Basilisk Lizard

I am a land animal. I understand that very clearly. Even though I enjoy spending time in the water, I know that if I met a hungry predator I would be doomed. My body is not built in a way for me to advantageously move through the water like a fish. I can run on land faster than I can swim in the water. However, if I could run on water I would have a better chance of surviving. Although I can’t run on water the basilisk lizard (Basiliscus plumifrons) can, but how is this tetrapod able to run on water bipedal?

The way a basilisk lizard runs on water has three main steps: slap, stroke, and recovery. During the first step the lizard slaps the water surface after swinging in through the air cavity. The lizard then strokes downwards allowing air to rush in behind the foot and produce an air cavity. In the last step the lizard will prepare for the next step after lifting its foot upwards within the air cavity (Glasheen & McMahon, 1996). The mode that basilisk lizards use for bipedal locomotion is different from legged running. The typical bipedal form of running consists of the hind limbs acting like a spring. However, in these lizards the hind limbs act more like a piston which only generates force during a step (Hsieh & Lauder, 2004).  The tail of the lizard is thought to be used mostly for counterbalance and may also produce some thrust (Hsieh, 2003).

The three steps of the basilisk lizard (Hsieh & Lauder, 2004).

The main reason they can run on water is likely to avoid predators both in the water and on land. To avoid terrestrial predators they will leave the land. By running on the water they are to able avoid aquatic predators. Even though they can swim well and hide under the surface of the water, they can move more quickly by running on the surface of the water than swimming in it (Rand & Marx, 1967). The lizards that are faster have a higher chance of survival than those that are slower.

Watch this lizard run on water:

References:

Glasheen, JW & McMahon, TA 1996, ‘A hydrodynamic model of locomotion in the basilisk lizard’, Nature, vol. 380, pp. 340-342, <http://www.life.illinois.edu/ib/426/handouts/Basilisk_Glasheen_%20McMahon.pdf>.

Hsieh, ST 2003, ‘Three-dimensional hindlimb kinematics of water running in the plumed basilisk lizard (Basiliscus plumifrons)’, Journal of Experimental Biology, vol. 206, pp. 4363-4377, doi:10.1242/jeb.00679.

Hsieh, ST & Lauder, GV 2004, ‘Running on water: Three-dimensional force generation by basilisk lizards’, Proceedings of the National Academy of Sciences of the United States of America, vol. 101, no. 48, pp. 16784-16788, doi:10.1073/pnas.0405736101.

Rand, AS & Marx, H 1967, ‘Running speed of the lizard Basiliscus basiliscus on water’, Copeia, vol. 1967, no. 1, pp. 230-233, doi:10.2307/1442206.