These delicately spotted crabs live in a symbiotic relationship with anemones. They keep the anemone clean while benefiting from its protection. Porcelain crabs have modified mouthparts which open out like fans into the oncoming current in order to trap tiny particles of plankton
They live for around 2-3 years.
They are less than 24mm in width.
They are found in the Indo-Pacific. You see them when you are diving around the Gili Islands Indonesia.
They are also known as anemone crabs, due to their close association with anemones. Porcelain crabs may be found singly or in pairs, hidden between the stinging tentacles, or near the mouth, of anemones. They are found in reef habitats, to depths of around 10m.
They are mainly plankton feeders, sieving tiny particles from the water column using their fan-like mouthparts. They also eat mucus from the anemone.
Porcelain crabs are relatively aggressive, using their large claws to deter invaders, including anemone fish. Although both use an anemone host, porcelain crabs and anemone fish are not commonly found together, the crab usually losing out to the tougher fish. Like anemone fish, porcelain crabs are immune to the anemone’s stinging tentacles. It is a mutualistic relationship, since both parties benefit from the arrangement: the crab gaining safety and shelter, in return for cleaning.
Porcelain crabs are often found in heterosexual pairs. They have internal fertilization, the male passing sperm to the female in the form of a tiny packet called a spermatophore. The eggs are carried by the female in a brood flap, on the abdomen. A single female may carry nearly 1,600 eggs at a time. The larvae are planktonic for several weeks before settling.
Porcelain crabs are not of the IUCN Red List, but suffer from habitat loss if reefs are damaged or polluted.