noun, plural: barophiles
A barophile is an organism that needs a high-pressure environment in order to grow. Barophiles are a type of an extremophile. An example of a high-pressure habitat is the deep-sea environment, such as ocean floors and dee lakes where the pressure can exceed 380 atm. Another is the subsurface rocks with high lithostatic pressures.
Barophiles that cannot survive outside their high-pressure habitats are referred to as obligate barophiles. Those that can live at high pressures and in less extreme environment are referred to as barotolerants. Halomonas salaria, a Gram-negative proteobacterium, is an example of an obligate barophile. It needs a pressure of 1000 atm.
Many barophiles are sensitive to ultraviolet rays and are susceptible to UV radiation. They lack the essential mechanisms of DNA repair to counter the effects of UV radiation. Thus, many of them grow in darkness. Because of this, they also tend to be psychrophilic. That means they live under cold temperatures, e.g. about 2-3 °C below 100 m.
Another example of barophile is the xenophyophores, which are single-celled eukaryotes found in the deepest ocean trench (i.e. about 6.6 miles below the surface).