View allAll Photos Tagged Compact,
Probably one of my favourite shots from the foray to Nunney. Again the N-grads came into play. Best NOT viewed large. The distortion caused buy the 10-20mm lens spoiled the foreground a little with soft focus, but the overall composition and colour combine in a shot that I have been longing to take for a long while. Without the wide angle lens this one would be almost impossible as the castle is tightly contained and the unexpected but glorious sunshine was really well timed.
An excellent property just ripe for conversion into a fancy modern home one feels – if it weren’t for the whacking great Cromwellian cavity in the other side of the building!
Source: en.wikipedia.org/wiki/Hoover_Dam
Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. Constructed between 1931 and 1936, during the Great Depression, it was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over 100 lives. In bills passed by Congress during its construction, it was referred to as the Hoover Dam, after President Herbert Hoover, but was named Boulder Dam by the Roosevelt administration. In 1947, the name Hoover Dam was restored by Congress.
Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water, and produce hydroelectric power. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium named Six Companies, Inc., which began construction in early 1931. Such a large concrete structure had never been built before, and some of the techniques used were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned the dam over to the federal government on March 1, 1936, more than two years ahead of schedule.
Hoover Dam impounds Lake Mead and is located near Boulder City, Nevada, a municipality originally constructed for workers on the construction project, about 30 mi (48 km) southeast of Las Vegas, Nevada. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction, with 7 million tourists a year. The heavily traveled U.S. Route 93 (US 93) ran along the dam's crest until October 2010, when the Hoover Dam Bypass opened.
Source: hoover.archives.gov/hoovers/hoover-dam
85 years after its completion, Hoover dam is still considered an engineering marvel. It is named in honor of President Herbert Hoover, who played a crucial role in its creation.
For many years, residents of the American southwest sought to tame the unpredictable Colorado River. Disastrous floods during the early 1900’s led residents of the area to look to the federal government for aid, and experiments with irrigation on a limited scale had shown that this arid region could be transformed into fertile cropland, if only the river could be controlled. The greatest obstacle to the construction of such a dam was the allocation of water rights among the seven states comprising the Colorado River drainage basin. Meetings were held in 1918, 1919 and 1920, but the states could not reach a consensus.
Herbert Hoover had visited the Lower Colorado region in the years before World War I and was familiar with its problems and the potential for development. Upon becoming Secretary of Commerce in 1921, Hoover proposed the construction of a dam on the Colorado River. In addition to flood control and irrigation, it would provide a dependable supply of water for Los Angeles and Southern California. The project would be self-supporting, recovering its cost through the sale of hydroelectric power generated by the dam.
In 1921, the state legislatures of the Colorado River basin authorized commissioners to negotiate an interstate agreement. Congress authorized President Harding to appoint a representative for the federal government to serve as chair of the Colorado River Commission and on December 17, 1921, Harding appointed Hoover to that role.
When the commission assembled in Santa Fe in November 1922, the seven states still disagreed over the fair distribution of water. The upstream states feared that the downstream states, with their rapidly developing agricultural and power demands, would quickly preempt rights to the water by the “first in time, first in right” doctrine. Hoover suggested a compromise that the water be divided between the upper and lower basins without individual state quotas. The resulting Colorado River Compact was signed on November 24, 1922. It split the river basin into upper and lower halves with the states within each region deciding amongst themselves how the water would be allocated.
A series of bills calling for Federal funding to build the dam were introduced by Congressman Phil D. Swing and Senator Hiram W. Johnson between 1922 and 1928, all of which were rejected. The last Swing-Johnson bill, titled the Boulder Canyon Project Act, was largely written by Hoover and Secretary of the Interior Hubert Work. Congress finally agreed, and the bill was signed into law on December 21, 1928 by President Coolidge. The dream was about to become reality.
