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Hermit crab, its features, lifestyle and habitat


Hermit crabs

Semi Land Hermit Crab Coenobita clypeatus
Scientific classification
Superfamily:Hermit crabs
International scientific name

Hermit crabs (lat. Paguroidea) - a superfamily of decapod crayfish from the infraorder of part-tailed (Anomura) Most representatives use empty shells of gastropod mollusks as a shelter (and sometimes they specially attack live mollusks to take possession of their houses). Hermit crabs live in the tidal zone and in the shallow waters of the seas (up to 80 meters). Some in their adult state are able to leave the aquatic environment for a long time, returning only during the breeding season. About 450 species are described. Some representatives, such as palm thief and king crab, do not use shells as shelters.


The appearance of hermit crabs is largely due to the habitat in a spiral-twisted shell. Only three pairs of walking legs stick out of the shell (pereopodov) The first pair carries claws of different sizes. Larger claws in many representatives are used to plug the entrance to the sink. The fourth and fifth pairs of walking legs are less developed and serve to be fixed in the shell.

The abdominal region is asymmetrical (twisted along the spiral axis) and, unlike the cephalothorax, is covered with a soft, unblocked cuticle. The exception is only the first and last (sixth) segments. Usually right abdomen (pleopods) undergo significant reduction, while the left is preserved and creates a current of water, due to which gas is exchanged through the covers coated with soft cuticles. Thus, the sink performs not only the function of mechanical protection, but also provides resistance to dry environments. Eggs develop on the left extremities of the female abdomen.

Nutrition [edit |

Description and Features

Hermit crab is considered a variety of decapod crayfish that live in sea waters. An empty mollusk shell once becomes the house of this representative, which he never leaves from caution. The back of the animal’s body is hidden in the depths of the shelter, and the front is located outside the shell to lead an active life.

Hermit Crab in the photo always imprinted in a house, ready to travel with cargo exceeding the volume of the animal itself. The size of a small inhabitant in length is 2.5-3 cm. Large representatives of the species grow up to 10-15 cm, giants of individual species - up to 40 cm.

The second name of the hermit is gout. The naked, not protected by chitin abdomen of cancer is a tidbit for numerous predators. A well-fed body hermit crab slides into an abandoned shell of a suitable size, inhabits a spiral tunnel.

The hind legs hold the animal so firmly in the house that it is not possible to pull out the crustacean - it simply breaks into pieces.

Evolution has adapted cancer to the wearing of houses of different "styles", so there is no clear answer to what a hermit looks like. Most often, various shells of marine mollusks settle in, but if they are not nearby, then a bamboo stalk or any suitable sized object that protects the delicate body of a crustacean can become a house.

The crustacean does not attack living snails, it does not forcibly evict. But hermit crab relationship with relatives not always worthy. A strong hermit crab can drive a weak neighbor out of the house to strengthen its security.

During the growth of the animal, the shell has to be changed to another shelter, suitable in size. This is not an easy task, as the house must be light - it is difficult to move a heavy carrying crustacean. Specialists notice that the hermits arrange an exchange of dwellings.

An interested crustacean taps on the neighbor’s house, if they want to enter into a voluntary deal with him. The sign of rejection is the entrance to the sink closed by a large claw. Only after successfully solving the "housing problem" does the animal gain weight.

Interestingly, in different types of hermit crabs, signals about the desire to exchange houses differ. Some tap the neighbor’s claw walls, others shake their favorite shells, and others use both methods of communication. Establishing contact is mutually beneficial. But it happens that a misunderstanding of the signal leads to a dull defense or a fight of crayfish.

The small crustacean has many enemies. Particular danger is manifested during the change of housing, when a defenseless creature becomes an easy prey for larger marine inhabitants. But even in the house, the crustaceans are vulnerable to octopuses, squids, cephalopods, in which strong jaws can easily crush any crustacean house.

Crustaceans are considered the most common on the planet. Animals vary in color, size, habitat. Allocate hundreds types of hermit crabs, not all of which are sufficiently studied. The most famous representatives are well known to the inhabitants of the coasts, to lovers of the inhabitants of water bodies.

