Japanese spider crab

The Japanese giant spider crab (Macrocheira kaempferi) is a species of marine crab and is the largest crab found in the waters around Japan. At around 3.75 meters (12 ft), it has the largest leg-span of any arthropod. The Japanese name for this species is taka-ashi-gani, (Japanese: 高脚蟹; タカアシガニ), literally translating to "tall-legged crab". It goes through three main larval stages along with a prezoeal stage to grow to its full size.

The Japanese giant spider crab is the sole living member of the genus Macrocheira. Three fossil species of this genus are known: M. ginzanensis and M. yabei from the Miocene of Japan, and M. teglandi from the Oligocene. They are sought by crab fisheries, and are considered a delicacy in Japan. To prevent overexploitation from harming the species, conservation efforts have been put in place to protect them and their population from overfishing.

The Japanese giant spider crab is similar in appearance to the much smaller European spider crab (Maja squinado), though the latter, while within the same superfamily, belongs to a different family: the Majidae.