On June 25, 1929, less than four months after his inauguration, President Herbert Hoover signed a proclamation declaring the Colorado River Compact effective at last. Appropriations were approved and construction began in 1930. The dam was dedicated in 1935 and the hydroelectric generators went online in 1937. In 1947, Congress officially "restored" Hoover's name to the dam, after FDR's Secretary of the Interior tried to remove it. Hoover Dam was built for a cost of $49 million (approximately $1 billion adjusted for inflation). The power plant and generators cost an additional $71 million, more than the cost of the dam itself. The sale of electrical power generated by the dam paid back its construction cost, with interest, by 1987.
Today the Hoover Dam controls the flooding of the Colorado River, irrigates more than 1.5 million acres of land, and provides water to more than 16 million people. Lake Mead supports recreational activities and provides habitats to fish and wildlife. Power generated by the dam provides energy to power over 500,000 homes. The Hoover Compromise still governs how the water is shared.
Additional Foreign Language Tags:
(United States) "الولايات المتحدة" "Vereinigte Staaten" "アメリカ" "美国" "미국" "Estados Unidos" "États-Unis"
(Nevada) "نيفادا" "内华达州" "नेवादा" "ネバダ" "네바다" "Невада"
(Arizona) "أريزونا" "亚利桑那州" "एरिजोना" "アリゾナ州" "애리조나" "Аризона"
(Hoover Dam) "سد هوفر" "胡佛水坝" "हूवर बांध" "フーバーダム" "후버 댐" "Гувера" "Presa Hoover"
Dawson City on Christmas Day 1976 (with texture) - 35mm Compact Film - Photographer Russell McNeil PhD (Physics) lives in Nanaimo, British Columbia where he works also as a writer and a personal trainer.
Appareil compact 35 mm assemblé à Hong Kong dès 1995. Viseur collimaté, objectif 3,5/35 mm, obturateur de 1 s à 1/250 s, ouvertures automatiques et mise au point AF de 0.5 m à l'infini. Cellule avec témoin d'expo, flash dans le volet de fermeture avec modes, moteur er 1 pile CR 123 A ou 2 LR 06. Film 135 DX de 50 à 3200 iso. Weatherproof, écrou de pied, écran sur le capot avec divers modes et retardateur de 12 s. 185 g et 11.8x6.3x4.4 cm.
ALMA antenas packed all close to each othe in the Compact Array configuration after a snowfall during December 2019
This is a roll-off compactor box seen at Trash Taxi in Winter Haven, FL.
Special THANKS to Trash Taxi for allowing me into the yard to take these pictures!
Because it occurred to me that it's a long time since I had a picture of me in me compact little kitchen.
Tangara guttata
Canopy San Luis, San Ramon
Historia Natural
Reproducción
Su nido consiste en una taza compacta y bien construida con raquis delgados de hojas compuestas pequeñas y fragmentos o venas de hojas de banano, forrada con materiales más finos y sin musgo verde. Se localiza entre 3 y 8 m. de altura entre el follaje.
Ponen 2 huevos blancos, con abundante moteado café. Se reproducen entre abril a junio.
Se observó un nido con 3 adultos que alimentaban a los pichones.
Alimentación
Se alimenta de bayas, semillas ariladas y de otros frutos, inclusive amentos de guarumo (Cecropia spp.). Al estar en el follaje se agacha para examinar el envés de ramas horizontales en busca de insectos y arañas. En raras ocasiones sale en pos de insectos en vuelo.
Comportamiento
Forman parejas o grupos pequeños de 3 a 6 individuos; a menudo se les observa en bandadas mixtas de aves frugívoras.
Habitat y Distribución
Habitat
Frecuenta niveles altos de los bosques húmedos y áreas aledañas de crecimiento secundario, y claros con árboles y arbustos esparcidos.
Distribución
Es una especie residente de poco común a relativamente común en los piedemontes, entre los 400 y los 1000 m. de altura en el lado del Caribe, desde la Cordillera de Tilarán hacia el sur. En el Pacífico se localiza entre los 300 y los 1400 m. En ambas vertientes se localizan algo más alto en las cercanías de la frontera con Panamá.
Distribución fuera de Costa Rica
Se encuentran desde Costa Rica hasta Trinidad, el sureste de Colombia y el norte de Brasil.
