Why Cuttlefish Eyes Are Shaped Like a Rounded W

A rapid-fire episode of the Monterey Bay Aquarium series Fast Ocean Facts explains exactly why the eyes of a cuttlefish are shaped like a rounded version of the letter “W”. As it turns out, cuttlefish can see what’s in front of them and what’s behind them at the same time, so the “W” flap limits light that would otherwise hinder locating hidden prey.

Weird, wonderful and shaped like a “W”, the wavy pupils and “eyelids” of a cuttlefish are designed to help even out the scattered light of a reef, revealing hidden prey. …By purposefully and rapidly focusing and blurring their vision, cephalopods can essentially differentiate between colors, and potential prey, depending on what’s in focus!