Blue Crab
Callinectes sapidus
Quick answer
The blue crab is a fast-swimming crustacean of the western Atlantic, named for the bright blue tint of its claws and legs. Its scientific name means "beautiful, savory swimmer," reflecting both its paddle-shaped rear legs and its value as seafood. Blue crabs live in estuaries and coastal waters from North America to Argentina, molt their shells to grow, and usually live about 3 to 4 years.
Blue Crab facts at a glance
| Scientific name | Callinectes sapidus |
|---|---|
| Diet | Omnivore (fish, mollusks, plants, carrion) |
| Habitat | Estuaries and coastal waters of the western Atlantic |
| Lifespan | 3–4 years |
| Size | Shell up to about 23 cm (9 in) across |
| Top speed | Swims sideways with paddle-shaped legs |
| Conservation status | Least Concern (IUCN) |
| Kingdom | Animalia |
|---|---|
| Phylum | Arthropoda |
| Class | Malacostraca |
| Order | Decapoda |
| Family | Portunidae |
| Genus | Callinectes |
Where it lives
Estuaries and coastal waters of the western Atlantic, from the eastern United States and Gulf of Mexico to Argentina.
A swimming crab
Unlike most crabs that only walk, the blue crab is a strong swimmer thanks to its flattened, paddle-shaped rear legs. It darts sideways through the water to chase prey and escape danger, then settles onto the seabed to forage. Its broad, spined shell and powerful claws make it a capable predator and a tough opponent for would-be attackers.
Diet and behavior
Blue crabs are opportunistic omnivores that eat fish, clams, mussels, snails, plants, and carrion, and they will even eat other crabs. They use their strong claws to crush shells and tear food apart. Aggressive and territorial, they play an important role in estuary food webs as both predator and prey.
Molting and the life cycle
Like all crustaceans, blue crabs grow by molting, shedding their hard shell and expanding before the new one hardens. Females mate just after their final molt, then migrate toward saltier waters near the coast to release their eggs. The tiny larvae drift in the plankton before settling and developing into young crabs.
Range and fisheries
Blue crabs are native to the western Atlantic, from the eastern United States and the Gulf of Mexico down to Argentina, and they have been introduced to parts of Europe and Asia. They support major fisheries, especially in places like the Chesapeake Bay, and are prized as seafood. Soft-shell crabs are simply blue crabs harvested just after molting, before the new shell hardens.
Frequently asked questions about the Blue Crab
Why are blue crabs blue?
Blue crabs get their blue color from pigments in their shell, most vivid on the claws and legs. When cooked, heat changes the pigments and the shell turns red, like other crabs and lobsters.
Can blue crabs swim?
Yes. Blue crabs are strong swimmers, using their flattened, paddle-shaped rear legs to move quickly sideways through the water. This sets them apart from most crabs, which mainly walk.
What do blue crabs eat?
Blue crabs are omnivores that eat fish, clams, mussels, snails, plants, and dead animals, and they will even eat other crabs. They crush shells and tear food using their strong claws.
What is a soft-shell crab?
A soft-shell crab is simply a blue crab caught just after it has molted, while its new shell is still soft. At this stage the entire crab can be eaten, shell and all.
How long do blue crabs live?
Blue crabs typically live about 3 to 4 years. They grow throughout this time by repeatedly molting their shells to allow their bodies to expand.
Where do blue crabs live?
Blue crabs live in estuaries and coastal waters of the western Atlantic, from the United States and the Gulf of Mexico to Argentina. They have also been introduced to parts of Europe and Asia.
