Slugs and snails are the closest relatives, only the former completely or, less often, partially, lack a shell. They move by contraction of the whole body, which acts as the sole and leg at the same time. Hence the scientific name - gastropods. They are ubiquitous, here are just a few types of slugs:
Sea slug is found in the water. Only here we are not talking about a relative of the snail, but about an unusual fish. She adapted to a deep-sea existence, which was previously considered impossible by scientists. In the photo, the sea slug looks more like an overgrown tadpole. This form is most suitable for living at an unthinkable depth (almost 8 thousand meters). Some sea slugs live close to the coast, not hiding under the huge water column. And this phrase is also popularly called nudibranch mollusks, the closest relatives of gastropods.
Animal colors vary. In addition to the usual gray or black ones, you can find purple slug, white, yellow, green slug, blue individuals and even red clams. It largely depends on the environment. Surprisingly, some species make interesting pets. They are kept in special terrariums, the bedding at the bottom of which must be mulched so that the pets can move freely without risking damage to the delicate body-sole. These include the Madagascar slug. It is flatter and smoother than the garden types we are used to, and outwardly resembles a fat, gluttonous worm covered with mucus.
What do slugs eat, and who eats them
In nature, slugs, most often, live in damp, sheltered from the sun, dark places. Their surface practically does not retain moisture, therefore, under direct rays, they dry out and die. This explains the fact that you will not find slugs in the desert, but in forests, gardens and orchards - in abundance. But even in the bath they will not take root either, despite the suitable conditions, since there is simply nothing for them to eat there.
Night creatures feed on the remains of organic food - humus, mulch, rot. But sometimes they are not averse to eating fresh plant leaves and berries, they are very fond of strawberries, for which they are quite dangerous garden pests. There are predatory species that attack worms, and especially large individuals can eat newborn mice or chicks.
Gardeners and gardeners invent many traps to scare or kill him. But! On the other hand, these creatures are actively involved in the formation of humus and process the topsoil, making it more fertile.
But how do they drink? Everything is simple here: the mollusk licks moisture from the surface of the leaves, thereby replenishing the supply of fluid, which is then processed into mucus, which is necessary for movement and maintaining normal body moisture.
Nature has taken care of the regulation of their numbers, creating a huge number of those who eat slugs, and moreover, considers them the best delicacy. One of the most terrible natural enemies is the ground beetle. This is a nocturnal predator, insatiable and incredibly voracious. Soft, defenseless gastropods are his favorite food. During the night, the ground beetle destroys up to several dozen small pests and several large ones.
Another lover to taste a big slug is a hedgehog. It also actively hunts at night, preferring the soft, nutrient-rich body of a shellless relative of the snail. Again, a dozen or two pests will die in one night under sharp hedgehog teeth. Toads, grasshoppers, frogs, salamanders and birds of prey also catch slugs.
Features of reproduction, or where the cubs come from
Of course, if there are adult slugs, then there must be “kids”. And this is so, and newborn individuals, or rather, eggs, become a delicacy for many birds, insects and mammals. But let's first understand how slugs reproduce. 
There is no need to talk about males and males, because gastropods are hermaphrodites. In other words, they have both male and female genital organs, and during mating they can act in any role. Surprisingly, in the animal environment, it is these ordinary-looking creatures that are recognized as "sexual giants"! The fact is that the length of the male penis is several times the length of the entire body! For example, a banana slug, on average, grows up to 15 cm, but at the same time, its erect penis reaches 81 cm! This is a real record that no one else can boast of.
The reproduction of slugs is a mysterious and incomprehensible process. When mating, adults seem to envelop each other with their genitals. It is often almost impossible to unravel such a “tangle”, so the animals just have to bite off the partner’s organ or their own. However, it does not always grow back, and the victim in the future can only use the remaining female part of the reproductive system. It is in this context that one can speak of a slug-girl.
