Beholders are like living balloon-like creatures that contain lighter-than-air gas. Could such an animal evolve naturally? Has any such being existed?
It seems unlikely. Fish use bladders to control depth, but a beholder couldn’t regulate floating height in the same way (once the gas is let out, it is out) so you’d get a creature that would always float around at the same height, with no evolutionary advantages I can see and plenty of disadvantages.
I don’t see why they could produce more anti-balast gas.
Also, maybe they could keep a steady amount of anti-balast gas, but vary their overall density by changing their shape. So lets say they have a closed air bladder filled with hydrogen or whatever and they can expand the size of the air bladder while keeping the contents the same, dropping pressure in the bladder, decreasing overall density, etc
After reading this, it strikes me that we should ask what the ABG (anti-ballast gas) would be. Are there any natural processes that produce He or H2?
Or perhaps the ABG would be hot air? (yeah, yeah, i know)
One siphonophore, the Portuguese Man O’ War, has evolved a balloon-like structure which allows it to float on the water. The velella is a chondrophore that has developed a similar float. I suppose a similar creature (or more accurately, colony of creatures) could develop to float in air.
IIAC, gastric acids are hydrochloric acid. If an animal were to exist whose gastric acids were HCl, and if it were to eat, say, zinc, then wouldn’t it create hydrogen gas? (IANA chemist.)
Such a creature would probably need to live in a place where the weather is always mild: gusty winds could easily overwhelm its ability to maneuver, and threaten its structural integrity. It’s the same problem faced by lighter-than-air craft - and many of these incorporate motors with a substantially higher specific power than is available in nature.
Methane could work as the gas.
Here’s a chart I found of densities of common gases:
Apparently the density of air at STP Standard Temperature and Pressure is about 1.2 kg/m^3.
The common gases with substantially lower densities are:
Ammonia 0.7;
Helium .17;
Hydrogen .08;
Methane 0.7
Natural Gas (0.7-0.9);
Helium seems like a poor candidate since it is not the product of any chemical reactions.
Methane and Ammonia seem like possibilities, although you’d need a heck of a big gas envelope to make use of them.
Also, methane and Hydrogen are quite combustible in an atmosphere that is 20% Oxygen.
Query whether a creature is likely to evolve that has a good chance of violently exploding near an open flame?
Seems like you always encounter them in caves, for what it’s worth.
Another question is what advantages a balloon-like creature would have over a bird-like creature. The only one I can think of is that a balloon-like creature could hover for long periods of time. But what’s the advantage in that?
Birds are perhaps more complex. Is it possible the balloons evolved before the birds?
Consider that man invented working hot-air balloons and zeppelins before powered airplanes.
Beating your wings X times per second would seem to be costlier, energy wise, than holding in a fart.
Yea, and right after the wizard has burned off his best spells for the day.
Why not? Open flames aren’t particularly common in most biomes. And even if these creatures did inhabit such a biome, presumably they would have some means of locomotion for avoiding flames. And again, even if they didn’t, what’s the big deal? Trees and grasses are combustible, have no means of locomotion to escape flames, are regularly consumed en masse in forest and bush fires, and yet they thrive.
I think that’s probably true. However, I can’t think of any creatures in nature that are explosively flammable.
The advantage that the creature involved evolved the ability to float and not flap; evolution has no foresight. It doesn’t think, “well, in the long run flying is more effective than floating, so I’ll evolve towards wings instead of gas floatation.” As well, if they evolved from some limbless creature, they have an extra hurdle in evolving wings.
Some types of trees burst fairly violently IIRC. And the flames aren’t going to be able to touch off the hydrogen inside a beholder until they’ve burned through it’s outer layer, it which case it’s dying anyway probably.
IANA bio-anything but I think balloon critters are structurally possible as discussed above.
Whether they’re ecologically possible is another question. I think the best analog that does exist are jellyfish; they have just enough structure to hold themselves together & live by floating in the medium with little or no locomotion.
So what do jellyfish eat? Some very small fish, but mostly the plankton & such that drift in the water. There are enough edibles floating in most ordinary seawater to sustain a population of very low energy-cost scavenging critters.
Is there an analagous food supply in the air for our balloons? Certainly in some parts of the world the supply of small insects seems infinite for at least part of the year. But there is nothing that corresponds to algal blooms or other situations involving vast numbers of unicellular (or darn close) plants forming drifting clouds of food.
And I think therein lies the problem. particularly trying to float in air, not water, our critter can’t store much energy becasue that storage (e.g. fat) would be heavy, which would necessitate a bigger gas bladder to carry it, which itself would need to be fed, etc. So our critter needs to eat pretty much continuously & would starve if unable to feed within a few hours tops.
Unlike a lot of the sea, the terrestrial world has seasons. In the equatorial regions, they tend to be more about wet vs dry than hot vs cold, but they still represent significant hanges in the environment & hence the type & abundance of food supply.
See http://weather.uk.msn.com/monthly_averages.aspx?wealocations=wc:PMXX0004 for an example I’m personally familiar with. The monthly average high temp only changes by 1 degree C (2 F) year round. Ditto the average low. But rainfall varies by a factor of 700 from the driest to wettest month.
My Bottom Line: They won’t work ecologically. There’s no terrestrial niche benign enough to give them a continuous dense food supply.
Perhaps they could evolve a froglike tongue, and catch birds or small animals. Perhaps supplemented by a plant symbiont in the skin or being naturally photosynthetic; a floater would be low-energy and that would make such a symbiosis more practical.
But yes, realistically they’d have serious problems in an Earth type ecology. Unless they changed that ecology; perhaps they could constantly spawn great numbers of sporelike microscopic floaters, which would take a bite out of anything they landed on long enough. The successful ones grow into beholders themselves; the vast majority get eaten by the big beholders or otherwise die. That would make beholders a sort of filter feeder, or at least supplemented by filter feeding. It would probably only work if they were in some valley, to help the “beholder-krill” and the beholders themselves from being blown away.
If animal, it could float from flower to flower consuming nectar.
If plant, it could float into caves to collect bat guano droppings, a nitrogen-rich substitute for not having a root system in soil.