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Japanese Spider Crab

Macrocheira kaempferi


The world's largest living arthropod, the Japanese Spider Crab has a leg span of up to 13 feet from claw to claw, a body up to 15 inches across, and weighs up to 44 pounds. Males and females are about the same size, but the front claws of males are actually longer than their legs while those of the females are about the same length as the legs. The crab's body is mostly red or orange in color, while the legs are red/orange with white lines and spots. Two compound eyes are positioned on the front of the body, with two thorn-like appendages between them.

Japanese Spider Crab

Distribution and Habitat

The Japanese spider crab is found on the Pacific side of the Japanese archipelago. It lives on the ocean floor at depths up to 2,000 feet, but does come into shallower water (up to 160 feet deep) when laying eggs.


An opportunistic feeder, the Japanese spider crab will eat any dead animal lying on the ocean floor, as well as some shellfish.

Fertilization of eggs is internal, but the eggs are deposited into the water soon after mating. It takes 54-72 days for the planktonic larvae to develop, depending on water temperature.

Japanese spider crabs can live up to 100 years or more.

Scientific Classification

phylum Arthropoda
subphylum Crustacea
class Malacostraca
order Decapoda
suborder Pleoxyemata
family Majidae
genus & species Macrocheira kaempferi

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The Robinson Library >> Crustaceans >> Order Decapoda

This page was last updated on June 12, 2018.