After the described process, fertilized eggs mature in the body of the participants. Then the adult lays them in the moist ground. On average, there are about 50 eggs in one clutch, they mature for about a month, and cubs are born. A newborn slug is no different from an adult, except perhaps only in size. This is a tiny copy of the gastropod mollusk familiar to all of us. After 2 months, the babies fully grow and become sexually mature, starting to actively multiply.
Pests or useful helpers
The answer to the question is ambiguous, because animals can cause significant harm and at the same time improve soil structure. But most often slugs in the garden are a real disaster, because:
- They develop rapidly and become ready for the reproduction of offspring.
- One individual lays several dozen fertilized eggs at once
- Structural features make them hermaphrodites, so there is simply no shortage of females or males.
Important! If you don't want to let slugs thrive in your garden or garden, keep the situation under control and, if necessary, take action to scare off pests or reduce their population.
Now you know what slugs look like, how they differ from snails, how they feed and reproduce. These are, indeed, unique creations of nature, whose life is unusual and interesting.
And since garden slugs are omnivores, most garden and garden crops can become spoiled. Of course, it is impossible to describe all the known species of terrestrial slugs, since there are quite a lot of them. We collected the most famous and widespread. See photos of slugs with names in the material.
Slug species
Garden (garden)
They are also called naked slugs. They have an elongated body, which can change shape due to muscle contractions. The body is always moistened with mucus, which is constantly secreted.
The color is inconspicuous - grayish, yellowish and light brown. There is a grater on the tongue- a lot of small cloves of a solid consistency, arranged in rows.
At the front edge are tentacles, with visual organs located on them. Sizes are small - 25-30 mm.
This species can eat a variety of fruits and vegetables, especially tomatoes, strawberries, cabbage and strawberries. Distributed throughout Europe. Harms plants by eating leaves and stems, in fruits and vegetables makes holes. Thanks to his activity, the crop begins to rot, loses commercial and decorative qualities.
Active in cloudy and rainy weather, at night and early in the morning. It hides from the sun in damp lowlands, under earthen clods.
In constantly wet areas(groundwater is almost on the surface, floodplains) there is an increased fertility. One adult is capable of laying 300-400 eggs. They hibernate in the ground, the young come out in the spring.
Naked
Small (up to 70 mm in length) and the most frequent visitor to gardens. Absolutely omnivorous, can eat almost any plants.
Scientists have found that in the diet of a voracious slug includes more than 160 types of crops. Outwardly, it is completely inconspicuous, due to the coloring it is difficult to detect.
The body may be brownish., gray or beige color with yellow and white tints. The mantle is weakly expressed, it is almost invisible on the body.
The body is richly lubricated with mucus, which is secreted more than in other species. His stay is not hard to find due to the large number of slimy paths left by him.
You can meet this species in almost any part of Europe. What is not surprising - after all a naked slug is fertile enough for this.
Big European
One of the largest pests of this family. big slug boasts a length of up to 150mm. The coloring is also quite unusual.
Over the main background color (gray or brown, sometimes light brown) there are stripes and spots of different colors from light, almost white to jet black.
What are the big slugs look at the photo. 
European resident who doesn't like to move at all and change habitat.
Most often settled in greenhouses and wet cellars and spends their whole life in them. It is omnivorous and non-capricious, it can eat any available vegetables, mushrooms and fruits of fruit trees.
Large roadside or leopard
The body length can grow up to 20 cm. One of the largest representatives of slugs. Body shriveled, mostly rounded, only in the back is pointed at the end.
The base color can vary from light gray to chestnut, with ashy and yellowish slugs often found. Black spots and stripes are scattered throughout the body..
What a large roadside slug looks like, see the photo below.
It lives in Europe, which is its homeland, especially in the Central and Northwestern parts.
Its main feature is the method of mating. Adults attach to trees or other suitable support with the help of thick strands of mucus and hang down. It looks like they are floating in the air.
big spotted
A large member of the family, which can reach 130 mm in length. It is distinguished by the presence of small black dots and specks. covering the mantle.
