The order of decapod crustaceans includes 93 families, the “members” of which number more than 6793 species. Among them are edible and poisonous, useful for humans and real pests, very tiny and huge. There are also types of crabs that are attractive for their uniqueness.
Consider the most interesting and significant representatives of this order.
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The blue crab living in the seas of the Far East is one of the most valuable commercial crustaceans. Its dimensions are comparable with Kamchatka – the width of the carapace is 24 centimeters, and the weight is 5 kilograms. The blue crab has received the name for the spots of the corresponding color located on each side.
In this case, the overall color of the top is red-brown, the bottom is yellowish or orange-yellow. It is noteworthy that the blue crab living in the Sea of Okhotsk has a brighter color than the inhabitants of the Bering Sea.
Another interesting feature of the population of the north-east of the Sea of Okhotsk is two generations that breed in odd and even years. In this case, females lay their eggs once every 2 years. The blue crab is remarkable for its ability to tolerate zero water temperature.
Most comfortable, he feels at 2.5-3ºС. The blue crab lives about 22-24 years. In winter, it goes to a depth of 400 meters, in the summer it moves to shallower, fifty-meter depths.
The molt of a crab does not depend on the time of year – the young individuals change their armor monthly.
Crustaceans inhabiting the Black Sea are no less interesting. They do not have commercial value, but deserve attention:
- The most common marble crab owes its name to the characteristic pattern on the gray-green or brown shell and limbs. The size of its carapace is 4.3 / 3.8 centimeters. The marble crab is notable for the fact that it is the only one of the Black Sea species willingly chosen to land.
- The red book crab blue got its name due to the shell painted in all shades of blue and lighter turquoise limbs.
- Green grass crab is rather large – with 6/8 centimeters of shell. This is the fastest representative of the Black Sea crustacean. It can move at a speed of 1 meter per second.
- Floating sand crab loves to dig into shallow ground. In addition, it is notable for its ability to swim in the water column with the help of strongly flattened hind legs.
- The unusual hairy crab is so named because its brown-purple shell is covered with yellowish bristles. These small, up to 28 millimeters, crustaceans hide in stones closer to the shore. Despite its size, the small crab has very strong claws.
Continuing the theme of unusual species of crustaceans, let’s talk about the strangest inhabitants of the sea and land.
The Chinese Moinhoroby Crab is introduced to Europe from the Yellow Sea. Its name is fully consistent with the appearance – claws covered with thick dark gray hairs.
The seven-centimeter shell itself is olive or light brown. The Japanese variety has a darker color.
The reputation of hairy crabs is badly tainted by the fact that they spread a dangerous disease – rachu plague. In addition, this moorish “vandal” can go far into the rivers and destroy dams with its burrows.
But the Chinese crab has its advantages – it is considered a delicacy in its historic homeland.
Funny coconut crabs are less similar to the representatives of their family and appearance and behavior. They got the other name palm thief for their collection of shiny objects and hiding them in their hole.
By the way, only young, up to 5 years old individuals lead the marine lifestyle. The remaining half century of palm thief lives and eats on land.
The diet includes coconuts, fruits and even small rodents, because the size of an adult reaches 40 centimeters. It reaches its maximum length by the age of 38, ceases to fade and until the end of life does not change its spectacular multi-colored color.
During the day, a palm thief hides in a shelter, going for prey in the cool time of the day.
Unpretentious Dutch crab is great for keeping in the general aquarium with fish. His discreet appearance – the size of up to 3 centimeters and light brown with dark speckled shell, more than offset by ease of care and breeding. Therefore, the Dutch crab is recommended for novice aquarists.
Only good aeration is important, the water temperature is 20-25ºС and a balanced diet.
The king crab does not need land, which can be selected on a stone, but does so reluctantly. Another name – leopard or panther, he received for a spectacular appearance.
Chocolate specks are scattered throughout the five-centimeter carapax and beige-colored legs. His company suits the fish.
But the frog does not get along with it – it will be uncomfortable for a static amphibian with an active crustacean. Conditions of detention – t22-28º with neutral acidity and sufficiently high rigidity.
Crustaceans are omnivorous, in nature they are assigned the role of nurses of the coastal zone. By the way, scientists have found that these creatures, as well as people, can be left-handers and right-handers. And the number of the latter is also much greater.
The validity of this statement can be seen by observing them in an aquarium or natural habitat.