As an Australian you would have learned about monotremes from a young age: the tiny category of mammals that lay eggs like birds and reptiles. But you never really think about just how weird it is. Well here's something that's even weirder: platypus mothers produce milk, but they don't actually have nipples. So how the hell does it work?
Platypuses, like echidnas, are a bit of a biological anomaly. While both placental and marsupial mammals are fairly widespread, monotremes include only two types of animal: echidnas and platypus. I mean, there are 4 different species of echidnas, but for us non-scientific folks it's basically two.
These monotremes are one of the weirdest parts of Australia's already unique native fauna, but it turns out that these weirdos are hiding even more strange secrets.
Platypuses are so odd that they were originally thought to be a hoax by European scientists, with its combination of different biological features. You probably also know that the males have poisonous spurs on their back legs, as well as their habit of laying eggs. Well here's one more thing to add to the weird pile.
Because they never developed nipples like most mammals, platypus have a different method of delivering milk to their puggles (that's what baby platypuses are called just fyi) - they concentrate it all towards their belly area, and then literally just sweat it out through their skin. Sounds delicious, right?
Weirdness aside, this odd delivery method has led to platypus milk taking on some interesting characterisations. Nipples are thought to be a development to guard against bacterial contamination of milk once outside the body, and because platypus don't have this system they have developed a special kind of anti-bacterial protein to keep their milk safe for their young.
As gross as sweating milk sounds, it's actually led to some interesting scientific discoveries, and may end up helping humanity combat the ever-growing threat of bacterial superbugs. Thanks, platypuses!