Distribución de Area de conservación
ArenalCordillera Volcanica CentralPacifico CentralAmistad CaribeAmistad PacificoHuetar NorteOsaTortuguero
Descripción
Descripción científica
Mide 13 cm. y pesa 20 grs. Ninguna otra tangara presenta un punteado negro por encima y por debajo.
El adulto muestra las plumas de la parte superior negras y bordeadas por un verde pasto brillante, lo cual produce un aspecto de punteado negro. La rabadilla y los flancos son verde sólido, y las alas y la cola son negras con bordes verde azulado. El área loreal y la lista ocular son negras sobre la cara amarilla. Las plumas de la garganta, pecho y el costado son negras con bordes entre verde azulado pálido y blancuzco, y el color se torna blanco en el abdomen. Las coberteras infracaudales verde amarillentas presentan manchas negras.
La hembra es similar pero con las marcas negras menos extensas en la parte baja del pecho, y los bordes verdes de la parte superior más anchos y no tan bien definidos. La maxila es negra y la mandíbula es plateada con la punta negra, y las patas son gris azulado.
Los ejemplares juveniles muestran un verde más opaco por encima, con las marcas negras reducidas a manchones fuscos y el área loreal fusca. La cara exhibe la frente teñida de amarillo. Por debajo es blancuzco opaco, con un moteado fusco en la garganta, y el pecho, costado y flancos con un tinte amarillo oliva. Las coberteras infracaudales son amarillentas.
Información taxonómica
Reino: Animalia
Filo: Chordata
Clase: Aves
Orden: Passeriformes
Familia: Thraupidae
Género: Tangara
Pretty unbelievable that there's a APS-C sensor in the NEX-3N body, which is only slightly larger than my Canon S90 P&S' body.
Ich habe des öfteren darüber nachgedacht, warum Hunde ein derart kurzes Leben haben, und bin zu dem Schluss gekommen, dass dies aus Mitleid mit der menschlichen Rasse geschieht; denn da wir bereits derart leiden, wenn wir einen Hund nach zehn oder zwölf Jahren verlieren, wie groß wäre der Schmerz, wenn sie doppelt so lange lebten?
(Walter Scott)
Sony tarafından üzerinde çalışmaların sürdürüldüğü önemli modellerden birisi Sony X Compact olurken, modelin üstün özelliklere sahip olacağı ifade edildi.
The Ricoh GRii is a compact digital point and shoot camera that is a redesign of the classic film cameras released by Ricoh in 1996. They were made famous by Daidō Moriyama the Japanese street photographer. Since then it has gone through many iterations and won several awards while staying faithful to the original cult classic and vintage design.
The Ricoh GRii has a fixed focal length that gives you a 28mm field of view (after crop factor). It has all the great functionality that you would take for granted with a professional DSLR, and is also packed full of great features that you would expect in any modern camera with extra goodies like an inbuilt ND filter (which you can set to auto) for those extra bright light situations when the maximum shutter speed of 1/4000 second won’t do, High Dynamic Range compensation for those high contrast situations that actually works. There is also interval and composite shooting modes, various prefocusing or “snap” modes that add extra punch to the focusing system and a whisper silent leaf shutter. And as you would expect, it’s extremely customisable.
When it comes to using the Ricoh GRii the menu although a nerds paradise is very intuitive to use. There is also a quick menu that allows you to get to all the functions you would need to change and adjust on the fly. It produces great DNG files that are rich in colour and crisp detail up to ISO 1600, the lens is super sharp at f4, and the controls are exactly where you would expect them, it’s an ergonomic dream.
The combination of great features and compact award winning design and a proven history of achievement, means you can shoot with something you know is reliable in any situation for capturing any subject of moment whether you are out with friends, or fancy a spot of macro. Where this camera really comes to life is street photography; as it offers precision with stealth. It’s a great little camera that you can always keep with you, and it’s great fun to use.
If you would like to use any of my photos please get in touch.
