They are known as voracious predators, eating everything from turtles and humans to discarded vehicle licence plates, but a tiger shark has astounded Australian scientists by swallowing an echidna, a spiky, egg-laying mammal that normally lives on land.

The tiger shark’s experiment in snacking on the prickly creature did not last long – it vomited up the animal, presumably because its spines were acutely painful to its insides.

The unusual episode was described by scientists as “a one-in-a-million event”.

It is thought that the echidna, an animal which is a surprisingly good swimmer despite its small appearance and dumpy proportions, was paddling along nonchalantly in the sea when it was eaten by the tiger shark.

The large shark was then caught by marine biologists near Orpheus Island off the coast of northern Queensland as part of a three-year tagging programme.

As scientists pulled it towards their boat, the shark appeared to be in discomfort and under stress. It soon vomited up the echidna, which was dead.

Nicolas Lubitz, a marine biologist from James Cook University, said he had never come across such an episode before.

“I reckon it’s about one in a million,” he said. “Sometime when you wrangle them they get a little bit stressed, and one of the stress responses is to throw up their food, especially if it’s food that is not quite sitting right,” he said.

“And I can imagine that an echidna wasn’t quite sitting right,” he told the Australian Broadcasting Corporation.

Echidnas are widely thought to be land-based animals but in fact they are sometimes seen swimming among mangroves off islands in northern Queensland.

“They use their little nose as a snorkel — they’re quite good swimmers, actually,” said Dr Lubitz.

Tiger sharks are not choosy in their choice of food. They will eat turtles, birds, sea snakes, stingrays and other sharks and occasionally attack surfers and swimmers. They have even been known to swallow discarded licence plates, tin cans, bones, car tyres and even a small television.

Dr Lubitz is part of a scientific project that tagged more than 800 marine mammals, including fish, shovelnose rays and several shark species, in Queensland waters between 2020 and 2023.

The echidna vomiting incident happened in May 2022, but has only been recounted now.

“We know that they have quite a wide range of prey species that they feed on, but I definitely didn’t think an echidna was on the menu,” he said.

Tiger sharks, which are found in warm waters worldwide, can grow up to 18ft long and weigh 2,000lbs. Equipped with large, saw-edged teeth, they have one of the most fearsome reputations of any shark.

Along with the platypus, the echidna is the world’s only other egg-laying mammal. They are renowned for a unique reproductive organ: a four-headed penis.