In addition, it also has a longitudinal black stripe running across the entire surface. body shape oval, rounded at the ends.
Distributed in the southern part of Europe and in Asia, as it is quite thermophilic. Can grow in greenhouses in colder areas and other warm areas.
Eats a variety of vegetables, but most of all loves mushrooms, especially champignons.
The damage is quite serious due to the large size and a fairly long period of life of 3-4 years.
big black
The biggest black slug in the whole world, which reaches 300 mm in length. The black slug has a black mantle, adorned around the edges with small light speckles.
Sole in two colors - gray on the sides and black in the center. The color of the body can differ even within the same family and vary from monophonic to decorated with a wide variety of patterns.
The black slug lives in Europe, most common in Western and Central. In the Northern regions, it can only live in greenhouses.
Black slug photo. 
It feeds mainly on mushrooms, will not give up vegetables. In the absence of a favorite food, lichen can be eaten. The large size of the body determines the great appetite and the great harm caused by the gluttonous giants.
There may be about 100 eggs in a clutch.
Ginger
Differs in medium size, the usual length is about 100 mm, but sometimes grows up to 180 mm. Has a very bright body color- brick, less often yellow, brownish-green or black.
Lives in Western, Eastern and Central Europe, North America. Listed in the Red Book in many countries.
In nature, lives next to a person, settling in the fields, in gardens, less often can be found in wooded areas, again close to human habitation.
red roadside
The people are also called Spanish and Lusitanian. Brought to Russia by accident lives in warm regions of Europe.
Portugal and Spain are considered its homeland. It can reach 200 mm, but this is rare. The average length of adult slugs is 9-11 cm.
The color is monophonic, usually red, brick, orange. The mantle and torso are colored the same. The horns are black. The body is completely covered with wrinkles.
It is omnivorous, eating fruits, berries, flowers, and vegetables from the garden. Likes mushrooms. Very prolific species. All adult slugs are hermaphrodites.
Mating, they mutually fertilize each other and lay eggs in 5-6 days in an amount of up to 400 pieces each. Unlike other varieties, egg laying occurs in spring and summer, young slugs "hatch" in a couple of weeks. Grow 2 months to the status of "pubescent adult".
Cabbage
Despite the relatively short length(3-4 cm), these slugs cause significant harm to all types of cabbage. They settle on heads of cabbage and begin to gnaw through many passages inside, not content with spoiling the outer leaves.
The body and mantle are brown or brown in color. with darker spots. The spots are not pronounced, arranged in random order. The sizes are varied. The horns and head are slightly darker.
They are found throughout Europe, excluding the most northern regions. Feeds mainly on cabbage, but with a lack of favorite food, it can eat mushrooms, various vegetables and leaves.
Field
The mollusk is small in size, growing in length by 3-4 cm. Coloring is inconspicuous and inconspicuous, varies from light gray to light chestnut.
Usually monophonic both on the body and on the mantle. Body shape is like a spindle- it is wide in the middle and narrowed towards the ends.
Lives throughout Europe. Lives on the edges of the forest, in constantly wet lowlands and meadows. Often moves to gardens, cultivated fields and vegetable gardens.
Feeds on young shoots, foliage, fruits and vegetables. Favorite food is strawberries.
Smooth
A small mollusk growing up to 25 mm in length. The mantle is located on the upper half of the body. The color is always monophonic, the color can be brown, reddish, black. Shape cylindrical, the ends are narrowed.
Lives in Europe, including the CIS countries. Settles in always wet meadows, near various reservoirs and swamps. Differs in increased moisture-loving, resistant to cold.
Feeds on various berries severely damages plants in greenhouses, in nature eats mushrooms and rotten plants.
Forest
A forest slug can grow up to 15 cm in length in its lifetime., and puberty occurs already at a length of 3 cm. Young individuals are always painted in a chestnut color, which most often changes.
The color of adult slugs is very diverse and varies from milky white to blue-black.
The habitat is very extensive and includes the British Isles., throughout Northern Europe and the Pacific Northwest.
