Algae

It is not an natural algae, it was created in a lab by inserting a single new gene into the DNA of a type of algae. It allows the microscopic plant to thrive in darkness, growing vigorously without the need for sunlight, scientists say.

Here is a good article on this amazing discovery :

http://www.sciencedaily.com/releases/2001/06/010615072508.htm

The red algae , can survive at 4000 m deep , without light. 

Most blue algae need light, in order to life. In waters, the light radiation is absorbed which means that in lakes with the depth around 10m, only about 10 %, in the ocean, at depths around 100m, only about 1% of the light intensity is available. Despite that, there are still some algae, which can survive in 4000m deep ocean basins. These however aren’t blue, they are red- violet coloured, the reason why the Red Sea got its name. The assimilation reaches its upper boundary at temperatures around 65 degrees Celsius. In the hoisting sources of mineral, the blue algae are the only "settlers", which lead assimilation and are actively viable up to temperatures around 75 degrees. Interesting is however, that the blue algae do not grow at temperatures under 30 degrees Celsius. But there are also many blue algae, which can bear very low temperatures. Thus, they occur in the Antarctic under the conditions of the extreme heat lack (temperatures around -88 degrees Celsius). Because the blue algae possess the possibility of binding nitrogen, they can easily adapt to almost each ecological condition, which could be the reason why the algae are predominant in our waters.

http://library.thinkquest.org/27115/pages/algae/algae_bottom2.html 

i want to say that i think there are algae at the galapagoes thermal vents, and some in the trophosome of the giant tubeworm, living there in symbiosis. they use the sulfur dioxide that spews forth from the vents to undergo metabolic process, the best work was done in the late 80's i think, by arnes through scripps institute.  complete absence of light--

also, i believe we will find several species in lake bakail in siberia, as research has found freshwater seals, sea  lions, over2000 species of plants and animals, but still little bit ICE so lated--burrr. needs protection and reasearch workers...