Portunidae is a family of crabs commonly known as swimming crabs. They are characterized by their flattened bodies and long, paddle-like hind legs, which enable them to swim efficiently in water. This family includes various species, many of which are found in coastal and estuarine environments. Members of the Portunidae family are typically omnivorous, feeding on a diet that includes fish, mollusks, and detritus. Some well-known species include the blue crab and the green crab. These crabs play important roles in their ecosystems, contributing to the balance of marine life.