Armour (zoology)

Armour in animals is external protection against attack by predators, formed as part of the body (rather than the behavioural use of protective external objects). It has therefore mostly developed in 'prey' species. Armoured structures are usually composed of hardened mineral deposits, chitin, bone or keratin.

Examples are:

• The shells of molluscs, gastropods etc.
• The exoskeleton of the arthropods.
• The scales on fish, whether 'cosmoid', 'ganoid' or 'placoid'.
• The spines on fish, such as the stickleback.
• Bony protection, such as in the Thyreophora (armoured dinosaurs) and in ceratopsian dinosaurs.
• The shells of the Chelonia (tortoises, turtles and terrapins).
• The spines on the Echidna (spiny anteaters) and of porcupines and hedgehogs.
• The bony shell of the armadillo.