Land crabs. The largest arthropod is the coconut crab. Description and photo. Reproduction of land hermit crabs

Seeing this amazing arthropod, anyone faint of heart will shudder in horror and surprise - after all, there is nothing in the world more interesting and, at the same time, more terrible than the coconut crab. In any case, among arthropods - after all, he is rightfully considered their largest representative.

1. The coconut crab has many other “names”: for example, thief crab or palm thief - after all, this strange arthropod actually steals its prey. Travelers of past centuries who visited the islands located in the West Pacific Ocean and in the Indian Ocean, they say that the coconut crab hides from prying eyes in the dense greenery of palm trees in order to then suddenly grab its prey lying right under a tree or not far from it.

2. The coconut crab (lat. Birgus latro) is not actually a crab at all, despite the striking resemblance to the arthropod relative mentioned in the name. This is a land hermit crab, belonging to the species of decapod crayfish.

Strictly speaking, calling the palm thief a land arthropod is also a stretch, since part of its life is spent in sea ​​elements, and even tiny crustaceans are born in the water column. Newborn babies with defenseless soft abdominal cavity They crawl busily along the bottom of the reservoir in search of a reliable house, which can serve as a nut shell or an empty mollusk shell.

3. In “childhood,” birgus latro is not too different from a hermit crab: it drags its shell around with it and spends almost all its time in water. But once it emerges from the larval state and leaves the water, it is no longer able to return there, and at some point, even carry a shell-house with it. Unlike the abdomens of hermit crabs, its abdomen is not an Achilles heel and gradually hardens, and the tail curls under the body, protecting the body from cuts. Thanks to special lungs, he begins to breathe out of water.

In truth, most legends noted precisely this feature - the first Europeans who arrived on the islands described coconut crabs as creatures hiding in the foliage of trees with long claws that suddenly reached out to the ground and captured prey, including sheep and goats. Scientists have confirmed that birgus latro has great strength and can lift up to 30 kg of weight. However, they found out that the crab uses its abilities to drag cargo from place to place, preferring to feed on dead animals, crabs and fallen fruits.

4. How do crayfish manage to exist equally comfortably both in water and on land? Turns out, wise nature provided them with two breathing instruments at once: lungs, ventilated by air on the surface of the earth, and gills, allowing breathing under water. But over time, the second organ loses its functions, and palm thieves have to completely switch to a terrestrial lifestyle.

5. Those who want to meet such a miracle would have to go to the tropics - coconut crabs are found on the islands Indian Ocean and on some western Pacific islands. It’s not easy to see them in daylight: palm thieves lead night look life, and in solar time They hide in rock crevices or in sandy burrows lined with coconut fibers - this helps maintain the required level of humidity in the home.

6. And although the version that the crayfish is capable of splitting a coconut with its front claws failed miserably, its limbs are nevertheless developed enough to nimbly climb the trunk of a palm tree or bite off a person’s phalanx of a finger. And cancer is really partial to coconuts: the nutritious pulp is the main dish on its menu, to which it owes its “coconut” name.

7. Sometimes the diet of crayfish is enriched with pandan fruits, and according to some sources, palm thieves sometimes eat their own kind. A hungry crayfish unerringly finds the nearest “restaurant”: its internal navigator is its excellent sense of smell, which leads it to the food source, even if it is many kilometers away.

8. As for the “thief status” of cancer, this is due to its uncontrollable desire to drag into its hole all sorts of things that are not good - edible and not so good.

Coconut crab meat is not only considered a delicacy, but also an aphrodisiac, which is why these arthropods are actively hunted. To prevent their complete extinction, some countries have strict restrictions on the harvesting of coconut crabs.

9. The body of the coconut crab, like all decapods, is divided into the front part (cephalothorax), on which there are 10 legs, and the stomach. The front, largest pair of legs has large claws (claws), and the left claw is much larger than the right. The next two pairs, like those of other hermits, are large, powerful with sharp ends, and are used by coconut crabs to travel along vertical or inclined surfaces. The fourth pair of legs is significantly smaller than the first three, which allows young coconut crabs to settle in mollusk shells or coconut shells and provide protection. Adults use this pair for walking and climbing. The last, very small pair, which is usually hidden inside the shell, is used by the females to care for the eggs and by the males for mating.

