There's an old joke which asks how do echidnas have sex? Very carefully. But Tasmanian researchers have discovered the spiky mammals aren't particularly careful at all.
In fact, new research has found echidnas are quite promiscuous creatures.
Gemma Morrow from the University of Tasmania has spent three years digging up echidnas and using ultra sound to study their mating habits.
She also installed infra-red cameras in their burrows and made some surprising discoveries.
"They have group sex - one female and many males - and that's basically because there's not as many reproductively active females as males because females don't reproduce every year," says Morrow.
As well as having echidna orgies, some male echidnas try to mate with females who are still hibernating.
"They're getting up about a month earlier than females and then jumping on top of them," says Morrow. "[The] females are then waking up and they're actually mating when they're not at a normal body temperature."
"Females are then sometimes re-entering hibernation so there's not a real clear distinction between hibernation and reproduction, which is quite unusual."
According to Morrow, echidnas are the most widespread native animal throughout Australia.
"The only animal which is more widespread than the echidna is the introduced house mouse," she says.
Co-researcher Stewart Nicol says the project has uncovered important information about how egg laying mammals reproduce.
"A lot of people got the impression that they're just a little primitive animal that's hanging on in a backwater because there's no competition, but in fact they're spread right round Australia and they're doing remarkably well," he says.
Most successful monotreme
Nicol says echidnas are special because they're one of the very few egg laying mammals.
"There's about 4000 to 6000 mammals species around the world - only five lay eggs - they're the monotremes and the echidna's the most successful one," he says.
It's hoped the information gathered by the research can be used to help conserve their relatives, the endangered long beaked echidnas, in Papua New Guinea.
It might also protect echidnas if they one day succumb to a deadly illness like the Tasmanian devils' facial cancers.
"Before the devil disease, no one actually paid attention to the devils and so a lot of their reproductive biology wasn't known," says Morrow. "It's only become known now that they're becoming endangered."
"What we're doing now is working out what's going on before anything happens and we can also apply it to other species."
The researchers have also discovered another peculiar thing about echidnas - they build communal toilets. It's not clear why they all go together, but it could be the subject of future research.