Tiny shrimps hold clue to alien life

A tiny shrimp residing at one of the world's deepest undersea hydrothermal vents holds clues about what life could be like on other planets, NASA scientists report.

These tiny shrimps in the Caribbean are piled on top of each other, layer upon layer, crawling on rock chimneys that spew hot water.

Bacteria inside the shrimps' mouths and in their specially evolved gill covers produce organic matter that feed the crustaceans.

"For two-thirds of the Earth's history, life has existed only as microbial life. On Europa (Jupiter's moon), the best chance for life would be microbial," said Max Coleman, senior research scientist at the NASA's Jet Propulsion Laboratory (JPL) in the US, in a statement.

The particular bacteria in the vents are able to survive in extreme environments because of chemosynthesis - a process that works in the absence of sunlight and involves organisms getting energy from chemical reactions.

In this case, the bacteria use hydrogen sulphide, a chemical abundant at the vents, to make organic matter.

"The overall objective of our research is to see how much life or biomass can be supported by the chemical energy of the hot submarine springs," Coleman added.

Hydrogen sulphide is toxic to organisms in high concentrations but the bacteria feeding the shrimp need a certain amount of this chemical to survive.

Nature has worked out a solution: The shrimp position themselves on the very border between normal, oxygenated ocean water and sulphide-rich water so that they and the bacteria can coexist in harmony.

"Whether an animal like this could exist on Europa heavily depends on the actual amount of energy that is released there through hydrothermal vents," said Emma Versteegh, a postdoctoral fellow at JPL.