The Japanese spider crab is an interesting representative of the order of decapods. This a real giant in the world of arthropods, reaching a length of 45 cm. You can meet this animal in the Pacific Ocean; it prefers a depth of 150 to 200 - 300 meters.
The Japanese spider crab is not directly related to spiders, but it earned its name due to its external resemblance to these eight-legged creatures.
- The body consists of a cephalothorax and legs.
- The average length is slightly more than 35 cm. But cases of lengths over 40 cm have been recorded.
- The chest and head are covered with a carapace, a shield that covers the top of the body.
- The carapace is equipped with an abundance of spines and tubercles, which help to reliably protect the delicate body.
- The carapace ends , a sharp spine-like growth.
- The length of the legs is impressive - up to 4 meters.
- The span of the first pair of legs can be 3 meters.
- Body weight up to 20 kg.
- The length of powerful pincers is about 40 cm.
- Males are slightly larger than females.
The body color of the giant underwater “spider” is very exotic: bright orange with white spots.
Thanks to a shell made of powerful chitin , the Japanese spider crab manages to live in deep-sea high pressure conditions. Due to the specific structure of the joints, this gigantic creature can only move sideways. Due to the smooth cartilaginous surfaces, friction can be reduced.
The movement occurs like this: the joint is flexed by one muscle, and extended by another. In this case, a pair of muscles in each segment of the leg is connected to rods in the next segment.
Appearance
The huntsman spider, or, as it is also called, the crab spider, is one of the largest representatives of its order. This insect got its name “Jager” due to its predatory lifestyle. This species was discovered quite recently - in 2001 in the Khammouan province in central Laos.
The leg span of females reaches 30 cm, males are half that size . The insect is distinguished by thin, elongated limbs, which are crowned at the ends with claws, like those of a crab. With these claws, like pincers, the predator grabs its prey.
The crab spider has an elongated, oval body, 3 to 5 cm long. It is connected to the cephalothorax by a thin bridge. There are 4 pairs of eyes on the head, which, although they provide a good all-round view, are not sharp.
Representatives of this species do not have excellent eyesight; they rely more on their sense of smell and touch during the hunting process. Predators react to movement, see shadows and silhouettes.
Insects have a brown, brown, sandy or even orange color. The limbs are pubescent and have unevenly spaced dark spots.
The special structure of the curved legs allows the crab spider to move not only forward, but also sideways. The head of the predator is crowned with a pair of powerful jaws that can cope with small rodents and birds.
Lifestyle
The side-walking spider is one of the few animals that does not weave webs; its huge advantages are:
- Powerful front legs;
- Ability to camouflage perfectly;
- Immobility;
Why, you ask, did we mention the word: “immobility”. Of course, camouflage is one of the most successful advantages that it uses during hunting, but immobility also plays an important role in the hunting process.
While scientists were observing different species of these spiders, it was recorded that a sitting spider on a red flower inflorescence had a white color and could successfully catch bumblebees, locusts, crickets, hornets, bees and flies. This makes it clear that its immobility during the hunt is as much an advantage as its camouflage.
Features of behavior
Researchers note the high reaction speed of the crab spider. The insect is able to turn 1800 and attack the victim in 1/8 of a second. For most of its life, the predator is passive, it hides under the foliage, waiting for its prey, and does not betray its presence with unnecessary movements.
In an effort to catch up with its prey, an arthropod can develop great speed . He is able to move equally effectively in all directions and even jump.
The female protects the egg laying. Seeing danger or, conversely, discovering a potential victim, it spreads its limbs in anticipation of the right moment and attacks with lightning speed.
Insects live alone, although they are quite social. Scientists often observed how spiders gathered in a “flock” consisting of 5-10 adults. They lead a predominantly nocturnal lifestyle.
Crab spiders have another unique feature - the ability to regenerate limbs.
Other representatives of this order also have this ability, however, most of them can regrow damaged body parts only for a limited period until they fully grow.
Interesting facts about crabs
The depths of the world's oceans hold many secrets. The Japanese spider crab is one of the most interesting underwater inhabitants. Amazing facts about them:
- The claws of the arthropod are very sharp; the underwater spider uses them to protect itself from enemies. In 1836, the oceanic inhabitant was discovered by explorer Jacob Temminck. He claimed that the crab attacked hunters, causing them serious damage with its claws.
- Arthropods are difficult to catch. They live at quite great depths, and not all hunters have submarines capable of diving so deep. Therefore, its extraction by hand, without special equipment, turns into a difficult task for hunters of the seafood delicacy.
- Underwater spiders defend themselves not only with their claws. They hide in the tentacles of Snakelock sea anemones, which leave burns, but the durable shell is insensitive to this effect. The animal rests under the tentacles of sea anemones, without fear of enemies, since it remains invisible and inaccessible to them.
Japanese arthropods are in danger of extinction. Their meat is a delicacy containing proteins and anti-inflammatory substances. Therefore, hunters, despite the prohibitions, continue to catch these amazing creatures.- To attract a female during the mating season, males knock with their claws and rattle their shells. For them it is a kind of dance.
- Japanese crabs are loners. They rarely make contact with other representatives of their species, and even those rare moments of interaction occur aggressively.
- To preserve and restore the population of arthropods, young individuals are raised in artificially created conditions and then released into the ocean.
