Of particular note are the extreme halophiles or halobacteria, a group of archaea, which require at least 2 M of salt and are usually found in saturated solutions. These are the primary inhabitants of salt lakes and inland seas, such as the Dead Sea, where they tint the sediments bright colors.
Among the adaptations that halophiles employ to survive in such environments are proteins designed to function in high ionic strength solution and maintaining high concentrations of inert solutes within their cytoplasm to reduce osmotic pressure. Most are unable to survive outside their high-salt native environment.
See also: Biosalinity, Halotolerance