The Decorator Crab, a.k.a. Sponge Crab, has a triangular shaped body with two long front claws. The claws are long because the Decorator Crab will pick at sponge, rock, barnacles, polyps, caulerpa, and the like, and then reach around to stick the item on its back; magically, the item immediately sticks to its back. They use the items they place on their back as camoflauge to protect them from predators. Decorator Crabs are very slow moving creatures and docile. They will accept most foods. They may remove some polyps from a coral, but they have no intention of damaging a coral. Decorator Crabs do not continuously remove polyps; once they have their back camoflauged they are comfortable. They come in various colors of orange, black, gray, and brown.Crabs belong to the Class Crustacea and Order Decapoda, which is characterized by two pair of antennae, three body parts, and five pairs of legs. The head of a Crab is connected to the thorax and covered by a shell called carapace. They have a smaller abdomen and tail compared to Shrimp and they keep this tucked beneath the carapace. The first pair of their legs are usually developed claws which they use to gather food, use as protection, and to move objects. In order for Crabs to grow they need to shed their exoskeleton, a process called "molting", which allows them to remove their restricting shell and begin a new one. Often times in the home aquarium Crabs will leave this translucent shell in full view so it can serve as a distraction while the Crab finds a hiding place and allows its new shell to harden.Photo by Saltwaterfish.com member, Al Mucciarone.