You can find me here on Facebook , Twitter , Instagram
Please visit my website www.sunprints.co.uk
Thank you
Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word slug is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a small internal shell, particularly sea slugs and semi-slugs (this is in contrast to the common name snail, which applies to gastropods that have a coiled shell large enough that they can fully retract their soft parts into it).
Various taxonomic families of land slugs form part of several quite different evolutionary lineages, which also include snails. Thus, the various families of slugs are not closely related, despite a superficial similarity in the overall body form. The shell-less condition has arisen many times independently as an example of convergent evolution, and thus the category "slug" is polyphyletic.
Taxonomy
Of the six orders of Pulmonata, two – the Onchidiacea and Soleolifera – solely comprise slugs. A third group, the Sigmurethra, contains various clades of snails, semi-slugs (i.e. snails whose shells are too small for them to retract fully into), and slugs.[1] The taxonomy of this group is in the process of being revised in light of DNA sequencing. It appears that pulmonates are paraphyletic and basal to the opisthobranchs, which are a terminal branch of the tree. The family Ellobiidae are also polyphyletic.
Subinfraorder Orthurethra
Superfamily Achatinelloidea Gulick, 1873
Superfamily Cochlicopoidea Pilsbry, 1900
Superfamily Partuloidea Pilsbry, 1900
Superfamily Pupilloidea Turton, 1831
Subinfraorder Sigmurethra
Superfamily Acavoidea Pilsbry, 1895
Superfamily Achatinoidea Swainson, 1840
Superfamily Aillyoidea Baker, 1960
Superfamily Arionoidea J.E. Gray in Turnton, 1840
Superfamily Athoracophoroidea
Family Athoracophoridae
Superfamily Orthalicoidea
Subfamily Bulimulinae
Superfamily Camaenoidea Pilsbry, 1895
Superfamily Clausilioidea Mörch, 1864
Superfamily Dyakioidea Gude & Woodward, 1921
Superfamily Gastrodontoidea Tryon, 1866
Superfamily Helicoidea Rafinesque, 1815
Superfamily Helixarionoidea Bourguignat, 1877
Superfamily Limacoidea Rafinesque, 1815
Superfamily Oleacinoidea H. & A. Adams, 1855
Superfamily Orthalicoidea Albers-Martens, 1860
Superfamily Plectopylidoidea Moellendorf, 1900
Superfamily Polygyroidea Pilsbry, 1894
Superfamily Punctoidea Morse, 1864
Superfamily Rhytidoidea Pilsbry, 1893
Family Rhytididae
Superfamily Sagdidoidera Pilsbry, 1895
Superfamily Staffordioidea Thiele, 1931
Superfamily Streptaxoidea J.E. Gray, 1806
Superfamily Strophocheiloidea Thiele, 1926
Superfamily Parmacelloidea
Superfamily Zonitoidea Mörch, 1864
Superfamily Quijotoidea Jesús Ortea and Juan José Bacallado, 2016
Family Quijotidae
Description
Tentacles: Like other pulmonate land gastropods, the majority of land slugs have two pairs of 'feelers' or tentacles on their head. The upper pair is light-sensing and has eyespots at the ends, while the lower pair provides the sense of smell. Both pairs are retractable in stylommatophoran slugs, but contractile in veronicellid slugs.
Mantle: On top of the slug, behind the head, is the saddle-shaped mantle. In stylommatophoran slugs, on the right-hand side of the mantle is a respiratory opening, the pneumostome, which is easier to see when open; also on the right side at the front are the genital opening and anus. Veronicellid slugs have a mantle covering the whole dorsal part of the body, they have no respiratory opening, and the anus opens posteriorly.
Tail: The part of a slug behind the mantle is called the 'tail'.
Keel: Some species of slugs, for example Tandonia budapestensis, have a prominent ridge running over their back along the middle of the tail (sometimes along the whole tail, sometimes only the posterior part).
