Colored eyes, like those of the soldier fly above, serve a specific purpose in insects: they narrow down the information being processed by each of the tiny lenses.

GOOGLY EYES These technicolor trees aren’t plants. They’re the gills of Christmas tree worms, which hide below in tubes within the coral. Nick Hobgood/Wikimedia Commons (CC BY-SA 3.0) ...

Dogs and cats are adorable creatures by day, but under the cover of night their eyes seem to shine like demon spawn. That’s the work of the light-reflecting tapetum lucidum, a layer of tissue ...