Wednesday, March 10, 1999 Published at 19:06 GMT
Shrimps blinded by science
The shrimp's specially adapted eye occupies about half of its back
Shrimps are literally being blinded by science, British biologists believe.
The biologists vacuumed up shrimps from the ocean floor into a blackout chamber. In the laboratory, they found that some had shiny pink eyes whilst others had matt, chalky white eyes.
Dr Gaten told BBC News Online: "I found the white ones had no photosensitive layer left. What effectively is the retina had been completely destroyed."
"This was almost certainly caused by the bright searchlights on the submersibles that scientists use to sample the vents. It's an unfortunate case of scientists blinding the shrimps without realising it."
This discovery means that previous observations of the shrimps' behaviour around the vents may not be reliable, as their eyesight, "exquisitely adapted for dim conditions" had been destroyed.
Using searchlights is unavoidable at the moment says Dr Gaten: "You can't do anything else. It's a very dangerous place at the bottom of the sea, with the rough volcanic landscape, and pilots must have strong lights to see.
"We have suggested using infrared for navigation near the vents, and also suggested using side-scan sonar. But these are expensive to develop and the pilots really want to see. I certainly wouldn't go down there without plenty of lights."
The shrimps, from the Bresiliidae family, were collected at the Rainbow site on the Mid-Atlantic Ridge, a volcanically-active place where the Earth's crust is splitting apart.
The biologists believe the damage takes up to a few weeks to sink in. This would explain why both seeing (pink-eyed) and blind (white-eyed) shrimps were found. The site had been visited a month before, so those caught in the headlights then were now blind. Those lucky to escape still had working pink eyes.
The study is published in Nature.