Thermophiles live in very hot places, typically from 60∘ to 80∘C. Many thermophiles (some eubacteria and archaebacteria) are autotrophs and have metabolisms based on sulphur. Some thermophilic archaebacteria form the basis of food webs around deep-sea thermal vents, where they must withstand extreme temperature and pressures. Archaebacteria can grow in highly acidic (pH=0.7) and very basic (pH=11) environments.