An extremophile is an organism, usually unicellular, which thrives in or requires "extreme" conditions. The definition of "extreme" is anthropocentric; to the organism itself its environment is completely normal. Non-extremophilic organisms are called mesophiles.
Many extremophiles are members of the Archaea family, and indeed the terms are occasionally used interchangeably even though there are many mesophilic archaea as well as many extremophilic bacteria and eukarya. Not all extremophiles are unicellular. Examples of extremophilic metazoa are the psychrophilicGrylloblattodea (insects) and antarctic krill (crustaceans).
Types of extremophiles
There are many different classes of extremophiles, each corresponding to a the way its environments differs from what is considered normal. These classifications are not exclusive. Many extremophiles fall under multiple categories. For example, organisms living inside hot rocks deep under Earth's surface are both thermophilic and barophilic.
Alkaliphile: An organism with optimal growth at pH values of 9 and above.
Barophile: An organism that lives optimally at high hydrostatic pressure.
Oligotroph: An organism with optimal growth in nutrient limited conditions.
Psychrophile: An organism having a growth temperature optimum of 15 °C or lower, and a maximum temperature of 20 °C.
Toxitolerant: An organism able to withstand high levels of damaging agents. For example, living in water saturated with benzene, or in the water-core of a nuclear reactor (see Deinococcus radiodurans).
Xerotolerant: An organism capable of growth at low water activity. For example, extreme halophile or endolith.
"Extremophiles" is a term that refers to bacteria that are able to exist and thrive in environments that are extremely harsh (harsh, that is, in comparison with those environments classically envisioned as being hospitable to bacterial growth).
An extremophile is an organism, usually unicellular, which thrives in or requires 'extreme' conditions that would exceed optimal conditions for growth and reproduction in the majority of mesophilic terrestrial organisms.
Extremophiles are nature’s pioneers, organisms that not only survive but thrive in the harshest environments.
Extremophiles are simple organisms; they are single-celled or in a filament of identical cells in alignment.
Through the study of extremophiles, though, scientists have discovered that there are special proteins (also known as “molecular chaperones”) that are either manufactured or mobilized at times when conditions stress an organism almost to the point of death.
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