Autotomy(redirected from Casting (tails))
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self-mutilation, a protective reaction observed in many animals upon acute stimulus; for example, seizure by a predator.
Autotomy consists in the spontaneous shedding of extremities, tail, or other parts of the body. The term “autotomy” was introduced and thoroughly examined by the Belgian physiologist L. Fredericq in 1883. Autotomy is encountered in invertebrates—certain hydroid polyps and actinia shed feelers; nemertines and segmented worms shed the end of the body; sea lilies, starfish, and other echinoderms lose arms; mollusks shed siphons; and crustaceans lose claws and other extremities. Among the vertebrates, autotomy is inherent only in lizards, which shed their tails. Autotomy is a reflex process, and the place of autotomy is determined specifically in each animal. For example, in lizards, autotomy is controlled by a nerve center located in the spinal cord, and the breaking occurs with a sharp contraction of muscles in the very spot of the backbone where a transverse cartilage plate is located. Autotomy is usually associated with the ability to regenerate the lost parts of the body; that is, regeneration occurs most easily at the site of autotomy.