Spider crab (lat. Macrocheira kaempferi) is considered the largest of the crustaceans, the largest in size lived to be 100 years old. The Japanese call it taka-ashi-gani, which means high-legged crab. The spider crab is incredibly large; in the span of its stretched limbs, it can reach a length of 1 to 4 m. Included in the order of decapod crayfish, he is the owner of the longest legs among the order of arthropods and his most famous representative. The first mention dates back to 1727, made by the researcher Engelbert Kampfer.
What does it look like
In Japanese culture, it is called the long-legged crab.
The size of the shell is small, about 40 cm. However, the total length due to long limbs varies up to 4-5 m. The shell is hard, covered with calcium, round in shape, closer to the head takes the form of a pear. The crab has a powerful weapon 40 cm claws. Reaches weight up to 20 kg. The shape of the female’s abdomen is wider than that of the male. The shell is covered with prickly, short protrusions and tubercles. The color of the growths is dark orange, light brown. Carapace on the head in the form of two thin spikes that protrude between the eyes. Remains the same size throughout life, while the size of the claws increases depending on the age of the crab. Its limbs are long, thin in girth, usually orange or white in color. The claws, with which the animal moves, have curved movable parts at the end of the limbs. With their help, the spider crab climbs and stays on the stones, clinging to them. However, with their help, he cannot lift various objects.
Having long legs does not guarantee their strength. The animal can easily lose limbs as a result of predation or being caught in fishing nets. With the help of the next molt, the crab can grow the missing walking leg.
Due to the high pressure at depth, durable chitin protects the shell from indentation and deformation. Features of the structure of the joints of the legs give him the opportunity to move sideways. Reduced friction due to smooth cartilage surfaces. With the help of muscles, the rods of the legs are attached to the following segments. Some muscles flex, while others extend the joints.
Females are smaller than males. The average lifespan is about 40-50 years, but you can find individuals who have lived for about a hundred years.
Where does it live
In the waters of the Pacific Ocean, in the areas of the islands of Honshu and Kyushu. For life, it prefers a sandy, rocky bottom, up to 200-300 m deep. Crustaceans hide in ocean vents and holes at great depths. Tolerates low temperatures. Living in Suruga Bay, spider crabs live there at a depth of 200 meters at a temperature of 10 degrees Celsius. A person cannot catch them in the water, as the animals try to get as deep as possible. Crabs placed in public aquariums tolerate temperatures from 5 to 15 degrees Celsius. Juveniles prefer warmer temperatures.
What do they eat
They feed on plant matter and particles of animal remains, for which he was nicknamed the omnivorous scavenger. He is not a predator, he does not hunt, but only collects decaying dead remains along the bottom. The crustacean feeds on small fish, carrion, various aquatic crustaceans, marine invertebrates, algae, macroalgae, detritus. A spider crab is a cleaner by nature, therefore it carefully collects the remains of vegetation and living creatures. Can eat live shellfish. Crabs are caught for human consumption as they are considered a great delicacy in Japan and around the world. In life, the spider crab leads a calm lifestyle, wanders in search of food, calmly moves among stones and potholes. Incapable of swimming. His claws serve him as knives, with which he can tear the necessary objects and attach them to his shell.
The crab regularly sheds its shell, in exchange for which a larger shell grows. The age of the largest crab caught has reached 40 years. How crabs interact with each other is not fully understood. It has been established that they lead a solitary lifestyle, have little contact with each other. Living in artificial conditions, in special aquariums, animals are isolated from any communication with their own kind.
Their sensory system is quite developed. Crabs that live off the coast of Japan are called decorator crabs. They got this name for their love of collecting various items and attaching them to their shells. This method helps them better camouflage and protect their existence.
social structure
The crustacean becomes sexually mature at 10 years of age. At the legislative level, there is a ban on catching spider crabs in the spring, as well as from the beginning of winter to April. During this period, animals actively mate, and the restriction allows you to save the population and increase the number. Mating takes place once a year, while the female can lay up to 1,000,000 eggs.
From the fertilized eggs, which are attached to the abdominal appendages, small planktonic larvae hatch. Their developmental interval lasts from 50 to 80 days. Larvae resemble plankton in appearance: small, transparent, drift on the water surface. The development of larvae takes place in stages: at the larval stage they live in shallow depths, growing up they go into deep waters.
natural enemies
Despite its gigantic size and menacing appearance, the spider crab has many enemies. To ensure their safety, crustaceans live at great depths, where it is difficult to reach, and also mask their shell, decorating it with sponges or algae. Due to the spotted color and irregularities, the shell is similar to a stone or the ocean floor. Despite its massive size, the spider crab should beware of the octopus, which can attack it.
Octopus the enemy of the spider crab
Animals are caught for placement in aquariums, for beauty and for food.
population
Over the past half century, the number of spider crabs has greatly decreased. It’s caused by overfishing. In Japanese cuisine, the animal is highly valued as a healthy and tasty delicacy. They like to be placed in aquariums in restaurants. Scientists are fighting to preserve the population of the species and apply the method of artificial rearing of young individuals in various fish farms in Japan.
For cooking, only young crabs that have not given offspring are used. Their meat has a delicate taste, very soft. They are used as exotic interiors.
Known Facts
- There are legends about how a huge crab dragged a sailor to the bottom and ate him. Of course, this is a big fantasy. The crustacean, despite its formidable appearance, is very peaceful.
- A young spider crab can only grow to adult size by shedding its hard outer shell. The old shell is discarded, and under it is found the inner soft one, which the crab stretches to a large size before it hardens.
- If he loses a leg, he can grow a new limb.
- Some species coexist with sea anemones. Their body is insensitive to burns. In this way, the spider crab protects itself by hiding in the numerous tentacles of anemones.
- Can be found on the shore after the surf. However, spider crabs cannot survive without water.
- One of the types of crabs spiders uses only plankton for food.
