Stranger Than Fiction

A mammal that lays eggs and secretes venom, the peculiar platypus has been fascinating scientists since the 19th century but faces an uncertain future.

- Linda Vergnani

A furry animal with a body the size of a hot-water bottle is cavorting through the waters of a clear, blue stream emerging from Jenolan caves, three hours west of Sydney. There is a splash as it dives down, paddling vigorously with its webbed front feet. When it reaches the bottom, the animal begins sweeping its flat, duck-like bill back and forth above the silt. The platypus is using thousands of minute receptors in its bill to detect the electrical fields made by the muscle movements of its prey – mainly insect larvae, aquatic insects, and sometimes freshwater crayfish and shrimp.

It is relatively easy to spot a platypus in the limpid stream and Blue Lake at Jenolan, but normally they are far harder to detect. Their waterproof brown coats offer good camouflage against the earthy banks of the permanent rivers, creeks, lakes and wetlands they inhabit in eastern Australia.

They’re also largely nocturnal, and usually spend the day sleeping in their burrows, which may be up to 30m long, in the river banks. They emerge at dusk to hunt for their aquatic prey and retreat at dawn. Females weigh 600–1,750g, while males are a heftier 800–3,000g (platypuses in north Queensland are about half the weight of those in Tasmania).

This curious creature is a monotreme: a form of egg-laying mammal that suckles its young. It has a single orifice – the cloaca – used for urination, defecation and reproduction. The only other monotremes are four species of echidna, but these are very different looking, spiny land dwellers.

Tom Grant, author of the natural history guide Platypus, spent over 40 years researching platypuses on a 5km stretch of the Shoalhaven River in New South Wales. He microchipped 812 individuals and found the oldest female platypus in his study was still breeding after 21 years.

WOULD YOU BELIEVE IT?