Extremals and extremophiles are related concepts. These include animals that can live in an environment such as: boiling water, radiation, space, bitumen, the Dead Sea.
Of course, most of these animals are just bacteria and microorganisms, but among the extremophiles (the so-called organisms that can live and reproduce in extreme environmental conditions) there are also larger creatures.
Feed on oil
Last year, German scientists discovered a new species of anaerobic bacteria in Peach Lake on the Caribbean island of Trinidad. And everything would be fine if Peach Lake was not filled with bitumen instead of life-giving water. This lake is one of the largest natural reservoirs of bitumen on the planet.
Until this point, scientists believed that anaerobic bacteria are capable of degrading oil only in conditions where the oil environment borders on the water. But after studying the composition of the oil, the researchers found very small, no more than 1-3 microliters in size, drops of water, which are probably of underground origin. These tiny water bubbles are filled with complex groups of methane-producing microbes that break down the oil, changing its chemical composition, thereby forming a viscous bitumen.
Radiation as a resort
Apparently, this is how the gram-positive coccus with the characteristic name Deinococcus radiodurans perceives radiation, since it is able to survive at a dose of up to 10 thousand (!) Gy. For comparison: the lethal dose of radiation for humans is 5 Gy. Deinococcus radiodurans is considered one of the most radiation-resistant organisms in the world. How does he do it? The fact is that this bacterium stores in its cell several copies of the genome, packed in the form of a torus or rings. These additional copies allow the genome to be accurately reconstructed after multiple single- and double-stranded breaks.
Organisms that grow and reproduce at temperatures above 60 ° C are called hyperthermophiles. The optimum temperature for these "hot" lovers is 80 ° C, and some can withstand higher temperatures - over 100 ° C. Moreover, some of these creatures are also able to withstand acidity and radiation.
The thing is that hyperthermophiles belong to archaea - the oldest domain of living organisms, which are unicellular and, as you know, do not have either a nucleus or any membranes. The living conditions on our planet in those distant times, when archaea were widespread on it, were appropriate, so these creatures feel at home in them.
But hot water is not only loved by microorganisms. In the depths of the Caribbean Sea, near hydrothermal springs, beautiful polychaete worms live, which, however, hide their bodies in long chitinous tubes.
Such a hard-to-pronounce name is used to refer to living beings who, on the contrary, prefer low temperatures. Thus, the nematode Panagrolaimus davidi is able to survive being completely frozen in ice. Why are there nematodes - some tailed amphibians, such as the Siberian salamander (specimens were found that were numb in permafrost conditions from 80 to 100 years (!), And then returned safely to life), tailless amphibians, some species of turtles and snakes can freeze the water that is outside their cells in order to preserve their cells in conditions of prolonged low temperatures.
But the fish of the Notothenium family, which live in the waters of the Arctic and Antarctic, do swim at temperatures down to -1.9 ° C, which is close to freezing.There is no need to talk about bacteria: as studies of the subglacial Lake Vostok in Antarctica have shown, some of the microorganisms are able to survive, being frozen into the ice, for millions of years.
Lovers of salty
They are called halophiles - extremophiles, which prefer conditions with high salinity as a habitat - seas, salt lakes, saline soils, etc. Of course, the most extreme are the microbes that inhabit the depths of the Dead Sea. But there are also halophilic animals, mainly marine ones, which are unable to tolerate salinity below 30 ppm. These are radiolarians, reef-forming corals, inhabitants of the same coral reefs and mangroves, echinoderms, cephalopods, many species of crustaceans, etc.
In an airless space, living organisms are also able to survive. These include, for example, the tardigrade - a very interesting animal, a type of microscopic invertebrates close to arthropods. This quite cute "bear" is able to withstand incredibly low and extremely high (up to 100 ° C) temperatures, high levels of radiation, incredible pressure (similar to that which exists at the bottom of the Mariana Trench), lack of moisture for more than a hundred years and, finally, open space (scientists sent tardigrades into orbit).
It is thanks to the existence of extremophiles that scientists have the hope that we will be able to find life on the frozen moons of Jupiter and Saturn - Europa and Titan.