About Percnon gibbesi (H.Milne Edwards, 1853)
Percnon gibbesi (H.Milne Edwards, 1853) is a species of grapsid crab. Adult individuals of this species have a carapace that measures 30 millimetres (1.2 in) wide, and their legs bear yellow rings at the joints. Each of the five pairs of walking legs has a row of spines running along its leading edge. Egg-carrying females of the species have been collected off the coast of West Africa between February and April, and again in August. The larvae that hatch from these eggs are planktonic and long-lived, a trait that may contribute to this species' ability to become invasive. P. gibbesi is one of the most widely distributed grapsid crabs, and is found on both sides of the Atlantic Ocean as well as on the Pacific coast of North America. On the Pacific coast of North America, its range extends from California to Chile. In the Atlantic Ocean, it occurs natively from Florida to Brazil, and from Madeira to the Gulf of Guinea. The species has recently invaded the Mediterranean Sea; it was first recorded at Linosa, Sicily in 1999, and has since been found on the Balearic Islands, as well as in Greece, Libya, Malta and Israel. Unusually for a temperate crab, P. gibbesi is strictly herbivorous. In the Caribbean Sea, P. gibbesi lives in association with the sea urchin Diadema antillarum. In the Mediterranean Sea, P. gibbesi lives almost exclusively among boulders, and is out-competed by the native crab species Pachygrapsus marmoratus. P. gibbesi is preyed upon by both fish and invertebrates.
