Walleyes are known for their marble-like eyes, which let them see well in dim light. Their retina has a layer of reflective pigment, called the tapetum lucidum, that intensifies any light the eye receives. (It's the same membrane that causes a cat's eyes to glow yellow.) But the walleye's close relative, the sauger, has even better night vision because the tapetum covers a much larger portion of its retinas.