Fire is a recurrent feature of dragons in many myths

Many legends tell of fire-breathing dragons. The first myth to report of this ability was possibly that of Beowulf, but earlier myths already featured creatures that spit flame such as the Chimera, which were then associated with dragons due to this ability.

Hard as it may be to believe, there is a possibility that some animals can produce fire.

Bombardier beetle

One should begin by considering a real-life specimen of "fire-breathing" animal. The bombardier beetle (Brachininae) cannot spit actual fire, rather a mixture of hot gas at 100 °C. It is often used as a rebuttal against the argument that fire-breathing animals cannot exist.

The beetle stores hydroquinone and hydrogen peroxide in its body. When threatened, the two chemicals are mixed and the enzymes catalase and peroxidase are added to it. The enzymes catalyse a chemical reaction, in which hydroquinone is converted into poisonous 1,4-benzoquinone, while the hydrogen peroxide is split into oxygen and hydrogen. The resulting mixture is not only extremely hot, but corrosive as well.[1]

The creationist Duane Gish hypothesised that the dinosaur Parasaurolophus used a similar mechanism, but this is considered unlikely today. Gish believed that their bone cavities contained hollow regions which were filled with similar chemicals as the bombardier beetle.[2] Although this theory is now considered unreasonable, it is not completely impossible that reptiles similar to the dragon developed similar mechanisms.

Formation of dragon fire

The following theories may explain how a dragon spits fire:

Flint theory

Dr. Drake's flint theory

Dr. Ernest Drake believed that every dragon has a piece of iron and flint in its mouth, which it rubs together to create sparks. Poison that is sprayed from a gland in the upper jaw is then ignited.[3]

Drake then compares the fire-breathing ability or inability of different types of dragons:[4]

✔ = can breathe fire / x = cannot breathe fire


Trey the Explainer proposes an alternative to the flint, saying that dragons ignite methane out of their flight bladders using a crystal that produces piezoelectricity. Such crystals generate potential difference when mechanically deformed, i.e. compressed. The electricity could have been used by dragons to ignite methane[5].

Naturally a dragon would have to consume these crystals, since no animal can form such materials in its body.

Chemical reaction

In most theories, a chemical reaction igniting the substances inside a dragon's body is responsible for the phenomenon of fire-breathing. As such, there are many possible combinations of flammable materials and reactions, such as:


The first explanation came from Peter Dickinson in his book The Flight of Dragons.

Dragon illustrated from The Flight of Dragons. Notice the rounded, gas-filled body

Dickinson suggested that dragons descended from dinosaurs, whose anatomy changed over the course of time. According to him, dragons produce acids that dissolve their constantly growing bones, releasing hydrogen gas. Through this, the dragon's body is greatly inflated and has an increased stability even without ribs, which may have resulted in those ribs developing into wings. Therefore, the dragon does not really fly, but rather floats. Strong gas pressures in the dragon force it to expel hydrogen regularly, which due to its high flammability allows it to breathe fire.[6]

A more realistic version of this theory can be found in the movie Dragon's World. Here, dragons possess a so-called flight bladder, which is formed like a second pair of lungs. These bladders collect digestive gases which provide extra lift during flight. The gases can be ejected from the mouth, where platinum is found, a metal that dragons often chew on. The metal acts as a catalyst speeding up the reaction between hydrogen (formed from the neutralisation of hydrochloric acid in the stomach and bone calcium) and oxygen (from the air).[7] The chemical formula is:

O2 + 2H2 - Pt → 2H2O

Laurie L. Dove hypothesised that dragons originally chewed platinum to aid in the digestive process, as birds swallow stones.[8] This could be a reason why dragons hoard treasure, which often contains precious metals.

Flyingfenix from draconian.com however notes that hydrocarbons are much easier "stored" by living organisms as compared to pure hydrogen gas, yet trigger a similar reaction.[9]


Another theory suggests the flight bladder also contains methane which the dragon ignites via an electric organ. For this to work, however, temperatures of 600 °C are required. The gas is produced in the digestive process.[10][11]


The paleontologist Henry Gee theorised that dragon fire could be based on diethyl. Organisms such as yeast produce ethanol (alcohol), and there are strains of bacteria that can produce sulfuric acid. Both microorganisms are found in the bodies of vertebrates. Ethanol and sulfuric acid can chemically react to form the highly flammable diethyl. This fire cannot be put out by water, which explains the immense destructive ability of dragon fire.[12]


According to this theory, dragons eat limestone which is then stored in a separate organ in the body. The dragon's organs also extract fluorine from its diet.

