Dermal photoreceptors regulate basking behavior in the lizard Podarcis muralis

Area of Science:

• Zoology
• Animal Behavior
• Sensory Biology

Background:

• Dermal light sensitivity has been observed in various animal species, including birds, mammals, and marine reptiles.
• The mechanisms and prevalence of light detection through the skin in terrestrial vertebrates remain largely unexplored.

Purpose of the Study:

• To investigate the presence and characteristics of a dermal light sense in the terrestrial lizard, Podarcis muralis.
• To determine the specific light wavelengths and intensities that trigger behavioral responses mediated by skin-based light detection.

Main Methods:

• The dorsal surface of Podarcis muralis lizards was painted with opaque black paint to block light penetration to the skin.
• Lizards were exposed to light sources of varying spectra and intensities, and their ability to orient towards the light was recorded.
• Control experiments were conducted to rule out thermal cues.

Main Results:

• Painting the lizard's dorsal surface impaired its ability to position itself under a heatless light source.
• The behavioral response was dependent on light wavelengths shorter than 600 nm and intensities exceeding 2.5 mW cm-2.
• These findings indicate a functional dermal light sense in this terrestrial vertebrate.

Conclusions:

• Podarcis muralis exhibits a behavioral response mediated by light detected through its skin.
• This study provides the first evidence of overt behavior in a terrestrial vertebrate being controlled by a dermal light sense.
• The dermal light sense in lizards may play a role in thermoregulation or other light-dependent behaviors.