The Atlantic Blue Crab
The Atlantic blue crab (Callinectes sapidus) is found in rivers, bays, inlets and other estuaries of the Atlantic Coast from Nova Scotia to Argentina.
Male crabs can be distinguished from females by the shape of the abdomen. The male has a T-shaped abdomen that is held tightly against the body until maturity when it becomes somewhat free.
The immature female has a triangle-shaped abdomen that is tightly sealed against the body. The mature female's abdomen becomes rounded and can be easily pulled away from the body after the final molt.
Breeding female blue crabs carry fertilized eggs under their abdomen. The egg mass resembles a sponge, hence the term "sponge" crab. It takes about two weeks for the eggs to mature and be released into the water to hatch.
Male blue crabs (called Jimmy crabs) have brilliant blue claws and legs. Mature females (sooks) can be distinguished by the bright orange tips on their claws. Males typically grow larger than females, sometimes reaching 7 or 8 inches from shell point to point. Male blue crabs have been reported to grow as large as 10 inches.
Blue crabs eat small fishes, oysters, clams, snails, shrimp, worms and other crabs. They sometimes burrow into the bottom with only their eye stalks visible, lying in wait for prey. Blue crabs are opportunistic by nature, eating whatever is available.
Commercial crab harvesters usually bait crab traps with oily fishes, which seem to work better than other baits. Blue crabs are thought to be able to detect and locate the source of fish oil from considerable distances.
A major harvesting area for blue crabs in North America is the Chesapeake Bay. In Chesapeake Bay communities, they are called "Maryland crabs", "hard crabs", or simply "crabs". Other crab harvests come from the Delaware Bay, North Carolina, South Carolina, Georgia and to a lesser extent, the Gulf Coast states.