Most crabs "walk" or run across the ocean bottom. Some, such as the commercially caught blue crab of the Atlantic coast (a member of the one family of "swimming crabs") can swim. Their rearmost pair of legs is modified for swimming and legs are paddle-shaped.
By shedding their outgrown shell. The rigid shell imprisons the crab and limits growth. Once the shell is shed, the crab can absorb water and expand into its newgrown shell.
Under normal conditions, about a one-third increase occurs with each molt.
They are the same species. A soft-shell crab is one that has just discarded its shell. Crabs which have just shed their shell hide in rocks or bury themselves in sand and mud to escape predators. They emerge after the new shell hardens, a quick process.
A female may live 2 years, a male 3.
A large, land hermit crab, which lives on tropical Pacific islands. The crab is so named because it eats coconuts, is even caught on coconut used as bait. The meat is considered a delicacy in the islands.
Fisherman often break off the large claw and throw the crab back into the water. If the break is made at the first joint, the crab is not harmed. The stone crab can and does sever its own claw at the first joint (by muscular contraction) to escape from danger.
These are "pea" crabs. They live, often in pairs, inside the oyster shell, eating food collected on mucous strands in the oyster. Because they do cause damage to oyster mantle and gills, the crabs are considered parasites. Pea crabs are not harmful to man.
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