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Why do many nocturnal animals have eyeshine?
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coloration
The anole changes color in response to its stress level.
Many nocturnal animals possess eyeshine because they have a specialized layer of tissue located behind or within the retina known as the tapetum lucidum (Latin for "bright tapestry").12
This structure acts as a mirrorlike surface, often containing the white compound guanine, which reflects light that has passed through the retina back outward. By reflecting this light, the tapetum lucidum provides the animal's visual pigments a second chance to absorb photons that were missed during the initial passage of light through the eye. This adaptation is highly beneficial for survival in low-light environments, as it significantly increases the animal's ability to capture and utilize available light for vision.23