Variety of animal uses
Keratins are the main constituent of structures that grow from the skin:
- the α-keratins in the
hooves of mammals
- the harder
β-keratins in the
scales and claws of
chelonia, such as
terrapin), and in the
beaks, and claws of
birds. These keratins are formed mainly in
beta sheets. However, beta sheets are also found in α-keratins.
Arthropods such as
crustaceans often have parts of their
exoskeleton made of keratin, sometimes in combination with
Keratins are also found in the
gastrointestinal tracts of many animals, including
roundworms (who also have an outer layer made of keratin).
Although it is now difficult to be certain, the scales, claws, some
protective armour and the beaks of
dinosaurs would, almost certainly, have been composed of a type of keratin.