[4] They are a distinct evolutionary branch of the Archaea distinguished by the possession of ether-linked lipids and the absence of murein in their cell walls.

[6] The extremely halophilic, aerobic members of Archaea are classified within the family Halobacteriaceae, order Halobacteriales in Class III.

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)[9] and National Center for Biotechnology Information (NCBI).

[2] Natronoarchaeaceae Haloparvum ** Halopenitus ** Halorubrum {Halorubraceae} Haloferacaceae Halobacteriaceae Haloarculaceae Halostella * {"Halostellaceae"} Halalkalicoccus {"Halalkalicoccaceae"} Halococcus {Halococcaceae} Salinarchaeum * {"Salinarchaeaceae"} Haladaptaceae (Halorubellaceae) Natrialbaceae Halorutilaceae Salinarchaeum * {"Salinarchaeaceae"} Halostella * {"Halostellaceae"} Natronoarchaeum {Natronoarchaeaceae} Natrialbaceae Halalkalicoccus {"Halalkalicoccaceae"} Haladaptaceae (Halorubellaceae) Halococcus {Halococcaceae} Haloarculaceae Halobacteriaceae Haloferacaceae (incl.

[21] The high solute concentration causes osmotic stress on microbes, which can cause cell lysis, unfolding of proteins, and inactivation of enzymes.

[22] Haloarchaea combat this by retaining compatible solutes such as potassium chloride (KCl) in their intracellular space to allow them to balance osmotic pressure.

Many haloarchaea also possess related pigments, including halorhodopsin, which pump chloride ions in the cell in response to photons, creating a voltage gradient and assisting in the production of energy from light.

One of the more unusually shaped Haloarchaea is the "Square Haloarchaeon of Walsby", classified in 2004 using a very low nutrition solution to allow growth along with a high salt concentration.

The presence of high salt concentrations in water lowers its freezing point, in theory allowing for halophiles to exist in saltwater on Mars.

[29] Haloarchaea have been proposed to help meet the high demand of carotenoids by pharmaceutical companies due to how easy it can be grown in a lab.

[30] Genes in Haloarchaea can also be manipulated in order to produce various strands of carotenoids, further helping meet pharmaceutical companies' needs.

If haloarchaea are complete denitrifiers, they could aid salt marshes and other salty environments by buffering these areas of nitrate and nitrite.

This means that if haloarchaea are used to treat areas that are high in nitrite and nitrate, they could contribute to nitrogen contaminates and cause an increase in ozone depletion, furthering climate change.