How to explain your dragon: a biological study of magical creatures

Using real-world science to deconstruct dragon physiology

By Abigail Joyce

Throughout history, dragons have been amongst the most intriguing and enduring mythical creatures in the world, with references to these beasts found in ancient Greek and Medieval texts as well as many, more modern fictitious worlds. While the dragons in these depictions vary in temperament, size and physiology, could there be a biological explanation for the common characteristics of these reptilian beings?

The distinctive flaming breath of dragons is a trait that has prevailed through many portrayals and could be explained by a number of phenomena. The fuel of choice for dragons could be derived from methane gas produced by the microbiota of the gut upon digestion; however, this would need to involve a high fibre intake, which carnivorous or omnivorous diets would be unable to provide in sufficient quantities. The other issues with methane are that it would have to be highly compressed for storage within the body and, upon release and ignition at high velocities and altitudes, it could blow back towards the dragon’s head, which would presumably not be biologically ideal.

Another approach to the fuel source could be a similar mechanism to the bombardier beetle, in which two glands containing a mixture of catalase and peroxidase enzymes are separated from chambers containing hydroquinones and hydrogen peroxide. Upon mixing, the resulting reaction decomposes hydrogen peroxide to steam, and oxidises the hydroquinones to produce an explosive exothermic expulsion of liquid at just under 100°C. This hypergolic spontaneous reaction would explain the damaging effects of dragon fire; however, the chemicals involved are not biologically “cheap” and would therefore require a high metabolism to produce within the body.

Many have hypothesised about the mechanism of ignition, and a common theory revolves around the dragon’s renowned teeth; while unlikely to generate a spark themselves, many believe that the ingestion of rocks, similar to the action of modern birds, could result in a coating of minerals on the teeth which, upon frictional force, would produce sparks and ignite the expelled fuel. If dragons followed the same evolutionary path as birds from a common ancestor, such as dinosaurs, they could have multiple stomachs and a gizzard to store rocks, which would aid in digestion. Rocks that have the ability to produce a spark often belong to the flint family, such as quartz, chert or obsidian.

Finally, presuming a dragon’s core body temperature, and its regulation, would be similar to that of lizards, their thermoregulatory mechanisms would have to involve long periods of quiescence to provide sufficient energy to hunt and propel their bodies through the air on large, bat-like, membranous wings. This theory coincides with the depiction of dragons as protective beings that hoard large volumes of precious rocks and jewels, and spend extended periods in a state of hibernation to conserve energy. However, this does raise questions about how an animal of such size and mass could generate sufficient energy for flight and hunting, without an endothermic regulatory mechanism.

Although the complexity of the hypothesised physiology of dragons may make their existence implausible, their representation in all forms of media continues to spark theories about how these otherworldly creatures could actually be residing within our world.

From Issue 18