Even though they're called blue crabs, these crustaceans may vary in color from blue to olive green. (Tonya Lane Rucker/Flickr)
The blue crab is a swimming crustacean with bright blue claws and a spiny, olive green shell. It is one of the most distinctive and recognizable species in the Chesapeake Bay
Varies in color from olive to bluish green
Carapace (shell) is more than twice as wide as its length, growing up to 9 inches across. The shell has nine teeth on the margin; the ninth tooth is a strong spine.
Bright blue claws. Mature females’ claws have red tips.
Paddle-shaped rear swimming legs
Three pairs of walking legs
Males have a strongly tapered abdomen, or “apron,” that resembles an inverted T. Mature females have a broad, rounded abdomen. Immature females have a triangular abdomen.
Uses all of the Chesapeake Bay’s habitats during the course of its life
Distribution varies depending on age, sex and season
Abundant in shallow waters during warm weather, particularly among bay grass beds. Hibernates in the Bay’s deep trenches in winter.
Males range farther up into fresher waters of the Bay and its rivers. Females tend to congregate in saltier waters.
Lives year-round throughout the Chesapeake Bay and its tidal rivers
Will eat nearly anything it can find, including clams, oysters, smaller crustaceans, dead fish, bristle worms, plant and animal detritus – even juvenile and soft-shelled blue crabs!
Predators include croakers, red drums, herons, sea turtles and humans
Reproduction and Life Cycle:
Mates from May through October in the brackish waters of the middle Bay
Prior to mating, a male cradles a soft-shelled female in his legs, carrying her for several days while he searches for a protected area for her final molt. Once she molts, the pair mates.
After mating, the male continues to cradle the female for several more days until her shell hardens
The male eventually leaves to search for another mate, while the female migrates to the saltier lower Bay. She develops an external egg mass, or sponge, beneath her apron. The bright orange egg mass may contain between 750,000 to two million eggs.
The egg mass darkens as the developing larvae consume the orange yolk. In about two weeks, the female releases her larvae (called zoea) into the salty waters near the mouth of the Bay.
Currents transport the planktonic zoea to the ocean, where they molt several times as they grow. Eventually, zoea return to the Bay and other estuaries.
During their last larval molt, the zoea metamorphose into a post-larval form called megalops. The megalops crawl over the Bay’s bottom to reach the upper Bay and its rivers.
Megalops eventually metamorphose into immature crabs, which look like tiny adults. Immature crabs molt several times before they reach maturity, about 12-18 months after hatching.
Few blue crabs live longer than three years
Callinectes, part of the blue crab’s scientific name, comes from the Greek words for “beautiful” and “swimmer”
Male blue crabs are known as “jimmies” and mature females are called “sooks”
One of the most important commercial and recreational species in the Chesapeake Bay