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Let's talk science in the sky ecosystem!

One of the biggest problems with trying to make a sky ecosystem in an earthlike atmosphere is that there's just not a lot of nutrients in the sky; most of it comes from seaspray. Our sky plants are fairly slow-growing as a result. But I've been working on an idea for a way to bring a ton of nutrients up there really, really fast.


The hairy sky phlyer pees out of its skin and all over its trichomes, which then float through the air after being shed. That right there is conveniently packaged and dried nitrogenous compounds that can be taken up by sky flora, allowing them to grow a lot faster if there's a lot of it.

Right now, the hairy sky phlyer eats stuff from the sky ecosystem. Therefore, it isn't really giving back more than it takes. But perhaps a descendant could.

I have confidence that anything in Serina is probably biologically feasible, therefore I'm gonna take inspiration from a species there. The shadowskimmer is a giant bird that flies eternally, skimming for fish by night and soaring fast asleep at stratospheric heights by day. The hairy sky phlyer is much like the shadowskimmer in that it almost never lands and is able to reproduce without a nest; perhaps a descendant converges on it, swooping lower and lower for mistswarmers until it begins to dip its lower jaw into the ocean itself, causing it to incidentally start catching miniswarmers, krillpedes, and gilltails. As this is a much better food source than aeroplankton, I think it would quickly begin to evolve skim-feeding adaptations. It would be able to reproduce a lot more often thanks to the increased nutritional intake, resulting in a much larger population. This would also make it able to produce more trichomes, which are shed more often to remove the increased amount of waste. And as it soars by day, trichomes containing nitrogenous compounds from its urine fill the atmosphere to get caught and utilized by the sky plants.

Someone on a spec server I'm on likened this concept to marine snow, but in the sky. It would likely become a keystone species.

Ecosystems so often forget the role of parasites. If hairy sky phlyers had parasites that themselves could fly, float, or hitch a ride, and other things ate those parasites, it would increase the amount of nutrients they could give back to the ecosystem. Indeed, if these parasites got attached to its trichomes, shedding trichomes more frequently to get rid of parasites would also work. Blood tropoflies are the most convenient ancestor of faunal parasites, though surely not the only one. Skin flora (e.g., perhaps sloth-fur-algae-esque nimbuses, or pathogenic or commensal microbes), could also increase the nutritional value of the trichomes.

Creating the equivalent of ballooning spiders or especially high-flying spores or seeds (which should be easy for various boreal or alpine flora or those in especially windy places) would also increase the amount of food in that ecosystem.

The blood tropofly exists to decrease the amount of nutrient loss from flying herbivores, yes. That doesn't increase the amount of nutrients available though, just reduces the nutrient sink. The idea with ocean feeders that fill the sky with food is that they actively increase the amount of food available just by existing.

Would abyssal gigantism apply to the atmosphere

That's a good question.
Judging by a quick check of deep-sea gigantism, it's unclear what causes the phenomenon. Some of the proposed factors could be in place for a sky environment, with the notable exception of oxygen concentrations.
It's likely that larger organisms here would have proportionately large wings, and perhaps extra-large gas sacs, if they use those to float. Beyond that, it is uncertain. Fur or feathers is an option in this environment, and the temperature properties of air and water are different.

Abyssal gigantism is a competition thing (and, in real life, does not exist as it is described in the rules). It would not be a thing at all if fish were more suited to deep sea life.