Carbohydrates are the main source of energy for all living things, whether plant or animal. A carbohydrate is comprised of carbon, hydrogen and oxygen (or simply, carbon and water). The simplest unit of a carbohydrate is called a monosaccaride, an example of which is glucose. A disaccaride is two monosaccarides joined by a covalent (double) bond, as in sucrose, for example. (Covalent bonds are energy storage molecules. When these break, energy is released). Several monosaccarides joined together form polysaccarides. Chitin is an example of a polysaccaride.
Monosaccarides join together to form different kinds of polysaccarides including starch, cellulose glycogen and chitin. Starch is a storage product of plants. Cellulose is a supporting material for plants. Glycogen is a storage product of animals. Chitin is the main structural component of exoskeletons.
This polysaccaride contains nitrogen and is the principal component of exoskeletons for many arthropods and cell walls of certain fungi. An arthropod is a phylum of animals with a chitinous shell that molts and includes insects, arachnids (spiders), crustaceans (crabs, lobsters), and myriapods (many legged insects such as centipedes). Chemically, chitin is known as poly (N-acetlyglucosamine).
Chitin is abundantly found in nature (second to cellulose). It is usually present with other polysaccarides and proteins. It can be isolated and is often a key component in waste water clearing, cosmetics, medical and veterinary applications (particularly in accelerating wound healing).