July 29, 2011 5:31 PM EDT
A recent study published in the scientific journal, Proceedings of the National Academy of Sciences, argues that despite having no eyes at all sea urchins actually see with their entire body. Research conducted at the University of Gothenburg in Sweden has empirically determined that sea urchins can react to light even in the absence of eyes. Predicated on previous studies showing that they have a large number of genes linked to the development of the retina, which is the light-sensitive tissue in the human eye, the Swedish researchers set out to determine where exactly the protein, Opsin, which these genes are coded to produce, were housed in sea urchins. Opsin combines with similar retinal compounds to form, rhodospin, which is the biological pigment of the retina responsible for the formation of photoreceptor cells. As explained by on the of the researchers from the study, Sam Dupont quote, “We wanted to see where the opsin was located in sea urchins so that we could find the sensory light structures, or photoreceptors. We quite simply wanted to know where the sea urchin sees from." Based on their research, the photoreceptors seem to be located on the tip and base of the tube feet that are found all over the sea urchin's body and used to move. This finding has led them to argue that the entire sea urchin can acts one huge compound eye, and that the shadow cast by the animal’s opaque skeleton over the photoreceptor cells gives it directional vision.