Sunday, June 15, 2008
Hairy Blobs,Evolutionary Biology. & Life on Mars
"Hairy Blobs" Discovered in Acidic Lake Could Have Evolved on Mars
At last, scientists have discovered a form of life that could have evolved on Mars. Geologists unearthed a treasure trove of fossilized remains in a salty, acidic lake in remote Australia — the creatures, probably about 250 million years old, were, according to New Scientist, "made up of a mix of inorganic crystals and 'hairs' stuck together in a mass" (pictured). The lake where they lived was filled with water whose extreme levels of salinity and acidity are a near-match for Martian water. Find out more, plus see more cool pictures of the blobs, below.
According to New Scientist:
Kathleen Benison, a geologist at Central Michigan University, Mount Pleasant, led a team that studied the sediments formed by acidic and very salty lakes in modern day Western Australia, and those deposited around 250 million years ago in North Dakota. It is very difficult to survive in such a tough environments and few signs of life have ever been found in these sorts of lakes.
Inside the halite and gypsum "evaporate" minerals, which form as the lake waters dry up, Benison and colleagues found previously unknown fossilised blobs at both the modern and ancient sites, ranging in size from 0.05 to 1.5 millimetres. They were made up of a mix of inorganic crystals and "hairs" stuck together in a mass (pictured). They named them hairy blobs.
The team argues that each hair was in fact a separate microorganism because the hair fossils are made of disordered graphite which, unlike inorganic graphite, has irregular layers that suggest it was once a live organism..
Many of the hairs are coated with crystals of gypsum, a calcium sulphate mineral. This link with gypsum suggests that the microorganisms were fuelled by chemical interactions with sulphur in the acidic water - which helped the gypsum to form.
Scientists are still divided on whether these crystal-hair creatures actually count as "life." As they run further tests on the fossils, the mere existence of such creatures fuels hope among astrobiologists that life could indeed have evolved on Mars and we might get a chance to meet it — or at least, to find its fossilized remains.
Salutations to Dad2059’s Blog for the above, "Hairy Blobs", article...
Evolutionary bioligist Olivia Judson has some interesting information to add to all this in her always interesting blog where she talks about the organisms that live in rocks deep in the earth.
Meet the Intraterrestrials
Some weeks ago, I wrote about microbes in the air and their possible role in helping clouds form, in causing rain and in altering the chemistry of the high atmosphere. This week, I want to go in the opposite direction and plunge down into the earth. For many bacteria live deep in the oceans and deep in the earth, far from light, far from what we normally think of as good, comfortable places to live.
For example: the bottom of the Mariana Trench. This is a seam on the sea floor in the northwestern Pacific, not far from the island of Guam; it’s where the Pacific plate is sliding under the Philippine plate. The ocean is deeper here than anywhere else in the world: the seabed is 11 kilometers (almost 7 miles) below the surface of the sea. Yet even here, where the pressure of the water would crush you or me, there are bacteria. Some of them won’t grow at all unless the atmospheric pressure is at least 50 megapascals (around 7,000 pounds per square inch), and they grow better if the pressure is greater — 70 megapascals (more than 10,000 pounds per square inch). For comparison, the pressure at sea level — the pressure we have evolved to bear — is 700 times less.
Then there are the “intraterrestrials” — the organisms that live in rocks deep in the earth, the creatures of the “deep subsurface biosphere.” Bacteria have been found in rock samples taken several hundred meters below the sea floor, even when the sea floor itself is 4 kilometers (2.5 miles) below sea level.
We don’t know how many organisms are living in this (to us) alien environment. But based on what’s been found in rock samples so far, the numbers are likely to be gigantic. One recent study found between 1 million and 1 billion bacteria per gram of rock (a gram is 1/28 of an ounce). It may be that a large proportion — perhaps as many as a third — of all bacteria on Earth live in rocks below the floor of the sea. That would be a lot of bacteria.
Until recently, it was assumed that the chemical alteration and decomposition of rocks in the ocean crust was due purely to elemental forces — the circulation of seawater, the grinding of rocks against one another. But increasingly, intraterrestrial bacteria are suspected of making a contribution, too. Shards of volcanic glass from basaltic rocks hundreds of meters beneath the seabed show grooves and etchings that appear to have been made by bacteria.
Hmm, life seems to be a bit more prolific than we thought. Perhaps a closer examination of the fossiles from astroids, comets, and such places is in order...G: