Scientists had theorized the animals’ spines simulate the light-blocking pigmented cells found in most animals’ eyes. Because light-receptor cells in the retina can soak up light from every direction, pigmented cells work to block light from the back and the sides so animals can “see” what’s in front of them.
Now, however, the scientists have found two distinct groups of bristly, light-receptor cells concentrated at the bases and tips of the purple sea urchin’s 1,400-plus tube feet. These long, suction-tipped tubes, located on the undersides of sea urchin bodies, help the organisms move.
The team suspects that sea urchins use their tube feet as retinas and the rest of their bodies to shield against the extra incoming light, said researcher Maria Ina Arnone, a developmental biologist at Anton Dohrn Zoological Station in Naples, Italy.
Prior studies did find the number and placement of spines on a sea urchin could affect how sharp its vision might be, and this new find “might well be part of the picture,” Arnone added.
- Sea urchins use their entire body as an eye | Not Exactly Rocket Science (blogs.discovermagazine.com)
- Sea Urchin Breeding (reefwatch.wordpress.com)
- A really great quote about sea urchins (redecky.wordpress.com)
- How Do I Tell if My Sea Urchin is Male or Female? (brighthub.com)