10. Except for the larval stage, coconut crabs cannot swim, and they will certainly drown if they remain in the water for more than an hour. To breathe, they use a special organ called gill lungs. This organ can be interpreted as a developmental stage between the gills and lungs, and is one of the coconut crab's most important adaptations to its environment. The branchial lungs contain tissues similar to those found in the gills, but are suitable for absorbing oxygen from the air rather than from water.

11. The coconut crab has a well-developed sense of smell, which it uses to search for food. Like most crabs that live in water, they have specialized bodies, located on antennas that determine the concentration and direction of the odor.

12. During the day, these arthropods sit out in burrows or rock crevices, which are lined with coconut fibers or leaves to increase the humidity in the home. While resting in its burrow, the coconut crab closes the entrance with one claw to maintain a humid microclimate in the burrow, which is necessary for its respiratory organs.

13. As the name suggests, this crab feeds on coconuts, and is in fact able to climb up to a height of 6 meters on a coconut tree, where it uses its powerful claws to pinch off coconuts if they are not already available on the ground. If a fallen coconut does not split when it falls, the crab will gut it for a week or even two until it gets to the juicy pulp of the nut. If the crab gets tired of this dreary work, he lifts the coconut up the tree and throws it down to make his work easier. Descending back to the ground, they sometimes fall, but without damage to their health they can survive a fall from a height of 4.5 meters. The coconut crab will not refuse other fruits, newborn turtles and carrion. They have also been observed catching and eating Polynesian rats.

14. Another name is palm thief, it received for its love of everything shiny. If a spoon, fork, or other shiny object gets in the way of a crab, you can be sure that he will certainly try to drag it into his hole.

15. From the beginning of June to the end of August, the breeding season begins for palm thieves. The courtship process lasts long and tediously, but mating itself occurs quite quickly. The female carries fertilized eggs for several months on the underside of her abdomen. When the eggs are ready to hatch, the female goes down to the seashore at high tide and releases the larvae into the water. Over the next three to four weeks, the larvae floating in the water go through several stages of development. After 25 - 30 days, small crabs sink to the bottom, settle in the shells of gastropods, and prepare to migrate to land. At this time, babies sometimes visit land, and gradually losing the ability to breathe under water, they finally move to the main habitat. Coconut crabs reach sexual maturity approximately five years after hatching, but reach their maximum size only by the age of 40.

16. Palm thieves live in the tropics, on the islands of the Indian and western Pacific oceans. Christmas Island in the Indian Ocean has the highest population density of coconut crabs in the world.

17. Swedish and Australian scientists have confirmed the veracity of all the stories about coconut crabs. Thus, residents of the Pacific Islands claimed that they could smell, for example, meat or ripe fruit several kilometers away. And indeed, the special baits placed by the researchers immediately attracted the attention of the thieving crabs, who nevertheless disdained the ordinary pieces of bread that ordinary crabs are greedy for.

18. The function of a janitor is, of course, not bad and useful, however, since birgus latro is a predominantly nocturnal creature and not very friendly, when you stumble upon it, local residents they are not particularly delighted. The decrease in its numbers forced local authorities to set a limit on catching birgus latro. On Papua New In Guinea it is prohibited to include it in restaurant menus, on the island of Saipan it is prohibited to catch crabs with a shell less than 3.5 cm, as well as from June to September, during the breeding season.

19. On the inner surface of the walls of the gill cavities of this land descendant of hermit crabs, grape-shaped folds of skin develop, in which numerous blood vessels branch. These are real lungs, allowing the use of oxygen from the air filling the gill cavities. The lungs are ventilated due to the movements of the scaphognathite, as well as due to the ability of animals from time to time to raise and lower the carapace, for which special muscles are used.

