Nature
PUBLISHED
In 2005, the German city of Hamburg was struck by an outbreak that sounded less like a biological phenomenon and more like a Biblical curse: exploding toads.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.It started in April when a spate of media reports claimed that thousands of the amphibians had died in Hamburg's Altona district over just a few days. As reported by BBC News in 2005, the toads would bloat like a beach ball to three-and-a-half times their normal size before popping, propelling their guts up to a meter (3.2 feet) into the air.
"You see the animals crawling on the ground, swelling and then exploding," Otto Horst, a local veterinarian, told AFP at the time.
"I have never seen such a thing," he said.
Many of the ill-fated amphibians croaked at a single pond in the city, which the tabloids of course llabeled the "POND OF DEATH.” Children were told to stay away, and wild rumours started circulating that a virus spread by South American racehorses might be to blame.
It wasn’t an isolated incident either. Exploding toads were reported across the border in Denmark at a pond near Laasby in central Jutland.
Scientists were stumped, but as public interest in the curious case increased, several theories arose. Many suspected the toads were suffering from an unknown virus or fungus that had infected the local ponds. However, the Hamburg Institute for Hygiene reportedly tested the water and did not detect anything unusual.
Some scientists began to doubt whether the accounts were true or the media had overhyped the reports, hoping to draw in readers with a sensational story in the pre-clickbait era. After all, the concept sounded oddly similar to one of Aesop’s fables, in which a cocky frog inflates itself to match the size of an ox until it finally bursts like a balloon.
"I really think someone needs to go back and check the primary source," said Barry Clarke, a herpetologist at the Natural History Museum, London, at the time, according to Nature. "I've learnt never to say with animals that anything is impossible. But the idea of exploding toads – well, let's face it, it's [Monty] Python-esque."
A mystery solved?
However, amid the confusion and skepticism, one theory did start to gain traction. Frank Mutschmann, a leading herpetologist in Germany, collected both dead and live toads from Hamburg and brought them back to his lab in Berlin. After carrying out several necropsies, it became apparent that the toads all had the same circular incision on their backs.
Mutschmann realized the "surgical" strike was the work of a bird – and only one bird would fit the bill: the ever-intelligent, occasionally evil crow.
"There were no bite or scratch marks, so we knew the toads weren't being attacked by a raccoon or rat, which would have also eaten the entire toad. It was clearly the work of crows, which are clever enough to know the toad's skin is toxic and realize the liver is the only part worth eating,” said Mutschmann, according to the Independent.
“Only once the liver is gone does the toad realize it's been attacked. It puffs itself up as a natural defence mechanism. But since it doesn't have a diaphragm or ribs, without the liver, there is nothing to hold the rest of its organs in. The lungs stretch out of all proportion and rip; the rest of the organs simply expel themselves."
Unfortunately, there’s no known scientific literature about this strange epidemic, other than a review in the Annals of Improbable Research. Now, over 20 years have passed, and the window of opportunity to study the event has likely slammed shut. Unless a similar event unfolds, which seems improbable, this will remain a bizarre footnote in the history of herpetology.
But never say never. If you ever find yourself wandering by a pond and you hear a strange pop, watch out for the fulminating mist of amphibian entrails.
