In A Nutshell
The echidna is a small mammal native to Australia and New Guinea. Small and unassuming, its diet consists mainly of ants and termites. But the male short-beaked echidna was recently observed mating with sleeping and hibernating females in Tasmania—adding to a lengthening list of the animal’s odd sexual behavior.
The Whole Bushel
The short-beaked echidna (Tachyglossus aculeatus) is one of the most widespread and common mammals in Australia and New Guinea, usually making its home wherever it can find ants or termites. The echidna even served as a mascot to the Sydney-hosted Summer Olympics in 2000 and provided the basis for the character Knuckles in the popular Sonic the Hedgehog franchise.
Despite this recognition, the short-beaked echidna’s mating habits have remained a mystery. Professor Stewart Nicol, an associate professor with the University of Tasmania, wanted to change that. Nicol and a team monitored 280 wild echidnas over a staggering 16-year period with support from the university and the Australian Geographic Society.
The conclusion? Male echidnas will seek out and mate with hibernating females, who often don’t even bother to yawn. The female might wake up, but when she finds out it’s just sex (no big deal), she’ll probably just go right back to sleep.
The short-beaked echidna will enter into hibernation only if living in a colder climate. Male and female echidnas do not coordinate their hibernation periods effectively; males enter and exit hibernation earlier than females, who need extra time to recover from mothering young.
When the male wakes up, he’s ready for sex. He’ll seek out and wander into the den of an unsuspecting female, asleep though she may be, and go for it. Scientists aren’t sure why the female stays asleep. Males can be quite competitive, and by sleeping, the female essentially forfeits the right to pick a suitable mate. One theory by Nicol suggests the female stores the sperm of multiple partners while hibernating. This way, there’s no need for active selective breeding, and she can get the rest she needs.
Sleeping sex isn’t particularly rare, either. During the last two years of the study, hibernating females declined to wake two-thirds of the time they were approached by a male.
But the echidna’s sexual oddities don’t end there. The male echidna has a four-headed penis. The purpose is unknown, but it’s probably related to the fact that the female echidna has two vaginal openings. The male’s hind legs feature pustules that are thought to contain pheromones. And nipples? The echidna doesn’t have them. Instead, the milk just sort of seeps through the skin.
To top it off, the short-beaked echidna is one of only three extant mammal species to lay eggs. The other monotremes are the long-beaked echidna and platypus.