Foot: The bottom side of a slug, which is flat, is called the 'foot'. Like almost all gastropods, a slug moves by rhythmic waves of muscular contraction on the underside of its foot. It simultaneously secretes a layer of mucus that it travels on, which helps prevent damage to the foot tissues. Around the edge of the foot in some slugs is a structure called the 'foot fringe'.
Vestigial shell: Most slugs retain a remnant of their shell, which is usually internalized. This organ generally serves as storage for calcium salts, often in conjunction with the digestive glands. An internal shell is present in the Limacidae and Parmacellidae. Adult Philomycidae, Onchidiidae and Veronicellidae lack shells.
Physiology
An active Ambigolimax slug in Fremont, California
Slugs' bodies are made up mostly of water and, without a full-sized shell, their soft tissues are prone to desiccation. They must generate protective mucus to survive. Many species are most active just after a rain because of the moist ground or during nighttime. In drier conditions, they hide in damp places such as under tree bark, fallen logs, rocks and manmade structures, such as planters, to help retain body moisture.[3] Like all other gastropods, they undergo torsion (a 180° twisting of the internal organs) during development. Internally, slug anatomy clearly shows the effects of this rotation—but externally, the bodies of slugs appear more or less symmetrical, except the pneumostome, which is on one side of the animal, normally the right-hand side.
Slugs produce two types of mucus: one is thin and watery, and the other thick and sticky. Both kinds are hygroscopic. The thin mucus spreads from the foot's centre to its edges, whereas the thick mucus spreads from front to back. Slugs also produce thick mucus that coats the whole body of the animal. The mucus secreted by the foot contains fibres that help prevent the slug from slipping down vertical surfaces.
The "slime trail" a slug leaves behind has some secondary effects: other slugs coming across a slime trail can recognise the slime trail as produced by one of the same species, which is useful in finding a mate. Following a slime trail is also part of the hunting behaviour of some carnivorous slugs. Body mucus provides some protection against predators, as it can make the slug hard to pick up and hold by a bird's beak, for example, or the mucus itself can be distasteful. Some slugs can also produce very sticky mucus which can incapacitate predators and can trap them within the secretion. Some species of slug, such as Limax maximus, secrete slime cords to suspend a pair during copulation.
Reproduction
Slugs are hermaphrodites, having both female and male reproductive organs. Once a slug has located a mate, they encircle each other and sperm is exchanged through their protruded genitalia. A few days later, the slugs lay approximately thirty eggs in a hole in the ground, or beneath the cover of an object such as a fallen log.
Apophallation has been reported only in some species of banana slug (Ariolimax) and one species of Deroceras. In the banana slugs, the penis sometimes becomes trapped inside the body of the partner. Apophallation allows the slugs to separate themselves by one or both of the slugs chewing off the other's or its own penis. Once the penis has been discarded, banana slugs are still able to mate using only the female parts of the reproductive system.
In a temperate climate, slugs usually live one year outdoors. In greenhouses, many adult slugs may live for more than one year.
Ecology
Slugs play an important role in the ecosystem by eating decaying plant material and fungi. Most carnivorous slugs on occasion also eat dead specimens of their own kind.
Feeding habits
Most species of slugs are generalists, feeding on a broad spectrum of organic materials, including leaves from living plants, lichens, mushrooms, and even carrion. Some slugs are predators and eat other slugs and snails, or earthworms.
Lehmannia feeding on a small fruit in Mexico City
Slugs can feed on a wide variety of vegetables and herbs, including flowers such as petunias, chrysanthemums, daisies, lobelia, lilies, dahlias, narcissus, gentians, primroses, tuberous begonias, hollyhocks, marigolds, and fruits such as strawberries. They also feed on carrots, peas, apples, and cabbage that are offered as a sole food source.
