Portunidae

Liocarcinus depurator

Portunidae is a family of crabs known as swimming crabs, belonging to the order Decapoda, which includes other familiar crustaceans such as lobsters, shrimp, and other types of crabs. The family Portunidae is distinguished by the adaptation of the last pair of their legs into flat, broad paddles, which enables these crabs to swim. This adaptation is a defining characteristic of the family and sets them apart from other crab families that are primarily adapted for walking on the seabed.

Description

Members of the Portunidae family vary greatly in size and color, but they all share the common feature of having the fifth pair of legs modified for swimming. These swimming legs, or flippers, allow them to move through the water with agility and speed, an ability that not only aids in escaping predators but also in capturing prey. The carapace of these crabs is typically broad and somewhat flattened, which reduces water resistance when swimming.

Habitat and Distribution

Portunidae crabs are found in a wide range of marine environments around the world, from tropical to temperate waters. They are commonly found in coastal areas, including estuaries and mangroves, where they play a significant role in the aquatic ecosystem. Some species are also found in deeper offshore waters.

Diet

The diet of Portunidae crabs is varied and includes both plant and animal matter. They are opportunistic feeders, preying on small fish, mollusks, and other invertebrates. Their ability to swim allows them to chase down prey or scavenge for food that other bottom-dwelling species might not access.

Economic Importance

Several species within the Portunidae family are of significant economic importance to humans, particularly as a source of food. The blue crab (Callinectes sapidus), for example, is a highly sought-after seafood in many parts of the world. The harvesting, farming, and trading of these crabs contribute to the livelihoods of many coastal communities.

Conservation

While some species of Portunidae are abundant and widely fished, others are facing threats from overfishing, habitat destruction, and pollution. Conservation efforts are necessary to ensure the sustainability of these species, which are vital to marine ecosystems and economies.

Notable Species

• Callinectes sapidus - Blue crab
• Portunus trituberculatus - Japanese blue crab or gazami crab
• Scylla serrata - Mud crab or mangrove crab

See Also

• Crustacean
• Decapoda
• Aquatic ecosystem