It is remarkable that the gills are also preserved, although they are relatively small in size. Removing the gills did not harm breathing at all; on the other hand, the crayfish completely lost the ability to breathe in water. The palm thief immersed in water died after 4 hours. The residual gills apparently do not function. The palm thief digs shallow burrows in the soil, which are lined with coconut fibers. Charles Darwin says that the natives on some islands select these fibers from the holes of the palm thief, which they need in their simple farming. Sometimes the palm thief is content with natural shelters - crevices in rocks, cavities in drained coral reefs, but even in such cases it uses plant material for their lining, which maintains high humidity in the home.

Crabs are a large group of aquatic and semi-aquatic animals belonging to the order Decapod Crustaceans. Crabs differ from related crayfish, shrimp, lobsters and lobsters by a noticeably shortened abdomen, tucked under a wide cephalothorax. This gives them a specific, well-recognized shape. At the same time, crabs have reached unprecedented diversity: 6,793 species of these animals are united in 93 families, which is half the number of the entire order.

The spotted-footed rock crab (Grapsus grapsus) is a native of the Galapagos Islands.

Along with a special body shape, crabs are characterized by the presence of 10 pairs of limbs. They are divided into thoracic and abdominal. The first 3 pairs of thoracic limbs are very short, they are called maxillae because they do not participate in movement, but only serve to bring food to the mouth. The remaining pairs of thoracic legs are used for locomotion, grasping and cutting food, and can also perform other auxiliary functions. The pair of the largest and most massive legs are claws. With their help, crabs can not only hunt, but also defend themselves and participate in mating fights. The narrow specialization of these organs affected their appearance: Often the right and left claws have different sizes and shapes, giving the crab’s body a noticeable asymmetry. As for the abdominal legs, they are small and are used for fertilization (in males) or bearing eggs (in females). Vital organs such as gills are connected to the chest legs of crabs. Often their petals are located directly on the leg segments or near the place of their attachment to the body.

Due to the huge difference in the size of the claws, lure crabs appear to be one-armed. Like people, these animals are right-handed and left-handed, with 85% being right-handed.

Crabs are one of the most advanced crustaceans, so they have developed sensory organs. Vision plays a big role in their lives. The eyes of these animals are complex, faceted. They are made up of thousands of eyes, each of which sees only a tiny part of the space directly in front of them. The final assembly of the image occurs in the animal’s brain. Numerous observations have proven that with the help of vision, crabs identify a potential enemy, find a partner during the breeding season, and navigate in search of food. But if an animal is blinded, it will only lose the ability to see danger, but will find food and a partner with almost the same efficiency. Antennas (“antennae”), capable of capturing odors, will help him with this. If the crab's antennae are also cut off, then it... will find food again. True, in this case he will have to spend a lot of time and effort, because he will literally move towards the prey by touch, tapping his claws on the ground. Some types of crabs have balance organs - statoliths. By the way, huge role their physiology is played by... eyestalks. These are real endocrine glands, capable of secreting hormones and regulating such body functions as the frequency of molting, the onset of puberty, and even color changes!

The Latreille's land bigeye (Macrophthalmus latreillei) has especially long eye stalks, which is associated with the need to inspect the area at a great distance.

Crabs do not have skin as such; it is replaced by a layer of hard and impenetrable chitin, which forms a kind of shell. Chitin is unable to stretch, making normal linear growth impossible. Crabs solve this problem by molting regularly. When the old shell bursts, a soft and defenseless animal emerges. It takes from several weeks to six months for the new cover to harden; during this period, the crab hides in a secluded place and grows intensively. Chitin can be impregnated with all kinds of pigments, so crabs can have almost any color.

The bicolor vampire crab (Geosesarma bicolor) gets its name from its unusual combination of bright yellow eyes with a dark purple shell. Due to its impressive appearance, it is often kept by amateur aquarists.

In addition, the chitinous cover may have outgrowths: sparse and hard, like spines, short and hard, like bristles, or long and thin, like wool.

The Chinese mitten crab (Eriocheir sinensis) stands out among its relatives with a “fur” muff on its claws.

