Blue Crab

Species Information
Exhibit Name and Location Maryland: Mountains to the Sea, Level 2
Description of Animal In spite of their colorful name, blue crabs are mainly grayish to bluish green. Only the claws are blue, and the claws of mature females also have bright orange-red tips. There’s another easy way to distinguish males from females: Maryland locals look for the "apron." Males have a “t” shaped abdomen, and females have triangular abdomens that become rounder as they age. Crabs grow by shedding their shells, a process called molting. They take in water to expand and break out of the old shell. A new soft shell underneath hardens quickly. With three pairs of walking legs, they generally walk sideways, clearing a path with sharp lateral spines. Large, powerful claws are used for defense, digging, sexual displays, and to gather food.
Aquarist's Note In the exhibit, a crab trap has a dual purpose: it prevents the crab from feeding freely on the fish in the exhibit. If you notice what seems to be a dead crab in the exhibit, relax! The crab molts periodically by backing out of its shell, and the old shell in the exhibit is sometimes mistaken for a dead crab. Crabbing is part of Maryland's heritage, and favorite summer “tribal rituals,” in Maryland, are crab feasts. Heaps of steamed blue crabs (now red, of course), 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.
Diet 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 resort to cannibalism on juvenile crabs.
Size Males typically grow larger than females, sometimes reaching seven or eight inches from point to point, although five inches is the legal size for harvesting. Reportedly, some males have grown to about ten inches.
Range Crabs are bottom-dwelling predators that live along the Atlantic Coast from Cape Cod to Florida.
Population Status Cannibalism of young blue crabs by larger crabs is common and it may regulate population abundance. Conservation Alert! Loss of habitat, combined with the blue crab’s popularity as a food for humans, has led to serious drops in populations. Population of Chesapeake Bay crabs has grown since 2001, but the future remains uncertain. Habitat restoration is essential for crab recovery. The Aquarium invites volunteers to help restore marshes throughout the Chesapeake Bay.
Predators They are not only predators, they are also prey: some bony fish, as well as some sharks and rays, feed on juveniles and larger crabs, and the blue crab is the preferred food of the Atlantic Ridley sea turtle.