Chitin
Chitin is a tough, nitrogen-rich carbohydrate polymer that forms the structural backbone of fungal cell walls and arthropod exoskeletons, providing strength and flexibility.
Chitin is a robust, nitrogen-containing polysaccharide that serves as the primary structural component in the cell walls of fungi and the exoskeletons of arthropods like insects and crustaceans. Derived from glucose units, it forms long, fibrous chains that provide exceptional toughness and flexibility. This biopolymer is also a key precursor in creating sustainable composite materials, particularly when combined with mycelium for biodegradable applications.
What this means in real life
When a lobster molts and sheds its hard shell, it's shedding a structure made largely of chitin. The same material gives a beetle's wing case its rigidity and a mushroom its firm texture.
What it isn’t
It is not a protein, though it is often confused with keratin (the protein in hair and nails). Chitin is a carbohydrate polymer, fundamentally different in chemistry and function from protein-based structural materials.
Commonly misused online
Social media often claims chitin is 'indigestible to humans' as absolute fact, when the reality is more nuanced—humans lack the enzyme to break it down efficiently, but some gut bacteria may process small amounts.