The sizes of these animals also vary widely. The diameter of the shell of the world's smallest pea crab does not exceed 1 cm, while the leg span of the largest Japanese spider crab reaches 4 m with a weight of 20 kg.

Pea crab (Pinnotheres boninensis) lives on the coast of the Azov and Black Seas.

Crabs inhabit all the seas and oceans of the planet, but they reach their greatest diversity in the tropics. The habitat of these crustaceans has a very wide range: crabs can be found in the shallow waters of seas and oceans, among thickets of corals on reefs, at depths of up to 5000 m, in cave ponds, in the intertidal zone, mangroves and even in the depths of islands far from the coast. The vast majority of them live in salt water, about 850 species live in fresh water. Crabs, long time Those that live on land store water under their shells or develop organs like lungs. Their underdeveloped gills almost do not work, and when constantly immersed in water, such individuals die. Bottom-dwelling species are often active in the dark; land crabs are most active during the day.

The second largest Tasmanian on the planet giant crab(Pseudocarcinus gigas) with a carapace width of 46 cm, weighs up to 13 kg.

When moving, these crustaceans never place both legs of one pair on the ground at the same time, which gives their gait stability, but their short body length and large number legs make it inconvenient to move forward, so crabs prefer to walk sideways. At the same time, this does not in the least prevent them from developing decent speed, for example, a grass crab covers 1 m in 1 second! But these animals swim poorly and reluctantly.

The exception is swimming crabs, whose back pair of legs are transformed into paddle-blades, thanks to which they feel in water element like home.

These crustaceans have a quarrelsome character; they all live alone and jealously guard their areas or shelters; Males are especially aggressive. At the same time, areas of small crabs are very small, so there can be up to 50 burrows per 1 sq.m. Danger is the only thing that makes the inhabitants of the colony forget about strife. When threatened, crabs signal their neighbors by waving their claws, making sounds, or tapping on the ground. Thanks to vibrations, even those individuals that do not see the enemy manage to hide.

Blue soldier crabs (Dotilla myctiroides) form large aggregations on beaches.

Shelters deserve special attention. In the simplest case, these animals hide among coral branches, in crevices between stones or shell valves, and in the cavities of sponges. But many crabs do not expect favors from nature, but instead dig holes in viscous silt or sand. These houses may have one straight passage (often quite deep), or several branched passages with emergency exits; beckoning crabs equip the entrance to the hole with a lid. Some species live under the canopy of jellyfish, among the tentacles of sea anemones, in the mantle cavity of mollusks, among the spines, or even in the rectum of sea urchins.

These holes on one of the beaches of Malaysia were dug by the closest relatives of soldier crabs - scopimera. Each individual, pushing sand out of its home, rolls it into a neat ball. The crab droppings have the same shape when they eat the soil.

Crabs have practically no food specialization; they are all omnivores to one degree or another. These animals can eat the bacterial film covering stones, algae, fallen leaves and flowers, bivalves, polychaete worms, starfish, small crustaceans and even octopuses. Like crayfish, crabs readily feast on carrion. Species living in shallow water happily “snack” the soil on regular food. By passing sludge through their intestines, they assimilate the microorganisms contained in it. Large prey the crabs not only grab it, but cut it up like real gourmets. At the same time, they use their claws like a knife and fork: they hold the prey with one, and cut off neat pieces with the other.

A grass crab (Carcinus maenas) is about to dine on a bivalve.

Reproduction in crabs has a pronounced seasonal character; different types it is dedicated to one or another natural phenomena(rainy season, highest tides). For example, Christmas Island red crabs (Gecarcoidea natalis) live on land away from the shore, but move to the surf line to lay eggs. Their migration is one of the most ambitious phenomena in nature.

Millions of individuals rush towards their goal like a living river, overcoming roads, ditches and other obstacles along the way.

At this time, crabs die en masse under the wheels of vehicles and under the feet of people who are tired of avoiding countless travelers.

To prevent the crabs from dying, Christmas Island is creating barriers along roads to divert migrants away from dangerous routes.

