Psychrophiles include bacteria, lichens, snow algae, phytoplankton, fungi, and insects.
Among the bacteria that can tolerate extreme cold are Arthrobacter sp., Psychrobacter sp. and members of the genera Halomonas, Pseudomonas, Hyphomonas, and Sphingomonas. Another example is Chryseobacterium greenlandensis, a psychrophile that was found in 120,000-year-old ice.
Umbilicaria antarctica and Xanthoria elegans are lichens that have been recorded photosynthesizing at temperatures ranging down to −24 °C, and they can grow down to around −10 °C. Some multicellular eukaryotes can also be metabolically active at sub-zero temperatures, such as some conifers; those in the Chironomidae family are still active at −16 °C.
Microalgae that live in snow and ice include green, brown, and red algae. Snow algae species such as Chloromonas sp., Chlamydomonas sp., and Chlorella sp. are found in polar environments.
Some phytoplankton can tolerate extremely cold temperatures and high salinities that occur in brine channels when sea ice forms in polar oceans. Some examples are diatoms like Fragilariopsis cylindrus, Nitzchia lecointeii, Entomoneis kjellmanii, Nitzchia stellata, Thalassiosira australis, Berkelaya adeliense, and Navicula glaciei.
Penicillium is a genus of fungi found in a wide range of environments including extreme cold.
Among the psychrophile insects, the Grylloblattidae or ice crawlers, found on mountaintops, have optimal temperatures between 1–4 °C. The wingless midge (Chironomidae) Belgica antarctica can tolerate salt, being frozen and strong ultraviolet, and has the smallest known genome of any insect. The small genome, of 99 million base pairs, is thought to be adaptive to extreme environments.