In food unpretentious, almost omnivorous. Can feed on live and half-decayed plants, any mushrooms, carrion.
In Ireland, Germany and the UK, it is listed in the Red Book.
Banana
It has a huge size, slightly short of the black slug. Its body length is about 250 mm. A striking feature is its color.
Most often it is a bright yellow color, but some individuals are colored white or green. Usually the color is monophonic, sometimes dark specks are scattered on the back. The eyes are on the upper horns., and the lower, shorter ones, have olfactory receptors.
The banana slug is native to North America., they can be found along the Pacific coast, all the way to Alaska.
Its diet contains mushrooms, lichens and rotten grass, as well as the feces of various animals. Depending on the prevailing food, body can change color.
After fertilization, the average clutch is 70-75 eggs. The dormant period is in winter when the temperature gets high and the weather is dry.
In addition, with an abundance of rain attacks for winter crops.
Conclusion
Despite the harmfulness, gastropods are very popular in modern society. Horned slugs are kept in apartments as pets.
In addition, they appear in computer games (for example, the Royal Slug in Terriak) and as characters in books (the Horned Slug is used as an ingredient in magic potions).
Useful video!
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Part one. Gastropods attack!
Spanish snail, Lusitanian slug, red slug...
This is a relatively new inhabitant of central Russia, which appeared in suburban areas near Moscow only in the last few years. A large, rapidly breeding, omnivorous slug of color options from orange-red to dark brown is perceived by many older summer residents as a kind of mutant of familiar slugs, and talk is usually about environmental degradation and the horrors of the chemical industry, but meanwhile this gastropod is a typical example of the importation of agricultural pest with vegetables and fruits. A foreign invader, so to speak.
Red roadside slug (Arion rufus)
Or perhaps the Lusitanian slug (Arion lusitanicus)
The folk names of this slug - the Spanish snail, the Lusitanian slug, the red slug and other variations on the theme of color and place - apparently go back to the names two species of lung snails from the genus Arion: Arion rufus and Arion lusitanicus. In Russian, these are, respectively, the red roadside slug and the Lusitanian slug. The species are similar to each other, it is hardly possible to determine which one you got among your favorite roses or in a gently cultivated greenhouse. It is definitely possible to exclude the black variation of the slug - Arion ater is an exclusively nocturnal species that is not yet found in our country, and in Northern Europe it is even listed in the Red Book (although not as an endangered species).
A large roadside slug also lives in Europe - but this spotted creature, growing up to 20 cm of average length, does not seem to live here either. (Although they write on the Internet that big slugs have taken root well in both Americas ...)
Initially, red slugs lived in the south of Portugal and Spain (on the territory of the ancient Roman province of Lusitania, from which one of the species got its name). Apparently, the main food for these gastropods at first was rotting forest litter, but the development of agriculture provided red slugs with much more satisfying and large "pastures". Climate warming, as well as an increase in agricultural land, trade relations, globalization and other achievements of human civilization contributed to the fact that red slugs, traveling throughout Europe, gradually acquired new habitats - preferring to capture vegetable fields, orchards, as well as planting cereals and various there are vineyards.
Until the first quarter or third of the 20th century, red slugs were considered the scourge of only their original habitats, but in the twentieth century, slugs captured almost all of Europe, after which they moved east, that is, towards us. It should also be noted that until the 1990s, the supply of agricultural products from Europe to Russia was simply not carried out, European fruits and vegetables came to us only a couple of decades ago. Along with them, apparently, came the red slugs, which by that time in Europe had already been recognized as catastrophic pests.
Welcome foreign invaders...
What provoked the rapid growth in the number of slugs and their rapid spread over such a large area? A couple of Internet publications evasively talk about the absence of natural enemies in slugs, which leads to an uncontrolled increase in their numbers. But there is obvious cunning in this kind of approach - slugs that have abandoned their protective shell are, in fact, simple and affordable food for a huge number of carnivores. First of all, slugs are prey for hedgehogs, moles and shrews. A hungry rat does not disdain a slug. Many amphibians like frogs, toads, salamanders are also willing to eat slugs. Slugs are included in the diet of lizards and snakes. And there are also birds: large passerines, most ravens, many waterfowl are ready to eat gastropods.