Pay attention to the insects in the frame. These are yellow crazy ants brought to the island by people. They turned out to be a very aggressive and prolific species and have already destroyed 1/3 of the crab population - 20 million individuals!

No less interesting are the mating battles of beckoning crabs. With their hypertrophied signal claw, they threaten their opponents and even fencing with it in a collision. Then they signal the female with waving movements, as if declaring their victory. This emphasized ritualism has led to the fact that in many species there is a very noticeable difference between males and females (sexual dimorphism).

Duel of beckoning crabs.

Before mating, the couple sometimes takes a “face to face” position and can remain in this position for several days. Interestingly, one mating is enough for a female to lay fertilized eggs throughout her life. This is explained by the fact that the male presents her with sperm packed in special bags - spermatophores. In them, the germ cells remain viable for many years; during the next season, the female dissolves the spermatophore membrane with special secretions and fertilization occurs again. The fertility of crabs is very high and amounts to tens of thousands and millions of eggs. The female carries them on her abdominal legs from a couple of weeks to several months. The hatched larvae begin to swim freely.

Swimming crab larva.

After several molts, they turn into young crabs, which settle in the biotopes characteristic of a particular species. The lifespan of these crustaceans ranges from 3-7 years for small species to 50-70 years for the huge spider crab.

Japanese spider crab (Macrocheira kaempferi).

Due to their great diversity and abundance, crabs have many enemies. Their lives are encroached upon by fish, octopuses, crocodiles, starfish, seagulls and almost all predatory animals that wander along the coast. Crayfish raccoons generally specialize in collecting crabs on the shore. Such intense interest on the part of carnivores has forced these crustaceans to develop a variety of defense mechanisms. The simplest of them is camouflage. This is achieved in some cases by coloring, which very accurately reproduces the color and even the pattern of the substrate on which the species is found.

The caramel crab (Hoplophrys oatesii) imitates the dendronephthia coral on which it lives in color and shape.

In other cases, surrounding objects are used for cover. For example, shy crabs cover themselves with a shell-shield, decorator crabs cut out pieces of bryozoans and hydroids with their claws and place them on their backs, gluing them together with special secretions. On the crab's back, these colonial animals continue to develop and transform its shell into a flower bed.

It is difficult to recognize the perfectly camouflaged decorator crab (Camposcia retusa) in this crawling bush.

The Dromia crab looks for a sponge and, like a real seamstress, cuts a piece out of it exactly to the size of its back.

The Dromia erythropus crab resembles an old woman in a beret. Since its body is quite fleshy, the dromia has to look for a flap with a curve that perfectly follows the convexities of its shell.

If disguise does not help, active methods of defense are used. Large crabs take a fighting stance and raise their claws up. If the offender does not understand the hint, they use their wire cutters and are capable of inflicting deep cuts. Boxer crabs always hold sea anemones in their claws, the stinging cells of which are dangerous even for relatively large animals.

A female boxer crab (Lybia tessellata) in a fighting stance with sea anemones. A clutch of eggs is visible on the abdomen of this individual.

Many species are capable of autotomy (self-amputation). When it sees an enemy, the crab throws its leg away by contracting special muscles. In this case, the valves at the tear site immediately close the wound and stop the bleeding. If such a handout was not enough, the victim offers the predator the next limb. Severed legs grow back after several molts.

• Class: Crustacea = Crustaceans, crayfish
• Subclass: Malacostraca = Higher crayfish
• Order Decapoda = Decapod crustaceans (crayfish, crabs...)
• Suborder: Pleocyemata Burkenroad, 1963 = Crabs
• Infraorder: Brachyura Latreille, 1802 = Crabs, short-tailed crayfish

Land (land) crabs

Crabs are marine creatures, and it is difficult to imagine that they can live on land, much less in trees or in arid regions. Therefore, land crabs are an unusual zoological phenomenon.

The conquest of land by crabs proceeded gradually. Crabs had 10 times less time to conquer land than insects, but their success in adapting to terrestrial existence is very significant. The initial stage of this process is the development of tropical beaches by ghost crabs and soldier crabs. These crabs live in burrows in areas of the coast that are regularly flooded by ocean tides.

