also reproduce asexually through budding and fragmentation, where pieces of the cell break
off and form a new cell, also producing genetically identical organisms.
Types of Archaea
The first archaea described were unique in that they could survive in extremely harsh en-
vironments where no other organisms could survive. For example, thehalophiles, which
means ”salt-loving,” live in environments with high levels of salt (Figure8.11). They have
been identified in the Great Salt Lake in Utah and in the Dead Sea between Israel and
Jordan, which have salt concentrations several times that of the oceans.
Figure 8.11: Halophiles, like the Halobacterium shown here, require high salt concentrations.
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Thethermophileslive in extremely hot environments (Figure8.12). For example, they
can grow in hot springs, geysers, and near volcanoes. Unlike other organisms, they can thrive
in temperatures near 100ºC, the boiling point of water!
Methanogenscan also live in some strange places, such as swamps, and inside the guts
of cows and termites. They help these animals break down cellulose, a tough carbohydrate
made by plants (Figure8.13). This would be an example of a mutualistic relationship.
Methanogens are named for their waste product, methane, which they make as they use
hydrogen gas to reduce carbon dioxide and gain energy. Methane is a greenhouse gas and