The last time I talked about the book Future Evolution, I mentioned that author Peter Ward and illustrator Alexis Rockman mostly did not engage in the kind of biological speculation that the title of their book seems to imply.
But there is one exception, when Ward asks what could possibly come after the Age of Mammals, in the same way that our rise came after the Age of Dinosaurs. What currently living animal could serve as the starting point for a new set of adaptive radiation? And what new body plan would these dominant creatures take on? In basically his sole flight of fancy in the book, Ward imagines frogs developing the ability to separate liquid water into gaseous oxygen and hydrogen, giving rise to a whole new variety of life...
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| Jellyblimp illustration by Michael Whelan for Our Universe |
"Can we imagine an entirely new type of animal that could replace the current evolutionary dominants, the large mammals? This new class would have to have evolved from some currently existing creature, but it could have characteristics and a body plan vastly different from those of the preceding dominants. Such a new body type could exploit some entirely new food type or habitat. Let us imagine such a breakthrough - the conquest of the lower atmosphere by floating organisms called Zeppelinoids."
"After the extinction of most mammals (and humanity), Zeppelinoids evolve (let's say from some species of toad, whose large gullet can swell outward and become a large gasbag). The great breakthrough comes when the toad evolves a biological mechanism inducing electrolysis of hydrogen from water. Gradually the toad evolves a way to store this light gas in its gullet, thus producing a gasbag. Sooner or later small toads are floating off into the sky for short hops (but longer hops than their ancestors were used to). More refinements and a set of wings give a modicum of directionality. Legs become tentacles, trailing down from the now thoroughly flight-adapted creatures, which can no longer be called toad: they have evolved a new body plan establishing them as a class of vertebrates, the Class Zeppelinoida.
"After the extinction of most mammals (and humanity), Zeppelinoids evolve (let's say from some species of toad, whose large gullet can swell outward and become a large gasbag). The great breakthrough comes when the toad evolves a biological mechanism inducing electrolysis of hydrogen from water. Gradually the toad evolves a way to store this light gas in its gullet, thus producing a gasbag. Sooner or later small toads are floating off into the sky for short hops (but longer hops than their ancestors were used to). More refinements and a set of wings give a modicum of directionality. Legs become tentacles, trailing down from the now thoroughly flight-adapted creatures, which can no longer be called toad: they have evolved a new body plan establishing them as a class of vertebrates, the Class Zeppelinoida.
"Like so many newly evolving creatures, the Zeps rapidly increase in size: when small they are sitting ducks (flying toads?) for faster-flying predatory birds. Because their gasbag is not size-limiting, they soon become large. Eventually they are the largest animals ever evolved on Earth, so large that terrestrial and avian predators no longer threaten them, reaching dimensions greater than the blue whale. Their only threat comes from lightning strikes, which result in spectacular, fatal explosions visible for miles. The Zeps can never get around this inherent flaw, for there is no biological means of producing the inflammable, inert gas helium and thus avoiding instant death from lightning. But then, life is never perfect, and the Zeps still do well, especially in areas with little lightning."
"Now the dominant animals of the world, the Zeps float above the ground like great overgrown jellyfish, snagging with their dragging tentacles the few species of deer (and other herbivorous vertebrates) still extant and stuffing them into a Jabba-the-Hutt-sized mouth. Because Zeps evolved from amphibians and are still cold-blooded, they have a very low metabolic rate, and thus need to feed only sparingly. Their design is so successful that they quickly diverge into many different types. Soon herbivorous forms are common, floating above the forests, eating the tops of trees, while others evolve into zep-eating Zeps. Still others become like whales, sieving insects out of the skies; in so doing, they soon drive many bird species to extinction. The world changes as more and more Zeps prowl the air, floating serenely above the treetops, filling the skies with their numbers, their shadows dominating the landscape. It is the Age of Zeppelinoids."
"A fairy tale - but there is a glimmer of reality in this fable. Evolution in the past has produced vast numbers of new species following some new morphological breakthrough that allows some lucky winner to colonize previously unexploited habitat. The first flying organisms, the first swimming organisms, the first floating organisms, all followed these breakthroughs with huge numbers of new species quickly radiating from the ancestral body type, all improving some aspects of the design or changing styles to allow variations on the original theme."
