Life in the deep sea

The seabed of our planet is teeming with life forms unknown, according to an article in the journal Nature. Bacteria on the seabed could be older than life on the planet's surface.

Scientists suggest that between 60% and 70% of all bacteria live deep in the seabed of the Earth, away from sunlight. Some of the new bacteria identified are about 16 million years and survived some 400 meters deep.

Experts estimate that this hostile habitat might be the place where some of the earliest forms of life more than 3,800 million years. "There is evidence that life arose in the deep sediments," he told the BBC co-author, John Parkes, of Cardiff University in the UK.

"There is clear evidence that life existed more than 3,800 million years." "Although biomass to become large enough that we could detect in the rocks, their development must have started long before that," he explained.

Hostile

Before that period, the surface of the Earth was a very hostile place, beaten by meteorites and volcanic eruptions. Dr. Parkes thinks deep sediments may have been a more propitious for the emergence of life.

"It could be that life was unfolding beneath the sea long before, where it was protected from the impacts of meteorites," said Parkes. "And as soon as the land area became a more hospitable, the bacteria could ascend and colonize" he added.

Energy Source

Traditional knowledge does not establish that life arose in the deep, in fact dictates that nothing can exist there. There is evidence that life arose in the deep sediments

John Parkes, researcher

"A classic publication of the 1950s claimed that life stopped a few feet of the surface sediments," said Parkes. "And now we find excess bodies 800 meters deep," said the scientist. Experts had good reason to believe that life could not exist well below the surface of the Earth. Life needs energy and there was no obvious source there.

"The usual approach of life on Earth is that in most cases, the surface is powered by sunlight," said the scientist. "And do not expect a large population, even bacteria, survive away from that source of energy," he added.

"But we're finding that there are a number of geological sources of energy below the surface. For example, there are many processes that produce hydrogen, which is a good source of energy for bacteria." The oldest evidence of life on rocky sediments and was found a few years ago, but until now it was thought that most of them were dead.

New Technique

In the past, scientists had to bacterial cells that contrast against the sediment, but this method does not differentiate between living cells and dead cells. Dr. Parkes and his team used a new technique that could identify living cells and were surprised to find that 30% of the cell samples made deep sediments were alive.

"We sampled sediments and dyed the living component of each cell so it could count living cells," said Parkes. "This reinforces the idea that this large bacterial biosphere is in fact alive and not a fossil." Some of the cells are embedded in sediments that are millions of years old, which mean they must be the same age.

"These bacteria are growing in the seabed" Parkes said. "They could be in effect immortal," he said.