Author: Skylear Shields

To explain the characteristics of Archaea, and to explain how they survive in extremities.

Archaeans are the prokaryotic cousins to Bacteria. Separated from aforementioned cousin in 1977, the archaean organisms have been researched independently through phylogenetics. They can live in extreme conditions, such as volcanic hot springs and acidic run-off, due to the unique enzymes that they produce.

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The Basics of Archaea

Unlike it's cousin domain, Bacteria, the Archaea domain has only recently popped up as a major group. The definitions for it's grouping are still debated, but here's the quite factual characteristics of Archaea...

  • They are prokaryotic cells, meaning they lack a nucleus and also lack organelles bound in membranes.
  • They live in the most extreme parts of out planet; in volcanic hot springs, some in acid drainage, and still others in colder places like the polar seas.
  • Archaea have genes more closely related to Eukaryotic cells.

For a little more than half of the 1900's, archaean organisms were classed together with bacteria. At that point in time, the visual and functional similarities between bacteria and archaea made it understandable to mix them. However, after discovering a new method in 1965, scientists were able to differentiate between bacteria and archaea via their gene sequences. This method was called phylogenetics.

It wasn't until 1977, however, that Carl Woese and George Fox classified Archaea as a group all their own. The argument for differentiating the two was that archaean organisms had unique ribosomal RNA gene sequences. After studying the phylogenetic tree of Archaea, it was found that archaean organisms have some connection to the evolution of Eukaryotic cells, but that's beyond the scope of this tutorial.

Archaea are also both autotropic (they make their own food) and heterotrophic (they consume other organisms).

Source: Wikipedia, Microbiology Textbook

The Extremists of Life on Earth

Archaeans are really neat, and that's mostly because of where they thrive. Unlike bacteria and eukaryotes, archaeans thrive in the most extreme places on earth. This unique characteristic defines them as extremophiles. Here's some of the places that archaeans thrive...


  • The extremely hot and acidic volcanic springs, such as the Grand Prismatic Spring at Yellowstone National Park.
  • Geysers and hydrothermal vents, such as El Tatio in Chile, and the "Godzilla" black smoker in Oregon.
  • Highly saline waters, such as the Great Salt Lakes.
  • The polar seas, near and under the north pole.
  • Highly acidic chemical waster run-off!

So what enables them to live in such insanely extreme environments? Enzymes. Those interesting proteins that speed up or enable different kinds of chemical reactions. Archaeans produce certain types of enzymes that protect against acids like sulfur. Strangely enough, the same enzymes protect against the salinity of the salt lakes and against the extreme hots and colds.