Chitin

Chitin is a special material found in nature. It is made of long chains of a sugar-like substance called N-acetylglucosamine. Chitin is very common—it is the second most abundant natural material.

You can find chitin in the outer shells of creatures like crabs, shrimps, and lobsters. It is also a key part of the hard outer coverings of insects and other arthropods. In fungi, chitin makes up their cell walls. Even some sea animals like squid and octopuses have chitin in their beaks and other body parts.

Because chitin is strong and useful, people often extract it from seafood waste. It has many important uses in medicine, industry, and biotechnology.

Etymology

The word "chitin" comes from a French word, chitine. This French word was made in 1821 from an ancient Greek word, χιτών (khitōn), which means "covering."

There is also a sea animal called a "chiton" that has a protective shell.

Chemistry, physical properties and biological function

The structure of chitin was discovered in 1929. Chitin is a special kind of sugar chain that contains nitrogen. It is made from units called N-acetyl-D-glucosamine, linking together like building blocks.

Chitin can be soft and flexible. When mixed with other materials, it becomes strong and hard. For example, in insects and crabs, chitin combines with proteins or minerals to make tough outer shells. In some butterflies, chitin helps create bright colors on wings. In certain beetles, it makes white, shiny scales. Chitin also has uses in medicine, like helping wounds heal.

Fossil record

For more on the preservation potential of chitin and other biopolymers, see taphonomy.

Chitin may have been part of the outer shells of ancient sea creatures called trilobites from the Cambrian period. The oldest pieces of chitin found are from about 25 million years ago. These pieces were protected inside tree resin called amber, which helped keep them safe.

Uses

Chitin helps plants stay healthy and fight off diseases, which is useful for farming. It can also improve soil, helping crops grow better and produce more food.

In factories, chitin is used in many ways. It can be changed to make safe, edible films and added to foods to thicken them and keep them from separating. Chitin is also used to make paper stronger and give it a special coating.

Research

Chitin can be changed to make a material called chitosan. This material is safe to use in the body and has many uses in medicine. Scientists are studying how chitin and chitosan can help the body heal wounds. They are also working on new kinds of medical bandages and threads for surgeries.

Chitosan might also be used to make a special kind of plastic that breaks down naturally. Tiny fibers from chitin, taken from shells and mushrooms, could be used in new medical treatments and medicines.