Red roadside slug at the edge of the forest
(near the reclamation ditch)
Even if all these enemies are not ready to attack an adult red slug, reaching a maximum length of 15 cm, they should have destroyed the vast majority of small gastropods. But that doesn't happen. For a very obvious reason - most of the listed enemies of slugs are enemies of agriculture, only larger and more visible, and not only European, but also our Russian farmers have been successfully fighting them for a long time. There are no moles - there are slugs. There are no frogs - there are slugs. There are no birds - there are slugs. Why be surprised?
Droughts in the south of Europe could have been a deterrent to the spread of slugs - slugs do not know how to live in a dry climate and quickly die in the absence of moisture. Land reclamation and the transition of agriculture to technologies that use irrigation contributed to the reproduction and comfortable life of slugs. You can, of course, scribble abstruse articles about the impact on the planet's biosphere of a comet named after an unknown astronomer, but in fact we ourselves have paved convenient travel routes for slugs and organized excellent feeding grounds for them.
In our Russian conditions, winter frost can affect the number of both Lusitanian and red slugs. Adults and small slugs hibernate in the soil, burrowing into it and falling into anabiosis. Our winters cannot be compared with Spanish ones, the soil in the forest can freeze several tens of centimeters deep. The dimensions of the European alien are quite large, it is much more difficult for him to keep all vital systems intact than for our ordinary slugs.
However the main thing for survival is to overwinter the eggs of slugs, and this, as you know, is a completely different matter. Eggs can be stored inside the root plexuses of trees, in earthen minks, and simply in the depths of a pile of leaves. The egg itself is a much more resistant form of life, and one slug can lay up to hundreds of eggs in one clutch. (I don’t know who it was and how it was considered, but the figure wanders from article to article.) How often a slug can lay eggs is unknown, I have not found reliable information. Our gray slugs seem to do this once a year - in the fall, with a lifespan of 1 to 3 years. But again, this is all separate empirical data.
And do not forget that any suburban area will provide slugs with enough secluded places where you can comfortably and calmly wait out the coldest winter. Perhaps that is why flower growers write hysterically about slugs in their blogs, and not pathos-tragically broadcast ministers from the screens of zombies.
Let's take it out, take it out... We'll live on a bare planet.
In the articles of noble agronomists and honored farmers, there would be further discussions about how and what is better to lime the slug. But I will not discuss the issues of mass killing of slugs. I myself am lazy for energetic military measures, and I consider it senseless to fuss for every inch of land free from pests on a scale of six, fifteen, thirty acres. In addition, I do not feel the right to deprive other creatures of life just because I was impatient here and now to admire some vegetation, and they prevented this. As long as we are not talking about cultivating the land for the sake of daily bread, there is no point in fighting what nature itself has come up with. And what chemists and biologists have come up with, let them figure it out themselves.
Estimate the size of the elongated slug
And it's not the largest specimen.
Slugs prevented me from admiring the flower? Well, so be it.
I will admire the amazing creatures that managed to capture Europe.
It turns out they are very, very interesting creatures.
And finally. How long have you seen a hedgehog in your summer cottage? Ah, long time ago. And no hedgehog will make it to your site, because you have a reliable fence, under which even a mouse will not slip. And how many years, how did you bring out all the moles? Ah, it's been a decade. And you don’t want to see any more such misfortune in yourself. What do you do with a randomly seen toad? Ah, you do the same. Dirty and nasty ... And if a snake? Ah, this is terrible...
Go on, dear summer residents, cleaning up your plots in accordance with your miserable illusions that it is you who decides who will live here. The red slugs are on their way. Get ready to meet uninvited guests. And get ready to give them everything - vegetables from the garden, fruits from the garden, and even flowers from your favorite flower bed. Slugs love everything. Everything will be eaten.
