What Divers Should Know About
Spider Crab

Spider crabs are a fascinating and diverse group, encompassing the broader Majoidea superfamily, which also includes the decorator crabs. Many of what we commonly refer to as "true" spider crabs belong to the family Majidae, often distinguished by their characteristically long, slender limbs. This superfamily exhibits a remarkable array of forms and ecological roles across marine environments.

One of the most impressive species is the Japanese spider crab (Macrocheira kaempferi), holding the title of the largest living species of crab, typically found deep on the bottom of the Pacific Ocean. Divers encountering spider crabs in other regions might observe distinct behaviors; for instance, Australian spider crabs off Tasmania are known for their unique habit of piling up in large aggregations, with faster crabs clambering over their slower counterparts.