I am a high school student. I'm doing a project where I need to find a planet in our galaxy that might be habitable. Then I need to create an organism that could live on that planet and justify everything about it Ex: Sight, whether or not it can see and why or why not / Touch / Smell / Respiration / Central Nervous System / Cell Count... My final outcome must have these and a lot more.

I just need to justify and explain where it lives on the planet I have chosen. I found a planet (Kepler-422b) which was described as being one of the most Earth-like planets, in terms of size and temperature, yet found. Since it is very Earth-like, it made my job a bit easier. But the planet orbits a red dwarf star that is cooler than our star, and this planet is -40 degrees Fahrenheit (80 degrees cooler than earth) so my organism will have to live in the ground of the planet and rely on the core for warmth. But I do not know how deep organisms can go into the Earth. Can someone please help me? I have done a lot of research and spent a lot of time trying to find this but extremophiles are the only organisms listed.

Thank you so much for helping me.

An extremophile is defined as a microorganism, especially an archaean, that lives in conditions of extreme temperature, acidity, alkalinity, or chemical concentration. Like the Tardigrade. Im sorry I did not make this clear initialy

  • $\begingroup$ Can you define what is an extremophile? It seems difficult to answer question when this is not properly defined. $\endgroup$
    – March Ho
    Apr 28, 2015 at 20:31
  • $\begingroup$ en.wikipedia.org/wiki/Gliese_422_b - It's like 10 times more massive than Earth - it's really not earthlike. Have you thought it out well? Also it's unconfirmed, so may don't even exist... $\endgroup$
    – Mithoron
    Apr 29, 2015 at 19:49

1 Answer 1


Welcome to Biology.SE and what a great project, it sounds fascinating!

A few years back there was an expedition that drilled down to the deepest layer of the ocean's crust. Down there they found hundreds of different species of bacteria (mostly Proteobacteria) surviving largely on hydrocarbons and other minerals found in the rock. The deepest (that was sequenced) was found 1391.01 mbsf (meters below sea floor) and survived at a temperature of about 102°C (215°F). Like I said, there were several species sequenced, so you could really use any of them that match your needs as at least a start to your organism.

This is the deepest point I know of that we have found life, and, considering your project, I don't think you have need to go much deeper. I assume Kepler-422b has liquid water (obviously not at the surface, but perhaps a few miles down)? If so, there is a chance that the water goes relatively close to that depth already.

I hope this helps and good luck!


Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2974637/

Edit: If you are looking for a multicellular organism that survives deep enough underground to rely on core warmth, I suggest Halicephalobus mephisto, a nematode living about 1.3 km underground at about 32°C (90°F). This is still considered an extremophile, however it is multicellular with a digestive tract, nervous system, etc. I apologize for the confusion in my initial answer and thanks to jamesqf for noticing my mistake. If you are not content with any extremophiles (even multicellular) please let me know and I will do my best to find something else. Again, I am very sorry for my error.

  • $\begingroup$ I think that living that far down makes them extremophiles, pretty much by definition. And for the OP, the planet could have an ice-covered internal ocean, like Jupiter's moon Europa. $\endgroup$
    – jamesqf
    Apr 28, 2015 at 4:25
  • $\begingroup$ As far as I know these species of bacteria are not officially considered extremophiles, I could be wrong though. I will pin-point a specific species and research it's classification tomorrow to confirm this though. $\endgroup$
    – CDB
    Apr 28, 2015 at 4:43
  • $\begingroup$ @jamesqf it would appear that you are correct. The mere fact that these bacteria can survive in this environment makes them extremophiles. For instance, Ralstonia pickettii was one of the species found and it can survive high concentrations of heavy metals and low nutrition, making it both Metallotolerant and Oligotrophic, however this species is not officially classified as an extremophile. This situation seems to be a double edged sword; an organism living deep enough underground to keep warm would need to be Metallotolerant, however an organism living on the surface must be Psychrophilic. $\endgroup$
    – CDB
    Apr 28, 2015 at 15:44
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    $\begingroup$ Just out of curiousity, when you say "not officially classified", who/what is the official doing the classifying? $\endgroup$
    – jamesqf
    Apr 28, 2015 at 18:28
  • $\begingroup$ You know, I'm actually not sure. I assume that it would be the team who discovered it. Usually anywhere you get reliable information on classification will specifically note that it is considered an extremophile and cite what type, but I'm not sure who officially decides. $\endgroup$
    – CDB
    Apr 28, 2015 at 18:37

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