The sea urchin don't have what might be called the eye. But he, like other echinoderms, responds to light. Scientists have found that almost all of the body of sea urchin is his light body.

Needles sea urchin are his eyes. Shown in red light-sensitive cells, green nervous.

"What echinoderms can respond to light, has been known for several centuries. However, about how they do it, there has been much discussion. One of the main ideas was that photosensitive cells distributed throughout the body. We have shown that in fact they are more difficult and orderly" - says DuPont (Sam Dupont), one of the authors of the article published in the Proceedings of the National Academy of Sciences.

Scientists were able to see the distribution opsin has been performed in the body of sea urchin, using fluorescent antibody to this protein. It turned out that the light-sensitive cells are located at the beginning and end of a small "needles" (ambulacral legs), outgoing from the body of this animal. These cells are connected with the Central nervous system, which processes the information. However, it is unlikely that the hedgehog was formed any image.

Scientists believe that casts a skeleton shadow can help sea urchins in the direction of the incident light.