High-speed camera reveals why lizards use hunting strategies

By recording movies of lizards hunting prey on a pint-size race track, researchers from Ohio University in Athens have discovered that the reptiles' physiology influences their predominant hunting style.

Lizards use two basic strategies to hunt prey. In the aptly named sit-and-wait approach, they linger until their prey passes by and then sprint toward it and grab it with their tongue. In a technique known as wide or active foraging, they use their chemosensory system to stalk prey. Lizards tend to use one strategy or the other. Whereas some wide foragers will move about 80 percent of the time, sit-and-wait foragers may move only about 10 percent of the time.

As reported in the April 1, 2008, issue of the Journal of Experimental Biology, the researchers studied a representative sample of 18 species of lizards, including skinks, iguanas and monitor lizards. They used a high-speed camera from NAC Image Technology to record the fastest reptiles at 500 or 1000 fps and a camera from JVC to videotape slower lizards at 120 or 240 fps, while the reptiles hunted for food on a metal plate that doubled as a means of measuring the force.

The researchers found that lizards that use the sit-and-wait strategy use running mechanics rather than walking mechanics — even when moving at slower speeds. In contrast to sit-and-wait foragers, the wide foragers use a walking gait. Remarkably, three groups of wide foragers that had evolutionarily reverted to the sit-and-wait method had lost the ability to walk.