They are common in hypersaline seas, salt evaporation pools, salted meats, dry soil, salt marshes, etc. They are also found in subterranean salt deposits, where micropockets of saturated water 'diffuse' around in the otherwise solid salt. For this reason, there is little or no net osmotic pressure on the cell wall, and some organisms take advantage of this by adopting high surface-area shapes that are not possible for organisms in 'normal' ionic strength. One example is Haloarcula , which comes in squares and triangles with straight edges, sharp corners, and is very flat. Other halophiles are rods or cocci.
Halophiles are mesophilic facultative aerobes.
Aerobically, they grow heterotrophically, via respiration, using O 2 as the terminal electron acceptor. They do not contain the usual photosystems or electron transport chain for gathering energy from light. Phototrophy is driven by a single protein, bacteriorhodopsin, that is a light-driven proton pump. This proton pump generates a proton gradient used to make ATP via ATPase, just like in other organisms. It's not nearly as efficient as the bacterial photosystems, but light is rarely limiting for growth in the desert salt lakes where they predominate.