Why does a detached lizard's tail keep on moving?

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Offline hamza

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What makes a lizards tail to move vigourously after dtachment.. i mean are there some kinda cells or some ATP stuff??

Moderator: clarified title.
« Last Edit: 05/06/2007 17:52:13 by another_someone »


Offline DoctorBeaver

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Re: Why does a detached lizard's tail keep on moving?
« Reply #1 on: 05/06/2007 17:24:31 »
It's probably down to nerve endings firing off & sending signals to the muscles.
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Offline SquarishTriangle

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Re: Why does a detached lizard's tail keep on moving?
« Reply #2 on: 13/06/2007 15:01:14 »
I have to say I've never seen a lizard's tail without its owner, but here's my explanation anyway:

The muscles in the tail, as with other skeletal muscles in the lizard's body are innervated by nerves. These (peripheral) nerves branch from the central nervous system which is made up of the brain and spinal cord. The spinal cord extends from the brain, down the length of the spine (or most of it anyway) including into the tail region. When the tail is detached from the rest of the body, ie. it is no longer connected to the brain, it remains in contact with the spinal cord and any associated ganglia (nerve concentrations) which can continue to innervate the muscles as long as ATP (for ion pumps, muscle contraction etc.) is available; so the brain does not actually have any input into these movements in this situation. Obviously, when the tail is intact, the brain would responsible for controlling voluntary muscle contractions throughout the body. I suspect there might be some reflex mechanism involved here as well.

In the toad, you can isolate a single hind limb from the spinal cord and brain in a recently dead specimen (recent because the nerves and muscles need to remain effectively living), and just by pinching the main nerve, the sciatic n., hard enough you can actually make the limb jump...which is kind of cool...but is also shows that a sufficient stimulus on a nerve can cause the contraction of the innervated muscle(s). I'm not actually sure if this stands for other species or just for frogs and toads, so hopefully someone else can take me up on that one.

Interestingly, I vaguely remember seeing a study where a salamander's spinal chord was isolated and used to stimulate movements in artificial, programmed body parts/limbs (like a robot) via its nervous output...with some exciting medical implications for spinal cord injury patients.