Technically Speaking

A group of US scientists believe that they have found the scientific reason behind the ability of lizards to walk on water. The theory going into the study was that the lizard was exerting so much force with each step that the water gave back the same amount allowing the lizard to stay on top of the surface. But there is more to that… “What we didn’t expect to see was very large medio-lateral forces; forces pretty much to the side of the lizards.”

The study, which was reported recently in the Proceedings of the National Academy of Sciences, reveals how a large upward force is produced every time the lizard slaps its foot down into the water.

This keeps the animal from sinking straight down into the liquid. But just like we tend to teeter forward when we run on a soft surface such as sand, the lizard would also stumble forward unless it had a mechanism for stabilising itself.

And this is where the sideways force comes in - and it is almost as strong as the initial slap down.

The findings are interesting because most of what we know about how animals with legs move is based on studies of them travelling across solid surfaces.

Animals that run on land with two legs, such as birds and humans, have little force directed out towards the sides. The basilisk lizard is very different.

“We were wondering why this is actually happening,” Dr Hsieh added.

“Our guess on this is that it appears to help maintain stability… as they’re running across water; they’re constantly tripping.

“It’s a matter of catching themselves and keeping themselves upright before they actually fall over.”

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The setup of the experiment is pretty interesting as well.

The experimental set-up used a small track, around a metre in length, with small, silver-covered reflective particles dropped in the test-tank water.

A laser light was then shone through the water, making the particles reflect. This allowed the scientists to visualise fluid flow induced by foot movements and to calculate the forces the lizards were producing.

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It is amazing what they can do with lasers these days, heh?

This entry was posted on Wednesday, November 24th, 2004 at 12:39 pm and is filed under Science. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.