NE of Bermuda's leading marine research experts has taken part in an international scientific breakthrough which may have discovered the first example of an organism that lives off a light source other than the sun.

Gerry Plumley, Deputy Director, Senior Research Scientist and Education Director at the Bermuda Biological Station for Research (BBSR), dived nearly 8,000 feet at nine degrees north on the East Pacific Rise in the submersible to help find examples of a new bacterial species; "green sulphur" microbes were found at a hydrothermal vent a few hundred miles north of the Galapagos Islands, where Charles Darwin found many of the species which led him to the conclusion that all living creatures evolved by natural selection.

The recent announcement of the previously unknown bacterial species led magazine to suggest that the discovery that it derives energy from light despite living in the blackest depths of the ocean "threatens to overthrow the dogma that photosynthesis depends on the sun".

Indeed, a belief that the discovery of the microbe may offer clues about early life on Earth, or on other planets, helped Dr. Plumley win grants for the team from the US National Science Foundation (NSF) and from NASA, the National Aeronautic and Space Administration.

Dr. Plumley told the that the first scientist to propose that certain deep-dwelling species might get life-giving energy from a light source other than the sun was Cindy Van Dover, a marine biologist at the College of William and Mary in Williamsburg. In the late '80s, she found a vent-dwelling eyeless shrimp with a light-sensitive patch on its back.

"Cindy was the first female pilot of advised Dr. Plumley, "so she has a really long history of working at deep-sea vents. She decided to go back and do a PhD, and of course she was interested in vents, because she had spent years looking at them through the porthole.

"She had observed shrimps which appeared to have very unusual eyes, and eyes on a creature living in total darkness seemed to make no sense. What she reasoned was that the eyes of these shrimp were not seeing visible light, but were seeing heat."

Deep-sea hydrothermal vents are formed along mid-ocean ridges or at the edges of the 'plates' which form the surface of the planet. Cold seawater penetrates deep into those cracks in the Earth's crust, and the resulting superheated water rises rapidly from the vents in the ocean floor, often as black "smokers", because minerals flow out with the scalding water plume.

"She caught some of those shrimp on the sea-floor, and took their 'eyes' out, and analysed them, and realised they could see heat, the infrared," explained Dr. Plumley. "The electromagnetic spectrum goes from ultra-violet, through the visible, what we can see, to the red and the infrared. Cindy dissected the eyes and worked out what wave-length they could absorb."

Unsurprisingly, inch-long shrimp evolved to live 8,000 feet down do not do well at the surface; they are blinded by the light, and the change of pressure leads to their early demise.

Plumley, who spent 15 years at the University of Alaska after pursuing "doctoral and post-doctoral studies at the University of Georgia, described his involvement in the "green sulphur bacterium" project.

"Cindy and I were friends, and she had hypothesised that if there was infrared light at the vents, which she had proven, there could be photosynthetic 'bugs', and I have been studying photosynthesis for longer than I care to admit! I was the 'PI', the principal investigator, and wrote the proposals for the research, and helped assemble the teams," said Dr. Plumley.

Since their discovery in 1977, deep-ocean vents have revealed a variety of remarkable creatures, including two-foot tubeworms and crabs without eyes; they survive near the sulphur and mineral-laden plumes of 350-degree Centigrade water that vent from the ocean floor into the crushing darkness.

The first expedition, in 1999, to a vent in the depths of the Juan de Fuca plate off the coast of British Columbia ended as "a total disaster", Dr. Plumley reported. They "went super high-tech" in their efforts to find their quarry, over-estimated the prospects for locating the deep-dwelling microbes, and the ten-person team shrank to six for the second expedition; the six flew down to Manzanilla in Mexico in December of 2001, and set off aboard the Woods Hole Oceanographic Institute's for a spot in the Pacific about 1,400 miles south-west of Costa Rica.

"My specialty was analysis of the pigments that absorb light in the photosynthetic bacteria," he said. "We think that this is the first creature that gains energy from light in a non-solar environment. The shrimp are on the sea-floor using light to orientate themselves and to help them find food, but these photosynthetic microbes are using that infrared light at the vents food, as an energy source. That's what photosynthesis is ? the conversion of light energy to chemical energy."

Van Dover and Dr. Plumley began to work on this research project in 1998, and he sent off the proposals to the NSF and NASA in 1999.

"They totally rejected us!" Dr. Plumley recalled. "Or, more accurately, although they didn't completely close the door on us, they sat on our proposal for two years."

Eventually, the NSF contributed $130,000 and NASA $160,000, and the other seven members of the team were able to organise some funding.

Dr. J.Thomas Beatty, a microbiologist at the University of British Columbia, and the lead author of the paper describing the findings in the www.pnas.org), warned the that without further experiments there was no way of knowing for certain if the bacterium was actually photosynthesising, "but it seems likely that geothermal light is harvested and used."

After analysing the bacteria, the scientists discovered that they used light on the boundary between visible and infrared. Geothermal vents produce most of their radiation in the form of heat.

"The rates at which photons are emitted from these vents are pretty low," Dr. Beatty said. "It's very dim."

Dr. Beatty was the lead author of the paper, Dr. Plumley described it as a "collaborative effort. The first guy usually drafts it out, leaving large holes, and there were sections that each of us wrote, depending on what we did as part of the team, and then we all iron out the bigger implications, the story line, if you will."

The team comprised, in addition to Dr. Beatty, Dr. Van Dover and Dr. Plumley, microbiologists J?rg Overmann and Ann Manske of the University of Munich, Michael Lince and Robert Blankenship of the Department of Biochemistry at Arizona State, and Andrew Lang and Tracey Martinson of the University of Alaska's Institute of Marine Science.

"The cruises were over years ago, but it took an extraordinary amount of laboratory work when we came back. A dive takes one morning, to collect the samples takes thirty seconds after you have gone down nearly 8,000 feet, and then there are years in the lab!"

The findings may have implications for life on other worlds, according to the . Scientists have speculated that on planets far from a star like the heat-and-light-giving dwarf star we call the sun, life would have to be chemotrophic, using chemical rather than solar energy to grow.

By showing that an organism can use another form of light, Dr. Plumley and his colleagues have shown that new possibilities can be contemplated.

"The abundance of life on Earth is almost entirely due to biological photosynthesis, which depends on light energy," the paper began, but Dr. Beatty concluded that "our results indicate that it's possible that photosynthesis could (also) form the foundation for an ecosystem" on far distant worlds.