If only Newton had met this fish . . .

Dolichopteryx longipes, or more commonly, the spookfish, sounds like something that the Cowardly Lion would be afraid of. The spookfish is an odd creature. Living at around 1,000 meters below the surface of the Atlantic, Pacific, and Indian Oceans, it has fixed barrel-shaped telescoping eyes pointing upward from the top of its head. Because of this, the family is also sometimes called Barreleye. This fish is now the center of a great biological (and optical) discovery. The spookfish is the first vertebrate known to have developed focusing mirrors for its eyes. Refractive (lens) eyes are very common in vertebrates and non-vertebrates alike: all the way from the single-lens, single-index eyes of some gastropods and annelids to the compound eyes of insects and the gradient index lenses of mammals. Before the recent study, mirrored eyes had been found in animals but they were usually in near-microscopic organisms or in some scallops and didn't focus light to form an image.
Scientists from Tuebingen University in Germany have published a paper in Current Biology about their study of fish and the finding of the focusing mirrors. The fish actually use both refractive (lens) and a reflective (mirror) vision to keep tabs on the world around them. The refractive portion of their sight is directed upwards (dorsally) to watch the faint light coming from the surface (at 1km deep, not much sunlight makes it down). The second half of the visual system, with the curved mirrors, is pointed downwards (ventrally) to catch the minuscule bioluminescent flickers from other sea creatures below them who may be looking for a spookfish snack.
The use of curved mirrors for imaging has probably been known by humans since the time of Euclid, and definitely by the 11th century, but it looks like biology has us beat again by at least a couple million years.

Found via BBC News. Image via Wikipedia.