To date, science knows 93 families of crabs. They include about 7 thousand species. Among them are small, not exceeding the size of the spider, and truly huge. There are poisonous and crabs with an unusual appearance. These include varieties found in home aquariums.
In this article we will look at the most popular crabs, photos and varieties of these marine inhabitants.
general description
These animals are classified as crustaceans and belong to the order of arthropods. Representatives of all varieties of crab (the names and photos of some are presented in the review) have 10 limbs, thanks to them they are able to move fairly quickly. In addition, they have a pair of claws. They are larger than the rest of the limbs and are sometimes asymmetrical. Crab claws carry two functions. The first is eating food. They are powerful and sharp enough to tear off chunks of food. In addition, claws are a weapon that helps them protect their lives and compete with their brethren. Often in such battles, an animal can lose one limb. However, pretty soon in its place a new one grows. This explains the asymmetry of the claws.
The limbs can take various forms. It depends on the crab species. In some, the last pair of paws has the shape of oars. Due to this feature, they swim faster than relatives.
The body of these animals also differs depending on the type. Some representatives of individual varieties of crab have a rounded 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 due to the fusion of the chest and head parts. The eyes are on the stalked processes. The body of this animal is protected by a strong chitinous shell. It serves the crab as a kind of outer skeleton that protects the internal organs from possible damage. During moulting, the crab's protective coat becomes soft. During this process, new, durable chitinous plates are formed. Old carapace animal dumps.
Russian crabs
The most valuable variety of crabs for fishing is blue. This crustacean is large in size and weighs up to 5 kilograms. This type of crabs acquired its name for the blue spots located on its body. However, the brown color is predominant in its color.
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. The specimens from the Sea of Okhotsk have a brighter color than individuals from Bering.
In addition to the blue crab, other species are found in Russia. Not all of them have commercial value, but are no less interesting animals.
Kamchatka crabs
This species has long been under the supervision of both scientists and ordinary lovers of marine animals. And this is by no means accidental. Kamchatka crabs are quite rare and unusual creatures. They are one of the largest arthropods. It is noteworthy that under the name "Kamchatka crab" they mean not one specific species, but several. All of them live in the Far East. The main types of king crab are:
- crab;
- blue crab;
- barbed;
- crab - Opilio strigun;
- crab - Byrd strigun;
- quadrangular hairy;
- Crab - red strigun.
Marble crab
This species has a square flat shell. Its distinguishing features are agility and tiny sizes. This animal breathes with the help of gills. It is noteworthy that his claws differ from each other. The right limb has large bent teeth. However, the left claw has tightly closed small teeth. The legs of this arthropod are completely covered with a pile. The color of the shell can vary from green to purple. At the same time, the drawing on the shell looks similar to the waves of marble, for which the animal got its name.
This crustacean lives, as a rule, in the coastal strip. Often marble crabs can be found basking on stones.
Blue crab
The width of the carapace of representatives of this variety of crabs can reach 20 centimeters. In this case, males are larger than females. The weight of adult animals can reach 1-1.2 kilograms. Blue crabs have brown, gray and blue shell color. At the same time, several orange spikes are located on it. They serve this arthropod protection. Each spike can reach a size of 7-8 cm. The lower part of the carapace 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. In males, they are bluish, and in females they have a reddish tint.
Blue crab is of particular value due to the taste of its meat. It is considered a delicacy. For this reason, this type of crabs was actively exterminated. 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 disguise abilities. He can literally dissolve in algae. He eats mainly carrion as food. From it he cleans the coastal zone.
The carapace 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 animals are small in size. They like to dig into the sand, for which they got their name. They have an oval shell, which can reach 4 centimeters in width. His paws 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 disproportionate to a crab of this size. The claw fingers are dark in color. Sometimes they are 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.