Do you think some cunning poison will help you? Imagine how much of this poison you yourself and your children will eat and inhale. And for a second, think that someone will come after the slugs. After all, someone will come. Necessarily. Are you ready for this meeting?
Photo and text: Lazy Summer Resident, 2014
Imago. The body is slender, pointed towards the tail. Body length when crawling without tentacles - 130-200 mm, with full contraction - 100 mm.
The keel is short, occupies 1/3 of the back. The mantle is rounded in front, angular in the back, covering about a third of the animal. There are 21-26 rows of wrinkles between the mantle fissure and the midline of the back.
The background color of the body is yellowish, ash-gray or off-white. The pattern consists of two or three pairs of stripes or rows of black spots. The mantle is covered with black spots, often forming a meander pattern.
The tentacles are pinkish-brown in color, there are no dark dots. The sole is white, without a pattern.
Mucus is colorless, thick.
Median and lateral teeth with small ecto- and endocones. The border between the lateral and marginal teeth is almost imperceptible. The marginal teeth are at first spiky, at the end two-pronged. The total number of lateral and marginal teeth in each row is 62-73, the number of rows is 138-157. The intestine is typical for the genus - with a shorter third loop, which occupies half of the back.
Postembryogenesis. All phases are similar in morphological structure to the adult animal. They differ in size and degree of development of the genital organs.
Development
Imago. In anthropogenic conditions, it is often found in parks and gardens, in various shelters (pieces of wood, hollows, under stones and bark). The pest can be found in greenhouses, cellars, underground channels and tunnels. Under natural conditions, it lives in mixed and deciduous forests. The ambient temperature greatly affects the reproduction of slugs. At temperatures below +10°C, the development of the gonad is delayed. At +25 °C and above, the number of oocytes decreases and they may disappear completely. Slugs cannot tolerate humidity below 90% for long periods of time. Initially, a decrease in humidity causes an increase in mobility. At this time, the slug is looking for shelter. If one is not found, he falls into a stupor and soon dies. A large slug can survive 50% loss of body moisture. When crawling, they leave behind a large number of white mucus, which, as it dries, acquires a pearly sheen. Mucus plays a big role in choosing a mating partner.
mating period. Copulation takes place at night or on damp, cloudy days. It is preceded by a series of behavioral reactions - mating games. Individuals copulate in limbo. When meeting, individuals lick and feel each other, then intertwine with their bodies and at the same time stick with the help of mucus to a branch or stone and hang upside down in the air on a long slimy cord 15-45 cm long. Copulation along with dancing lasts at least 10 hours.
Eggs are laid in crevices in the soil, at the foot of various herbaceous plants, and in other shelters protected from sunlight and sufficiently moistened. Most often, eggs are laid in portions in several places located close to each other. The number of eggs depends on age, nutrition, physiological state and weather conditions. On average, the fecundity of a large slug is from 100 to 500 pieces.
Egg. Embryonic development lasts at least 18-21 days and does not occur in all eggs at the same time. The process of crushing begins in the body of the mother's organism. Along with ordinary eggs, abortive ones are often found, from which juveniles do not hatch. The end of embryonic development and hatching of individuals from eggs is observed in autumn.
Postembryogenesis big slug, like the whole family Limacidae, consists of three phases: infantile, juvenile and adult. Phases are characterized by the rate of growth of the body and the condition of the genitals.
Infantile phase. In this phase, a high growth rate of the animal's body is observed. Gonad and genital tract rudimentary. The oviduct seed begins to differentiate.
juvenile phase. The growth rate drops. The gonad intensively increases in size and differentiates into separate lobes, and by the end of the phase its mass reaches a maximum.
adult phase. Body growth stops. The formation of all organs of the genital tract is completed. At the beginning of this phase, spermatogenesis ends, and the gonad is filled with mature sperm. By the end of the phase, the protein gland begins to function. The prostate finishes secreting in the middle of the adult phase, and the development of the glands of the female canal of the oviduct begins. By the end of the adult phase, copulation and oviposition are timed.
