The Emerald Crab makes a great valuable addition to any aquarium. It is basically introduced into tanks to help take care of bubble algae problems. The Emerald Crab mainly feeds on it and maintains a clean and clear surface of the rocks present in the aquarium. It is a complete reef safe, and is very easy to take care of. The Emerald Crab is often considered as scavengers as they clean out most organic debris from the aquarium. They 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 Emerald Crab is an extremely hardy creature that can survive a lot of harsh conditions, that?s why they can tolerate water temperatures within the outer range of their habitat, i.e. from nineties to as low as fifty-five degrees Fahrenheit. This creature is found in abundance within their specific habitat. The Emerald Crab is green in color with very rough texture, and has hairy legs, and smooth claws which they use to gather food, use as protection, and to move objects. Their head is mainly connected to the thorax and covered by a shell called carapace, beneath which the small abdomen and tail lies. The Emerald Crab mainly stays hidden during the day time and mainly ventures out in the evening to forage upon various types of algae. Within a reef aquarium environment the Emerald Crab quickly becomes adapted to the aquarium and will venture out more often to forage upon algae. It sheds its exoskeleton which allows them to remove their restricting shell and begin a fresh new shell, and this process is known as ??molting??. The Emerald Crab basically occupies small crevices within rocks and lives on the underside of coral rubble. It can very well get adapted to the environment and gets along well with other tank mates.