Sea urchins 'look' with thorny feathers

A new study confirms that the sea urchin's bristling body acts as a large eye covered with thorns.

A close-up of a sea urchin.

Sea urchins are like relatives close to them, starfish, both without eyes. Instead, this spherical hair-like invertebrate uses their thorns to detect light and compare the intensity of light rays to locate.

Although there is no eye, the sea urchin's ability to visualize is similar to that of some species of invertebrate marine life such as the British snail or horseshoe crab.