Could large organisms on a nutrient-poor world be inflatable?

[Lren Zvsm]

I'd like some input in this speculation about aliens: On a world that was nutrient-poor compared to Earth, there could of course be a lot of microbes, but macroscopic organisms (visible to the naked eye from 20 feet) would have trouble developing because there wouldn't be enough nutrients to nourish all of their flesh. But suppose that the macroscopic organisms were mostly composed of air rather than flesh? Such living balloon animals would not need as much nutrition as Earth animals of comparable volume. They couldn't compete with Earth animals--but they're not on Earth. They're on a different planet whose macroscopic life is dominated by balloon net oxygen producers and balloon net CO2 producers. Come to think of it, they wouldn't need as much oxygen or CO2 as Earth organisms of comparable volume. Thoughts?

 

[Lren Zvsm]

Could these "balloon" organisms reproduce by budding? Could they be sapient?

 

[member 656954]

Could they be sapient?

Do you mean 'sentient'?

On a world that was nutrient-poor compared to Earth

Presumably, the early-Earth was 'nutrient poor' but life still developed into complex forms, so perhaps this is more a function of population size, rather than how complex they are?

But suppose that the macroscopic organisms were mostly composed of air rather than flesh?

It's not obvious how an air organism would evolve - or why they would evolve - merely from lack of nutrients. What competitive pressure do you fee would force them along that line?

 

[Klystron]

Consider 'inflatable' and floating organisms on Earth as a point of departure for alien life.

Most jellyfish 'inflate' with surrounding seawater, while some species of man-of-wars use a gas-filled bladder IIRC. Giant California kelp grow flotation bladders inflated with produced gas. Puffer fish inflate with a mixture of internal oxygen and surrounding water. Many fish species compensate for buoyancy by inflating and deflating internal swim bladders. As a related aside, many fish species control internal salinity and PH by various methods to excrete 'fresh' water and intake seawater via osmosis.

Thus, your alien life forms whether classified as animal, vegetable or bacteria would likely develop flotation organs consistent with their environment.

 

[Lren Zvsm]

[Do you mean 'sentient'?]

With all due respect to the writers on Star Trek: The Next Generation, "sentient" does not mean "intelligent at the human level." It simply refers to creatures who most likely have experiences, sensations and feelings: https://www.merriam-webster.com/dictionary/sentient

The word "sapient," means "wise or sagacious". It is part of the Latin name of our species, and so can be used to mean "intelligent" when used to refer to species. https://www.merriam-webster.com/dictionary/sapient#synonyms

[Presumably, the early-Earth was 'nutrient poor' but life still developed into complex forms, so perhaps this is more a function of population size, rather than how complex they are?]

By the time complex, multicellular life evolved, Earth was far from nutrient poor.

[It's not obvious how an air organism would evolve - or why they would evolve - merely from lack of nutrients. What competitive pressure do you fee would force them along that line?]

Macroscopic multicellular "balloon life" would do better on a permanently nutrient poor planet--or biome-- because of the advantage of having a heck of a lot less flesh to oxygenate, hydrate, and feed than an Earth animal of similar volume.

 

[Lren Zvsm]

Do you mean 'sentient'?

With all due respect to the writers on Star Trek: The Next Generation, "sentient" does not mean "intelligent at the human level." It simply refers to creatures who most likely have experiences, sensations and feelings: https://www.merriam-webster.com/dictionary/sentient

The word "sapient," means "wise or sagacious". It is part of the Latin name of our species, and so can be used to mean "intelligent" when used to refer to species. https://www.merriam-webster.com/dictionary/sapient#synonyms

[QUOTE = Presumably, the early-Earth was 'nutrient poor' but life still developed into complex forms, so perhaps this is more a function of population size, rather than how complex they are?[/QUOTE]

By the time complex, multicellular life evolved here, Earth was far from nutrient poor.

[QUOTE = It's not obvious how an air organism would evolve - or why they would evolve - merely from lack of nutrients. What competitive pressure do you fee would force them along that line? [/QUOTE]

I'll admit, I'm just doing some wild speculation here. I'm thinking that macroscopic multicellular "balloon life" would do better on a permanently nutrient poor planet--or biome-- because of the advantage of having a heck of a lot less flesh to oxygenate, hydrate, and nourish than an Earth animal of similar volume.

