Blue Crab
Blue crabs are crustaceans found in the Western Atlantic Ocean and the Gulf of Mexico, named for the blue coloration on their claws and legs.
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Family: Portunidae
Genus: Callinectes
Species: C. sapidus
Common Names: Blue Crab, Chesapeake Blue Crab, Atlantic Blue Crab
Blue crabs are very opportunistic in their choice of food, and will each just about anything they can find, including clams, oysters, mussels and other small crustaceans. They will also scavenge dead animal and plant material. Sometimes, they even eat smaller blue crabs!
Blue crabs undergo a periodic process called “molting” where they shed their hard shell as they grow and revealing a new larger shell underneath, which then hardens and becomes rigid.
The blue crab has many natural predators, including several varieties of fish, such as sharks, rays, trout, and others. It is also frequently consumed by humans!
Male blue crabs mate many times in their life, but females will mate only once, during their final molting period. Due to this, mating is a complicated ordeal that involves precision timing, usually only occurring during warmer months.
A female may produce up to 2 million eggs in every brood. The eggs typically hatch in coastal estuaries, after which the baby (larval) crabs are carried by tides out to the ocean, where they float around with other types of plankton. Eventually, after going through their larval stages, they will travel back to coastal waters, where they will change into their adult crab form. The crabs reach maturity at around 1 year after hatching, and can live up to three years.
Blue crabs feature a flattened, roughly hexagon-shaped carapace, or shell, that can grow to 9 inches wide. Males can be distinguished from females by the shape of the “apron”, a shell part covering their abdomen –females have a wider abdomen, shaped like the dome of the United States Capitol Building, while males have a more narrow abdomen, shaped like the Washington Monument.
The crab’s shell is mostly a drab blue-green above and white below, while its claws and legs are blue in color. This blue color can appear dull or very vibrant. Mature females have red tips on their claws.
Blue crabs have three pairs of legs for walking and a fourth pair of flatter legs that are used for paddling. Using these legs, blue crabs can paddle through the water, and their scientific name actually means “beautiful swimmer”.
Blue crabs are an important seafood item for humans. Native Americans and European settlers have fed on blue crabs since the 1600s. The largest blue crab harvest has historically been the Chesapeake Bay, though Louisiana has recently surpassed them to gain the title of the world’s biggest blue crab fishery.
When blue crabs are cooked, certain pigments in their shell break down, which turns the color from a blue green to a red coloration.
Blue crabs have a high commercial value, so their fisheries have undergone management plans to ensure the crabs are not overfished. Louisiana’s fishery has been certified as a sustainable blue crab fishery, the only one in the world. Chesapeake Bay has implemented a management plan of female blue crabs since 2008.