|
Dear
Davis,
All
lizards have tails and all lizards can lose their tails, but
not all lizards can grow them back. The tail is an important
structure. We know that individuals with tails can run faster
than those without tails. We also know that lizards that lose
their tails lose an important source of energy because these
animals store fats at the base of their tails. Finally, many
species, like our local Green Anole, fight to establish their
dominance over a territory and we know that individuals that
lose their tails lose their ability to maintain a territory.
So, lizards generally want to keep their tails.
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.
In other lizards, especially big ones like iguanas and Komodo
Dragons, the tail bones are not designed to break and the
tail muscles are not designed to pull apart. These lizards
can lose their tails, but it takes a much stronger pull to
make this happen. The wound will heal, but the tail does not
grow back.
Biologists have studied lizard tails for decades trying to
discover how these animals can replace a body part that has
been lost. To date, we do not totally understand how this
happens. However, if we can unravel this mystery, then perhaps
we can learn how to treat humans who lose limbs.
Thanks
for your question,
Aubie and Dr. Guyer
|
Davis
Tullier, First Grader