The duckbill platypus is one of the three species of monotremes mammals that lay eggs, a shy animal which lives in some rivers in the east of Australia.
The duckbill platypus looks like an impossible compendium of different zoological types. From the time Dawson sent his controversial example to the British Natural History Museum, there were constant scientific discussions, lasting for over a hundred years, until, finally, two zoologist demonstrated irrefutably that they were indeed mammals, and reproduced by laying eggs.
Although they are small in size, the duckbill platypuses would seem to have an insatiable appetite. This one has found a river crab. Crustaceans, molluscs, annelids, and even amphibians form part of their extremely varied diet. And their peculiar morphology means they are able to hunt their prey even in muddy waters.
Using its webbed feet and broad muscular tail to propel itself along, the archaic platypus searches the river bottom. The sensors on its beak detect the slightest movement or change in temperature. Any animal crawling or swimming along the river bed is rapidly located and, if it of any interest, devoured. In the rivers of Australia, the platypus is so well-adapted it has no competitors. Or rather, almost none.
As in so many other environmental niches, the placentary mammals have also come up with a prototype.
On this occasion, the result of the evolutionary process was the water rat, or beaver rat, which was able to thrive in the aquatic world thanks to its water-proof fur and partially-webbed feet.
Strangely, no marsupial tried developed to colonise the rivers of Australia, and so the freshwater resources of this continent are shared between the modern water rat and the archaic duckbill platypus.
The aborigines, who arrived in Australia fifty thousand years ago, already knew the duckbill platypus, which they named the “water mole”, a very appropriate name, given that the platypus lives out its amphibious life between the water, where it finds food, and the river banks, where it digs its tunnels.
Their dependence on the rivers however limited the spread of this survivor from Gondwana because as Australia became increasingly dry, and the rivers of the interior slowly disappeared, with the rising of the temperature deserts were formed.
The other two mammals thay lay eggs are echidnas the long-snouted variety in New Guinea, and the short-snouted variety, which can be found throughout Australia.