The Family Portunidae refers to a group of crab that are characterized by their powerful claws. These crabs are commonly known as swimming crabs, due to their ability to move quickly through water using their hind legs. While this term is well-known among researchers and scientists, there are many synonyms for the term that may be more familiar to the average person. These include blue crabs, sand crabs, and even stone crabs. Each of these terms refers to a specific type of crab that falls under the Portunidae family. No matter what name is used, however, these crabs are considered an important part of many marine ecosystems around the world.