Can organisms survive on Mars, and can we identify them?

Earth is a very special planet. It is the only celestial body in the solar system on which we know life exists. Could there be life on other planets or moons? Mars is always the first mentioned in this context; it has many ...

Getting out of hot water—does mobile DNA help?

Extremophiles—hardy organisms living in places that would kill most life on Earth—provide fascinating insights into evolution, metabolism and even possible extraterrestrial life. A new study provides insights into how ...

Image: Concordia Antarctic research station in winter

This modified container in Antarctica is part of the Franco–Italian Concordia research station and is used to store snow samples –and with temperatures regularly below –70°C no extra refrigeration is required. The ...

'Goldilocks Zone' may go colder than previously thought

( -- The survival of life on Earth is possible only within a relatively narrow temperature range known as the "Goldilocks Zone," which ranges from around 0 to 100°C. In many ecosystems life is limited by cold ...

Seeking Life's Shadow

They haven't yet figured out how to draw blood from stones, but a group of French researchers is offering new insight that could change how scientists search for signs of life in Martian rocks.


An extremophile (from Latin extremus meaning "extreme" and Greek philiā (φιλία) meaning "love") is an organism that thrives in physically or geochemically extreme conditions that are detrimental to most life on Earth. In contrast, organisms that live in more moderate environments may be termed mesophiles or neutrophiles. The category name is unfortunate as it calls for subjective judgements of two issues - firstly, the degree of deviation from 'normal' justifying the use of 'extreme', and secondly, whether the organism prefers the environment or merely tolerates it.

In the 1980s and 1990s, biologists found that microbial life has an amazing flexibility for surviving in extreme environments - niches that are extraordinarily hot, or acidic, for example - that would be completely inhospitable to complex organisms. Some scientists even concluded that life may have begun on Earth in hydrothermal vents far under the ocean's surface. According to astrophysicist Dr. Steinn Sigurdsson, "There are viable bacterial spores that have been found that are 40 million years old on Earth - and we know they're very hardened to radiation."

Most known extremophiles are microbes. The domain Archaea contains renowned examples, but extremophiles are present in numerous and diverse genetic lineages of both bacteria and archaeans. Furthermore, it is erroneous to use the term extremophile to encompass all archaeans, as some are mesophilic. Neither are all extremophiles unicellular; protostome animals found in similar environments include the Pompeii worm, the psychrophilic Grylloblattodea (insects), Antarctic krill (a crustacean) and Tardigrades (water bears).

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