The ‘water-walking’ lizard
A lizard that walks on water? The Basiliscus genus of lizard is often irreverently called the ‘Jesus lizard’, an obvious allusion to the miraculous act when the Lord Jesus Christ walked on water. But a far more accurate description is that the basilisk (as it is commonly known) runs on water.
Basilisk lizards consist of four species ranging from areas of southern Mexico to the northern areas of South America, as well as Florida in the United States. They are excellent swimmers and climbers, but when a predator threatens, escape comes by sprinting across the water’s surface.
Unlike the miraculous event the disciples witnessed, the basilisk’s ability operates within the bounds of the natural laws God has set in place. The lizard’s large hind feet have long toes with a scaly fringe on either side of the third, fourth and fifth digits. When on solid ground, these fringes remain folded. But when it is on water, the fringes spread out, providing a greater surface area for the foot.
Bicycle pedal motion
Consider how the pedal and crank mechanism of a bicycle rotates. The hind legs (the cranks) of the basilisk move in a similar manner. One foot (the pedal) strikes or ‘slaps’ down on the surface of the water. With the increased surface area of the fringed toes, this ‘slapping’, creates an air cavity, which acts like a flotation cushion, briefly helping to support the animal’s weight.
The foot, continuing on from the initial surface strike, then pushes backward through the water providing forward momentum, while the corresponding ‘back’ pressure of the water against the foot keeps the cavity (very temporarily) sealed. At the same time, the opposite foot is circling up in preparation to strike the water and create another air cushion.
By means of this ‘pedalling’ motion (more elliptical than circular, though), at any point in time one or the other foot is powering through the water. Each stride across the water surface also pushes outward slightly, which, in concert with the basilisk’s long tail (acting as a counterbalance), helps maintain an upright position.
All these movements happen very rapidly. Each foot must step out of the air cavity before it completely collapses, which occurs in less than a tenth of a second. For the basilisk, it’s not a problem, though, with the smallest, lightest lizards able to take 20 steps per second.1 Basilisks reach speeds of nearly 10 km/h (6 mph) on water, and they can travel up to 20m (65ft) before they tire and start sinking. Though larger adults can still manage this amazing feat, juveniles and lighter specimens travel fastest and farthest, as they are able to generate larger upward forces in proportion to their weight. A 2g (0.07oz) lizard can generate enough force to support 225% of its weight. But the force generated by a 200g (7oz) lizard, though greater, is only enough to support 111% of its weight.2 Once a basilisk sinks it reverts to the much slower mode of swimming.
Thomas McMahon, Professor of Applied Mechanics at Harvard University said of the basilisk, "Using the physics we learned from lizards, it's possible to design machines that could run across water."1People continue to be inspired by what they see in nature to design and create copies, but they seldom acknowledge the Designer and Creator of the original. And while a lizard running on water isn’t supernatural, God’s creative work surely was. The One who walked on water around 2,000 years ago was also the One who created the basilisk lizard kind.
References and notes
- . Cromie, W. J., Biologists discover how to walk on water, news.harvard.edu/gazette, 4 April 1996. Return to text.
- Glasheen, J. W. and McMahon, T. A., Size-dependence of water-running ability in basilisk lizards (Basiliscus Basiliscus), life.illinois.edu, 14 August 1996. Return to text.
- For more examples of such biomimetics of biomimicry, see creation.com/biomimetics. Return to text.