To date, 93 families of crabs are known to science. They include about 7 thousand species. Among them there are small ones, not exceeding the size of a spider, and really huge ones. There are poisonous and crabs with an unusual appearance. These include varieties kept in home aquariums.
In this article we will look at the most popular crabs, photos and varieties of these marine life.
General Description
These animals are classified as crustaceans and belong to the arthropod order. Representatives of all varieties of crabs (the names and photos of some are presented in the review) have 10 limbs, thanks to which they are able to move quite quickly. In addition, they have a pair of claws available. They are larger than the rest of the limbs and are sometimes asymmetrical. Crab claws have two functions. The first is eating. They are powerful and sharp enough to tear off chunks of food. In addition, the claws are weapons that help them protect their lives and compete with their brethren. Often in such battles, the animal can lose one limb. However, pretty soon a new one grows in its place. This explains the asymmetry of the claws.
Limbs can have different shapes. It depends on the type of crab. In some, the last pair of legs is oar-shaped. Thanks to this feature, they swim faster than their relatives.
The body of these animals also has differences depending on the type. Some representatives of individual varieties of crabs are round in shape, others are triangular. It is noteworthy that even individuals with a square body are found in nature. It, in turn, smoothly passes into the cephalothorax. This part of the body got its name from the fusion of the chest and head parts. The eyes are on stalked processes. The body of this animal is protected by a strong chitinous shell. It serves as a kind of external skeleton for the crab, which protects the internal organs from possible damage. During periods of molting, the protective cover of the crab becomes soft. During this process, new, durable chitinous plates are formed. The animal sheds its old shell.
Russian crabs
The most valuable variety of crabs for fishing is blue. This crustacean is large and weighs up to 5 kilograms. This type of crabs got its name for the blue spots located on its body. However, the predominant color in its color is brown.
This type of arthropod is found in the Sea of Okhotsk and the Bering Sea. Interestingly, the color of these crabs differs depending on the habitat. Instancesfrom the Sea of Okhotsk have a brighter color than individuals from the Bering Sea.
In addition to the blue crab, there are other species on the territory of Russia. Not all of them are of commercial importance, but they are no less interesting animals.
King crabs
This species has long been under the supervision of both scientists and ordinary fans of marine animals. And this is not at all accidental. Kamchatka crabs are quite rare and unusual creatures. They are one of the largest arthropods. It is noteworthy that the name "King crab" means not one specific species, but several. All of them live in the Far East. The main types of king crab are:
- isthorn crab;
- crab blue;
- prickly;
- Crab - Opilio snowman;
- Crab - Baird's snowman;
- quadrilateral hairy;
- Crab - red shearer.
Marble crab
This species has a square flat shell. Its distinguishing features are its agility and tiny size. This animal breathes with gills. It is noteworthy that his claws are different from each other. The right limb has large curved teeth. However, the left claw has tightly interlocking small teeth. The paws of this arthropod are completely covered with pile. The color of the shell can vary from green to purple. At the same time, the pattern on the shell is outwardly similar to the waves of marble, for which the animal got its name.
This crustacean lives, as a rule, in the coastal strip. Oftenmarble crabs can be found basking on rocks.
Blue crab
The width of the shell of representatives of this species of crabs can reach 20 centimeters. At the same time, males are larger than females. The weight of adult animals can reach 1-1.2 kilograms. Blue crabs have brown, gray and blue shells. At the same time, there are several spikes of orange color on it. They serve as protection for this arthropod. Each spike can reach a size of 7-8 cm. The lower part of the shell and abdomen of the blue crab has a light color.
The claws of these creatures have different shades. It depends on the sex of the animal. They are bluish in males and reddish in females.
Blue crab has a special value because of the taste of its meat. It is considered a delicacy. For this reason, this species of crabs was subjected to active extermination. Today it is listed in the Red Book.
Grass crab
This species is widespread on the Black Sea coast. The name of this animal is due to its unique camouflage abilities. He knows how to literally dissolve in algae. It eats mostly carrion. From it, he clears the coastal zone.
The shell of this crab is colored green. The abdomen in this case is pale orange or white. The size of the shell does not exceed 8 centimeters in length and 6 in width.
Sand crab
These animalsare small in size. They love to burrow into the sand, which is why they got their name. They have an oval shell that can be up to 4 centimeters wide. His legs are short, which, however, does not prevent him from moving quickly. A distinctive feature of this animal is its ability to swim in the water column.
Large claws. Seem out of proportion for a crab of this size. The claw fingers are dark in color. Sometimes black.
Hairy crab
This animal got its unusual name for the bristles that completely cover its body. The hairy crab is one of the smallest species of crustaceans. Its dimensions do not exceed 28 millimeters. They live in the coastal strip.
Aquarium varieties of crabs
These unique crustaceans have become a favorite pet among aquarium lovers. Today, in almost any pet store you can buy varieties of aquarium crabs that survive perfectly in an artificial environment. When choosing such a pet, it is worth considering its size and the temperature of the water in which it will be kept. For some types of crabs, aeration is very important and warm water is not lower than 20-25 degrees Celsius. Animals brought from the northern regions, on the contrary, require cooler water.
Names of crab varieties intended for keeping in aquariums:
- Dutch crab. Ideal for beginners. Unpretentious in care. The optimum water temperature is 24-25 degrees Celsius. Animal notneeds dry land.
- Leopard crab. It got its name for its bright color. Works great with aquarium fish. Like the Dutch crab, it does not require sushi. The neighborhood with frogs is undesirable. The optimum temperature for keeping is 22-28 degrees Celsius.
Crustaceans are omnivores. In the wild, they are assigned the role of orderlies of the coastal strip. Unfortunately, today some of them are on the verge of extinction. Guilty of this, as a rule, a person.