If the dragon is to spit fire, it needs only to expel both substances simultaneously; the resulting chemical reaction will produce fire.


In Anne McCaffrey's Dragons of Pern, dragons have two phosphorus-digesting stomachs. The resulting substance is flammable and allows the dragon to spit fire.

A similar theory is found in the "Big Book of Monsters" by Joey Levy. It is described that dragons consume rocks containing phosphorus, which mix freely with gases in the stomach. The mixture ignites spontaneously on contact with air.[13]


Many fantasy novels simply attribute dragon fire to the power of magic. This theory is scientifically unprovable.

Alternative theories

The following theories are based on the premise that dragons do not breathe fire, but rather have some other sort of biological weapon which is the real basis of the mythological dragon fire.

Dragon poison

The venom glands of Aviiguana atrox

While some dragons can ignite their poison according to Dr. Drake, there are some that suggest dragons do not spew fire but poison, akin to the spitting cobra, or inject poison into its victims like many other poisonous snakes. Through oral retelling and subsequent exaggeration, the idea of dragons breathing "fire" developed.

A very detailed description of this theory is provided by Joschua Knüppe in his article Dragon toxins (the real dragon fire). Here, dragons (Draconiformes) have a flesh-dissolving poison similar to that of spiders. This is an important adaption as the lungs increased in size due to evolution, in order to reduce the dragon's weight, subsequently shrinking its digestive tract greatly.

The poison purportedly causes death even in adult humans in under half an hour. Survivors reported burning sensations as the venom breaks down skin tissue. This also left behind boil-shaped burns. These symptoms may have lead to the fire-breathing myth.[14]

To counter the existense of poisonous dragons, some scientists argue that dragons are principally non-venomous. To quote John of Damascus as an example: "This dragon is a type of beast, like the rest of the animals, for it has a goat-like beard, and a horn at the back of its head. Its eyes are large and gold-coloured. These dragons can be either big or small. All serpent kinds are poisonous, except dragons, for they do not emit poison."

The statement however refers to specific types of dragon called the Agaphodemons, which are very rarely mentioned in mythology. Comparable myths could not be verified, but the assumption that dragons are non-toxic is recurrent in medieval bestiaries. The dragons of India and Ethiopia are more likely giant snakes that are truly non-toxic.

Poisonous saliva

Komodo dragon uses bacteria in conjunction with poison

Komodo dragon have poison glands in their mouths, as well as large amounts of bacteria in their saliva, obtained from rotting meat. It was long believed that the bacteria cause blood infections in wounds, killing the prey.

While it is now known that the lizard's venom plays a more significant role in killing prey than bacteria, the myth of dragon fire may have emerged from the aforementioned belief.


Parasitologists suspect that the Guinea worm (Dracunculus medinensis), the vector of dracunculiasis, could be responsible for the description of "fiery serpent"s in the Bible. The parasite is a long and thin worm, entering a person's body through drinking water, which then manifests itself as worm-infested copepods in the larval stage. The female worm can grow to 3 feet long. It travels under the surface of the skin, usually around the lower limbs.

About a year later the female breaks the skin and emerges from the body, forming a painful, burning blister at the leg or foot. The swelling leaves part of the worm exposed. To relieve himself of the intense burning sensation, the victim seeks the nearest water source (often small ponds or wells, used in villages for bathing and drinking), where the parasite releases up to a milion larvae.

The infected people experienced burning pains, which probably earned the Guinea worm its title of the "fiery serpent". Interestingly, the Latin genus of the worm, Dracunculus, means "little snake" or "little dragon".[15][16]


A sea serpent expels blow

Whales release blow when emerging from the waters, which is water-enriched exhaled air. It looks like steam and could have been assumed by sailors as such. Some old illustrations show sea serpents that emit water or blow from the mouth or the blowhole.

This is an obvious explaination for the occurance of dragon fire especially in the few cases of fire-breathing species of water dragons such as the Leviathan.


Yet another possible explanation would be Bioluminescence. It is the ability of an organism to chemically produce light, usually through bacteria.

