Stokkan et al., Proc. Royal Soc. B, 2013.
Figure 1. Tapetum lucidum [membrane] in (a) winter and (b) summer eyes following removal of the cornea, lens and vitreous. The winter eye was deep blue and the summer eye was golden with elements of turquoise around the edges.
Rudolf the . . . yellow-and-blue-eyed reindeer?
This is Sandra Tsing Loh with the Loh Down on Science.
Meet Glen Jeffery from University College London. He wondered how Arctic reindeer deal visually with life near the North Pole. How do their eyes manage nonstop sunlight in summer but permanent darkness in winter?
To understand, he harvested the eyes of dead deer. Awwww—but it was for science. Some in winter, others in summer. And when he shined light into them? Summer eyes lit up golden yellow. Winter baby blues? Well, blue! The color comes from a reflective membrane behind the retina. It sends light back into the eye for a second round of reception.
Jeffery found that the protein fabric of winter membranes has a much tighter weave. So light doesn’t just bounce back out the eye, as in summer. Rather, it’s shattered into smaller wavelengths. These look blue, and scatter inside the eye. Hence, the retina captures more photons. Indeed, winter eyes retained 60 percent more light.
This way? Deer with the blues can see the light in their darkest moments. As for deer in the headlights? They're still just gonna stand there.
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