Light Detection Outside the Eyes and Body Clock Alignment in Non-Mammal Vertebrates

Nonmammalian vertebrates utilize multiple extraocular photoreceptors for regulating circadian rhythms and photoperiodic responses.

• Extraocular photoreceptors include deep brain photoreceptors and components of the pineal complex.
• The pineal complex consists of intracranial structures (pineal and parapineal) and extracranial components (frontal organ and parietal eye).
• Research highlights the significant roles of these extraocular photoreceptors in circadian physiology and behavior.
• Key functions associated with these photoreceptors include photic entrainment and sun compass orientation.

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