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Purple Porcelain Crab aka Banded Porcelain Crab
A mature Purple Porcelain Crab, Petrolisthes galathinus, showing early signs of limb regeneration of right middle leg.
Common names: Purple Porcelain Crab, Banded Porcelain Crab
Geographic Range: Beaufort, North Carolina to Gulf of Mexico, West Indies to Brazil
Porcelain crabs are common commensal inhabitants of sea anemones. They can be found living in the rocks immediately adjacent to large anemones, or often directly on the foot of the anemone itself. These species are filter feeders, collecting diatoms and other nutrients from the water. They also have tufts of hair on their claws that they use to brush bits of food up from rock surfaces. Porcelain crabs have a unique defense mechanism in which if they are threatened or disturbed, they may drop one of their appendages. The lost limb will eventually grow back.
Porcelain crabs are not true crabs, but belong to a group called anomurans, making them more closely related to hermit crabs and king crabs. One easily observed distinction between true cabs and anomurans is that in anomurans, only 4 pairs of legs are normally visible where as in true crabs, 5 pairs can be seen.