The study, led by behavioral ecologist Kristopher Karsten of Texas Christian University in Forth Worth, analyzed two groups of panther chameleons in order to find a connection between reptiles' diets and sunning habits. With a control group of lizards eating regular crickets and another eating crickets dusted with vitamin D, researchers discovered that lizards eating diets higher in vitamin D spent less time in the sun. As reported in the May/June 2009 issue of  Physiological and Biochemical Zoology, researchers concluded reptiles sun bathe to receive the essential vitamin.

According to the Science News Web site, vitamin D plays an important part in reptiles' reproduction and ability to absorb calcium, helping keep their bones strong and healthy. Be sure to ask reptile owners whether they're providing their pets with sufficient sun, natural or artificial.