Tail Shedding Protects From Predators

a light brown lizard with a nubby tail displays regeneration

Biological Strategy

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Image: Anita Gould / Flickr / Some rights reserved

Protect From Animals

Animals–organisms that range from microscopic to larger than a bus–embody a wide variety of harms to living systems, including other animals. They threaten through predation, herbivory, defense, and parasitism, and they compete for resources such as water, nutrients, and space. Any given living organism commonly faces threats from a variety of animals, requiring strategies that effectively defend from each. Trout and other bony fish, for example, escape predators by having scales made of very thin, flake-like pieces of bone covered with slippery mucus. They also have behavioral strategies such as camouflage, fast swimming, and twisting and turning to achieve release from a predator’s grip.

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Physically Assemble Structure

Living systems use physical materials to create structures to serve as protection, insulation, and other purposes. These structures can be internal (within or attached to the system itself), such as cell membranes, shells, and fur. They can also be external (detached), such as nests, burrows, cocoons, or webs. Because physical materials are limited and the energy required to gather and create new structures is costly, living systems must use both conservatively. Therefore, they optimize the structures’ size, weight, and density. For example, weaver birds use two types of vegetation to create their nests: strong, a few stiff fibers and numerous thin fibers. Combined, they make a strong, yet flexible, nest. An example of an internal structure is a bird’s bone. The bone is comprised of a mineral matrix assembled to create strong cross-supports and a tubular outer surface filled with air to minimize weight.

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Reptiles

Class Reptilia (“creeping”): Lizards, crocodiles, turtles, snakes

Reptiles retain some of the key characteristics that first enabled vertebrates to live permanently on land. They have dry skin covered in scales made of keratin that help prevent water loss. (Amphibians still need to stick close to water to keep their skin moist.) Many reptiles reproduce by laying eggs that are watertight and have a yolk, so eggs can develop on land while staying moist and nourished. Reptiles are also ectotherms, meaning they don’t produce their own body heat. This means they burn through energy much more slowly than “warm blooded” creatures of the same size. It also means that they need to keep warm to keep active, which is why you might see them spending a seemingly inordinate amount of time simply basking in the sun.

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The tail of a lizard helps it escape predators by breaking off at one of the cartilaginous fracture planes within its caudal vertebrae.

“The shedding of tails, and sometimes other limbs too, is not uncommon in the natural world. Autotomy, as scientists call it, is a clever means of getting away from predators, which are literally left holding a part of the intended victim’s body. Not only is the victim able to survive the incident, it is able to replace the lost body part. Species from no less than 11 of the 16 classified families of lizard shed their tails in this way. The secret of the process lies in the structure of a typical lizard’s tail. Each of its caudal vertebrae from the sixth onward contains a weak horizontal ‘break’ or fracture plane, which is made of cartilage instead of bone and will snap easily if held. Also, within each vertebra’s fracture plane the blood vessels and nerves are constricted, so that if the tail does snap off, blood loss will be minimal.” (Shuker 2001:131)

Last Updated August 18, 2016

References

Book

The Hidden Powers of Animals: Uncovering the Secrets of Nature

Marshall Editions Ltd. | 26/02/2021 | Dr. Karl P. N. Shuker

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