Slugs from different families are fungivores. It is the case in the Philomycidae (e. g. Philomycus carolinianus and Phylomicus flexuolaris) and Ariolimacidae (Ariolimax californianus), which respectively feed on slime molds (myxomycetes) and mushrooms (basidiomycetes).[16] Species of mushroom producing fungi used as food source by slugs include milk-caps, Lactarius spp., the oyster mushroom, Pleurotus ostreatus and the penny bun, Boletus edulis. Other species pertaining to different genera, such as Agaricus, Pleurocybella and Russula, are also eaten by slugs. Slime molds used as food source by slugs include Stemonitis axifera and Symphytocarpus flaccidus. Some slugs are selective towards certain parts or developmental stages of the fungi they eat, though this is very variable. Depending on the species and other factors, slugs eat only fungi at specific stages of development. Moreover, in other cases, whole mushrooms can be eaten, without any selection or bias towards ontogenetic stages.
Predators
Slugs are preyed upon by various vertebrates and invertebrates. The predation of slugs has been the subject of studies for at least a century. Because some species of slugs are considered agricultural pests, research investments have been made to discover and investigate potential predators in order to establish biological control strategies.
Vertebrates
Slugs are preyed upon by virtually every major vertebrate group. With many examples among reptiles, birds, mammals, amphibians and fish, vertebrates can occasionally feed on, or be specialised predators of, slugs. Fish that feed on slugs include the brown trout (Salmo trutta), which occasionally feeds on Arion circumscriptus, an arionid slug. Similarly, the shortjaw kokopu (Galaxias postvectis) includes slugs in its diet. Amphibians such as frogs and toads have long been regarded as important predators of slugs. Among them are species in the genus Bufo, Rhinella and Ceratophrys.
Reptiles that feed on slugs include mainly snakes and lizards. Some colubrid snakes are known predators of slugs. Coastal populations of the garter snake, Thamnophis elegans, have a specialised diet consisting of slugs, such as Ariolimax, while inland populations have a generalized diet. One of its congeners, the Northwestern garter snake (Thamnophis ordinoides), is not a specialized predator of slugs but occasionally feeds on them. The redbelly snake (Storeria occipitomaculata) and the brown snake (Storeria dekayi) feed mainly but not solely on slugs, while some species in the genus Dipsas (e.g. Dipsas neuwiedi) and the common slug eater snake (Duberria lutrix), are exclusively slug eaters. Several lizards include slugs in their diet. This is the case in the slowworm (Anguis fragilis), the bobtail lizard (Tiliqua rugosa), the she-oak skink (Cyclodomorphus casuarinae) and the common lizard (Zootoca vivipara).
Birds that prey upon slugs include common blackbirds (Turdus merula), starlings (Sturnus vulgaris), rooks (Corvus frugilegus), jackdaws (Corvus monedula), owls, vultures and ducks. Studies on slug predation also cite fieldfares (feeding on Deroceras reticulatum), redwings (feeding on Limax and Arion), thrushes (on Limax and Arion ater), red grouse (on Deroceras and Arion hortensis), game birds, wrynecks (on Limax flavus), rock doves and charadriiform birds as slug predators.
Mammals that eat slugs include foxes, badgers and hedgehogs.
Invertebrates
Beetles in the family Carabidae, such as Carabus violaceus and Pterostichus melanarius, are known to feed on slugs.Ants are a common predator of slugs; some ant species are deterred by the slug's mucus coating, while others such as driver ants will roll the slug in dirt to absorb its mucus.
Parasites and parasitoids
Slugs are parasitised by several organisms, including acari and a wide variety of nematodes. The slug mite, Riccardoella limacum, is known to parasitise several dozen species of molluscs, including many slugs, such as Deroceras reticulatum, Arianta arbustorum, Arion ater, Arion hortensis, Limax maximus, Tandonia budapestensis, Milax gagates, and Tandonia sowerbyi. R. limacum can often be seen swarming about their host's body, and live in its respiratory cavity.
Several species of nematodes are known to parasitise slugs. The nematode worms Agfa flexilis and Angiostoma limacis respectively live in the salivary glands and rectum of Limax maximus. Species of widely known medical importance pertaining to the genus Angiostrongylus are also parasites of slugs. Both Angiostrongylus costaricensis and Angiostrongylus cantonensis, a meningitis-causing nematode, have larval stages that can only live in molluscs, including slugs, such as Limax maximus.
