivalves and cephalopods (ink sac).
imbricate = shell sculpture of growth-line ornament overlapping like roof tiles.
MHWN = mean high water neap tide level (mean level reached by weakest high tides for a few days every fortnight).
MHWS = mean high water spring tide level (mean level reached by highest tides for a few days every fortnight; Pelvetia zone on rocky coasts).
MLWN = mean low water neap tide level (mean level reached by weakest low tides for a few days every fortnight. i.e. those that fall the least).
mantle = sheet of tissue that secretes the shell and forms a cavity for the gill in most marine molluscs.
mesopodium = middle section of gastropod foot. (see propodium & metapodium).
metapodium = rear section of gastropod foot. (see mesopodium & propodium).
myoglobin – red oxygen-binding protein in muscle tissue; often in buccal-mass muscles of gastropods. Similar to red haemoglobin in vertebrate blood, but green haemocyanin is usual oxygen-carrier in mollusc blood. See www.researchgate.net/publication/251227038_Radular_myoglo...
N = (See Newton).
Newton = (abbreviation N) force exerted by Earth’s gravity on approx. 100g.
odontophore = cartilaginous “tongue” that supports and protracts /retracts the radula.
opercular = (adj.) of the operculum.
opercular disc = part of foot attached to inner face of operculum.
opercular lobe = extension of opercular disc round edge of part of operculum.
operculum = plate of horny conchiolin, rarely calcareous, used to close shell aperture.
osphradium = chemo-receptor organ in molluscs that tests inhalent water flow approaching ctenidium (gill) for “smell” of food, prey, predators, mates and/or water quality.
penes = (plural of penis) male copulatory organs.
periostracum = thin horny layer of chitinous material often coating shells.
plankton = animals and plants that drift in pelagic zone (main body of water).
propodium = front section of gastropod foot. (Cf. mesopodium & metapodium).
prosobranchia = 20th Century term for subclass of Gastropoda that included most marine snails with ctenidia. Now distributed between several subclasses. See note at www.marinespecies.org/aphia.php?p=taxdetails&id=102
rectal gland = (a.k.a. anal gland) Function uncertain, perhaps produces substances that supplement the excretory activity of the kidney.
retrograde = (of locomotion waves on foot) waves travel from anterior to posterior.
sessile = (of organism) fixed in one place, e.g. barnacles.
siphon = extension of mantle to form a channel for inhalent respiratory water current.
siphonal canal = grooved or tubular extension of outer lip of the shell aperture on some snails to support the siphon.
siphonal fasciole = raised rib along columellar side of siphonal canal, bearing curved growth lines formed by successive positions of canal end.
sperm ingesting gland = (in female Nucella lapillus) group of dark brown blind-ended tubules at posterior of capsule gland where excess sperm unrequired by female are trapped, engulfed by cells and digested.
suture = groove or line where whorls of gastropod shell adjoin.
vas deferens = tube carrying sperm to male’s penis.
veliger = shelled larva of marine gastropod or bivalve mollusc which swims by beating cilia of a velum (bilobed flap).