Archaea and the hotpots of Yellowstone

A lecture for college biology students.

Archaea are the extremists. They are also ancient. Most have a group name that ends in -phile, ie extremophiles, halophiles, thermophiles. They are the lovers of the extreme environments (-phile means loving, halo = salt, thermo = heat). One extreme environment relatively close to us is a geothermal hotspring. 

In fact, it is in Yellowstone that biologists (Woese et al mentioned above) first came to conclude that Archaeans needed their own phylogenetic group. Less than 70 years ago, we had no idea that Archaea existed. When first discovered, they were thought to be closely related to bacteria and so they were called archaebacteria. We now understand that Archaea are unique. Although they are unicellular prokaryotes like bacteria, they have similar genes and DNA biochemistry to eukaryotes. They employ alternate biochemical pathways for cellular respiration. In other words, they are autotrophs, but they do not use oxygen as the primary electron receptor. The Yellowstone Archaea are chemoautotrophs. The Sulfolobus archaea found in Yellowstone use hydrogen, sulfur, and carbon dioxide for their metabolic processes.  

National Park Service (NPS). 2019. Yellowstone: Thermophilic Archaea.

Speer, B.R. and Waggoner, B. 2001. Introduction to the Archaea: Life’s extremists. UC Berkeley. Retrieved from

Hotsprings in Yellowstone anyone? I got my suit! JK. This is NOT one of the ones into which you can dip your delicate biological self. 🙂

That being said, some of the most breath-taking wilderness experiences I have ever had involved cross-country skiing into remote hotsprings in Yellowstone in the winter. For winter soaking, it’s something like this photo depicts (below)…you soak where the geothermally heated water mixes with the river. And I suppose the Archaea are diluted as well. I am not sure if any Archaean organisms are part of the human microbiome or not…

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