Crustaceans
crustaceans' skeletal systems are located on the outer side of the anatomy and are commonly referred to as exoskeletons. The exoskeletons are made of chitin, which is responsible for making the shells hard. The shells of crustaceans provide more than just protection. The shells also provide a large diversity of life sustaining functions for these tiny sea creatures as their exoskeleton. Crustaceans go through a molting process as they grow. A new exoskeleton grows underneath the existing one the process takes two to four days. Once the new exoskeleton is in place, the old one is shredded. It takes an additional two to three days for the new one to completely attach and adjust to the crustacean's body. The shell also provides support for the muscles and joints so it can move about freely.