Thaindian News

London, July 18 (IANS) Most lizards are content scurrying in and out of nooks and crannies in walls and between rocks. But neon blue tailed tree lizards (Holaspis guentheri) leap from branch to branch as they scamper through trees in the African forest. A new study has found their bones are full of air to enable them to glide.
Bieke Vanhooydonck from the University of Antwerp and her colleagues, Anthony Herrel and Peter Aerts, decided to find out whether neon blue tailed tree lizards really glide.

they began filming dainty neon blue tailed tree lizards, gliding geckos (Ptychozoon kuhli) and the common wall lizard (Podarcis muralis) as the animals leapt from a two metre high platform to see if the neon blue tailed tree lizards really could glide.

Filming the lizards was extremely difficult. Having startled the small animals into leaping off the platform, the team had little control over the animal’s direction, and couldn’t guarantee that it was parallel to their camera.

But after weeks of persistence the team finally collected enough film, as the lizards leapt, to compare their performances.

At first, it didn’t look as if the African lizard was gliding any better than the common wall lizard. Both animals were able to cover horizontal distances of half a metre after leaping from the platform, while the gliding gecko covered distances greater than one metre, aided by its webbed feet and skin flaps.

But when the team compared the lizards’ sizes, they noticed that there was a big difference between the common wall lizard and the tree lizard.

The tiny tree lizard only weighed 1.5 grams, almost a third of the larger common wall lizard’s weight and a tenth of the gliding gecko’s mass, so Aerts calculated how far each lizard would travel horizontally if they fell like a stone.

This time it was clear that the tiny tree lizard was travelling 20 cm further than Aerts would have expected if it were simply jumping off the platform.

The tree lizard was definitely delaying its descent and landing more slowly than the common wall lizard; the tree lizard was gliding.

But how was the tiny tree lizard able to remain airborne for so long? The team realised that instead of increasing its surface area to generate lift, the tree lizard is able to glide because it is so light.

Curious to find out why the tree lizard is so light, Herrel contacted Renaud Boistel, Paul Tafforeau and Vincent Fernandez at the European Synchrotron Radiation Facility to scan all three lizards’ bodies, said an Antwerp release.

Visualising the animals’ skeletons with X-rays, it was clear that the tree lizard’s bones were packed full of air spaces, making the lizard’s skeleton feather light for gliding.

These findings were published in the Thursday edition of the Journal of Experimental Biology.