The Scarlet Reef Hermit is a very popular crab because of its brilliant red color, yellow eyes, peaceful disposition, and algae diet. These hermits are an absolute must for any home aquarium. Most of their day is spent scurrying around the aquarium doing a tremendous job keeping aquariums clean of detritus and algae. Scarlet Hermits prefer to be kept in groups. They are voracious algae eaters.Crabs belong to the Class Crustacea and Order Decapoda. Hermits and Porcelain Crabs belong to the Section Anomura, which consists of long antennae and three pair of walking legs. The head of the 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. Hermit Crabs use abandoned shells as their home. These Crabs usually have extended abdomens that they wrap around the inside of the spiraling shell leaving only their head and claws exposed. When approached these Crabs can recoil into the shell for protection. When a Hermit Crab grows it will often seek out a new larger shell.