The largest arthropod is the coconut crab. Description and photo

Five hundred million years ago, in the waters of the Cambrian seas, among the feathery colonies of sea anemones, the ancestors of modern crustaceans swarmed along the bottom and swarmed in the mud. In the process of evolution, more than 70 thousand species of these creatures were formed on Earth, of which approximately 7 thousand species are crabs. What are these creatures now, where do they live and what are their sizes - the article talks about this.

What kind of creatures are crabs?

The word “crab” itself comes from the Dutch krab or German krabbe, a derivative of krabbein, which means “to crawl, crawl,” derived from the way these animals move.

Short-tailed crayfish are called crabs. special squad crustaceans. Crayfish are a type of arthropod, so named because of the peculiar structure of their legs. The body of these animals is covered with a chitinous shell, which is an exoskeleton. As they grow, crabs shed their old, now small, shells, leaving their soft bodies defenseless. During the molting period, until the animal has grown a new hard shell, the crabs begin their breeding season.

Five pairs of legs were the reason for calling the crustaceans decapods. The front pair of legs, armed with claws, serve as crayfish arms and weapons. U different types Crayfish have different shapes and claw lengths. There are individuals with claws of the same length, and there are creatures with claws of different lengths and shapes. The last pair in some aquatic species was transformed in the process of evolution into a kind of oars. Crabs cannot swim; they move along the ocean floor on their legs, mostly sideways.

Decapod crustaceans feed on mollusks, small fish, algae, carrion, and everything they find at the bottom or can catch themselves. Crayfish hunt and obtain food using claws, which can have different purposes. In some species, the larger claw is used for splitting hard shells or protection, and the smaller claw is used to cut soft food. Interesting fact Scientists have discovered by observing the behavior of crustaceans: among them there are right-handers and left-handers.

Crabs differ from crayfish in the rounded shape of their shell, which protects the cephalothorax, internal organs and a short abdomen tucked under the carapace. An interesting feature of crab molting: when molting, the animal sheds its chitinous cover completely, including its eyes, legs, and surface. internal organs. After molting several times, an individual can regrow severed limbs. Young crabs molt much more often than adults. Some types of crabs molt for the rest of their lives as they are constantly growing. Among those that grow to the end of their days are the largest crabs in the world.

What are the biggest crabs?

Among the many species of crabs, there is no absolute leader in size, but several species are distinguished by very large individuals. Today, the record holder for size is the spider crab living in the Sea of ​​Japan. The diameter of the carapace of a huge individual reaches 1.5 m, and the distance between the straightened claws is up to four meters. The weight of this specimen is more than 40 kg. But this is an isolated case; on average, the size of these arthropods is about half a meter across the shell and the claw span is up to three meters, and the weight is about 20 kg. These creatures supposedly live up to a hundred years.

The next largest crab is the king or Kamchatka crab. Individuals with a shell up to thirty centimeters wide and a leg span of up to 1.5 meters reach a weight of about 7 kg, and some specimens approach the ten-kilogram mark. This animal lives in the seas washing the shores Far East and in the Barents Sea, where it was artificially populated.

Slightly behind the king crab is the large land crab, known in Russia as brown, or edible. The body measures about 25 cm and weighs up to three and a half kilograms, making it one of the largest representatives of crustaceans. There are isolated cases where the brown crab reached larger sizes. The range covers the northern part of the Atlantic Ocean.

Coconut crab

But large crabs live not only in the seas. The islands of the Indian Ocean are home to the world's largest land crab, the coconut crab. One of the names of this creature is palm thief, for its habit of dragging to itself everything that lies poorly and glitters. Although the palm thief looks like a crab, strictly scientifically it is not one. Rather, it is one of the varieties of hermit crab.

With a body measuring approximately 40 cm, this crayfish is the largest land arthropod. Adults reach a weight of around four kilos. The palm thief reaches a similar size by the age of forty, and their life expectancy exceeds sixty years.

Thieves lead night look life, feeding on the fruits of plants, small animals or other representatives of their species. Awesome appearance makes it undesirable to meet him in the dark, but the animals themselves do not pose a threat to humans. Only if when meeting with palm thief try to grab it, you can say goodbye to your fingers. The claws of this cancer are adapted to split coconuts, and the strength in the paws is enough to carry a load weighing thirty kilos.

