Why chameleons are the only lizards that eat breakfast

A chilly, sluggish chameleon can still deliver a good tongue-lashing. High-speed video images show the lizards can catch prey with their rubber band-like tongues equally well whether their body temperature is a cool 15 °C or a warmer 35 °C.

Cold-blooded animals are typically less active – with a corresponding decline in hunting performance – when temperatures drop. Not so for chameleons. Chris Anderson and Stephen Deban of the University of South Florida in Tampa filmed veiled chameleons (Chamaeleo calyptratus, pictured) catching prey at different temperatures. They found the muscles that coil the tongue into a spring-loaded structure were slower to contract at low temperatures. But once loaded, the tongue uncoils equally fast in warm and cool climes.

"This allows chameleons to take advantage of feeding opportunities early in the morning when they have not yet been able to elevate their core body temperature," says Anderson.

The projectile tongue's secret is coiled collagen. Muscle spring-loads the collagen, which, unlike muscle, is not slowed by cooler temperatures. "So while a cold chameleon can catch prey just as fast as a warm one, it takes a lot longer to deliver this meal to the mouth," says Ulrike Müller of California State University in Fresno.