Cell walls are pigmented in some forms of algae and present, generally, a brownish caste to the plants. Habitats Algae can be found in habitats ranging from snow fields to animal hair. Some species can exist at 70 C while others grow at subfreezing temperatures. There are taxa that are symbiotic with other algae, vascular plants, fungi, and animals. Some taxa can tolerate and even flourish in waters with a pH of 3.0 while others flourish in strongly alkaline areas.
Many species are strictly freshwater, some are stenohaline, and others are euryhaline.
There are a variety of terms that apply to algae that occupy specific sites. Benthic algae are generally attached to some substrate. Epilithic algae are attached to rock, epiphytic algae are attached to plants, and epizoic algae are attached to animal carapaces, hairs, and other features of animals. Psammon are those algae attached to sand particles. Tychoplankton are algae generally drifting in flowing waters of creeks, streams, and rivers that have become detached from some form of substrate.