Let playground tongue more accurate when it applied Anableps anableps, a fish related to the garbe. It lives in the blackish water of mangoswan in central of South America in hunts for food of the water surface. Its bozing eyes submerged half way which poses revolution problems. Should those eyes be attuning the greenish light drifting the mango, or the yellowish ray drifting up through murky water? Well, these fish eyes see both.

 

Anableps doesn't actually has four eyes, just the usual two. But each eye has two pupils, one above water, one below. And each pupil sends incoming visual inform of the different side of the fish's retina. Coming each of the retina adapted produces different light filtering pigments. So c.. under water ray is primate sense a longer way from yellow light. C.. by daily a sense of the short way from green light. The finding appears on a journal biology letters.

 

The entire arrangement makes it easy for this bifocal fish just spot attested above from above water or bet it voyage below. For when it comes revolution, the eye's habit.

 

Thanks for the minute for Scientific American 60-s Science. I'm Christopher Intagliata.