Sheep crab

Did you know?

These animals are the largest members of the California spider crabs family Majidae. To camouflage themselves, juvenile sheep crabs decorate their carapaces with barnacles, bryozoans, hydroids, and algae. Adult crabs often stop decorating themselves and a thin film of fuzzy green algae replaces the masking organisms. Divers have seen sheep crabs walking openly on sandy seafloors.

Conservation

A market exists for whole live sheep crabs and their large claws. Fishers gather claws from adult male crabs caught in gillnets, usually killing the crabs in the process, and use traps to catch live crabs. 

In Southern California, fisheries for claws and whole live sheep crabs thrived in the 1980s. After a 1990 California State initiative barred the use of gillnets in shallow water, the catch of claws plummeted.

At present, trap fishermen and gillnetters supply the market, which remains relatively low. Large-scale fishing for sheep crabs is no longer economically feasible.

Cool facts

• Male sheep crabs spend the winter in deep water. In early spring, both sexes migrate to shallow water. Sheep crabs aren't social animals, but in the spring mating season divers see adult females in piles surrounded by adult males.
• Since females can store sperm for multiple broods, they can continue to fertilize eggs even in the absence males. Broods can contain 125,000 to 500,000 eggs.
• Like all crustaceans, sheep crabs molt, or shed, their too-small shells. They grow a soft shell under the old carapace, back out of it, and then take in water to expand the new soft shell. The new shell then quickly hardens and the crab has room to grow. Some species of crabs molt their entire lives, but adult sheep crabs have a final terminal molt. After this molt, they're unable to increase in size or regenerate lost limbs.