Diogenes. The hermit is often found on the sea coast of Anapa. Entangled traces on the sandy beaches they leave spiral shells of net trice. The crustacean got its name in honor of the philosopher of Greece, famous according to legend that he lived in a barrel.

The hermit size is small, about 3 cm. The color of the calf is gray or pink. Legs protrude from the shell, eyes on the stems, feathery antennas of the organs of touch and smell.

Clebanarium. The bottom dwellers of pebble beaches are found in rocky places. Large crustaceans are several times larger in size than diogenes, and are colonized in spacious rapan shells. The color is bright orange, red, corresponding to coral reefs.

Palm thief. Unlike relatives, empty shells are needed for cancer only at an early stage of development. Adults are real giants, grow up to 40 cm, weight up to 4 kg. The locals use meat of crayfish for food. Crayfish live on the skeleton of the Indian Ocean, lead a land lifestyle. Named for their interest in coconut fruits falling to the ground. Cancer is often confused with crab.

Fans of aquariums often choose the inhabitants of the color scheme. Bright representatives of hermit crabs are popular:

  • golden spotted
  • Mexican Redfoot
  • orange striped
  • blue-striped.

The appearance of animals is largely shaped by their presence in an elongated shell. The structure of the hermit crab you can see when he is in rare moments outside the sink. Nature has endowed the animal with many devices with which it feels protected. The front of the body is covered with a thick layer of chitin.

The shell protects the animal from enemies. A strong outer skeleton does not grow as the animal develops. During molting, the hermit crab drops its carapace, which is an unusual occurrence. After some time, a new chitinous layer grows. Old clothes, if left in the aquarium where the crustacean lives, become his food.

Claws are the main weapon of a crustacean. Compared to the cephalothorax and trunk, they look massive. The right claw, larger, blocks the inlet to the sink if it is in danger.

The left one, smaller in size, is active in finding food. Claws are located close to the head. Nearby are two pairs of walking legs. They move cancer over the surface. Other legs, two hidden pairs, very small, do not participate in walking.

The body part hidden in the shell, covered with a soft cuticle, is not protected by chitin. Covers provide gas exchange of the body. Hermit crab has to hide an unprotected body in a shell. To stay in the house helps just the little legs that prevent the house from falling off. Nature took care of the appointment of each organ.

Lifestyle & Habitat

Hermit crab is found on the coasts of Europe, the shores of Australia, the islands of the Caribbean. Various species are settled around the world mainly in shallow areas of the seas and oceans with ebbs and flows, but crustaceans also live on sandy river banks, in forests along the coasts.

They leave the aquatic environment, return to it only during the breeding season. Some species of hermits go deep under water to 80-90 meters. The main element is salty and fresh waters.

A small crustacean is considered a bold and hardy animal. The ability to defend oneself, to carry one’s dwelling throughout one’s life, to build relationships with relatives is not given to every living organism.

The greatest risk of becoming a victim of predators is that the crustaceans experience during the change of the house. Low tide opens their shelter under the stones, among the gorges. Many lone crustaceans live in symbiosis with poisonous sea anemones, polychaete worms. A mutually beneficial existence strengthens each side in the problems of independence and the provision of feed.

Widely known symbiosis of hermit crab and sea anemone - a close relative of jellyfish. They settle with hermits on their territory, use them as carriers, feed on the remains of feed. Hermit Crab and Sea Anemone together confront the enemies. Coexistence of two organisms is an example of beneficial symbiosis - mutualism.

The benefit of sea anemone is that it moves slowly and lacks food - marine inhabitants remember its location and avoid appearing nearby. Movement on the hermit's shell increases the chances of catching prey.

Marine hermit crab receives powerful protection - the poison of anemone kills small organisms, and large causes severe burns. Interestingly, the cohabitants do not harm each other. Unions sometimes break up due to the need to change the close housing of the growing crustacean. An empty sink does not stand idle for a long time, there is a new tenant, pleased with the house with a live guard.