Mangrove crabs, which live on the roots and branches of mangrove trees in tropical rain forests, have taken the next step towards conquering land. All these crabs migrate to the sea to breed, and after breeding is completed, they again go many kilometers from the coast.

Another way for crabs to explore continents is their adaptation to life in fresh water (see). Along rivers and streams, these crabs penetrated far into the continents, climbed mountains, and even mastered the Himalayas. Some crabs, such as the bromeliad crab Metopaulias depressus, have adapted to live in the axils of large leaves of land plants, where rainwater accumulates.

Tropical earth crabs spend their entire lives on land, living in bare desert areas where huge cacti proudly rise above the sands. These crabs can be found several kilometers from the sea, where they scour clearings overgrown with thorny bushes and barren savannas in search of food. These crabs feed on leaves and other greens.

In the deserts of Australia, thousands of kilometers from the sea, there lives a crab that uses night dew and carries its young in a tightly closed “pocket” on its abdomen. The main problem for land crabs is fighting desiccation. They solve this problem in several ways. Firstly, the dense calcareous coverings of the body prevent drying, and secondly, the crabs go hunting only at night or after heavy tropical downpours, hiding in underground burrows during dry times. In addition, the real gills of land crabs are transformed into a “lung”, the respiratory surface of which is moistened by the presence of tufts of bristles that absorb water from the sand. Crab burrows dug in soft soil form complex labyrinths several meters long. Often one of the exits leads to a pond, which maintains high humidity in the crab's cave.

An extremely unusual respiratory organ was formed in the land crabs Scopimera and Dotilla. These crabs live at the very edge of the water, collecting food on the bare water at low tide. seabed, and at high tide hiding in deep holes where air is retained. They breathe with their feet. The thighs of the walking legs of these crabs are greatly expanded, and in their middle there is a “window” covered with a thin membrane. In Skopimera, fenestrae, the width of the entire segment, are located even on the front claws. In dotilla they are smaller, but they are also located on the sides of the shell. It was previously assumed that these windows served as hearing organs, but it turned out that these were real respiratory organs. The crabs with their windows smeared with paint begin to choke and try with all their might to peel off the paint. Directly under the membrane, inside the segment, is located complex system blood-filled tubules. The venous blood passing through them comes into contact with the “gas window” and is enriched with oxygen. The total gas exchange surface of these crabs is large - up to square millimeters, that is, more than that of terrestrial crabs that breathe with lungs.

Ghost crabs are nocturnal. During the day, they escape from overheating and drying out in deep burrows (up to 1.8 meters deep for large individuals) with a lockable entrance. They feed on live crustaceans, mollusks, plant foods (even seeds), and decaying debris. On land, ghost crabs move in sharp bursts at speeds of up to 1.8 meters per second on sand and up to 2.3 meters per second on solid soil. Crabs do not avoid humans and even concentrate in places where they find remains of human food (near baths, beach cafes, etc.).

The coconut crab is considered the world's largest representative of arthropods and, being in fact a hermit crab and not a crab, belongs to the species of decapod crayfish. Its impressive appearance and enormous size frightens anyone, even the bravest person. For those faint of heart, it is better not to meet such a creature of nature, whose powerful claws can easily break small bones, and especially not to get acquainted, because there is a risk of an unsuccessful handshake.

Coconut crab: where is it found?

The habitat of such an amazing monster can be considered the islands of the Indian Ocean, in particular Christmas Island, where these arthropods are represented in the largest concentration.

Christmas Island is considered Australian territory and is located 2,600 km northwest of Perth. Being the birthplace of the coconut crab, Christmas Island has become famous for another feature that has become a landmark of its business card. This is the migration of red crabs, which every year, in numbers of more than 50 million individuals, move from forests to the ocean coast for the purpose of reproduction. Moreover, such a massive trip covers the entire area of ​​the island and takes, by time standards, about a week. During this period, most roads are closed to all types of transport.

The largest of the arthropods, the coconut crab, has also successfully settled down and feels great on the western part of the Pacific Islands - the most big ocean on the planet, amazing with the diversity of life forms.

