The mangrove tree crab, Aratus pisonii, is one of several species of crabs belonging to the Family Sesarmidae. The carapace is mottled brown to olive-green (Kaplan 1988) and is widest at the front, tapering posteriorly (Abele 1986). Eyes are widespread at the front corners of the carapace. Legs are brown to mottled, and the claws bear tufts of black hair. Sharp tips at the end of the legs allow A. pisonii to climb mangrove trees and other vertical surfaces (Kaplan 1988).