Blue Crab

Callinectes sapidus


Image of a blue crab on sand.
Image by James St. John on Flickr, CC BY 2.0

Physical: The Blue Crab carapace (hard upper shell) reaches up to 9 inches point to point, with nine marginal teeth around the edges; the ninth is the point of measurement. The appendages are bright blue when they are older, paler as juveniles. The two paddle-shaped back appendages are called swimmerets; they help the crab swim quickly.

Habitat: C. sapidus range from Cape Cod to Uruguay, and live in estuaries, bays, and the open ocean, varying in salinities. They take shelter in eel grass beds and other structures for protection while breeding and molting.

Feeding: Blue Crabs are scavengers of the sea floor. They are omnivores that eat anything they find, such as oysters, mussels, clams, smaller crustaceans, freshly dead fish, and plant and animal detritus.

Breeding: The female egg cases resembles a sponge attached to the apron (triangle on the underside of the crab’s body). Male aprons are long and tapered, with a pointed tip. Immature females have triangular aprons, and mature females have aprons that are dome-like in shape. When eggs are released, over 1,000,000 eggs hatch into larva and attempt to survive. The female can only mate once.

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