Which type of bacteria is known for existing in extreme environments?

Bacteria that thrive in extreme environments belong to a group called Archaebacteria. These microorganisms are unique because they possess distinct properties that allow them to survive in harsh conditions, such as high temperatures, high salinity, or extreme pH levels.

Archaebacteria have specialized membranes and cellular structures that enable them to withstand environments that would be inhospitable to most other life forms. For example, some species are known to live in hot springs and hydrothermal vents, where temperatures can exceed boiling point, while others flourish in highly acidic or alkaline conditions, or in salt-rich ecosystems like salt flats or salt mines.

In contrast, Eubacteria, while also diverse and widely distributed, typically inhabit more moderate environments such as soil, water, and the human body. Protozoa and fungi are not types of bacteria; they are different categories of organisms that have their own adaptations but do not specifically occupy the extreme environments dominated by Archaebacteria. Thus, Archaebacteria is the correct choice for bacteria that are adapted to extreme conditions.