Are there any species that would be able to sustain themselves on the sunlit face of the planet, the habitable Terminator-zone or even the freezing icy side of the planet? How would animals adapt to these environments? If needed, what genetic tweaks could be made to make some animals perfect for surviving in this new alien ecosystem?

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    $\begingroup$ Welcome to worldbuilding. As it stands now, your questions doesn't really meet our standards. First of all, there are 3 different questions, loosely related. Then, one of this is opinion based (we have no living being on a tidally locked world, how can we tell you which is the most suited?). Please take the tour and visit the help center to get familiar with our standards, then rework your question to fit them. $\endgroup$ – L.Dutch - Reinstate Monica Jun 11 at 8:22
  • $\begingroup$ Another thing that would be good in a future question is if you explained what some of the various concepts are when they aren't common knowledge or straight-forward. If you describe in your own words the consequences of a tidally-locked world we'll better understand what you envision. $\endgroup$ – Thymine Jun 11 at 9:33
  • $\begingroup$ Welcome to the site, QUESTER42. Please note that the Worldbuilding SE is dedicated to providing detailed answers to specific questions you have while developing your fictional world. To that end, we strongly encourage a question post to contain a single question; multiple questions is likely to get a post put on hold for being too broad. To avoid that action, I would suggest limiting this post to one question and asking follow-up questions later, linking back to this one if needed. $\endgroup$ – Frostfyre Jun 11 at 12:47

A tidally locked planet does not need to have the extremes of the scorching hot sun-facing side and nitrogen freezing cold side.

So you could have a planet which still has fairly "normal" living conditions. A planet that isn't super close to a star and has a thick atmosphere would be able to "regulate" it's temperature quite well.

But assuming you have a tidally locked planet with extreme conditions (such as Mercury) and animals similar to how they are on earth I would assume to following:

Sunny Side:

Surface temperatures of a couple of hundred degrees mean that animals would need to stay underground to not die. The only way an animal could live on the surface is if it would have some kind of highly reflective "umbrella" big enough to not only shield itself but also the surrounding ground.

Terminator Zone

Depending on how big your terminator is (the bigger the better), normal life as it is on earth would be possible.

Shade Side

Surface temperatures constantly under the freezing point of water and even air means that animals would need to stay underground so that they do not freeze.

I would suggest you watch this video from Isaac Arthur about humans colonizing Mercury. The video goes into great detail on what human life on such a planet would look like. These circumstances are the same for animals so you can adept human solutions to animal ones.


I would argue that any animal that can borrow underground will do great on this world. Flight wold be very difficult due to strong winds generated by the difference in temperature so bird like creatures are very unlikely to form. Cold blooded animals would exist but would be dominated by their warm blooded counterparts due to the fact that they cannot leave the warm side of the life belt. With the exception of flying animals I think you can have most of the animals that you have here on earth (but even those can exist).

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    $\begingroup$ You are answering only one of the 3 questions asked by the OP. This is why we generally advise against answering poorly asked questions, until they are fixed. $\endgroup$ – L.Dutch - Reinstate Monica Jun 11 at 9:02

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