Is The Japanese Spider Crab Dangerous?

By Antonia Čirjak on February 27 2020 in Answer

The Japanese spider crab belongs to a species of crab living in the waters around Japan. Takashi Hososhima from Tokyo, Japan / CC BY-SA (
The Japanese spider crab belongs to a species of crab living in the waters around Japan. Takashi Hososhima from Tokyo, Japan / CC BY-SA (
  • Japanese spider crabs are some of the biggest arthropods, with leg spans being almost 13 feet long.
  • They are not dangerous, and are very gentle, unless provoked.
  • They feed on plants and animals, although they prefer to scavenge rather than hunt.

The Japanese spider crab belongs to a species of crab living in the waters around Japan. They are known for their large leg spans, larger than in any other arthropod. They are considered a delicacy all across the world. Japanese spider crabs can grow to be enormous, over twelve feet long. This is, of course, because of their legs, but can still be frightening. They can also weigh up to 40 pounds. 

They are not considered dangerous because they are never aggressive toward humans. However, if they wanted to, they could cause serious damage. Their legs are extremely muscular and can be used to kill smaller animals, although the Japanese spider crabs rarely do this. Their claws are also very strong and large, which could also prove to be a problem if we treat them incorrectly. However, if we do not try to hurt them, they will not do anything to us.

Threatening Physical Appearance

Having the greatest leg span out of all the arthropods makes the Japanese spider crabs look especially dangerous. Their leg span can sometimes reach up to 18 feet when measured from claw to claw. The body itself, however, remains relatively small, only 16 inches in size. However, that is still larger than the majority of other crabs. They can reach the second-highest weight out of all the arthropods, reaching up to 42 pounds. The only ones that can weigh more than that are the American lobsters.

Japanese spider crabs differ from other crab species, not only in size. The females have shorter chelipeds than males, and males usually have twisted pleopods. They are orange in color, with white spots going through their legs. Despite looking threatening, they are reportedly quite calm and gentle and will not react unless heavily provoked. They have an armored exoskeleton that protects them from larger predators. Their carapace looks very bumpy, resembling rocks, so they often use that as a way of camouflage.

Gentle Demeanor Of Japanese Crabs

Japanese spider crabs are situated mostly off the southern coast of the Japanese island of Honshu. They can be found at varying depths, anywhere from 160 to 1,970 feet. They do, however, prefer to live in deeper parts of the ocean. During the breeding season, they tend to migrate to depths of around 160 feet. They are omnivores, which means that they eat plants and animals. They are known to scavenge corpses of dead animals for food occasionally, and can also open the shells of mollusks using their strong claws, to eat them. 

The Japanese spider crab can live longer than most other crab species. It is believed that they can reach the age of at least one hundred years, possibly even longer than that. Interestingly, they get bigger with age constantly, because they molt. That means that they shed their shells and grow new ones, a little bigger each time.

Despite being able to grow tremendously in size, they start extremely small when they are born. The eggs hatch into tiny babies that resemble plankton that is almost invisible to the naked eye. It takes around 70 days for them to start resembling crabs. With all that was said about them, these crabs may seem terrifying and dangerous. However, it was reported that they are incredibly gentle and easy to handle.

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