Portunidae - Swimming Crabs

Portunids are the swimming crabs. Their last pair of legs are modified into flattened, paddle-shaped appendages, called swimmerets, which help the crabs to swim. They usually swim sideways but can also swim backwards and sometimes forward. Their bodies are streamlined for faster swimming. Their carapace is usually flattened and broader than long, the greatest width usually being between the two lateral spines. Most have a series of spines along the lateral margins and between the orbits of the carapace. They have large pincers, usually with spines, to snag and capture fast moving prey. Despite being able to swim, these crabs spend most of their time on the bottom among seagrasses, rocks and reefs or on floating objects. They are opportunistic eaters, eating anything from decaying matter to living organisms. Most of the crabs eaten in restaurants come from this family.