Coconut Crab Dimensions

The average height of such an interesting specimen - the coconut crab - is 40 centimeters with low weight (only about 4 kg); the length of one claw when unfolded can exceed 90 centimeters. The life expectancy of an arthropod is about 60 years, although, according to scientists, this is a controversial issue and this age is due to slowness life cycle may exceed the approximately established figure. The coconut crab, whose size at 5 years of age reaches only 10 centimeters, is very popular among exotic lovers; Many collectors of curiosities dream of adding such a cute pet to their collections.

Coconut crab: description

The coconut crab's body consists of two halves. The first is the cephalothorax with ten legs, which is the front part, the second half is the stomach. The front, most massive pair of legs is equipped with large claws, with the left claw being an order of magnitude larger than the right one. The next two pairs of legs, like those of other crabs, are powerful and large, ending in sharp ends. Thanks to them, crabs can easily overcome inclined or vertical surfaces. The fourth pair of legs is much smaller than the previous three and allows the young coconut crab to settle in coconut shells or mollusk shells for protection. By adults, the fourth pair is used for walking and mountaineering. The last pair of paws, the smallest and least developed (as well as the fourth pair), is usually hidden inside the shell. It is used by males for mating and by females to care for eggs.

Coconut crab, the photo of which fully conveys it unusual beauty and evokes emotions of uncontrollable fear; in fact, the creature is harmless, unless, of course, you get into trouble and try to get to know it better. Otherwise, you may end up without fingers.

Where does the crustacean monster live?

The coconut crab's habitat is exclusively terrestrial; an adult cannot live in water due to the fact that the gill lungs (something between gills and lungs) are adapted for breathing land air, despite the fact that in such respiratory organ tissues present in the gills are present. More precisely, the ability to exist in two environments (aquatic and terrestrial) is present at the initial life stage of the crab; as it grows, such an individual switches to a land lifestyle. In addition, these arthropods do not know how to swim at all and if they stay in the water for more than an hour, they will definitely drown. The exception is when the coconut crab is still in the larval stage; V in this case aquatic environment is native to him.

Coconut Crab Lifestyle

Meet the coconut crab in daytime not easy because he prefers to lead nightlife, hiding in sunny times in sandy holes, cavities of coral reefs or rock crevices, the bottom of which is lined with leaves and fibers from coconuts. This is done by the coconut thief - “Crab with a capital C” - in order to maintain an optimal level of humidity in his home.

Also, during rest, he closes the entrance to his home with one claw. This also helps to maintain a comfortable microclimate for the palm inhabitants.

First impression of coconut crab

From the point of view of the first Europeans who arrived on the islands where the coconut crab lived, the latter appeared to them as a creature with long claws, hiding in the green foliage of palm trees and suddenly seizing prey passing by or located under a tree, among which there were even goats and sheep. Indeed, the palm coconut crab is the largest representative of decapods; it has enormous strength and is capable of lifting a load weighing about 30 kg. IN to a greater extent The crab uses this skill to drag prey from place to place, and in its diet it prefers dead animals, crabs (of course, a little smaller than itself), young turtles and fallen fruits, in particular, pandan fruits and the contents of chopped coconut palm nuts. Also, palm thieves (the second name for coconut crab) were caught catching and eating Polynesian rats and gutting garbage cans, where they are looking for some “delicious food”. Moreover, the presence of people is not at all the threatening factor that the palm coconut crab would be afraid of.

The photo clearly conveys the clawfoot’s desire to profit, especially since it has a formidable weapon - huge claws of terrifying size.

What does the palm thief eat?

