The shell, greenish on top and dingy white below, is about 7.5 cm (3 inches) long and 15 to 18 cm wide; the legs are bluish. A distinctive, large, sharp spine projects from each side. Eight short spines occur on each side between the large spine and the eyes. The chelae, or pincers, are large and somewhat unequal in size. The fifth pair of legs is flattened for swimming. The crabs are scavengers, feeding on the bodies of dead animals. At spawning time the female's abdomen swells with eggs. Larvae hatch two weeks after fertilization and pass through a number of zoeal, or early larval, stages before metamorphosing into conventional crablike forms.