Autotomise

Autotomise is the verb used to describe the voluntary shedding of a body part by an animal, typically a limb or tail, in response to predation or injury. The noun autotomy refers to the process itself. The term derives from Greek autos meaning “self” and tomia meaning “cutting.”

Autotomy is most prominently studied in reptiles, but it occurs across several animal groups, including amphibians, echinoderms, crustaceans, and cephalopods. In lizards and some other reptiles, tail autotomy occurs at predefined fracture planes within the caudal vertebrae. Muscles and connective tissue constrict to minimize blood loss, and the tail breaks away at the plane. The detached tail often continues to wriggle or flick, distracting the predator and increasing the animal’s chances of escape. In many species the tail regenerates, producing a new a tail that is typically cartilaginous and functionally adequate but may differ in appearance and strength from the original.

Across other taxa, autotomy can involve limbs or arms. Starfish and other echinoderms can shed arms at specialized breakage points; many crustaceans can lose legs or claws; cephalopods such as octopuses can detach an arm that may continue to move before it regenerates. Regeneration varies by group and individual, ranging from partial to complete replacement and often taking weeks to months.

Adaptive significance lies in predator escape and survival, balanced by costs such as reduced locomotion or grasping ability and the energetic demands of regeneration. Autotomy has evolved independently in multiple lineages and remains an important area of study in regenerative biology.