Development features. The lifespan of a slug is two and a half to three years. The first year, animals only grow, but do not reproduce. The first copulation is observed in June - July of the second year of life, that is, on the 21st-22nd month after hatching. The second copulation takes place in the third year of life, in May - June. Egg laying stretches for two months. In total, the life expectancy of a large slug is 2.5-3 years.
Morphologically related species
In morphology (appearance) it is close to the described species Limaxcinereoniger. It is distinguished by a strongly twisted penis, shorter in length than the body of a slug.
In addition to this species, it is often found Limaxdobrogicus, also similar in appearance to a large slug ( Limax maximus).
Geographic distribution
The large slug in Russia is distributed in the Kaliningrad, Leningrad, Yaroslavl, Smolensk, Moscow, Gorky, Oryol regions. As a synanthropic species, the pest is found throughout Europe, especially in the northern and eastern regions of the continent. The natural range covers the mountainous regions of Western, Southern and Central Europe, as well as North Africa. The pest has been introduced to South Africa, North America, Australia and New Zealand.
Maliciousness
Slug big harms many vegetable crops: cabbage, carrots, rutabaga, parsley, eggplant, turnip and others. It causes great harm to seedlings and young plants. Harmful in vegetable stores and greenhouses. Slugs are able to eat a wide range of plants, both fresh and in various phases of decay. It prefers succulent and soft parts of plants, avoiding areas with hard covers and vascular-fibrous bundles.
Slugs are terrestrial gastropod molluscs with a reduced shell or no shell at all. Slugs include all representatives of the Onchidiacea and Soleolifera families and some species from the Sigmurethra family. There are several hundred species of these animals in the world, their relatives are snails, as well as nudibranch molluscs, which are sometimes called sea slugs.
Long banana slug (Ariolimax dolichophallus).
Anatomically, slugs are very similar to snails: their body actually consists of one large foot-sole, merged with the head. On the upper side of the body, behind the head, a mantle is visible - a kind of plate that hides the genitals and anus of the mollusk. Some species (they are called semi-slugs) also have a tiny shell, but it is not visible from the outside, because it is covered by a mantle. In general, slugs are characterized by bilateral symmetry, which is broken only by an unpaired pulmonary opening, always located on the right.
Two pairs of thin mobile "horns" rise on the head of a banana slug: one of them serves for smell, and the second carries tiny eyes.
Most of these molluscs measure a few centimeters in size, but large species (banana, large roadside, blue-black slug) can reach a length of 15-30 cm! These animals are painted mainly in nondescript shades of brown, but the forest slug, for example, has an anthracite-black color, the red roadside slug is chestnut or orange-red, the long banana slug is bright yellow.
The red triangular slug (Triboniophorus graeffei) from Australia is one of the brightest colored species.
Slugs are found everywhere, but they reach the greatest species diversity and abundance in areas with a temperate and humid climate: the forest zone North America, Western and Central Europe, humid forests of Australia and New Zealand. In these areas, slugs inhabit forests, fields, gardens, and meadows. Very unusual is the narrow endemic Sokolov's troglolestes, which is found only in the caves of the Caucasus. Such a pattern of settlement of these mollusks is explained by the absence of a shell that could serve as a shelter from cold, heat and drought. Tender slugs are forced to hide from the direct rays of the sun, so they are active mainly at night, in the evening and in the morning, and during the day they hide in thick grass and under leaves. Due to this vulnerability, slugs are forced to winter in the depths of the soil, with some species wintering adults, while others - eggs.
The world's largest blue-black slug (Limax cinereoniger) reaches a length of 30 cm.
