Short · Animals
Why do deer freeze in your headlights?
A mirror behind a deer's retina, the tapetum lucidum, gives its eyes a second chance at light and sends your headlights straight back. Why deer freeze is still an open question.
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Transcript
Why do deer freeze in your headlights? Their eyes are built for the dark. Behind the retina sits a mirror-like layer, the tapetum lucidum. Light that slips past the retina bounces back for a second chance, then heads straight back toward your headlights. That's the glow. Now take the mirror away. The glow vanishes, and less light is caught. So why the freeze? Biologists aren't sure. The glare may swamp eyes tuned for the dark, or two bright lights may not look like danger. Slow down: where there's one deer, there are often more. Try it yourself at Explainer Tools dot com.