Unions of the Hermit Pride and Actinia Adamsia - for life. In the process of life, anemone completes the shell with secreted mucus, which quickly hardens. The crustacean does not have to look for a new home.

Relations with the Nereis worm are also built on mutual interest. The tenant in the crustacean house eats the remains of food, at the same time tidying up the shell. Nereis cleans the inner walls of the house, takes care of the abdomen of the crustacean, removing all parasites. The hermit crab’s attitude towards the neighbor is the most tender, although if he wanted to, he could easily crush his tenant. An adult cancer is a large and powerful animal.

An important feature of the life of a hermit is the condition for the purity of the reservoir. A large number of inhabitants on the coast - a sign of environmental safety. Unfortunately, pollution of the European seas is causing a decrease in population.

Activity is inherent in cancers at any time of the day. They lead a continuous journey in search of food. Omnivore pushes them to this. They cut dead fish to a naked skeleton in a few hours.

Modern aquarium enthusiasts bring hermit crabs into their autonomous reservoirs. Care for the inhabitants is simple. It is important to gradually acclimatize animals to aquarium water.

A change in habitat sometimes manifests itself in premature molting of crayfish. Observation of animal behavior is a very exciting activity. With other inhabitants of the aquarium they are very friendly, never show aggression.

The diet of hermit crabs varies depending on the region of habitat. In general, they are omnivorous - consume plant and animal feed. The food includes annelids, mollusks, other representatives of crustaceans, echinoderms. Do not disdain dead fish, other carrion.

Food is sought in the supply and tidal coastal strip, on rocky surfaces. Algae, sticking eggs, the remains of someone else's feast - everything will be a treat for crayfish. Land animals feed on carrion fruits, small insects, coconuts.

Inhabitants of aquariums consume special food or everything that falls from the dining table - meat, cereals, oatmeal, groceries. Dried seaweed, fruit slices will enrich the diet with vitamins.

Reproduction and longevity

Spring and summer are periods of competition between males for females, which play a major role in the breeding process. They produce eggs, carry future offspring (up to 15,000 individuals) on the abdomen. In a week, larvae are formed, ready for independent life in the water.

There are four stages of molting, during which young hermit crabs are formed that have sunk to the bottom. The main task of juveniles is to quickly find a shell shelter until they become food for aquatic predators.

Not all survive to the settlement stage. Many larvae die at maturity. In nature, the process of reproduction of crustaceans is year-round. In captivity, hermits do not produce offspring. The life span of the formed crustacean is 10-11 years.

The Importance of Hermit Crab

Gluttonous crustaceans are the real orderlies of ponds. About hermit crab, we can say that he is a real beach cleaner. The lifestyle of wonderful animals allows you to get rid of natural organic carrion.

The importance of hermit crab for the cleanliness of the aquarium is noted by the owners of large tanks. The red-blue varieties of crustaceans are especially remarkable in restoring sanitary order. Getting rid of cyanobacteria, detritus, and many harmful substances in an artificial body of water takes place naturally thanks to the wonderful hermit crabs.

Hermit Cancer Features and Habitat

Meet hermit crab It is possible in the Baltic, Northern, Mediterranean seas, near the islands of the Caribbean Sea and on the coasts of Europe. Basically, these creatures prefer to live in shallow water, only some of them can climb to a depth of 70-90 meters.

Pictured is a hermit crab

A rather strange sight is for the observer who sees how along the smooth folds of sand at the bottom of the sea the snail moves at an incredible speed, which is quite unusual for her. And only after pulling out this snail can you find a reasonable explanation for this rapid movement.

The thing is that this is not a snail at all, as it is initially shown to everyone, but Hermit Crab Shell which he found thrown at the bottom and uses for his safety.

Looking more closely at the bottom, you can see a huge number of such shells with hermit crabs inside, both very small with a pea and large with a fist.

On hermit crab photo it is seen how three pairs of limbs, as well as claws, peep out from under his house from the shell. The left claw is usually used by a hermit crab for hunting, while the right claw protects the entrance to the shell.