During the day, the palm thief hides in holes dug in the sand or in crevices of coastal rocks. The crayfish lines its shelters with coconut fibers to protect it from drying out. Although the adult crab prefers to live on land due to its breathing habits, young crabs live in coastal waters for up to five years. By the age of five, the size of the coconut crab's carapace reaches 10 cm, and the gills are rebuilt to breathe atmospheric oxygen. At this age, a young thief moves to land, to a permanent place of residence, never to return to the sea to live.

Crabs reach sexual maturity at ten years of age. After this age, animals participate in the process of reproduction. Mating of crabs occurs at the moment of molting of females, when the new exoskeleton is still soft and does not interfere with the fertilization of eggs, which the female carries under her abdomen, holding with a pair of legs. Since males molt later than females, during the mating season they protect females from enemies. After the eggs mature, the female goes to the sea and lays eggs in the water at high tide. She does not go into the water at all, since she is no longer able to breathe under water.

Although thieves love solitude, from mid-June to the end of August the desire for procreation takes over and male crabs can smell their girlfriend at a distance of several kilometers. Crustaceans of this species have a very highly developed sense of smell, which distinguishes it from representatives of other types of crayfish. Receptors and special body sense of smell, absent in other crabs.

Although the appearance of a crab may cause a state of horror in an unaccustomed person, the population of these extraordinary animals is decreasing every year. The massive catch of young mature individuals and young animals that have not reached maturity has led to a significant reduction in the populations of these crustaceans.

The meat of palm thieves, like other types of crabs, is a delicacy. Tasty, healthy meat of young animals is highly valued by gourmets around the world. Rich in fatty acids, proteins and iodine, it is considered dietary due to the lack of carbohydrates in it.

The meat of thieves is a generally recognized aphrodisiac, affecting both men and women. Because of such unique properties The population of crayfish has decreased greatly, so the authorities of countries where there are populations of these animals have limited hunting for them in order to protect them from extinction.

About which one is the most big crab in the world, watch the next video.

17/10/2016, 15:00

Without a doubt, it is possible! Crabs that live on the shore near the water are quite unpretentious and easy to care for. Therefore, certain species of these invertebrates can be kept as pets. They are fun to watch and don't require expensive equipment.

Land crabs cannot be kept in an aquarium with fish, but they are still fairly easy to care for and the time you spend caring for the crab is comparable to maintaining a regular aquatic aquarium.

What types of land crabs can you keep at home?
The most popular pet species are rainbow crabs and harlequin crabs. Both of these species are quite unpretentious, have modest sizes and live mainly on land. However, like all other species, they need access to water, so a crab aquarium must have a water area and dry land.

The colors of the rainbow crab, as you can easily guess from the name, combine shades of purple, blue, orange and cream. The harlequin crab's body is usually black and its legs are orange, with purple markings on the claws. Representatives of both species are very brightly colored and look beautiful!

Housing for land crabs

Land crabs do not need huge aquariums. They are territorial animals that in nature usually limit their movements to a specific area. It is better to keep land crabs in pairs; If you plan to keep a group, the aquarium should be very spacious, otherwise your pets may start fighting for territory. An aquarium measuring 60x30x30 cm will be sufficient for two crabs.

An aquarium with crabs must have both water and dry land. It is best to form a “shore” of special sand for reptiles near one of the walls of the aquarium. The water depth should be about 7-9 cm. Crabs will dig burrows in the sand, so it is very important to use sand that will retain its shape when wet and will not fall into these burrows. Over time, part of the shore is gradually washed away, therefore, to preserve its shape, you can create “dams” from driftwood or aquarium decor items.

Even if the water area in the aquarium is relatively small and shallow, a small aquarium filter is still necessary to keep the water clean.

Crabs love to eat fish, so don't populate them. aquarium fish into the water area of ​​the aquarium!

Temperature and conditions of detention
The sand in a crab's aquarium should always be kept moist; Most often this happens due to constant contact with water. If you notice that the sand is dry, the air in the aquarium may be too dry or the water volume is not large enough.

Both rainbow crabs and harlequin crabs live near fresh water. You can use regular tap water, but you need to add special dechlorinating agents or let it sit before pouring it into the aquarium.

In the wild, crabs typically live in warm climates, so you'll need a heating mat and a thermometer to monitor the temperature in your tank. The mat should be placed under the part of the aquarium filled with water. The thermostat should be set to 22 degrees.

What do land crabs eat?
They are omnivores. In nature, crabs eat plants, fish and anything else they can find. Special food for hermit crabs is also suitable for land crabs. You can also feed them raw fish, small cubes of frozen food intended for aquarium fish, potatoes, and apples. In addition, your pet will need special calcium supplements to grow and have a healthy shell.

