Meeting Abstract
Walking on water is a form of locomotion employed by many different species of animals ranging in size from water-walking insects to dolphins. The best studied is the basilisk lizard (Basiliscus spp.) Basilisks are able to run on water using a variety of different hydrodynamic forces that are produced during the stride cycle, which is comprised of a slap, stroke, and recovery phase. Lift forces are only generated during slap and stroke, during which the lizard is moving its foot down and posteriorly through the water at a high velocity and a high stride frequency. Juvenile basilisks have relatively larger feet and are able to generate relatively higher hydrodynamic forces than large basilisks. Basilisks are big enough that surface tension of the water does not contribute to lift. Recent work has shown that smaller animals, such as small geckos use both surface tension and hydrodynamic lift forces to keep them above the water’s surface. However, there is a lot of intra- and inter-individual variation in how much of the animal is pushed out of the water while it is running. Here we show that the small, quadrupedal lizard, Anolis sagrei, is also able to run on water. We use high-speed video (480fps) to understand what factors explain how far out of the water A. sagrei run. We consider variation in running velocity, stride frequency, foot velocity, foot depth, and foot surface area to explain variation in how far out of the water the animal is while running. We find that there is no significant relationship between how much of the body is out of the water and the surface area of either the front and hind feet, but, there is a significant relationship with both the maximum and average forward velocity of the lizard.