During evolution, the back pair of paws has become much shorter. These hind limbs help the cancer keep its house in motion. In nature there is a huge amount types of hermit crabs, they have similarities in common to help distinguish them from all other crustaceans. Their front part is covered with chitinous shell, and the long soft abdomen has absolutely no hard protective coating.

To protect this soft part of the body, the hermit has to look for a shell by its parameters. If you pull him out of this shelter by force, he will behave very restlessly.Why hermit cancer doesn’t part with the shell? She protects him not only during the attack on him, but during the hunt. Over time, it grows from a shell.

He has to look for and choose for himself a larger and more accommodating home. Interesting facts about hermit crab They say that for their protective house they can use shells of about 25 species of gastropods.

Basically, they prefer spacious and light sinks. But for the lack of such, they can also settle in a not very convenient sink or even in a piece of bamboo in order to feel protected from external factors and potential enemies.

There have been cases when, having looked closely at their cousins, the cancer notices that their shell does not quite fit their size. By tapping, cancer offers an exchange. Sometimes it occurs, but sometimes the hermit cancer rejects this offer. Failure is manifested by closing the claw of the entrance to the shell.

Pretty interesting tandem are Hermit crab and sea anemone. For greater protection, the crayfish plant anemone on their left claw and so along with it move along the seabed. At the moment when the claw closes the entrance to the shell, the sea anemone remains from the inside and guards the entrance.

Pictured is a hermit crab and anemone

For sea anemone, it is very convenient, therefore, to quickly move along the seabed and get food or eat it after cancer. This symbiosis of hermit cancer It benefits both for him and for anemone. She perfectly protects cancer from enemies with her poisonous tentacles, the same in turn acts as its convenient means of transportation.

If it is necessary to replace the sink, the cancer with great care transfers the sea anemone to its new home. If it so happens that the dwelling has not yet been found, he places his neighbor right on his body.

The nature and lifestyle of hermit cancer

In general, they are quite peaceful creatures. But there are sometimes conflicts between them. Most often they happen because of a cozy living space. It sometimes even comes to a fight.

Concerning взаимоотношений рака отшельника и актинии, то между ними всегда царит мир и дружба. Выгодное соседство для обоих приносит свои полезные плоды. Это типичные обитатели мелководий. In tropical and subtropical waters, those species of hermit crabs that prefer depth are also found.

But not for all hermits, their favorite habitat is water. Krudasan Island, located in the Indian Ocean, is rich in land crayfish hermits. They spend most of their lives on land. The entire coastal zone of this territory is dotted with their tracks, which are very reminiscent of the track of a caterpillar tractor in miniature.

About Hermit Cancer under the name palm thief or “coconut crab” they say that it is a very strong crustacean that can even bite a person’s finger with a claw.

Pictured crab hermit palm thief

Young hermit crabs of this species live in water in the shell of some mollusk. After one of the links, an already older creature drops its shell and goes to land.

With subsequent molting, the cancer body is shortened and bent under the chest. It is a large and strong cancer, reaching up to 3 kg of weight. Some representatives of this species, in order to hide from a possible danger, use minks that they dig out on their own.

There have been cases when crayfish used plastic bottles or wide-necked glass bottles for these purposes, which appear on the seabed thanks to people. Hermit crabs are not at all easy to move around with shells, but this does not prevent them from being predators. Mostly they lead a reclusive life, from this comes the name for crayfish.

Types of Hermit Crab

There are just a huge number of types of hermit crabs. They differ in some of their features, but in general the structure of hermit crabs completely identical, so they are easy to classify.

They can be distinguished mainly by color scheme and habitat. There are, for example, hermit crab mexican redfoot, orange-striped, steppe cancer, blue-striped, black, gold-spotted, dwarf and many others. Each of them is original in something and in something similar.

This omnivorous creature does not sort out food at all. Hermit crabs eat both plant and animal food. They love algae, eggs, shellfish, worms, fish, as well as the remains of anemones. Never disdain crayfish and carrion.

With the help of their claws, they do not tear food into small pieces and only after that they absorb everything with pleasure. Hermit crabs land dilute their diet with fruits, coconuts and small insects.