Blue Crab

Callinectes sapidus

The blue crab — one of the most famous and iconic species in the Bay — is a swimming crustacean that varies in color from olive to bluish green. Adults have:

• Bright blue claws. The claws of mature females are "painted" red at the tips.
• Paddle-shaped rear swimming legs
• Three pairs of walking legs.

The male blue crab's abdomen, or apron, is strongly tapered, resembling an inverted "T." The female abdomen is broad and rounded, while the immature female's is triangular.

The blue crab's carapace, or shell, width is more than twice its length, growing up to 9 inches across. The carapace has nine teeth on the margin; the ninth tooth is a strong spine.

Where does the blue crab live?

Throughout the course of their lives, blue crabs use all habitats in the Bay. Their distribution varies with age, sex and season.

• Blue crabs tend to be abundant in shallow-water areas during warm weather, while in winter they are plentiful in the Bay's deeper portions.
• Males range farther up into the fresher waters of the Bay and its rivers than females, who congregate in saltier waters.
• Blue crabs are bottom-dwellers, using bay grass beds as a source of food, nursery habitat for young and shelter during mating and molting.

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 crabs mate from May through October in the brackish waters of the middle Bay.

• 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 across the Bay bottom to the upper reaches of the Bay and into its rivers.
• Eventually the megalops settle and metamorphose into immature crabs, which look 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."