Lazy Lizards Run, Don't Walk

Scientists filmed lizards like this plated lizard running and walking on a racetrack.

(Image credit: Stephen Reilly, Ohio University.)

Like humans, some lizards are always on the go, grabbing food en route, while others wait like couch potatoes expecting pizza delivery.

New video research finds the lazy lizards that wait for food to pass by on a seeming silver platter actually have evolved into skilled sprinters, while the constantly active foragers are built for long walks.

Monitor lizards and some skinks are considered wide foragers. They spend 80 percent of their lives on the move, slowly slinking about using their specialized tongues to chemically sniff out prey. The sit-and-wait lizards, well, sit and wait. Then when a meal passes by, the iguana, for instance, lunges like a hungry delivery customer hearing the doorbell, to sprint after the unsuspecting morsel and snatch it up with a tongue flick.

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How to tell the difference? "When you walk, your foot hits the ground and your center of mass sort of goes up in the air and then falls over like an upside-down pendulum," said co-researcher Stephen Reilly, a biologist at Ohio University. When you run, your center of mass first dips down before springing upward as you push off the ground with your leg muscles. Running involves a bouncing movement.

Jeanna Bryner is managing editor of Scientific American. Previously she was editor in chief of Live Science and, prior to that, an editor at Scholastic's Science World magazine. Bryner has an English degree from Salisbury University, a master's degree in biogeochemistry and environmental sciences from the University of Maryland and a graduate science journalism degree from New York University. She has worked as a biologist in Florida, where she monitored wetlands and did field surveys for endangered species, including the gorgeous Florida Scrub Jay. She also received an ocean sciences journalism fellowship from the Woods Hole Oceanographic Institution. She is a firm believer that science is for everyone and that just about everything can be viewed through the lens of science.