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Reproduced from Shock and Holland (2007). Tap the image to reposition or zoom.
Shock, Everett L., and Melanie E. Holland. "Quantitative habitability." Astrobiology 7.6 (2007): 839-851.
Skills challenge
Skills challenge
Graph Guide
Graph Guide
Scientists analyze graphs (above). The graph is part of a research paper that looks at the types of environments (places) that are habitable (can support life).
Let's break looking at the graph into steps so we know what is shown.
The green square contains all the organisms we usually think of as being alive: not too hot and not too cold, not too acid and not to basic.
Each red dot in this graph is a living organism that lives in an extreme environment. These are called "extremophiles" (lovers of extremes).
The right side axis of the graph shows the temperature, from freezing 0 Celsius, to boiling 100 Celsius. Celsius and Centigrade are the same.
The left side axis explains where these temperatures are found on Earth.
At high pressure under the ocean, water boils at a higher temperature than at sea level. This means that underwater volcanoes can heat water to very high temperatures while remaining liquid.
The bottom axis of the graph shows the acidity in pH, with a neutral pH of 7 in the middle. You can see where different familiar items fall on the scale.
Chiswick Chap, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
On Earth, life is grouped into three main Domains and six Kingdoms. Their relatedness is shown on this diagram, all having evolved from a theoretical Last Universal Common Ancestor LUCA. We are more familiar with some of the Kingdoms within the Euykarya: animals, plants, and fungi which are organisms whose cells have a nucleus. But there are two others Domains calked Bacteria and Archaea. The single-celled organisms called Archaea live by volcanoes, under the ice, or other extreme environments. Bacteria are found everywhere there is life on Earth, and perhaps on moons like Europa.
The following image carousel shows some of the organisms that are on the graph, including animals, Archaea, and Bacteria.
"Strain 121" Archaea lookalikes. S. Skorstein, NOAA CC BY SA 2.0
Alvinellid worm. National Science Foundation (University of Delaware College of Marine Studies) Public Domain.
Sulfolobus Archaea. S Yiftah CC BY-SA 3.0 https://commons.wikimedia.org/wiki/File:Solfatara_volcano_Fumarole_6791.JPG
Winter midge (related to Himalaya midge). Owen Strickland. CC BY 4.0 https://www.inaturalist.org/photos/61987956
Picrophilius Archaea at Midway Basin, Yellowstone. Wing-Chi Poon CC BY SA 2.5
Do the Google Classroom assignment 1.1.2 Q
Do the Google Classroom assignment 1.1.2 Q
From the desk of Hannah Robinson
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