A few days ago I asked this question. In it asked about flora that could survive under a permanently dark sky.

In this regard this regard this question is quite similar. Though now the question is what kind of fauna can survive under these conditions?


  1. Assume an European ecosystems
  2. 90% to 98% of sunlight is blocked
  3. Higher frequency = higher block %
  4. Lower frequency = lower block %
  5. The conditions are PERMANENT

Ignore the following

  1. Temperatures differences
  2. Changes to wind and rain
  3. Microbes and ocean life

Established flora

Here is how the flora looks in my world. If you want additional information read the accepted answer in the previous question.

  1. There is a lot of dead biomass
  2. Mushrooms and molds run rampant
  3. There are some low low light plants
  4. Rare spots with dense low light vegetation.

Structure of the Solution

By many solutions

Name what can survive in broad categories and don't focus on individual species.

By a few solutions

Name the individual species that could survive.

By no solution

Just say so, having no possible surviving species is also a valid solution.

Related questions:

Part 1: What flora can survive a permanently dark sky?

Part 3: Living under a permanent dark

Related: Highly resistant House Plant

  • $\begingroup$ Approximately how long after the darkening are we talking about? $\endgroup$
    – g s
    Apr 13 at 23:01
  • $\begingroup$ @g s go with around 150 years of worsening conditions leading eventually to this point. $\endgroup$ Apr 13 at 23:07
  • 1
    $\begingroup$ The olm. $\endgroup$ Apr 14 at 13:33
  • 1
    $\begingroup$ You have created a new mass extinction, most every dies, only a few small fecund generalists survive by basically pure luck. Just like every mass extinction. $\endgroup$
    – John
    Apr 14 at 23:54
  • 2
    $\begingroup$ small fecund generalists, past that its pure luck. $\endgroup$
    – John
    Apr 15 at 20:15

3 Answers 3


As long as there something to feed on, some fauna can survive.

Look at the black smokers at the bottom of the ocean: the flora thriving on the chemicals emitted by the smokers sustain a good amount of fauna.

In your case you would have fauna feeding on dead biomass, mold and the few plants able to survive in the environment. You will hardly have any megafauna, but invertebrates (worms, insects, slugs, snails...) would surely manage.

  • 1
    $\begingroup$ Would manage for a while. $\endgroup$ Apr 14 at 3:08
  • $\begingroup$ @L.Dutch thanks you for your input. While i know it's been a while do you think sone niche selection of bigger animals could potentially manage to survive? Like maybe the size of wolf's or something. $\endgroup$ May 1 at 7:46

Some thoughts:

If there's an average of 5% of the available solar power, there's a lot less growth and death of plants. Maybe 5% as much, but assuming a linear relationship seems like a risky assumption. This means a lot less calories are available for microbes and animals. This is going to favor small animals over big ones.

By 150 years after the event, almost all of the high-sun plants are probably extinct or almost extinct. Animals that depend on those are probably also extinct, as are animals that depend on those animals. I think there's a lot of cross-over with large animals, here. I'd guess that almost all herbivores bigger than a human are extinct.

Since oceans are unaffected, any land animals that can prey on ocean creatures for most of their calories - including humans - will thrive on coastlines. With human predation greatly diminished by the collapse of the human population in the first decades after the event, fish populations should be back up to their ancient levels by now. Many ocean fish have lots of vitamin D, which means that even dark-skinned humans living in cold places will be okay. Low-light-plant based agriculture will still be possible in such places but yields will be small.

Pale-skinned humans who can synthesize adequate vitamin D from scarce sunlight, living in warm regions where they don't have to wear much clothing, and where the growing season is long and the soil is good, will be able to have a plant-focused diet based on low-light crops.

Large predators which can't get much of their diet from the ocean are probably also almost all extinct.

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    $\begingroup$ @g s the oceans being unaffected is not entirely true they are effected differently. I just left out asking how they would be effected to narrow down the scope of the question. $\endgroup$ Apr 14 at 6:56
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    $\begingroup$ 20x as much farmland is unnecessary if they change over to low-light crops. You bring your northern crops down south and they will make way better use out of what sunlight they do get as the old crops did. $\endgroup$
    – Nosajimiki
    Apr 16 at 19:58
  • $\begingroup$ @nosajimiki good point, will edit $\endgroup$
    – g s
    Apr 16 at 20:49
  • $\begingroup$ @Fallenspacerock the oceans part is quite crucial. If oceans were unaffected then I agree that the fauna (at least on the larger side) would be dominated by fish eaters... think seals, dolphins, wales, cormorants, sea gulls, fishing eagles, etc. Obviously only on/near water. $\endgroup$
    – fgysin
    May 3 at 11:17
  • $\begingroup$ @fgysin the oceans are effected differently but they aren't doing to well either. What i had in mind are that they are polluted and full of things that thrive in such water like a certain kind of algae. But assume for the sake of this question that my fauna gains no nourishment from there. $\endgroup$ May 3 at 13:04

Life requires energy flux. In current ecosystems we're most familiar with, solar energy coming from the sun provides most of that flux. There are niche ecosystems that use other sources of energy. We have been instructed to ignore "temperatures differences", but this is the key to the whole thing. Assuming that temperature is somehow maintained over a significant time period of complete darkness (days, months, years), then there must either be a magical force adding energy to the system at the same rate that Earth is radiating it to the new darkness, or the emission spectra of the Earth must be magically changed drastically. The former obviously provides a source of energy flux for life trivially, and the latter likely does too, depending on the mechanism. So -- the same magic that maintains your temperature, which we are ignoring, can trivially maintain whatever ecosystem you want.

  • $\begingroup$ Yes this is essentially how it would work though the exact mechanism aren't fully worked out. That is why i have hardly mentioned them. I n regards to the ecosystem in think it depends on the kind of energy we are talking about. Sure there are beings in my world that use supernatural energy. But this question is about what what creatures would survive with the establishment plant live and what ever eats these herbivores. $\endgroup$ May 3 at 13:00

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