Insects such as dipterans are known parasitoids of molluscs. To complete their development, many dipterans use slugs as hosts during their ontogeny. Some species of blow-flies (Calliphoridae) in the genus Melinda are known parasitoids of Arionidae, Limacidae and Philomycidae. Flies in the family Phoridae, specially those in the genus Megaselia, are parasitoids of Agriolimacidae, including many species of Deroceras. House flies in the family Muscidae, mainly those in the genus Sarcophaga, are facultative parasitoids of Arionidae.
Behavior
Slug contracts itself and retracts its tentacles when attacked
A brown and yellow spotted slug curled up into a tight ball so that its head is withdrawn completely, its mantle edge and tail are nearly touching, and none of its foot surface is exposed
The alarm response posture of the Kerry slug, which is found only in this species
When attacked, slugs can contract their body, making themselves harder and more compact and more still and round. By doing this, they become firmly attached to the substrate. This, combined with the slippery mucus they produce, makes slugs more difficult for predators to grasp. The unpleasant taste of the mucus is also a deterrent. Slugs can also incapacitate predators through the production of a highly sticky and elastic mucus which can trap predators in the secretion.
Some species present different response behaviors when attacked, such as the Kerry slug. In contrast to the general behavioral pattern, the Kerry slug retracts its head, lets go of the substrate, rolls up completely, and stays contracted in a ball-like shape. This is a unique feature among all the Arionidae, and among most other slugs. Some slugs can self-amputate (autotomy) a portion of their tail to help the slug escape from a predator. Some slug species hibernate underground during the winter in temperate climates, but in other species, the adults die in the autumn.
Intra- and inter-specific agonistic behavior is documented, but varies greatly among slug species. Slugs often resort to aggression, attacking both conspecifics and individuals from other species when competing for resources. This aggressiveness is also influenced by seasonality, because the availability of resources such as shelter and food may be compromised due to climatic conditions. Slugs are prone to attack during the summer, when the availability of resources is reduced. During winter, the aggressive responses are substituted by a gregarious behavior.
Human relevance
The great majority of slug species are harmless to humans and to their interests, but a small number of species are serious pests of agriculture and horticulture. They can destroy foliage faster than plants can grow, thus killing even fairly large plants. They also feed on fruits and vegetables prior to harvest, making holes in the crop, which can make individual items unsuitable to sell for aesthetic reasons, and can make the crop more vulnerable to rot and disease. Excessive buildup of slugs within some wastewater treatment plants with inadequate screening have been found to cause process issues resulting in increased energy and chemical use.
In a few rare cases, humans have developed Angiostrongylus cantonensis-induced meningitis from eating raw slugs. Live slugs that are accidentally eaten with improperly cleaned vegetables (such as lettuce), or improperly cooked slugs (for use in recipes requiring larger slugs such as banana slugs), can act as a vector for a parasitic infection in humans.
Prevention
As control measures, baits are commonly used in both agriculture and the garden. In recent years, iron phosphate baits have emerged and are preferred over the more toxic metaldehyde, especially because domestic or wild animals may be exposed to the bait. The environmentally safer iron phosphate has been shown to be at least as effective as baits. Methiocarb baits are no longer widely used. Parasitic nematodes (Phasmarhabditis hermaphrodita) are a commercially available biological control method that are effective against a wide range of common slug species. The nematodes are applied in water and actively seek out slugs in the soil and infect them, leading to the death of the slug. This control method is suitable for use in organic growing systems.
Other slug control methods are generally ineffective on a large scale, but can be somewhat useful in small gardens. These include beer traps [de], diatomaceous earth, crushed eggshells, coffee grounds, and copper. Salt kills slugs by causing water to leave the body owing to osmosis but this is not used for agricultural control as soil salinity is detrimental to crops. Conservation tillage worsens slug infestations. Hammond et al. 1999 find maize/corn and soybean in the US to be more severely affected under low till because this increases organic matter, thus providing food and shelter.