Jonathan Whitcomb suggested that the Bible's accounts of "fiery serpents" are based on bioluminescent animals, whose light was commonly associated with fire. This interpretation lead to the belief that fiery serpents could spit fire. According to Whitcomb, the animal this belief is based on is the Ropen, a cryptid pterosaur from Paupa-Neuguinea[17].

However, this explanation is higly unlikely for a couple of reasons. First, there are no bioluminescent animals except for the Ropen, whose existence would contradict itself and is thus very unlikely. Second, the translation "fiery serpent" is just one of several possible interpretations of the bible text Whitcomb is talking about. The word for fiery, seraph, could also mean venomous, which is much more likely for a serpent. Also, seraph is a type of angel featured in the bible[18].


To breathe fire, an animal must be protected from its own flame. Dragons of fantasy are often even completely immune to fire.


This flaps keep the jaws of a crocodile waterproof

In Dragon's World, it is theorised that the inside of a dragon's mouth is armored, to protect itself from its own flame. The throat is closed by a flap, much like the palatal valve of crocodiles. While this prevents crocodiles from drowning during long periods of submersion in water, it protects the dragon from "swallowing" its own fire.

The Nature magazine describes the flattened cervical ribs of Smaugia volans', which form a tube protecting the soft neck tissues close to the dragon's fire.[19]

The dragon's skin should also be protected from fire. More details can be found in the dragon skin article.


Thermophiles are organisms whose cell structure allows them to survive at extremely high temperatures. Most thermophiles are archaea or bacteria, but there are multicellular organisms such as the water bear, which survive temperatures of up to 150 °C. There is also a possibility that ultrathermophiles exist, resisting far higher temperatures.[20]

There is no known case of themophilicity among vertebrates (or that this title is applied at lower temperatures), but dragons may be protected from fire by another biological mechanism.

It could be that dragons achieve a form of symbiosis with thermophilic organisms that protect it from its own fire. This is the method that the Pompeii worm (Alvinella pompejana) uses to survive in hot volcanic springs on the Pacific ocean floor. But this worm also uses other methodes for cooling[21].

Side effects

The chemicals that allow a dragon to breathe fire have other side effects. One of these may be the dissolving of the dragon's bones upon death, which explains why dragon bones have never been found.

Dickinson also describes that dragons release gases which are poisonous to many plants, which are interpreted in folklore as poison. The salamander, basilisk and some drakes are especially infamous for polluting entire regions from their expelled gases.

The swamp dragon of the Discworld novels live in constant danger of spontaneous explosion, as the fire-producing chemicals within them could ignite involuntarily. They owe their survival solely to the fact that, due to this condition, they have no natural enemies.

See also


Wiki-wordmark.png This article has been translated from German by Brandon_Pow from the Language Brigade Wiki.

The original article can be found through the Interlanguage-Link at the bottom of the page.

  1. Wikipedia: Bombardier beetle
  2. Gish, Duane T. (1992). Dinosaurs by Design, Green Forest: Master Books. p. 82. ISBN 0-89051-165-9.
  3. Dr. Ernest Drake (2003), Dragonology: The complete Book of Dragons, Templar Publishing plc, ISBN 1-84011-503-3
  4. Dr. Ernest Drake (2009):Drake's Comprehensive Compendium of Dragonology,Candlewick Press, ISBN 978-0763646233, S. 178-179
  5. TREY the Explainer: Science of Dragons
  6. Peter Dickinson: The Flight of Dragons, 1979, ISBN-10: 0060110740, ISBN-13:978-0060110741
  7. Dragon's World - A Fantasy made real, 2004, Documentary fiction
  8. Discovery Magazine: How to explain your Dragon
  9. Draconian.com: Dragonfire
  10. Drachenflamme.de
  11. The Guardian: If dragons were real, what biological mechanisms might they use to spout fire?
  12. Discovery Magazine: How to explain your Dragon
  13. Drachenkompendium: Der Flammenatem (German)
  14. Hyrotrioskjan: Dracotoxine (the real Dragon fire) (German)
  15. Praying the Gospels: How to Cast Out Demons & Unclean Spirits
  16. Cielo Global Health Media: Foul Water Fiery Serpent - A New Documentary
  17. The Bible and modern Pterosaurs: New view on the “fiery flying serpent”
  18. TREY the Explainer: Cryptid Profile - The Ropen or "The Living Pterosaur"
  19. Nature.com: Of Dinosaurs and Dragons
  20. Wikipedia: Thermophile
  21. Wikipedia:Pompeii worm