Crabs in Hawaii
Crabs are common along Hawaii's rocky shores, sandy areas, tide pools and reefs. Nearly 200 crab species live in Hawaiian waters, from tiny shoreline crabs to larger reef and deeper-water types. Their hard shells, quick movements and busy claws make them fun to watch near the ocean's edge.
Crabs belong to a group called decapod crustaceans. “Decapod” means ten-footed, which refers to their ten legs. True crabs usually have a short tail or small abdomen tucked under the body, giving them the broad, armored shape most people recognize.
How Crabs Move and Communicate
Many crabs walk sideways because of how their legs are shaped and attached. This lets them move quickly over rocks, sand and reef surfaces. Some can also move forward or use a more flexible walking style.
Claws are used for more than grabbing food. Crabs may wave, drum or tap with their claws to send signals, warn rivals, defend shelters or attract mates. Males may also fight over burrows, hiding places or females.
Food and Tide Pool Life
Most crabs are omnivores, meaning they eat both plant and animal material. Their diet may include algae, bacteria, fungi, worms, small animals and other crustaceans. By eating many kinds of food, crabs help clean and recycle material in tide pools and reef habitats.
When looking for crabs, move slowly and avoid lifting rocks or stepping in tide pools. Many small animals rely on those shelters. Crabs can pinch, so it is best to watch without handling them. Related pages include the Hawaii fish guide, sea cucumbers, rays, goatfishes and Hawaii beach safety tips.
