''Chlamydomonas nivalis'', also referred to as ''Chloromonas typhlos'',
is a
unicellular
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and ...
red-coloured
photosynthetic
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...
green alga
The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...
that is found in the
snowfield
A snow field, snowfield or neve is an accumulation of permanent snow and ice, typically found above the snow line, normally in mountainous and glacial terrain.
Glaciers originate in snowfields. The lower end of a glacier is usually free from ...
s of the
alps
The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...
and
polar region
The polar regions, also called the frigid geographical zone, zones or polar zones, of Earth are the regions of the planet that surround its geographical poles (the North Pole, North and South Poles), lying within the polar circles. These high l ...
s all over the world. They are one of the main algae responsible for causing the phenomenon of
watermelon snow
Watermelon snow, also called snow algae, pink snow, red snow, or blood snow, is a phenomenon caused by '' Chlamydomonas nivalis'', a species of green algae containing a secondary red carotenoid pigment (astaxanthin) in addition to chlorophyll. Unli ...
(also ''blood snow'', ''raspberry snow''), where patches of snow appear red or pink. The first account of microbial communities that form red snow was made by
Aristotle
Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...
. Researchers have been active in studying this organism for over 100 years.
Although ''C. nivalis'' is closely related to ''
Chlamydomonas reinhardtii
''Chlamydomonas reinhardtii'' is a single-cell green alga about 10 micrometres in diameter that swims with two flagella. It has a cell wall made of hydroxyproline-rich glycoproteins, a large cup-shaped chloroplast, a large pyrenoid, and an ...
'', the environmental conditions each species inhabits are very different. ''C. nivalis'' can be found in
mountain
A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited Summit (topography), summit area, and ...
s, snowfields, and polar regions around the world. The habitat of ''C. nivalis'' subjects the cells to environmental extremes including limited nutrients, low temperatures, and intense sunlight. In comparison with the
mesophilic
A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, with an optimum growth range from . The optimum growth temperature for these organisms is 37°C. The term is mainly applied to microorganisms. Organi ...
''C. reinhardtii'', ''C. nivalis'' has special mechanisms that allow it to be