Chitin is a rigid material that gives external strength and protection to the soft bodies of many invertebrates. Chitin makes up the chitinous shells or exoskeletons (hard outer protective layer) of arthropods such as shrimp, crabs, and lobsters. The oldest known evidence of chitin can be found in 25 million year old fossils of trilobites, whose shells were made of chitin. The beaks of octopus and squid are made of chitin. Many insects’ exoskeletons are composed of chitin, such as grasshoppers and cockroaches. The shells of beetles and webs of spiders contain chitin. True fungi have cell walls made of chitin, unlike most plants whose cell walls get strength from cellulose.
Chitin is a flexible, strong material with many medical, industrial, and agricultural uses. It is the second most abundant natural polysaccharide (after cellulose) on earth. Chitin’s abundance and low cost make it desirable as a raw material. Chitin is a precursor to glucosamine and chitosan. The chitin molecule is a polysaccharide composed of many units of glucosamine. Glucosamine is made by hydrolyzing chitin. Chitosan is made by the deacetylation of chitin.
Chitin protects plants from fungus in two ways: internally and externally. When exposed to chitin, plants turn on natural “internal” defenses to protect themselves against fungal infection. Chitin feeds good bacteria in the soil that kill (and live off of) fungus that might otherwise harm the plant. This is a form of “external” protection from fungus.
Farmers protect plants from fungus infection with pesticides called “fungicides.” Pesticides are chemicals that can be dangerous and harmful to the environment. Chitin is an organic form of fungus control that is not dangerous and does not hurt the environment. Farmers could reduce the use of pesticides by using organic alternatives such as chitin.
Acetylated chitin nanofiber sheets are used as a protective coating over everything from solar panels to cell phone screens to car paint. Chitin nanofiber sheets form a clear, protective, self-healing barrier for wear and tear.
Chitin is used in wound-care for bandages, to block pain due to exposed nerve endings, and to help accelerate the healing of wounds. An ideal surgical thread is made from chitin due to its flexibility and strength.