“Atmospheric beasts,” sometimes called sky critters or space animals, are hypothetical living creatures that would inhabit the upper atmosphere, invisible or nearly so, and might explain some UFO sightings. The idea is not ancient folklore. It has a clear modern history: a 1913 short story by Arthur Conan Doyle, the musings of Charles Fort, and a small group of UFO writers in the mid-twentieth century who argued that “flying saucers” might be animals rather than spacecraft.[1][2]
| Other names | Sky critters, space animals, living UFOs |
|---|---|
| Type | Hypothetical airborne life forms; a UFO theory |
| Key promoters | Charles Fort, John Philip Bessor, Kenneth Arnold, Trevor James Constable, Ivan T. Sanderson |
| Earliest influential depiction | Arthur Conan Doyle, “The Horror of the Heights” (1913), fiction |
| Evidence | Interpretations of photographs and UFO reports; no specimens |
| Scientific status | Not supported |
Fiction first: “The Horror of the Heights”
In 1913 Arthur Conan Doyle published “The Horror of the Heights,” a short story told through the notebook of an aviator who climbs to a record altitude and discovers an “air jungle” full of translucent creatures, some like vast jellyfish and others like serpents. The aviator is killed, and his blood-stained notebook is all that is found.[1][3] The story planted a vivid picture of life in the sky that later writers returned to again and again.
Charles Fort and the flying saucer era
The writer Charles Fort, who collected reports of anomalies, wrote in 1923 that living things in the apparently empty sky seemed no more incredible than life in the ocean.[1]
After the “flying saucer” wave of 1947, the idea was taken up seriously:[1]
- John Philip Bessor, a Fort enthusiast, wrote to the US Air Force in 1947 suggesting that the discs might be animals rather than machines, and later compared them to octopuses.
- Kenneth Arnold, whose 1947 sighting launched the term “flying saucer,” was by 1955 describing UFOs as something like sky jellyfish, and in 1962 argued that they were living organisms native to the atmosphere.
- Ivan T. Sanderson, a biologist and writer, explored the idea in his 1967 book Uninvited Visitors: A Biologist Looks at UFOs.
Trevor James Constable’s “critters”
The best-known champion of sky animals was Trevor James Constable (1925–2016), a New Zealand-born radio officer in the US merchant marine. Influenced by radionics and Wilhelm Reich’s theory of “orgone” energy, he photographed the sky using film and filters sensitive to light outside the normal visible range, and interpreted the blobs and discolorations on his pictures as amoeba-like animals. He called them “macrobacteria” and argued that they ranged from the size of a coin to half a mile across.[2]
He published his ideas in They Live in the Sky! (1958) and The Cosmic Pulse of Life (1976), later reissued as Sky Creatures: Living UFOs. He even blamed the creatures for cattle mutilations, claiming that radar angered them.[1][2]
Why scientists do not accept sky animals
- Physics and biology. A large animal needs a body, and staying aloft indefinitely without wings or a gas bag strong enough to lift it is not plausible. No known biology could produce the vast, invisible organisms described.
- Photographic artifacts. Constable’s “critters” appear on processed film rather than to the eye, which fits flaws, light leaks and development artifacts. The same is true of the video “rods” described in our Air Rods entry.
- Better explanations for UFOs. Balloons, aircraft, birds, insects, clouds and atmospheric optics account for the great majority of investigated sightings.
What scientists have actually found in the sky
Although sky animals in the Constable sense are not supported, the atmosphere really is full of life, and the science behind that is fascinating in its own right.
