London: Sea urchins are one of the rarest of creatures who can see with their whole body, without any eyes.
Previous studies have shown that they have a large number of genes linked to the development of the retina -- the light-sensitive tissue in the human eye.
This means that sea urchins have several genes that are coded for a widely occurring eye protein, opsin, reports the journal Proceedings of the National Academy of Sciences.
"It was this discovery that underpinned our research," says Sam Dupont, marine ecologist and study co-author from the University of Gothenburg, Sweden.
"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," adds Dupoint, according to a Gothenburg statement.
Researchers showed that 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 are used by it to move.
"We argue that the entire adult sea urchin can act as a huge compound eye, and that the shadow that is cast by the animal`s opaque skeleton over the light-sensitive cells can give it directional vision," says Dupont.