Porcelain crabs are not true crabs. While true crabs (Suborder Brachyura) have four pairs of walking legs and short antennae, the porcelain crab has only three pairs and often has long antennae. The abdomen of the porcelain crab is long and folded under it. The abdomen remains free to move. In fact, when alarmed, the crab might swim by flapping its abdomen!
Fragile Crab: The porcelain crab tends to shed limbs if stressed, hence its common name. This is a useful trait, in case a limb is trapped between rocks shifting in the currents, or grabbed by a predator. A dropped pincer may continue to move, to distract the predator while the crab makes its getaway. The lost limb eventually re-grows but this takes time.
Flat Crab: The porcelain crab is really flat and so it is able to squeeze into nooks and crannies. Its flatness plus its oversized pincers makes the crab appear two-dimensional and cartoonish!
Porcelain Food: Porcelain crabs filter feed at high tide. They have large mouthparts which are feathery with long silky hairs. These are extended into the water like nets to strain plankton from the water. Internal mouthparts scrape off any edible bits caught on the hairs and transfer them to the mouth.
Porcelain Babies: Porcelain crab eggs hatch into free-swimming larvae that only later settle down and develop into miniatures of their parents.
