Wednesday, June 22, 2011

Tale of a Tail

Juvenile Five-lined Skink
If you ever have tried to catch a five-lined skink, you probably have found that all you get is the tail.  Many of our native lizards have tails that break off easily and most will regenerate a tail, although seldom as long as the original.  

There must be  biological advantage to having a tail to justify the energy expended in regeneration.  It turns out that individuals with tails can run faster than those without tails. The lizards tail also stores fat at the base, a backup supply of energy.  Some lizards fight for dominance of their territory and may lose stature in their territory if they lose their tail.

The loss of the tail has no immediate impact on our common lizard's survival.  According to
Dr. Craig Guyer at Auburn.edu, losing their tail is a defensive adaptation. 
"There are two ways that lizards lose their tails. In all lizards around Auburn, the tail bones have central regions that break easily when the tail is pulled. The muscles of the tail pull apart easily and the blood vessels constrict to stop the wounded tail from bleeding. So, if a predator attacks a local lizard, the tail is designed to separate from the body, allowing the lizard to escape while the predator eats the tail. 
In species like Broad-headed Skinks, the tail is brightly colored (blue in this case) and is frequently twitched by the lizard so that predators see and attack the tail but not the body. Lizards that lose their tails in this way can grow them back but the replacement tail is never as long as nor as colorful as the original one. Replacement tails grow back in as little as three months or as long as two years."
Large lizards lack this defensive adaptation and do not regenerate their tails if they are bitten off. To date, no one know how the regeneration occurs. Imagine the ramifications to treating human injuries if we understood this. One more reason why all "all God's creatures got a place in the choir."

An extended discussion of autotomy (self-amputation) is at http://en.wikipedia.org/wiki/Autotomy

2 comments:

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  2. This is totally true, and I must say I feel intrigued about it, I mean, why lizards can regenarate their tail, but humans are not able to do it with legs or other part of our body... that's not fair.

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