Wednesday, November 24, 2004
The Jesus Lizard explained
I first came across the Basilisk, or the Jesus Lizard, while watching some documentary and doing research for a quiz I was setting. The video was totally amazing to me since the lizards were truly walking on water (and not just in the sea of Galilee). Researchers may have finally discovered what enables these lizards to walk on water.
Harvard University's Dr Tonia Hsieh told the BBC World Service that experiments showed the lizard to be producing massive sideways force to stay upright. "We did expect that we would see that they were producing enough force to run on the top of the water," the researcher in the institution's department of organismic and evolutionary biology explained. "What we didn't expect to see was very large medio-lateral forces; forces pretty much to the side of the lizards."
The study 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 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.
Harvard University's Dr Tonia Hsieh told the BBC World Service that experiments showed the lizard to be producing massive sideways force to stay upright. "We did expect that we would see that they were producing enough force to run on the top of the water," the researcher in the institution's department of organismic and evolutionary biology explained. "What we didn't expect to see was very large medio-lateral forces; forces pretty much to the side of the lizards."
The study 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 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.
