Japanese spider crab

The Japanese spider crab (Macrocheira kaempferi) is a species of marine crab, and is the only member in the genus Macrocheira. It is found only in the waters around Japan. The Japanese spider crab has the largest leg span of any arthropod in the world, reaching up to 3.8 meters (12 ft) long, and weighing up to 41 pounds (19 kg).^[1]

Japanese spider crab
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Order:	Decapoda
Infraorder:	Brachyura
Superfamily:	Majoidea
Family:	Inachidae
Genus:	Macrocheira
Species:	M. kaempferi

A Japanese spider crab at the Manila Ocean Park

Description

The Japanese spider crab is red or orange, with white spots on its legs. has the largest leg span of any arthropod in the world, reaching up to 3.7 meters (12 ft) long, and weighing up to 19 kg (41 pounds). The actual body of the Japanese spider crab is only 38 cm (15 inches) long.^[2][1] Males are larger than females and have larger claws.^[3]

The Japanese spider crab has 8 legs and 2 arms used for feeding.^[4] Each feeding arm is 1.5 meters (5 ft) long.^[5] The Japanese spider crab is different from other crab species because the first pleopods (legs which help them swim, catch food, hold their eggs, and sometimes has gills on it) of the males are twisted. Its larvae are not very complicated organisms, unlike the larvae of other crab species. Although the Japanese spider crab has some wild appearances, it is known to be gentle towards others.^[6]

Habitat and distribution

The Japanese spider crab is found in the Pacific side of the Japanese islands, Honshu and Kyushu, usually at a latitude between 30 and 40 degrees North. They are found usually in the Sagami, Suruga, and Tosa bays, as well as off the coast of the Kii Peninsula.

A Japanese spider crab was once found as far south as Su-ao, in eastern Taiwan. This is most likely a one-time event; it is possible a fishing trawler or extreme weather may have carried this individual much further south than its home range.^[7] The Japanese spider crab is found up to the depths of 2,500 feet (750 meters).^[5]

Life cycle

The Japanese spider crab is a scavenger, meaning it feeds mostly on dead animals. It also feeds on shellfish, opening the shells with its giant claws to feed on them. After molting, these crabs will eat their own shell to get some important nutrients.^[8] It is one of the longest living creatures in the world, living up to 100 years.^[6]