Biological Functions of Lizards Basking
Basking in the Sun By Lizards is Not An Idle Activity.
May 5, 2009
The present assumption is that the reptiles bask in the sun for thermo-regulation of their body. New research is throwing light on other surprising facets of this behavior and how it benefits the reptiles. Scientists have discovered from their new experiments that there is obviously more than what meets the eye. The new inquiry was initiated by scientists Dr Kristopher B. Karsten of Texas Christian University in Fort Worth and associates. The subject of research was basking behavior of panther chameleons (Furcifer pardalis).
Surprising Results
The research on panther chameleons indicates that one of the main functions of the seemingly lazy behavior of reptiles, sun- basking, is to acquire vitamin D, just as it is happening in human beings .This is not a mechanical process. In fact the reptiles alter their sunbathing behavior based on their need for vitamin D. Prey items of most vertebrates tend to be low in vitamin D. According to Dr Karsten they regulate exposure to UV in natural sunlight with incredibly high precision, accuracy, and effectiveness. Lack of vitamin D makes the reptiles sick. Their growth is affected which in turn impacts reproduction. Thus Vitamin D plays a very crucial role in the life of reptiles.
Methods Followed
To test whether chameleons alter their sunning behavior based on dietary vitamin D intake, Dr Karsten observed the behavior of two different groups of chameleons. One group was given high vitamin D levels. This was done with the diet of crickets dusted with a vitamin D powder. The other group was fed regular crickets and thus 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. Dr Karsten observed that chameleons fed on low vitamin D diet compensated by increasing their exposure to the sun’s UV rays. According to Dr Karsten, “The chameleons were as effective as mathematically possible by our methods at regulating toward optimal UV exposure for their vitamin D profile,”
Scientists have not been able to crack the exact mechanism that enables the lizards to sense their internal vitamin D levels. Dr Karsten thinks there may be a brain receptor sensitive to the vitamin D levels which in turn triggers the behavior of sun basking. The study is published in the May/June 2009 issue of Physiological and Biochemical Zoology.
References
Kristopher B. Karsten, Gary W. Ferguson, Tai C. Chen, and Michael F. Holick, “Panther Chameleons, Furcifer pardalis, Behaviorally Regulate Optimal Exposure to UV Depending on Dietary Vitamin D3 Status,” Physiological and Biochemical Zoology May/June 2009.
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