Rat King: The Mysterious Conjoined Creature

On a cold January morning in 2005, in the village of Saru in southern Estonia, farmer Rein Kıiv and his son made a curious discovery. On the sandy floor of their shed, they found a cluster of 16 rats with their tails inexplicably tangled into a knot. The rats were squeaking and struggling to escape but the harder they pulled the tighter the knot became. The animals were apparently trying to dig themselves out of a narrow burrow but in the struggle some of them got buried under the sand. Seven of the rats in the tangle were already dead. Rein’s son decided to put the diabolic little scene to an end, and picking up a stick, killed the rest of the wretched animals.

Rein Kıiv didn’t know then, but what he had discovered was an extremely rare phenomenon called rat kings. They have been sighted since the past five centuries with approximately 60 such sightings recorded in history books.

Rat king from Dellfeld, Germany, found in 1895. Photo credit: Edelseider/Wikimedia

A handful of preserved specimens are also kept in various museums. The largest known rat king, which was found in 1828 in a miller's fireplace at Buchheim, consist of 32 rats, and is preserved at the museum Mauritianum in Altenburg, Germany. The rat king of Saru is now located at the Natural History (Zoological) Museum at the University of Tartu, preserved in alcohol and exhibited to visitors. Due to long-lasting exposure to open air, the tails of the rats had dried up and the knot had became loose. Nevertheless, the heavily compressed parts of the tails testified that the knot had once been very tight.

Rat kings are apparently a freak of nature, but what exactly causes them is debatable. According to one hypothesis, a rat king is created when rats are frightened and nervously grasp each other with their tails. Or when it’s cold and the rats huddle together as they usually do when sleeping, and their tails become glued together by tree sap, blood, food, feces etc., and the bonding material freeze as the animals slept. Once the animals awaken they try to free themselves by moving in different directions causing their tails to become entangled in a tighter knot.

The explanation has a ring of truth considering that most rat kings were discovered in colder countries during winter. All rat kings studied so far also involve the black rat, except for one rare discovery in Java, which doesn’t even have a freezing climate.

Illustration of a rat king discovered in 1683.

Professor Andrei Miljutin from the University of Tartu believes that rat kings occur in regions where two factors coincide—cold winters and the presence of the black rat.

“Indeed, the black rat is more common in Southern Europe, but there are mild winters there,” Andrei Miljutin wrote in a paper. “Winters are severe in Northern Europe and Canada, but there are no black rats or they are very rare. There are large numbers of brown rats, R. norvegicus, in Northern Europe and North America, but they do not create rat kings. This is obviously due to their relatively shorter, thicker, and less flexible tails than in R. rattus. “

Andrei Miljutin also believes that the occurrence of rat kings is more frequent than presumed. During his research, Miljutin was able to find three examples in Estonia, only one of which was widely reported in the media and only because the finder had a journalist among his relatives. Many discoveries never leave the local community and remains overlooked by scientists at large. Besides, who knows how many rats kings remain buried in tunnels and underground burrows undiscovered?

Rats aren’t the only animal that can become entangled by their tails in this fashion. In 2013, six living squirrels were found stuck together with pine sap in a “squirrel king” in Regina, Canada. They had to be separated by veterinarians.

A rat king at Châteaudun museum, France. Photo credit: Selbymay/Wikimedia

A rat king preserved at the museum Mauritianum in Altenburg, Germany. Photo credit: Wikimedia