Lake Vostok is a body of water buried nearly 4 kilometers underneath nearly Antarctica's glaciers. Scientists believe it has been isolated from the atmosphere since the middle Miocene , some 15 million years ago, and it is subject to extremes of pressure and nutrient deprivation. In order to find out whether life exists under such conditions, Russian scientists have drilling through the overlying ice, recently reaching the surface of the lake. Recently, a team analyzed ice cores dating from 1998, from depths representing a mixture of glacial and lake waters, for DNA content.
What they found was pretty surprising. It has become almost routine to find microbial life in very harsh corners of the earth, from hot vents to the depths of abandoned mines; and, in fact, previous studies of Lake Vostok accretion ice suggested that hot vent bacteria might be present in the lake. But the DNA recovered from Lake Vostok in this study also contained sequences with similarity to the animal kingdom. Specifically, they found DNA evidence for worms, mollusks and sea anemones. All of these species are also found near deep-sea hydrothermal vents-- so, the authors of this paper contend that animals may live in a hydrothermal vent community. Indeed, the geology of the Lake Vostok region has some resemblance to volcanically formed subglacial lakes in Iceland.
This suggestion has received some criticism from other Antarctic researchers-- mainly following the dictum that extraordinary claims require extraordinary evidence. The lake is really cold and under tremendous pressure. The possibility of a multicellular organism surviving down there seems so remote, that the possibility of a technical problem, such as contamination of the experiment, starts to loom. For example, the Russian drillers have used kerosene to aid the drilling, introducing a possible source of DNA. Finally, the extreme cold itself may have preserved non-Antarctic DNA which blows in and can be detected in the surface ices. Thus, without extreme care, the animal sequences may be real but might not be from the lake.
Future experiments may resolve what critters might be living in such a harsh environment. It represents the nearest thing yet to an extraterrerstrial environment.