How Hemphill's Kelp Crab Uses Camouflage to Evade Predators

Hemphill's kelp crab is a small decorator crab species with a triangular carapace. These crabs are reported to inhabit the eastern Pacific ocean from central California to Panama. They often decorate their body by attaching bits of algae and bryozoans. Their decorations are typically concentrated on their walking legs, with much of their carapace usually bare. But some individuals are eventually covered everywhere except for their moving mouthparts. The pieces of decorating material are impaled on the small clusters of barbed hooked setae on their shell.

The crabs also have straight setae, which function as tactile sensory organs. Decorator crabs have many predators, but with the help of their decorations, these crabs are very good at disappearing into the background. Hemphill's kelp crabs further enhance their camouflage by moving to wave their attached algae back and forth, simulating the sway of seaweeds in the ocean's surge. These crabs can also attach stinging hydroids to their shell that further deter predators. Hemphill's kelp crabs can be found in a variety of habitats. They can be spotted in the

low intertidal and subtidal zones. Sometimes they are found on docks and wharf pilings, or among low-growing algae on rocks. Diatoms often settle on the pieces of branched bryozoans sticking out from their walking legs. The crabs sometimes eat the algae stored on their shell. Their carapace only attains a width of about ¾ of an inch. For more marine facts, click the SUBSCRIBE button!