Petrolisthes cinctipes
Petrolisthes cinctipes, commonly known as the flat porcelain crab, is an abundant species of marine porcelain crab found in the upper and middle intertidal, primarily in mussel beds, along the eastern Pacific Ocean, from British Columbia to Mexico. This species was first described by John Witt Randall in 1840.
Description
P. cinctipes has a flat carapace up to 24 mm in diameter. It is generally a dark blue-brown color, and more starkly blue around the time of molting. The species name cinctipes is derived from the Latin for "banded legs," since the legs of this species are blue banded with white. Unlike other sympatric species of Petrolisthes, this species has dark red antennal flagellae, and a distinct lobe on the inner margin of its carpus, which has non-parallel margins.Biology
P. cinctipes does not use its chelae for feeding. Like other porcelain crabs, P. cinctipes is a suspension-feeding crab that uses its maxillipeds to sweep phytoplankton and other detritus from the water. It can voluntarily detach its claw through a reflex called autotomy, which it deploys in approximately 40% of predator attacks or more, especially among smaller female porcelain crabs. The claw stops pinching once it detaches, which is not the case for other species in the genus, like P. eriomerus. After autonomy, a membrane is sealed over the stump, and within a few weeks a small limb bud will form at the amputation site. After several molting cycles, the limb bud will retain its full size.P. cinctipes generally reproduce all year round. Eggs hatch into zoea, or early-stage planktonic larvae with long spines, which the larvae use both for lateral swimming and to discourage predators. Zoeal larvae molt once before entering a post-larval stage as planktonic, filter feeding megalopae with fully developed appendages. After molting again, individuals generally lose the ability to swim as they reach the juvenile stage. However, adults, can swim with their ventral side up if they are forced to.