The question is how? And why?
How do lizards lose their tails?
Photo courtesy Wikimedia Commons
Most lizards (such as the Brown Anole, Indo-pacific Gecko, etc.), have a natural weak point in the central region of their tail vertebrae which can easily break apart. Apart from that, the muscles of the tail can also tear apart easily. So, when the tail is pulled with sufficient amount of force, it is severed without much difficulty. It has also been said that even though it seems the tail comes off because of pulling, it is the lizards themselves who control the severing.
What about excessive bleeding?
When the appendage gets severed, the muscles around the severed point, contract. This in turn, constricts the blood vessels around that point. Hence excessive bleeding is prevented.
But this is only part of the story. The fascinating thing is that many lizards have the ability to re-grow or regenerate their removed appendage.
However, it takes time for the tail to grow back. It can vary from a few months to a couple of years. Also, the new appendage generally does not possess the colours and patterns of the original one and often appears dark grey in colour.
There are a few lizards, especially the larger ones such as iguanas and komodo dragons, whose tails do not break easily since their tail bone and muscles are not designed to sever.However, their tails can be separated with a larger amount of force than what is required for most other types of lizards. Another interesting thing is that their tails do not grow back.
Why do lizards lose their tails?
The primary reason appears to be predators. Often, a predator tries to capture a lizard from behind by grabbing on to or biting its tail. The tail gets severed providing the lizard a chance to escape.
Besides, a lizard can cast off its tail when it feels threatened or cornered. The cast away appendage continues to wriggle, thus drawing the attention of the predator such as a bird or a cat while the lizard makes its escape.
Lizard tails have been known to perform a variety of motions even after being severed. To read more, click here.
In some places, venomous creatures such as vipers, hunt lizards. When a viper injects venom into a lizard’s tail, it becomes important for the lizard to shed its appendage before the venom reaches its vital organs.
A report published in 2009, describes the factors affecting the ability of a lizard to shed its tail.
Studies consisted of laboratory experiments and field measurements carried out in mainland Greece and several offshore Aegean Sea islands inhabited by different combinations of predators.
It was found that in the islands containing vipers, the lizards could shed their tails quite easily. However, in the island with no vipers, the lizards had largely lost their ability to shed their tails. To read more about it, click here.
Citation: University of Michigan. “A Venomous Tale: How Lizards Can Shed Their Tail When Predators Attack.” ScienceDaily 27 March 2009. 24 July 2010 <http://www.sciencedaily.com /releases/2009/03/090325170604.htm>.
Photo courtesy Wikimedia Commons
Does losing a tail affect the lizard?
Well…yes, it does.
Although, the resulting wound gets cured, losing a tail can cause three main problems
- reduced mobility
- loss of energy (the lizard’s tail stores a lot of energy in the form of fat)
- reduced social status and reduced ability to maintain territory
Interest to humans
The lizard’s ability to regenerate its tail and the ability of the severed tail to perform movements on its own may have interesting connotations for humans
Understanding how lizards regenerate a lost body part may help in treatment of people who have lost limbs
The ability of the severed tail to perform complex motions seems to indicate the presence of a control center at the far end of its tail thus providing a possibility of a model to study the human spinal chord and spinal chord injuries.
To know more about this, click here.
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