by neufer » Mon Jan 03, 2022 4:36 pm
https://en.wikipedia.org/wiki/Autotomy wrote:
Click to play embedded YouTube video.
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Autotomy (from the Greek auto-, "self-" and tome, "severing", αὐτοτομία) or self-amputation, is the behaviour whereby an animal sheds or discards one or more of its own appendages, usually as a self-defense mechanism to elude a predator's grasp or to distract the predator and thereby allow escape. [Note: not to be confused with Autonomy (from the Greek auto-, "self" (see auto-) and nomos "custom, law"): the capacity to make an informed, uncoerced decision.] Some animals have the ability to regenerate the lost body part later. Autotomy has multiple evolutionary origins and is thought to have evolved at least nine times independently in animalia.
Some lizards, salamanders and tuatara when caught by the tail will shed part of it in attempting to escape. In many species the detached tail will continue to wriggle, creating a deceptive sense of continued struggle, and distracting the predator's attention from the fleeing prey animal. In addition,
many species of lizards have elaborately colored blue tails which have been shown to divert predatory attacks toward the tail and away from the body and head. Depending upon the species, the animal may be able to partially regenerate its tail, typically over a period of weeks or months. Though functional, the new tail section often is shorter and will contain cartilage rather than regenerated vertebrae of bone, and in color and texture the skin of the regenerated organ generally differs distinctly from its original appearance. However, some salamanders can regenerate a morphologically complete and identical tail. Some reptiles such as the crested gecko do not regenerate the tail after autotomy.
The technical term for this ability to drop the tail is caudal autotomy. In most lizards that sacrifice the tail in this manner, breakage occurs only when the tail is grasped with sufficient force, but some animals, such as some species of geckos, can perform true autotomy, throwing off the tail when sufficiently stressed, such as when attacked by ants. Caudal autotomy in lizards takes two forms. In the first form, called intervertebral autotomy, the tail breaks between the vertebrae. The second form of caudal autotomy is intravertebral autotomy, in which there are zones of weakness, fracture planes across each vertebra in the mid-part of the tail. In this second type of autotomy the lizard contracts a muscle to fracture a vertebra, rather than break the tail between two vertebrae.Sphincter muscles in the tail then contract around the caudal artery to minimize bleeding. Another adaptation associated with intravertebral autotomy is that skin flaps fold over the wound at the site of autotomy to readily seal the wound, which can minimize infection at the autotomy site. Caudal autotomy is prevalent among lizards; it has been recorded in 13 of approximately 20 families.>>
[quote=https://en.wikipedia.org/wiki/Autotomy]
[float=right][youtube]https://www.youtube.com/watch?v=cjewFIUaBtU[/youtube][img3=Dwarf yellow-headed gecko with regenerating blue tail]https://upload.wikimedia.org/wikipedia/commons/f/fe/Dwarf_Yellow-headed_gecko_edit.jpg[/img3][/float]
<<[b]Autotomy (from the Greek auto-, "self-" and tome, "severing", αὐτοτομία) or self-amputation, is the behaviour whereby an animal sheds or discards one or more of its own appendages, usually as a self-defense mechanism to elude a predator's grasp or to distract the predator and thereby allow escape. [color=#0000FF][Note: not to be confused with Autonomy (from the Greek auto-, "self" (see auto-) and nomos "custom, law"): the capacity to make an informed, uncoerced decision.][/color] Some animals have the ability to regenerate the lost body part later. Autotomy has multiple evolutionary origins and is thought to have evolved at least nine times independently in animalia.[/b]
Some lizards, salamanders and tuatara when caught by the tail will shed part of it in attempting to escape. In many species the detached tail will continue to wriggle, creating a deceptive sense of continued struggle, and distracting the predator's attention from the fleeing prey animal. In addition, [b][color=#0000FF]many species of lizards have elaborately colored blue tails which have been shown to divert predatory attacks toward the tail and away from the body and head.[/color][/b] Depending upon the species, the animal may be able to partially regenerate its tail, typically over a period of weeks or months. Though functional, the new tail section often is shorter and will contain cartilage rather than regenerated vertebrae of bone, and in color and texture the skin of the regenerated organ generally differs distinctly from its original appearance. However, some salamanders can regenerate a morphologically complete and identical tail. Some reptiles such as the crested gecko do not regenerate the tail after autotomy.
The technical term for this ability to drop the tail is caudal autotomy. In most lizards that sacrifice the tail in this manner, breakage occurs only when the tail is grasped with sufficient force, but some animals, such as some species of geckos, can perform true autotomy, throwing off the tail when sufficiently stressed, such as when attacked by ants. Caudal autotomy in lizards takes two forms. In the first form, called intervertebral autotomy, the tail breaks between the vertebrae. The second form of caudal autotomy is intravertebral autotomy, in which there are zones of weakness, fracture planes across each vertebra in the mid-part of the tail. In this second type of autotomy the lizard contracts a muscle to fracture a vertebra, rather than break the tail between two vertebrae.Sphincter muscles in the tail then contract around the caudal artery to minimize bleeding. Another adaptation associated with intravertebral autotomy is that skin flaps fold over the wound at the site of autotomy to readily seal the wound, which can minimize infection at the autotomy site. Caudal autotomy is prevalent among lizards; it has been recorded in 13 of approximately 20 families.>>[/quote]