“Rat King” by Reid Psaltis (left) and “R Is for Rat King” by Amanda R. (right) aren’t sci-fi or fantasy art, but I think they’re weird enough to belong on this blog.  The latter (from a series called “the Alphabestiary”) is what rekindled my interest in rat kings.

Groups of rats are sometimes found dead or dying with their tails inextricably entwined.  This happens to at least eight species of rodents, but in most cases it’s Rattus rattus.  These conglomerations, which can contain over thirty rats, are called “rat kings.”  The phenomenon is well-documented, but continues to puzzle rodent biologists.  No one has observed a rat king forming, and there is no wholly convincing hypothesis for how it happens.

There seem to be three commonly invoked explanations.  Rats huddling together in filth might become accidentally stuck together, then make the problem worse by panicking.  Rats will deliberately grasp each other with their tails when frightened or anxious.  One hypothesis holds that, when rats are present in large groups, this behavior could escalate to the point where some of the tails become too tightly intertwined.  Finally, some animals are known to exhibit hysterical self-destructive behavior when their populations become too dense.  Rats winding their tails together could be an example of this.  What is known from forensic analysis is that the rats do not die immediately after they form a rat king.  This makes the issue even more perplexing, since rats usually gnaw their own tails off if they become hopelessly caught in something.