"Now the dominant animals of the world, the Zeps float above the ground like great overgrown jellyfish, snagging with their dragging tentacles the few species of deer (and other herbivorous vertebrates) still extant and stuffing them into a Jabba-the-Hutt-sized mouth. Because Zeps evolved from amphibians and are still cold-blooded, they have a very low metabolic rate, and thus need to feed only sparingly. Their design is so successful that they quickly diverge into many different types. Soon herbivorous forms are common, floating above the forests, eating the tops of trees, while others evolve into zep-eating Zeps. Still others become like whales, sieving insects out of the skies; in so doing, they soon drive many bird species to extinction. The world changes as more and more Zeps prowl the air, floating serenely above the treetops, filling the skies with their numbers, their shadows dominating the landscape. It is the Age of Zeppelinoids."
"A fairy tale - but there is a glimmer of reality in this fable. Evolution in the past has produced vast numbers of new species following some new morphological breakthrough that allows some lucky winner to colonize previously unexploited habitat. The first flying organisms, the first swimming organisms, the first floating organisms, all followed these breakthroughs with huge numbers of new species quickly radiating from the ancestral body type, all improving some aspects of the design or changing styles to allow variations on the original theme."
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| the skies above Atlas on Alien Worlds |
The idea of floating animals shows up in a couple other places. In my childhood favorite, National Geographic's Our Universe book, illustrator Michael Whelan imagined Jellyblimps and predatory Swordtails in the endless skies of Jupiter.
Netflix's Alien Worlds documentary miniseries, which I've recommended before, includes the speculative planet Atlas, which has a higher mass than Earth, and thus a denser, more buoyant atmosphere. The show's creators also thought of floating animals filling the skies.
On both Jupiter and Atlas, the stronger gravity creates much stronger atmospheric pressure, so that, ironically, floating is easier there than it is on Earth. (Think of how much easier it is to float in water than in air!) The Zeppelinoids are unique among these floating species because their specific lighter-than-air gas is hydrogen. This creates a special peril for them, as Ward mentioned in the quote, but also creates a special opportunity.
The ability to separate hydrogen gas out of water might only evolve a single time, but once it does, the lifeform that evolved it might diverge into a number of new species that use it in different ways. In other words, the Zeppelinoids could be cousins to hydrogen-fueled fire-breathing dragons.
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| Zeppelinoid sketch, by me |
Above is my own, very rough, sketch of a Zeppelinoid. (Possibly one still at an intermediate stage of evolution, not even its final form.) We see the base frog's throat pouch and belly monstrously distended into a spherical hydrogen bag. The Zep's spine is at the bottom of its body and its head, from the perspective of terrestrial beings, is upside down. Its fore-limbs have become bat-like wings, with the fingers of the frog's front feet becoming the spars of the wings, and the webbed skin between those fingers forming the membrane. Its hind-limbs have become masses of tentacles, with the toes of the frog's back feet becoming grossly elongated to allow the Zep to wrap them around its prey.
A fully evolved Zeppelinoid might have an even more specialized body, one that looks more like an octopus or jellyfish, whose original species might be much less evident.
In an adventure setting, relatively stationary Zeppelinoids might serve as a landmark by floating above a particular lake or body of water. Or their migratory routes might bob along a north-south or east-west axis, aiding navigation. They might even fly directly over a specific important trade route, showing the way from one city to another.
A setting that has Zeppelinoids could easily have airships. People might use a Zep as a draft animal, using it to pull a carriage through the sky. Or Zep hide might be used as the bag for an airship. Or the sight of them might simply serve as inspiration, letting humanity know that lighter-than-air flight is possible. Large enough Zeps might serve as a navigational hazard, like living icebergs. Predatory Zeps might attack airships, whether to eat the cargo, or the passengers and crew, or just to defend their territory against intruders. And of course, an airship might attempt to camouflage itself and hide from other human pilots by steering a course among a population of Zeppelinoids.
As a monster, a Zeppelinoid is a challenging foe. It likely hovers outside of missile range, untouchable until it's ready to engage in combat. It could pluck an adventurer from the ground or off of horseback, crushing them with its tentacle, biting them with its mouth, or most frighteningly, simply dropping them from a great height.
The Zeps' weakness is that they'll die instantly if they take any damage from lightning or fire. An exploding Zeppelinoid might threaten adventurers if it's floating low enough at the time it combusts. There's also a chance that one exploding Zep could ignite any others nearby.