Portunus is a genus of crabs commonly known as swimming crabs. They are characterized by their flattened bodies and long, slender legs, which allow them to swim efficiently in the water. These crabs are typically found in coastal regions and estuaries, where they inhabit sandy or muddy substrates. One of the most well-known species within this genus is Portunus pelagicus, also known as the blue swimming crab. This species is popular in fisheries and is valued for its sweet, tender meat. Portunus crabs play an important role in marine ecosystems, serving as both predators and prey.