Appearance
Prior to 2005, the name Hemigrapsus penicillatus was used to cover animals that are now known to represent two distinct species. Hemigrapsus penicillatus (sensu stricto) has smaller patches of setae (bristles) on the chelae (claws) in males; Hemigrapsus takanoi has larger setal patches and larger coloured spots on the exoskeleton. It can be a variety of colors, including orange-brown, maroon, or green, with striped legs and spotted claws. Male brush-clawed shore crabs have a patch of light brown or yellow bristles (known as setae) on their chelae (pincers). Their carapace width typically reaches about 2.5 centimetres (1.0 in), and has three spines. Before developing into juvenile crabs, larval brush-clawed crabs spend almost one month floating in the ocean. This allows them to find food and new habitats.