The Helmet Crab has an almost pentagonal-shaped body or carapace. The carapace, claws and legs are covered with stiff bristles and the lateral margin of the carapace has six large, jagged teeth on each side. The Helmet Crab is predominantly yellow-green, with darker claws. Helmet Crabs eat the softer, sweeter portions of eelgrass. They also scavenge for dead invertebrates and fish, or will attack and eat other crabs. The animal is very active and will usually run from a human diver. Sea Gulls will hunt Helmet crabs at low tide by wading through the eelgrass. When a seabird finds a Helmet crab, the bird flips it over and eats the insides. Helmet crabs are also eaten by bottom fishes and Giant Pacific Octopuses.
Range & Habitat
Helmet crabs live on rocky as well as sandy bottoms from low intertidal to 130 feet (39 m) deep. Usually they live subtidally in or near dense eelgrass beds but have been found in heavy algal coverings on rocky areas. They are seldom found in open coastal areas. They range from Norton Sound, Alaska to Monterey, California, but are rare south of Puget Sound. On the western side of the Pacific Ocean, they can be found from Siberia to Japan.