Sally lightfoot crabs are also known as red rock crabs. Adults vary in colour, from reddish-brown, to mottled or spotted brown, pink or yellow. When they are young they are dark brown, which allows them to camouflage easily with the volcanic rocks. They are the most common saltwater crabs along the western coast of South America and are one of the few saltwater crabs that inhabit the Galápagos Islands. Sally lightfoot crabs are between eight to twelve centimetres in length and are flat and low to the ground.