These animals move due to the wave-like contraction of the sole. Since the delicate body is subject to friction against a hard substrate, mollusks secrete mucus as a lubricant. Interestingly, it comes in two forms: the watery one spreads from the center of the leg to its edges, while the thicker and stickier one stretches from the head to the tail. In some species, the mucus is almost transparent, in others it is whitish, and a long visible trail is left behind the crawling mollusk. Both types of mucus are hygroscopic and can retain water, so the mucus not only facilitates movement, but also prevents the defenseless mollusk from drying out. This substance has other uses. The mucus of some species is unpleasant in taste and protects the molluscs from being eaten by predators. In a number of species, it is so dense that its owner is able to move along vertical surfaces or upside down, and even hang on it, as if on a thread. Despite the extremely low speed of movement, slugs sometimes make relatively long migrations - in search of food, they can crawl over a distance of several hundred meters.
The red roadside slug (Arion rufus), like its counterparts, is able to change the shape of the body from an elongated worm-like to a compact, almost round due to strong muscle contraction.
Among slugs there are species with all types of food. Most of these mollusks are herbivorous. They are not particularly picky and gnaw on leaves, aerial parts of root crops, flowers and fruits. Some specialize in feeding on mushrooms, others are detritophages, that is, they eat dead parts of living organisms (fallen leaves, carrion, moss, lichens, feces). Finally, among the slugs there are omnivorous and predatory species. Predatory molluscs catch earthworms, their smaller relatives, there are cases when they attacked even small chicks and mice. Slugs absorb food with the help of the so-called grater (radula). It is a discoid tongue studded with thousands of small teeth. The mollusk methodically rips off soft tissues layer by layer and becomes saturated.
Forest slug (Arion ater) feasts on red fly agaric (Amanita muscaria).
These animals breed once a year. Like all mollusks, slugs are hermaphrodites: each individual has female and male genital organs, but the reproductive products do not mature at the same time. At first, sperm matures, packed in special bags - spermatophores. During this period, the slug begins to secrete mucus with pheromones, by the smell of which it is found by the same kindred.
During the marriage ceremony, large roadside or leopard slugs (Limax maximus) are hung upside down on slimy threads and woven into a “pigtail” with their bodies. Their blue penises are twisted into a ball.
In people, the word "slug" is associated with a weak and useless creature. In fact, among animals, slugs are a kind of "sexual giants", since they have the largest penis relative to body size. Its length is equal to or exceeds the length of the body, the absolute record holder is a long banana slug. His penis reaches 81 cm, with a body length of only 15 cm! The mating process itself is also unusual. When they meet, the molluscs intertwine with their genitals, and given their great length, it is not easy to unravel this tangle. Therefore, after mating, many slugs simply bite off the sexual organ of their partner or their own. Over time, the lost parts of the body grow back. After mating, the maturation of eggs in the body of the slug ends, fertilization occurs, and the adult lays eggs in the ground. On average, each mollusk lays 30-70 large white or transparent eggs. Their development lasts 3-5 weeks. The eggs hatch into fully formed tiny slugs. They grow rapidly and reach sexual maturity in 2 months. The life expectancy of these animals does not exceed 1-2 years.
Due to the lack of a shell, slugs are easy and desirable prey for many animals. They are eaten by raccoons, noses, wild boars, ducks, chickens, hedgehogs, storks, waders, pheasants, starlings, pigeons, jackdaws, magpies, toads, frogs, salamanders. From the attack of slugs, only nondescript coloring and low mobility protect. Minor damage and bitten off "horns" in mollusks are easily restored. In some areas, slugs are eaten raw or cooked, but raw slugs can carry helminths and meningitis.
Slug clutch.
In nature, slugs are of great benefit, destroying fallen leaves and turning them into humus, but there are pests among them. Agricultural crops are threatened primarily by field and net slugs. These species damage strawberries, cucumbers, beets, turnips, lettuce, dill, zucchini, pumpkin, watermelons, melons, and wheat. Slugs not only gnaw on the fruits and sprouts of these plants, but also spread dangerous viral, bacterial, fungal diseases of crops. Crawling on the grass, they can infect goats, sheep and chickens with helminths.