FORT WORTH, Texas, April 21 (UPI) -- U.S. scientists say they have discovered lizards and other cold-blooded animals that like to bask in sunlight do so for more than just warmth.
Researchers from Texas Christian University said they discovered chameleons alter their sunbathing behavior based on their need for vitamin D.
"It's a longstanding assumption that thermoregulation is the only reason that lizards bask," said biologist Kristopher Karsten, who led the study." Our results suggest that, in addition to thermoregulation, vitamin D regulation appears to have a significant impact on basking behavior as well."
To test whether chameleons alter their sunning behavior based on dietary vitamin D intake, Karsten observed two groups of chameleons. One group had high internal vitamin D levels, thanks to a diet of crickets dusted with a vitamin D powder. The other group ate regular crickets and had low vitamin D. The chameleons were then placed in individual outdoor enclosures that offered open area for direct sun, and a tree to offer filtered sun and shade.
Karsten found chameleons fed the low vitamin D diet compensated by increasing their exposure to the sun's UV rays. Chameleons with high vitamin D diets limited their UV exposure.
The study appears in the May-June issue of the journal Physiological and Biochemical Zoology.