Where to buy crabs
Land crabs are sold in some pet stores that sell exotic animals. But it is better to purchase them from private breeders who can advise you on everything related to caring for the crab.

Crabs, along with crayfish, are the most famous representatives of the crustacean order (and also delicacies for which consumer demand has not subsided for many years). But not all specimens of these animals are used for food - sometimes fishermen catch gigantic specimens that are worthy of being placed in an aquarium and admiring this miracle of nature. Let's figure out what is the largest crab in the world?

This arthropod, belonging to the order Majidae, lives at a depth of four hundred meters in the Sea of ​​Japan and has a size that boggles the imagination. The largest crab in the world reaches a weight of twenty kilograms, the circumference of its shell is up to one and a half meters, and the length of each limb is almost four meters. The claws themselves, which are powerful weapon, can be 40 centimeters long in males, usually smaller in females. Crabs of this species strongly resemble huge spiders, which is why they were named " giant spider crabs".

The spider crab was first described by naturalist and traveler from Germany E. Kampfer. The head and thorax of the arthropod are protected by a flat carapace ending acute angle. The shell is abundantly covered with tubercles and spines, which provides the animal with reliable protection from predators. In addition, the shell contains a huge amount of a substance called chitin, due to which it can resist water pressure. The joints in the crab's legs have very smooth cartilage that reduces friction and allows the arthropod to move only sideways.

Scientists say the spider crab can live up to hundreds of years, although the exact age of the oldest specimens has not been determined.

Functions Japanese spider crab for the ecosystem are approximately the same as those of the vulture bird: it eats the skeletons of dead marine animals, plants and shellfish. Because of this, the meat of adult crabs becomes somewhat bitter. Therefore, only young animals are suitable for human nutrition, and old individuals caught in the net are either released or sent to zoos and aquariums.

In 2013, the largest famous representative species - a crab, which was named Kong. The span of its legs was three meters, but the crab is still young and will continue to grow, so it is predicted that in the future it will be able to easily ride even a car. At first, the village fishermen planned to make soup from this large animal, but then they changed their minds and called a biologist they knew, who came and bought Kong for British zoo in the town of Weysmouth. This made this crab the largest ever kept in captivity. Soon it is planned to transport him to the Munich Zoo.

The number of these amazing animals is decreasing every year. The fact is that these crabs reach sexual maturity only in the tenth year of life, and until that time they live in smaller areas of reservoirs, where there is a high risk of being caught by poachers or predators. This is why the species is very vulnerable and needs protection. But on this moment the catching of its representatives is not limited to anything. Crab is caught both for food because of its unusually tasty and tender meat, and for decorative purposes.

A specimen of this animal was caught off the Australian coast and weighed seven kilograms, which significantly exceeds the weight of the rest of its relatives. The diameter of the shell was 38 centimeters. Its claws are comparable in size to the palm of an adult man. Although this crab is smaller in size than the champion - the spider crab - it also looks very impressive.

It is predicted that when it will reach maximum size, his weight will reach 13 kilograms

The animal, caught by Australian fishermen, was not sent to a restaurant to be eaten, but, on the contrary, its quality of life was improved - it was placed in the aquarium of the English city of Weymouth, whose authorities did not hesitate to pay as much as five thousand dollars for a valuable specimen. The crab was transported to the site by plane, so it spent almost 30 hours in flight. We can say that the animal was very lucky, because in its homeland it would be considered a delicacy.

Now Claude (as the arthropod was named) lives in comfort and satiety and pleases the eyes of those who come to look at the curiosity. He is carefully looked after, ensuring best conditions for growth and development. By the way, the lifespan of this species is approximately twenty years, and Claude is still very young.

It has a second name - Kamchatka and is the largest crustacean in the Far Eastern waters. Because of the most tender, nutritious and healthy meat, the animal is constantly hunted, including illegally. The king crab is a rather impressive and powerful representative of crustaceans; its shell can reach 26-29 cm in width, its leg span can be up to one and a half meters, and its weight can be up to 7 kg. The front pair of legs has strong claws (with the left claw usually being slightly smaller and weaker than the right). With his right hand he gets food: he destroys the shells of mussels, sea ​​urchins etc. And the left one is necessary for grinding food and placing it in the mouth.

The king crab has a fairly large habitat: the Sea of ​​Okhotsk, the Sea of ​​Japan, and the Bering Sea. According to the observations of zoologists, the largest population of crabs lives near west coast Kamchatka Peninsula, and it is there that crab fishing takes place every year.