 

[member 656954]

I'll admit, I'm just doing some wild speculation here.

As are we all

I'm thinking that macroscopic multicellular "balloon life" would do better on a permanently nutrient poor planet

I understand, I'm just not seeing the evolutionary motivation. If the planet is truly nutrient poor, then I can see pathways for life to evolve where nutrients concentrate...but also die out if the nutrients are truly sparse. In the latter case, the environment would be so inconsistent that life would perhaps develop ways to enter a suspended hibernation-like state until the next food event occurs, but an air-sac that presumably blows around the place would seem to introduce too much randomness in your locale to survive.

What outcome do you need from the story perspective?

With all due respect to the writers on Star Trek

Not just them! But I'm truly wondering whether any species that evolves and is therefore subject to competitive pressure can ever be sapient? Greedy, needy, and shortsighted seems to be consequence of natural selection...wise or sage? Not so much!

 

[BillTre]

I think the most common drives to evolve larger size in organisms are thought to be either:

• being large enough to predate upon smaller species, or
• having a wider environmental snare for environmental resources (like a tree spreading out to catch more photons).

If you are concerned about this, you might want an ecological justification for their size, something smaller to eat or some environmental resource to gather.

Another reason would be to avoid predation by being big.

 

[some bloke]

If the world is nutrient-poor, then there would be an evolutionary advantage for macroscopic animals to develop live-cultures within themselves to feed themselves. Kind of like if a whale turned into a zeppelin filled with an endless krill-orgy. Now there's an image.

Cultivating bacteria in their guts as a food source would create quantities of gas from the bacterias respiration, and this could inflate their bodies. Provided no evolutionary disadvantages were found by swelling up, the most successful of the species would be those which could swell more and so cultivate larger quantities of bacteria without exploding. Thus nature would set a course for these creatures to evolve into balloons.

If the terrain was particularly hazardous, IE lots of falls and such which could kill a non-inflated creature, then there is an evolutionary driver for the less inflated to die and the more inflated to survive. Perhaps the inflation helps them to capture more food for their gut bacteria, or stretches their skin to allow more light in for an algae living inside them.

I suspect that symbiosis (two life forms living together - big one provides shelter, small one provides food) is going to be your best route.

As for sentience, there's no reason for the size of a creatures body to negatively impact its intelligence. Their brains may have had to evolve to use tools due to being incapable of running. Perhaps they have a vent valve for their gas which they have learned to use a blowpipe with.

 

[Office_Shredder]

How do they keep the live cultures fed? Seems like they are just a complicated digestive system.

 

[jim mcnamara]

As a general answer - consider the Gaia Hypothesis:
Organisms over long periods of time change the environment generally in ways that favor their reproduction. Synergistically.
https://en.wikipedia.org/wiki/Gaia_hypothesis

 

[BillTre]

Cultivating bacteria in their guts as a food source would create quantities of gas from the bacteria's respiration, and this could inflate their bodies. Provided no evolutionary disadvantages were found by swelling up, the most successful of the species would be those which could swell more and so cultivate larger quantities of bacteria without exploding. Thus nature would set a course for these creatures to evolve into balloons.

Biological analogues of this could be the bacteria in termites that digest cellulose from which the termites benefit, the microbes in your gut which digest things that human enzymes can not, and photosynthesizing algae that reside in some corals.

A more thoroughly mixed example might be lichens (a fungus, algae, and a yeast (also a fungus).

Mitochondria in eukaryotic cells could be another example, but taken much farther such that the mitochondria lost their obvious bacteria-ness which took a while to be discovered.

 

[Rive]

Such living balloon animals would not need as much nutrition as Earth animals of comparable volume.

Maybe you should consider this part from a different angle: in that nutrient-poor environment your balloon animals would be 'the' rich nutrient source, so they need some kind of strategy to come out on top. But what kind of strategy would be fitting for a balloon? At what price?

 

[member 656954]

But what kind of strategy would be fitting for a balloon? At what price?

Maybe their 'balloon' evolved as a flying analog so they can float above the fray and not be prey?

The price is harder to imagine. It may limit their size, as, like birds, if they become too heavy they cannot escape. Or their maturation may be extended such that their infant years leave them vulnerable longer than other species (this may give rise to sociability and the sapient aspect @Lren Zvsm mentioned earlier)?