Based on the name of this crab, we can conclude that its favorite food item is coconuts. This arthropod can quickly climb palm trunks, and conquering a 6-meter height is quite a common activity for it. Looking from the side as a huge multi-legged monster crawls along a smooth tree trunk, along with the delight of such an unusual sight, any person will experience fear and horror from the unusualness of what is happening: it would seem that a crab, an inhabitant of the water element, is on a tree! Isn't it a paradox?! With powerful claws, the crab plucks off coconuts, which fall to the ground and break. If the nut remains intact when it falls, the coconut crab will persistently gut it in order to get to the juicy nut pulp; This monotonous process can last more than two weeks. If all attempts are unsuccessful, the crustacean will achieve its goal in another way. The palm thief (coconut crab, that is) will lift the fruit back onto the palm tree and throw it down again. Although information about persistent cracking of coconuts is according to some sources unverified; in fact, crabs feed on already split fruits that have fallen from the tree and lie on the ground.

When descending to the ground, crabs, due to their own clumsiness, sometimes cannot hold on and fall down. Without harming themselves, they can easily endure a fall from a 4-5 meter height.

Interesting Features of Coconut Crab

Thanks to special organs located on the antennae, which determine the direction of the smell and its concentration, the coconut crab, unlike its crustacean relatives, has an excellent sense of smell. Like any crab, it has tactile receptors: hairs and bristles of varying lengths. In addition, it has olfactory organs, which the rest of its brothers lack. Their presence is due specific features the development of the palm thief, which at one point was unable to exist in the water and moved to live on land. Being hungry, he hears his prey even at a distance of several kilometers.

“Palm thief” - the coconut crab received its second name for its love of everything shiny. If on the path of an arthropod any shiny object is encountered (be it a spoon, fork, metal utensil, household utensils or something more attractive), the crab will not crawl past and will definitely profit from an interesting find (even if the latter is completely inedible), which it will drag into its crab den.

Measures being taken to conserve coconut crab

Separately, I would like to talk about why coconut crab is so valued. A photo of such a monster with huge claws clearly does not evoke sympathy for it.

Why do women and men love him so much if such a unique islander is constantly being hunted? Coconut crab meat, in addition to being considered a delicacy, is also an aphrodisiac (a substance that triggers the process of sexual arousal in the body and enhances sexual desire in females and males), which leads to fairly intensive hunting for this species of arthropod. It tastes like lobster or lobster meat and is prepared in the same way.

The most traditional dish on the islands is coconut crab served with a sauce made from... coconut milk or boiled in such milk for a little more than a quarter of an hour. By the way, in Guinea, in order to preserve the population of coconut crab, it is prohibited to include the latter in restaurant menus.

In some countries, in order to prevent complete extinction, strict restrictions have been placed on the harvesting of coconut crabs. Thus, on the island of Saipan a ban has been imposed on catching crabs during the breeding season and on individuals whose shell size is less than 3.5 centimeters.

Tricks for catching coconut crab

Although, for the sake of curiosity, I still wonder how such huge, fearsome centipedes are caught? In the Mariana Islands, bait traps are made for them from coconuts, into which the coconut itself is finely grated. This bait is left for a couple of days to “sour”, which is necessary for the crab to smell the dinner prepared for it. The trap does not even need to be hidden, it only needs to be tied to some tree so that the crab cannot drag its prey in an unknown direction.

Reproduction of palm thief

From the beginning of June to the end of August palm thieves begin to reproduce. The courtship process continues for quite a long time, while mating occurs many times faster. For several months, the female carries fertilized eggs on the underside of her abdomen, and at the time of hatching, the female coconut crab releases larvae into sea ​​water at high tide. Over the next three to four weeks, the larvae floating in the water go through several stages of development. After 25-30 days, full-fledged crabs sink to the bottom, where they settle in the shells of gastropods or in nut shells, gradually preparing to migrate to land, which they periodically visit.

How do small crabs develop?

During this period of life, with a shell on their back, the crabs closely resemble hermit crabs and carry a house until the abdomen begins to gradually harden. Further in the development of the young crab, a period of molting occurs, during which the arthropod repeatedly sheds its shell.

The final stage of “growing up” of a young crab is tucking its tail under its abdomen, which provides a kind of protective measure against possible damage. As they grow, crabs gradually lose the ability to breathe underwater and soon finally move to their main habitat - on land.

Coconut crabs reach maturity approximately 5 years after hatching; They reach their maximum size at about 40 years of age.