Porcelain Crabs (Petrolisthes cinctipes)

Contributed by Dr. Bonnie Becker

Where found:  Under rocks in the upper to middle intertidal

Interesting facts:  They will drop or “autotomize” a leg or a claw quite easily to get out of a tough spot. The point at which the limb breaks is predetermined and marked with a groove. After autotomy a membrane is sealed over the stump and blood vessels are closed to prevent bleeding to death. Regeneration begins and a miniature limb grows out of the stump. It will remain small until the next molt, when it will grow very quickly. This species are popular in the curio business. They are used to make plastic key rings.

Adaptations:  Their “flatness” allows them to squeeze into crevices and under rocks.

Food:  Porcelain crabs are filter feeders, eating phytoplankton and organic debris that is strained from the water with their hairy appendages.

Life history:  Egg bearing females have been found in all months except November. Eggs hatch into the first planktonic larval stages called zoeae, which metamorphoses into planktonic megalops. Megalops will molt a few times before maturing into an adult crab.

Classification:
Phylum:           Arthropoda (Finn, jointed exoskeleton and jointed appendages)
Class:              Crustacea (Barnacles, Beach hoppers, Shrimps, Lobsters, Crabs, etc.)
Subclass:         Malacostraca (isopods, amphipods, decapods)
Order:             Decapoda (Shrimps, Lobsters, Crabs, etc.)
Infraorder:      Brachyura (“True” crabs)

Last revised 18-Aug-14