No Eyes? No Problem. Sea Urchins See with Their Feet

Threaten a sea urchin, and you may see it point its spines at you. This defensive response is pretty unremarkable--except for the fact that, if you look closer, you will not see the sea urchin's eyes. It doesn't have any. Sea urchins are the only animals that have vision despite "conspicuously lacking eyes," write Dan-Eric Nilsson, a biologist at the University of Lund in Sweden who studies animal vision, and his colleagues. In a new study, the researchers gave the spiny sea creatures a ki