Xenophyophores

Xenophyroes Image NOOA wikimedia

For your convenience I copy first paragraph of the wikipedia article

Xenophyophores are giant unicellular organisms found throughout the world's oceans, at depths of up to 10,641 meters (6.6 miles). When first described in 1889, the xenophyophores were placed with the sponges. Later they were classified as testate amoeboids (Arcellinida), then in their own phylum of Protista.

A recent genetic study suggests the xenophyophores are a specialized group of Foraminifera.

Xenophyophores are found in the greatest numbers on the abyssal plains of the deep ocean. They are placed in two orders in 13 genera with approximately 42 recognized species; one species,

Syringammina fragilissima, is among the largest known single-celled organisms at up to 20 centimetres in diameter.
Read the entire wikipedia article from here

Mariana Trench

Mariana Trench
Image wikimedia

"The deepest place in the ocean is teeming with microscopic life, a study suggests.

An international team of scientists found that the very bottom of the Mariana Trench, which lies almost 11km (7 miles) down in the Pacific Ocean, had high levels of microbial activity.

The research is published in the journal Nature Geoscience.

The underwater canyon was once thought to be too hostile an environment for life to exist.

But this study adds to a growing body of evidence that a range of creatures can cope with the near-freezing temperatures, immense pressures and complete darkness.

Dr Robert Turnewitsch, one of the authors of the paper from the Scottish Association for Marine Science, said: "The deepest parts of the deep sea are certainly not dead zones."
Rebecca Morelle
BBC Science news March 18, 2013 

Wikipedia tells about the environment in this deepest trench on Earth

The Mariana Trench or Marianas Trench is the deepest part of the world's oceans. It is located in the western Pacific Ocean, to the east of the Mariana Islands. The trench is about 2,550 kilometres (1,580 mi) long but has an average width of only 69 kilometres (43 mi). It reaches a maximum-known depth of 10.911 km (10,911 ± 40 m) or 6.831 mi (36,069 ± 131 ft) at the Challenger Deep, a small slot-shaped valley in its floor, at its southern end, although some unrepeated measurements place the deepest portion at 11.03 kilometres (6.85 mi).

At the bottom of the trench the water column above exerts a pressure of 1,086 bars (15,750 psi), over one thousand times the standard atmospheric pressure at sea level. At this pressure the density of water is increased by 4.96%, making ninety-five litres of water under the pressure of the Challenger Deep contain the same mass as a hundred litres at the surface. The temperature at the bottom is 1 to 4 ⁰C.

The trench is not the part of the seafloor closest to the center of the Earth. This is because the Earth is not a perfect sphere: its radius is about 25 kilometres (16 mi) less at the poles than at the equator.[5] As a result, parts of the Arctic Ocean seabed are at least 13 kilometres (8.1 mi) closer to the Earth's center than the Challenger Deep seafloor.

Xenophyophores have been found in the trench by Scripps Institution of Oceanography researchers at a record depth of 10.6 km (6.6 mi) below the sea surface. In 17 March 2013, researchers reported data that suggested microbial life forms thrive in the Mariana Trench. Other researchers reported related studies that microbes thrive inside rocks up to 1900 feet below the sea floor under 8500 feet of ocean off the coast of the north western United States. According to one of the researchers,"You can find microbes everywhere — they're extremely adaptable to conditions, and survive wherever they are."

Read the entire wikipedia article from here

Tardigrade!

Tardigrade!
Image Eye of Science APOD 

"Is this an alien? Probably not, but of all the animals on Earth, the tardigrade might be the best candidate. That's because tardigrades are known to be able to go for decades without food or water, to survive temperatures from near absolute zero to well above the boiling point of water, to survive pressures from near zero to well above that on ocean floors, and to survive direct exposure to dangerous radiations...."
March 6, 2013 APOD 

Bookmarked here because IMHO this is the most striking and educational image so far in the glorious gallery of APOD 2013.