- Insects at altitude. In the 1930s the British entomologists Alister Hardy and P. S. Milne flew nets on kites over England and caught insects hundreds of meters up, showing that small insects ride air currents high above the ground.[6]
- Trillions of migrants. Using specially designed vertical-looking radar, a team led by Gao Hu and Jason Chapman estimated in 2016 that about 3.5 trillion insects, more than 3,000 tonnes of them, migrate high over southern Britain every year, mostly unseen from the ground.[7]
- Flying spiders. Young spiders “balloon” on strands of silk, sometimes traveling hundreds of kilometers. A 2018 study by Erica Morley and Daniel Robert showed that spiders can sense the atmosphere’s natural electric field and use it to take off, even when there is no wind.[8]
- Microbes in the clouds. Aircraft sampling during NASA hurricane missions found living bacteria making up a significant fraction of the particles in the air 8 to 15 kilometers above the Earth, reported by Natasha DeLeon-Rodriguez and colleagues in 2013.[9]
So the sky does have an ecosystem: a thin, drifting, mostly microscopic one, sometimes called aerial plankton. It contains no gas-bag jellyfish or half-mile amoebas, but it is far richer than Fort or Conan Doyle could have known.
Sky creatures on other worlds
Scientists have also taken the idea seriously as a thought experiment for other planets. In 1976 the astronomers Carl Sagan and Edwin Salpeter published a paper imagining an ecology in the deep atmosphere of Jupiter: tiny “sinkers,” huge balloon-like “floaters” many kilometers across that would drift and feed on organic molecules, and “hunters” that would prey on them. They were explicit that this was speculation about what physics and chemistry would allow, not a claim that such creatures exist. Sagan later popularized the floaters in his television series Cosmos (1980).[10]
The idea that life might float in a planet’s clouds resurfaced in 2020, when astronomers reported a possible detection of phosphine gas in the atmosphere of Venus and suggested it might be produced by microbes in the temperate cloud layer. Later analyses disputed the detection, and the question remains open. Either way, the modern scientific version of “atmospheric beasts” is about microbes and thought experiments, not giant invisible animals over Earth.[11]
Atmospheric beasts in popular culture
The idea has had a long life in fiction. Jordan Peele’s 2022 film Nope reveals a “UFO” to be a living predator. The filmmakers consulted marine biologists and drew on jellyfish and octopuses for its design, an image that leads straight back to Conan Doyle’s 1913 air jungle.[1]
References
- “Space animal hypothesis,” Wikipedia, citing C. Fort, New Lands (1923); the Saturday Evening Post (2 July 1949); the La Grande Observer (29 January 1955); Flying Saucer Magazine (November 1962); and others.
- “Trevor James Constable,” Wikipedia.
- Arthur Conan Doyle, “The Horror of the Heights,” The Strand Magazine (November 1913).
- Ivan T. Sanderson, Uninvited Visitors: A Biologist Looks at UFOs (1967).
- Trevor James [Constable], They Live in the Sky! (Los Angeles: New Age Publishing, 1958).
- A. C. Hardy and P. S. Milne, “Studies in the distribution of insects by aerial currents: experiments in aerial tow-netting from kites,” Journal of Animal Ecology 7, no. 2 (1938): 199–229.
- G. Hu et al., “Mass seasonal bioflows of high-flying insect migrants,” Science 354 (2016): 1584–1587.
- E. L. Morley and D. Robert, “Electric fields elicit ballooning in spiders,” Current Biology 28 (2018): 2324–2330.
- N. DeLeon-Rodriguez et al., “Microbiome of the upper troposphere: species composition and prevalence, effects of tropical storms, and atmospheric implications,” PNAS 110 (2013): 2575–2580.
- C. Sagan and E. E. Salpeter, “Particles, environments, and possible ecologies in the Jovian atmosphere,” Astrophysical Journal Supplement Series 32 (1976): 737–755.
- J. S. Greaves et al., “Phosphine gas in the cloud decks of Venus,” Nature Astronomy 5 (2021): 655–664 (published online September 2020), and subsequent critiques.
Correction note (October 2026): This entry was rewritten to describe the documented history of the idea. An earlier version described glowing, gelatinous atmospheric creatures hundreds of feet long and traced them to ancient folklore about “sky spirits,” without sources. These claims have been removed. The illustration above is an artistic impression.