Blue Crab

Callinectes sapidus

What does the blue crab look like?

The blue crab—one of the most famous and important species in the Bay—is a swimming crustacean with five pair of legs. Blue crabs vary in color from olive to bluish green with white underneath. Adults have:

• Bright blue claws. The claws of mature females are "painted" red at the tips.
• Paddle-shaped rear swimming legs and three pairs of walking legs.
• The width of the carapace, or shell, is more than twice its length. Blue crabs can grow to 9 inches wide across the carapace.
• Carapace has nine teeth on the margin; the ninth tooth is a strong spine.
• Male abdomen, or apron, is strongly tapered, resembling an inverted "T." The female abdomen is broad and rounded, while the immature female's is triangular.

Where does the blue crab live?

During the course of their lives, blue crabs utilize all habitats within the Bay. Their distribution varies with age, sex and season.

• They tend to be most abundant in shallower areas during warm weather and are plentiful in the Bay's deeper portions during winter.
• Males range much farther up the Bay and tributaries than females, which congregate in saltier waters.
• They are bottom-dwellers, using bay grass beds for mating, shelter and nursery habitat and to find food.

What does the blue crab eat?

Blue crabs are omnivores and will feed on nearly anything they can find, including:

• Bivalves, such as clams and oysters
• Crustaceans
• Dead fish
• Bristle worms
• Plant and animal detritus
• Juvenile and soft-shelled blue crabs

How does the blue crab reproduce?

Blue crab mating takes place from May through October in mid-salinity Bay waters.

• Before mating, a male "cradles" a soft-shelled female in its legs and carries her for several days while searching for a protected area for her final molt. Mating takes place after the female molts.
• After mating, the male resumes cradling the female for several more days until her shell hardens.
• The male departs to search for another mate and the female migrates to the saltier lower Bay to spawn.
• The female develops an external orange egg mass, or sponge, beneath her apron. The egg mass may contain between 750,000 and two million eggs.
• Over the next two weeks, the egg mass darkens as the developing larvae consume the orange yolk.
• In about two weeks the female releases the larvae, called zoea , into the high-salinity waters near the mouth of the Bay.
• Currents transport the planktonic zoea to the ocean, where they molt several times to progressively larger stages. Winds eventually carry the zoea back into the Bay and other estuaries.
• At the last larval molt the zoea metamorphoses into a post-larval form called the megalops . The megalops crawl on the bottom, farther up into the Bay and its tributaries.
• Eventually the megalops settles and metamorphoses to the first crab stage, which looks like a tiny version of the adult blue crab.
• Immature crabs molt several times before they reach maturity at about 12 to 18 months old.

Other facts about the blue crab:

• Callinectes, part of its scientific name, comes from the Greek for "beautiful swimmer."
• Few blue crabs live longer than three years.
• Mature females are known as “sooks” and males are called "jimmies."