Crabs belong to the class Higher crayfish, the type of Arthropods, a group of Decapods crustaceans. Meet these animals on our planet can be everywhere. The crabs have five pairs of limbs. The first of them has long been turned into quite powerful claws. The size of these animals depends on the species. Usually, the width of the shell of an arthropod varies from two to thirty centimeters.
Variety of species
On the European coasts, land crabs are most common. They can be found on the surf strip with soft ground. There is also a swimming crab. In this animal, the last pair of limbs is a small blade. Crabs of this species are excellent swimmers. They get their food in water. The closest relative of these two species is the Chinese crab. Spider, he is a giant crab, lives near the Japanese islands in the waters of the Pacific Ocean.
The largest arthropod
The Japanese spider crab belongs to the family Majidae. The scientific name of the arthropod in Latin is Macrocheira kaempferi. His crab was given in honor of Engelbert Kempfer - a German naturalist and traveler. This crustacean was first described in 1836 by Konrad Jacob Temminck, a Dutch zoologist.
The Japanese spider crab (photo below) is the largest of all arthropods.
The largest individuals of this species of crabs have a carapace length of up to forty-five centimeters. However, they are owners of fairly long legs. It should be said that the span of the first pair can reach three meters. Such a crab is equipped with forty-centimeter claws. They serve as a powerful weapon for arthropods. There are individuals whose maximum body length with legs reaches four meters.
The breast and head of the Japanese crab are covered with a short and flat carapace, ending in a sharp rostrum. Arthropod protection is provided by numerous spikes and mounds. They are located at the top of the carapace. The weight of these giants is often twenty kilograms.
At the depths of the ocean, high pressure is created by the water column. However, the shell of a giant crab is protected from being pressed by a layer of durable chitin.
In a special way the joints of the legs of the animal. They allow him to move only sideways. The surfaces of the cartilage in the joint are very smooth. This significantly reduces friction.
The Japanese spider crab is an arthropod with an orange body. His legs are decorated with white spots. The eyes of the crab are located on the front of the head. Between them stick two thorns.
Nutrition and reproduction
The Japanese spider crab performs the same work on the ocean floor as the vulture bird on land. It feeds on skeletons of dead animals, mollusks and plants.
It is believed that this arthropod can live up to a hundred years. Individuals of this species are found at a depth of one hundred and fifty to eight hundred meters. With the onset of spring, crabs rise closer to the surface. At this time they can be found at a depth of fifty meters. Why is this happening? It is at this depth that crabs are engaged in the continuation of their own kind. During this period there is a ban on catching them.
During spawning, one female can lay one and a half million eggs. However, only a small number of them can live to reproductive age. Predatory ocean dwellers hunt small crabs. Those individuals that are larger, become prey of man. Japanese spider crab is capable of reproducing offspring from the age of ten.
Crab meat is recommended for dietary nutrition. It contains a small amount of carbohydrates and unhealthy fats. In addition, crab meat has a pleasant taste and is easily digested.
As well as possible this delicacy product is suitable for those who wish to get rid of extra pounds. This process helps coarse fibers, which are found in large quantities in crab meat. The product is rich in taurine, iodine, vitamins and many other healthy ingredients.
The giant Japanese crab is often caught for food. Only young individuals that did not have time to produce offspring are suitable for fishing. The meat of such crabs is considered very tender. It is a delicacy everywhere. Unfortunately, the capture of these arthropods affects the reduction of their population.
And now for the adults. Due to the fact that their food consists of mollusks, carrion and all that is at a great depth, the meat of such spider crabs gets a bitter taste. Therefore, it is not suitable for gastronomic purposes. If such a copy falls into the net of fishermen, then it is sold to a terrarium or water park to the delight of visitors.
A huge specimen of this arthropod species was recently caught. He was given the nickname Crab-Kong. The size of this specimen in diameter is three meters. The distance between claws exceeds 240 cm. But this crab will still grow. When he becomes an adult, he can easily ride the car.
The sea crab spider caught in the fishing nets southwest of Tokyo, in the Suruga Bay area. Due to the fact that the gastronomic qualities of the meat of this animal are very highly valued, the fishermen initially planned to make soup from it. However, the crab was lucky. The fishermen contacted Robin James, a biologist who had recently visited their village.
Crab Kong is currently contained in the Weymouth Sea Life Park, a zoo in the English city of Weysmouth. This fifteen kilogram monster is the largest crab ever held in captivity.
Crab Kong, which is a true marvel of the deep sea, will not be long in Weysmouth. After some time, it is planned to transport it to Munich and place it in the Sea Life center.
Despite the fact that this specimen is considered the largest of those held in captivity, it is believed that the Japanese spider crab can reach such dimensions when the distance between its claws exceeds three and a half meters.
A young specimen of a spider crab can grow only if it drops the outer hard shell. Below it is a soft inner, which the arthropod must have time to inflate to hardening.
In the case when the crab accidentally remains without a leg, a new one will certainly grow. Sometimes spider crabs ashore sea wave. If the animal is entangled in the dam between the stones, then it will not be able to survive.
The history of the study of the giant Japanese spider crab
The largest crustacean in the world is recognized as a giant spider crab. Its first description was compiled by Japanese naturalists in the seventeenth century. Western scientists met him only in 1727, after the publication of the German biologist E. Kampfer. Somewhat later, this huge sea dweller will be given the name Macrocheira kaempferi, consonant with the name of the German naturalist who told the world about its existence.
Japanese spider crab is incredibly huge. The span of the stretched limbs of individuals resembling the structure of spiders approaches 4 meters. And this is with a relatively small body. The head of the "monsters" reaches in the diameter of 37-60 centimeters. The mass of adult specimens is approaching 20 kilograms. Females are slightly inferior in weight to males. Crabs have powerful weapons - claws, growing in length up to 40 centimeters.