In our country's waters king crab did not appear by chance, but was deliberately introduced into the Barents Sea

Throughout their lives, they constantly travel, moving along a certain route depending on the season and changes in water temperature. They winter at a depth of 250 meters, and in the spring they approach the shore to search for mates and reproduce. When a whole colony of long-legged crabs moves towards the shore along the bottom, it is an amazing sight.

During the mating period, a female crab is capable of laying an incredible number of eggs, up to three hundred thousand. She carries the formed larvae on her legs throughout the year. Approaching shallow water, the young hatch from the eggs and begin to swim independently, while the mothers continue to move along their route as if nothing had happened. Unfortunately, most of small crabs do not have time to grow, becoming prey for various sea ​​predators.

Males of the king crab reach sexual maturity at about 9 years, females a little earlier

Here even the name of the species speaks for itself. However, to the average Russian this crab is better known as brown. Oval crab body, claws middle length. The shell usually has a reddish-brown tint.

An adult specimen of this crab grows up to 25 centimeters in length and weighs up to 3.5 kilograms. Nevertheless, science knows cases when an animal achieved much greater parameters.

The habitat of the large land animal is the northern part of the Atlantic, but some individuals are found even in the Mediterranean Sea

Crabs are very unusual animals that are constantly hunted for their meat. Let's hope that the contemplation of the largest representatives of the species will make hunters looking for easy money think.

Crabs are very strange and unusual creatures. In their appearance they resemble space aliens. They are especially interesting to those people who live in regions where crabs are not found.

Speaking of stars, there are even constellations named after these unusual animals.

However, you can not only watch the crabs. You can eat them. They are very tasty! True, not all crabs are edible, but only some.

The following types of crabs exist:

1. Common crab

– It has ten legs connected to each other.

– The two front legs are claws. Sometimes one of them is much larger than the other and looks threatening and even scary.

– He has 2 eyes on stalks.

– The crab breathes through its gills both in water and in air. True, the breathing process can only occur in cases where the gills are wet. As soon as they begin to dry out, the crab rushes back into the water.

– This crab has a hard shell.

– As the crab grows, its shell cracks, after which a new one grows, bigger size.

– The crab lays eggs, which are usually carried by the female until they hatch into small crabs. Babies can already swim independently and get their own food in the water.

2. Shore crab

The best place to look for crabs is seashore. Coastal crabs can breathe not only in water, but also on land. Moreover, they can spend quite a lot of time on the shore. They usually live where the tides ebb and flow, which helps them survive.

The shore crab has many enemies. These include large fish in the sea, birds on land, and even people.

A hard shell helps crabs protect themselves a little from enemies. During the day they hide in wet sand, mud or among stones if there is water there. This helps them not to dry out and protect themselves from enemies.

3. Swimming crab

Many species of swimming crab are edible. For example, blue swimming crabs are primarily found in rivers in Asia and Australia.

These crabs also often come ashore. While waiting for the tide, they hide on the shore in the sand. As soon as they are picked up by a wave, they rush deeper into the water in search of food. The flat, strong legs of these crabs make them excellent swimmers.

Swimming crabs feed on shellfish, algae and small fish.

4. Ocean crab

Christopher Columbus was the first European to see crabs in the Atlantic Ocean.

IN Pacific Ocean There are crabs too. They have not yet been studied enough. It is known that they are able to change color to match the color of the objects around them, and also have very small size– the largest of them reach 7 cm.

5. Deep sea crab

Some types of crabs live only at the bottom of seas and oceans. These include the red king crab, which lives near Alaska and the North Pacific Ocean.

Sometimes deep-sea crabs can be found on the slopes of seamounts. Typically these animals live in a certain depth range.

The Japanese spider crab is also a deep-sea fish. It can only live at a depth of 600 meters.

Many deep sea crabs are very large. If all of their legs were stretched out, their length could be longer than a person's height!

6. Land crabs

There are crabs that always live on land. Their gills are designed in such a way that they can go without water for a long time. These crabs go to sea only to mate.

The Halloween crab, or harlequin crab, is one of the land crabs. He is so beautiful and harmless that many people keep him at home as a pet.

There are also representatives of land crabs that do not need water for mating. They are constantly on land.

In countries Caribbean It is common for crabs to invade towns and villages during mating season. Tens of thousands of land crabs head to the sea, storming gardens and roads. Many of their species are inedible and even toxic, which is why people do not catch them.

Christmas Island in the Indian Ocean is a paradise for land crabs. There are countless of them there!