- Researchers often refer to crabs as living fossils, as the spider crab is the only surviving member of the Macrocheira. However, there are still contradictions in the classification of this species. Previously they were assigned to the genus Maja.
Human poaching behavior can drive the Japanese spider crab species to extinction. Government regulatory measures, the introduction of bans during spring breeding and the raising of young individuals to restore the population show little effectiveness. The number of arthropods is steadily declining. Therefore, only a rational attitude towards the species and its perception not only as a culinary delight can correct the current situation.
Nutrition
Thanks to its impressive size, the predator can diversify its diet not only with small insects, but also with quite large animals.
The basis of nutrition is:
- mice, as well as other rodents.
- Small lizards, frogs.
- Comparable in size.
- Insects (cockroaches, beetles, flies).
When attacking a prey, a predator immediately injects poison into its body. The substances it contains instantly paralyze the insect or frog, preventing resistance.
Simultaneously with the poison, the crab spider introduces enzymes contained in the saliva into the body of the victim. Their task is to soften the insides, preparing the prey for eating.
Since crab spiders became known to the world, many cases of attacks by these creatures on small reptiles and rodents have been recorded.
Thus, in the Australian city of Coppabella, a large representative of this species caught a mouse. The size of the animal’s body was comparable to the body of the spider itself, which did not stop it from lifting its prey up the vertical wall of the refrigerator.
An interesting incident happened in the Australian city of Queensland. A couple preparing for Sunday dinner discovered a crab spider hanging from the living room window. The insect was one of the largest representatives of its genus and was the size of a dinner plate. The owners of the house managed to record how he successfully attacked and ate a long gecko, the size of a spider itself.
Habitats
The Japanese crab lives at a depth of up to 300 m. It has a durable shell that can withstand great pressure. In the spring, when animals lay eggs, they are found at a depth of 50 m. Cancer lives near the islands of Honshu and Kyushu; they are very rarely seen in the Russian Far East.
Researchers from Japan first described this natural creation in the 17th century. Later, at the beginning of the 18th century, it became known in the West thanks to the work of the famous scientist Engelbert Kampfer, a German traveler and naturalist. He was secretary of the Swedish embassy in Persia at the end of the 17th century, and entered the service of a cruiser that visited many countries in the Indian and Pacific Oceans. The scientist remained in Japan for 2 years, when he was able to familiarize himself with the research and work of local scientists studying the fauna of the sea and ocean.
Reproduction
The giant crab spider begins the reproduction process with ritual courtship. Unlike most of their brethren, individuals of this species do not show aggression towards their partner.
Courtship continues for hours and, in addition to direct copulation, includes hugs and close bodily contact.
At one time, the female brings up to 200 new individuals. In order to preserve the offspring, she weaves a special bag from the web in which she places the eggs.
This protective cover is designed to protect future babies from external influences. The mother does not stray far from her cubs and often carries this bag with her. During this period, she is quite aggressive and can attack first if she notices danger.
The truth about the inhabitant of the Weymouth aquarium
As mentioned earlier, the world's largest crab, according to the owners of the aquarium, lives in the city of Weymouth. However, how did he get there and is he really the absolute record holder?
It all started when a family of fishermen caught a huge king crab off the coast of Australia. Its weight was about 7 kilograms, and the length of its shell was 38 centimeters. This made it one of the largest crabs caught in the last decade.
After the huge inhabitant of the seas, he bought a famous aquarium. And thanks to its advertising, it became the most famous crab on the planet. True, it cannot be said with certainty that this is the largest representative of crustaceans caught by humans. He's just the only one who managed to become a real star.
Source: fb.ru
animals, nature
Danger to humans
Those who have had the chance to meet this giant arthropod first of all want to know what danger this meeting brings. The size of the insect causes hostility among people, even if the person does not suffer from arachnophobia.
Indeed, an encounter with such an arthropod can be quite unpleasant. Powerful jaws that crush reptiles will easily bite through skin.
Due to their large size, crab spiders bite very sensitively, but a collision with a predator does not pose a mortal danger.
Possible consequences of a bite for an adult:
- pain that occurs when punctured.
- Redness of the skin.
- Edema, swelling.
All of these symptoms disappear after a few days and, as a rule, do not require medical intervention. In people prone to allergies, as well as young children, the consequences of a bite may be more pronounced.
Occasionally, typical signs of intoxication are observed : nausea, diarrhea, muscle pain, general weakness, difficulty breathing.
All symptoms go away within a couple of days. To alleviate the condition, you can take antihistamines. Difficulty breathing indicates a severe allergy to the predator's venom. This condition requires immediate medical intervention.
The biggest crab
A Japanese crab was caught near the Tokyo coast, strikingly different from previous caught specimens in its gigantic size. After research, we found out that this underwater spider is not long-lived - it is a young individual that will still grow. But already at this age its diameter is 3 m. The amazing animal was named Crab Kong. The current record holder, Crabzilla, weighed 15 kg, but researchers believe that within a few years, Crab Kong will overtake him in weight and size.
The record holder's fate was unenviable. It was caught for gastronomic purposes and wanted to be cooked. But the specimen was noticed by scientist Robin James. He convinced the hunters that the giant Japanese crab belonged not in the kitchen, but in a museum. It was scheduled to be transported to Munich, and before being transported it entertained tourists and locals at an amusement park in Dorset.
