Spine (zoology)

This article is about needle-like growths in animals. For backbone, see Vertebral column. For other uses, see spine (disambiguation).

North American Porcupine

A spine is a hard, thorny or needle-like structure which occurs on various animals. Animals such as porcupines and sea urchins grow spines as a self-defense mechanism. Spines are often formed of keratin. Other animals with spines are hedgehogs, spiny mice and at least two ornithischian dinosaurs.

In the context of neuroscience, is also used as shorthand for dendritic spines, tiny protusions on the surface of nerve cells that are contacted by presynaptic terminals.