The National Aquarium and its Animal Care and Rescue Center are temporarily closed in response to COVID-19. Help support us while we are closed by Donating Today.

Blue Crab

Blue Crab

Callinectes sapidus

Blue Crab Blue Crab Blue Crab Blue Crab Blue Crab

Despite their name, blue crabs are typically more of a gray to dull blue-green in color. Only their claws are truly blue, with the claws of mature females tipped in a bright orange-red.

There’s another easy way to distinguish between a male and female blue crab: Maryland locals know to look for the "apron." Males have a T-shaped abdomen, while females have a triangular abdomens that becomes rounder as they age.

As crabs grow, they shed their shells, a process called molting. The crab takes in water to expand and break out of its old shell. A new, soft shell is revealed underneath and quickly hardens.

With three pairs of walking legs, blue crabs generally walk sideways, clearing a path with sharp lateral spines. Large, powerful claws are used for defense, digging, sexual displays and to gather food.

Crabbing is part of Maryland's heritage, and crab feasts are a favorite local summer tradition. Heaps of blue crabs (now red, after steaming), spicy and hot, are piled high on newspaper-covered tables and eagerly devoured in backyards, restaurants and picnic sites. Nearly every Marylander has his or her own recipe for steamed blue crabs.

Did You Know?

Blue crabs have three pairs of legs and walk sideways.


Adult blue crabs feed on bivalves, crustaceans, fish, worms, plants, detritus and nearly anything else they can find, including dead fish and plants. The blue crab's favorite food may be thin-shelled bivalves. When these are scarce, they sometimes cannibalize juvenile crabs.


Males typically grow larger than females, sometimes reaching 8 inches from point to point, although 5 inches is the legal size for harvesting. Reportedly, some males have grown to about 10 inches.


Blue crabs are bottom-dwelling predators and live along the Atlantic coast, from Cape Cod to Florida.

Population Status

Loss of habitat, combined with the blue crab’s popularity as food for humans, has led to serious population declines. The population of Chesapeake Bay crabs has grown since 2001, but the future remains uncertain. Habitat restoration is essential for crab recovery. The National Aquarium invites you to help us restore marshes throughout the Chesapeake Bay.


Some bony fish, as well as some sharks and rays feed on crabs. The blue crab is the preferred food of the Kemp’s ridley sea turtle.

Back to the Top