7. Coconut crab

This crab, also called the palm thief, is the largest of all land species. Its weight can reach 4 kg, and it can be the size of a cat. These crabs are omnivores. They are not averse to eating both fruits and dead animals. They are called palm trees because they easily crack coconuts with their claws.

8. Freshwater crab

There are many types of crabs that live in fresh water. They are especially common in Australia.

Freshwater crabs were also found in southern Europe, but since they had been eaten by humans since Roman times, they almost completely disappeared there. At least those that remain are protected by law and cannot be caught.

9. Hermit crab

Hermit crabs are also crabs. They live on land, on the shores of seas and oceans, and in deep waters.

The back of a hermit crab is soft, without a shell, and therefore very vulnerable. True, despite their small size, hermit crabs are very smart and deftly use hard parts of their bodies for protection.

They usually find an uninhabited sea shell that is the right size for them and climb into it. When they grow up and it becomes crowded there, they choose another, larger one.

Why are they doing that?

– The shell saves their energy as they grow. The hermit crabs themselves can have a partial outer hard shell and not build up.

– The curled sea shells in which hermit crabs live are very hard and protect them well from predators.

Names: land hermit crab, tropical land hermit crab, Caribbean hermit crab, tree crab .

Area: The hermit crab lives in the Caribbean Sea (Bahamas, Belize, Venezuela, Virgin Islands, West Indies and Florida), up to 880 m above sea level.

Description: there are seven varieties. The land hermit crab has five pairs of legs. The first pair are claws. The left claw is used for protection, and the right one is for food. When in danger, the crab's left claw blocks the entrance to the shell. The second and third pair of legs are used for walking. The fourth and fifth pair of legs are very small and the hermit crab never protrudes them from the shell. Respiration occurs through the gills. The body is cylindrical, elongated, covered with hairs. The front part of the crab's body is covered with a hard shell, the abdominal part is softer. Two pairs of retractable antennae: a long pair is used for touch, a short pair for smell. Vision is good. The sex of the crab can be determined from outside the shell. The male has hairs on the first segment of the last pair of legs and no appendages on the abdominal cavity.

Color: The claws are colored purple (in most crabs), brown, lemon and red.

Size: up to 3 cm.

Weight: An adult hermit crab weighs up to 110 grams.

Lifespan: in captivity up to 11 years.

Habitat: sandy shores of the Caribbean islands, 1.8-3.5 km from the water's edge. Can be found in coastal plants: trees and mangroves. The hermit crab avoids places with dense vegetation and swamps. Prefers water with low salinity.

Enemies: The larvae are preyed upon by fish.

Food/food: feeds at night. Omnivorous scavenger, even eats cactus fruits and fresh horse or cow droppings.

Behavior: nocturnal animal. Doesn't like the sun and high temperature. During the day it hides in small burrows, under leaves, stones and logs. If you stay in water for a long time, you will drown. An adult hermit crab molts once every 12-18 months, young ones - several times a year. After molting, it moves into a new, larger shell. Peak activity occurs at eight o'clock in the evening. At temperatures of 20"C and below, activity decreases; at 18"C it goes into hibernation.

Social structure: social animal - lives in large groups.

Reproduction: sex ratio: for crabs weighing less than 10 grams. - 4-25 females per male; weighing 20-50 grams. - 1-2 females for three males weighing more than 50 grams. - 3-4 males per female. To mate, males and females emerge from their shells. One young female lays 800-1200 eggs, an adult - 40-50000. Freshly laid eggs are red-brown in color. Over the next month, they gradually turn gray or blue. Three weeks after mating, the female goes to shallow water. There she collects eggs with her fifth pair of legs and places them on wet stones, where they are washed away by the waves into the sea.

Breeding season/period: August-October.

Puberty: in the second year of life.

Offspring: The larva goes through several stages of development: zoe, glaucotoe, young hermit crab. Having undergone metamorphosis, the larva settles to the bottom and later emerges onto land. Zoe (zoea) is long, thin, with two large eyes, reaching up to 3 mm in length. Feeds on plankton. Grows through molting (3-4 moults). After 4-5 molts, the zoe enters the glaucotoe stage. Now the larva's eyes are on stalks. Two pairs of microscopic antennae appear. The first pair of legs turns into claws. At this stage, the larva looks like an adult. The glaucotoe stage lasts about a month (at the end of the stage the larva reaches 5 mm in length). Before the end of this stage of development, young crabs begin to look for suitable shells. Crabs that come out of the sea without a shell usually die. Once on land, young crabs lead a predominantly nocturnal lifestyle. During the day they hide in various cracks, under logs, or bury themselves in the sand.

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