The Pacific waters washing the Japanese islands of Honshu and Kyushu are the abode of these fantastic arthropods. Sometimes they enter the Russian Far Eastern possessions. Adult crabs spiders have mastered the upper territories of the continental slope. Here they go down to 300-400 meters. They feed on clams and fish.
The spider-crab reaches puberty by 10 years. With the onset of spring, adults begin to migrate, moving to coastal waters. There they produce their numerous offspring. Each female will sweep over 1.5 million larvae. Only a small part of them will survive. The life expectancy of these crustaceans is 50 years. Although there are some instances that live to 100 years.
The quality of the meat in adult spider crabs is low. At great depths their dead food becomes their staple food. Because of this, the meat is bitter. Adult "monsters" are caught in isolated cases. They are placed in aquariums and show visitors aquariums.
Another thing is young. The meat of young spider crabs is tender. It is counted among the delicacies. Harvesting young stock is a snap. The abode of crabs - coastal waters. Here, hunters set traps with bait, where individuals can easily come across who have not gained enough experience in life.
Thus, a significant number of young animals are exterminated, not reaching sexual maturity and not giving offspring. This causes serious concerns of specialists. They are sure that the giant spider crab is in danger. If you do not take measures to protect it, the population will quickly be reduced to a critical number, or even disappear altogether.
Characteristics of the flower crab spider
This animal has nothing to do with crustaceans. It is a representative of the arachnids of the family of bokohod, including about 2000 species. These species are so named because of the characteristic manner of movement.
Such spiders do not spin webs. Their arms are front paws and the ability to disguise. Almost all the time, the yellow crab spider spends on flowers, stalking the prey. He does not threaten the person.
Male and female individuals differ in color and size. Females are small - only 10 mm in length. And males in comparison with them at all crumbs. The length of their body is only 4 mm.
White or yellowish abdomen of males are decorated with long dark stripes. Their heads are black. The forelimbs are colored with brown and black stripes. The hind legs have the same color as the abdomen. Females "flaunt" in bright outfits of green and yellow shades. Their sides are often painted with red stripes.
A yellow crab-like spider has captured a vast area stretching from subtropics to the arctic zone. It is found on the lands of Alaska, USA, Japan and Portugal. All Europe, with the exception of Iceland, has become its abode. He lives in open areas, covered with a large number of flowering plants.
The flower crab spider guards its victims on flowers. Depending on the color of the inflorescences, it also changes its own pigmentation. Only adults are capable of such a disguise. Eyes help them to control the coloring of the body.
These arthropods are real hunters. They feed on a variety of pollinators: butterflies, bees, wasps, hoverlings and small bugs. Often, prey is much larger than the most treacherous predator.
After waiting for the victim to lower the head into the stamens, the yellow spider attacks it, spreading its front legs wide. Seized prey, he bites the neck. Poisonous bites instantly kill the victim.
Thanks to the ability to skillfully disguise, the crab spider goes unnoticed, being in close proximity to its victim. He prefers to hunt plants with yellow or white inflorescences, therefore his body has the same shade. Buttercups and cornflower are his favorite flowers for hunting.
However, according to scientists, the yellow color of spiders is just a special case. In fact, colors can be any, as long as it matches the color of the plants.
Japanese Spider Crab
Our terrestrial fauna is inhabited by many amazing creatures. Sometimes, it seems that nature decided to make fun of animals and mix several types at once into one. Living proof of this Japanese spider crab. What kind of creature is this, you ask? What type of animal is it? To crustaceans or spiders? It turns out that the Japanese spider crab is a representative of crustaceans, just the structure of the body very much resembles a spider.
This natural creature belongs to the order of decapods and is the largest among all arthropod animals living in the waters of the Pacific Ocean!
Japanese Spider Crab
What is remarkable about the appearance of the Japanese spider crab?
Sometimes this animal is also called a giant crab, because its dimensions are truly amazing: when a Japanese crab is in a “unfolded” state with extended limbs, the length from the end of one claw to the end of the other can reach four meters! The adult spider crab weighs about 20 kilograms. The extremities of this aquatic inhabitant are 5 pairs. But evolution has turned two limbs into huge claws, which grow to a length of up to 40 centimeters.
The body color of this Pacific giant is orange, and there are white spots on its legs. The shell of the animal has protective spikes.
Crab spider lifestyle and behavior in nature
As mentioned above, this giant crab is a deep-sea creature. He lives at a depth of over 400 meters. However, to the surface of the waters, he, nevertheless, occasionally rises. And this happens in the spring, during the breeding season. It is at shallow depth that he leaves his larvae.
As for the nature and character of this animal, then its formidable appearance is not at all an indicator. In fact, the spider crab is a non-aggressive and very harmless creature. Therefore, it is popular with aquarists.
In the wild, the giant spider crab lives half a century, and sometimes lives to 100 years! Such is the deep-sea giant survivor.
Does the Japanese Spider Crab have value to humans?
With confidence we can say yes! Especially it concerns young individuals of giant crabs. Their tender meat is considered an expensive delicacy in the cuisine of many nations of the world. It is young meat that is valued because adults eat carrion and their meat has an unpleasant taste.
Here is such a giant "spider"!
In addition to its gastronomic value, the Pacific Spider Crab is trapped for living in aquariums. Due to its docile nature, problems in aquarists with spider crab does not arise, and this giant crab gets along very easily with other inhabitants.
Despite its intimidating appearance, the Japanese spider crab is a peaceful and harmless creature.
Because of their attractive human qualities, giant Japanese crabs are currently on the verge of extinction.