The platypus is an extraordinary mammal that is only found in Australia, residing in permanent freshwater systems. The platypus inhabits a wide range of climates from tropical to alpine environments along Australia’s eastern mainland and Tasmania. The platypus represents an ancient lineage, sharing a common ancestor with us that existed more than 150 million years ago, when dinosaurs still roamed the earth and the first flower evolved. Back then, mammals were very different to those found today, and did not have a placenta. For some reason, the platypus maintained many of its ancient features, and is one of only two mammal species which lays eggs. The other, the terrestrial echidna, is the only other member of this ancient lineage called the monotremes. The word monotreme comes from their posterior opening, called a cloaca, that serves as the only opening for the digestive, reproductive, and urinary tracts, which predominantly exists in amphibians, reptiles and birds.

The size of platypuses varies along its range, increasing in size from tropical north Queensland (700–1,100 g) to the colder climate of Tasmania (1,200–3,000 g). Male platypuses, which are larger than females, are also armed with venomous spurs on their hind ankles. If a human is spurred by a platypus, the venom can be quite excruciating, with pain lasting for several months. The use of such a potent venom may be more related to breeding than fending off predators, possibly used between males fighting over territories and access to females. The platypus is most famous for its leathery duck-like bill which is equipped with electro- and mechanoreceptors at its tip. The platypus uses these receptors to find freshwater macro-invertebrates such as yabbies and nymph stages of dragonflies and mayflies in the water while diving with its eyes closed.

European colonization of Australia quickly impacted platypuses. They were hunted for their fur and for sport until 1912. But many other threatening processes pursued. Widespread land clearing and access by livestock to creeks and rivers destroyed riparian vegetation and riverbanks. Trees are important for shading and for supporting earthen banks which are critical for platypuses who build their burrows for shelter and nests. Riparian vegetation also providing organic materials to support healthy freshwater food webs. Land clearing and degradation of riverbanks have also increased sedimentation, smothering stream beds, further degrading foraging habitat and creating shallower rivers which are more likely to dry out during extreme droughts. Building of dams and extracting water have also had a significant impact on freshwater habitats across much of the platypus’ range, lowering water availability, changing the timing of flows, and posing barriers for movement.

Until only recently, not much attention has been given to platypuses, likely because of its cryptic and nocturnal nature. For many years, most people assumed that platypuses were doing just fine. Researching platypuses is very difficult and time consuming, with most of the work done at night. But conservationists have become aware that this is not the case and that platypus numbers have considerably decreased over the years. Accounts of platypuses in historical newspapers suggest that a shift in our collective memory of how numerous platypuses used to be may have occurred. This is often called a ‘shifting baseline syndrome’, occurring when knowledge of past conditions is lacking.

Understanding this is important for assessing the impact we have had on our environment. Examples of shifting baselines are all around us, often relating to fish stocks, extent of forests and bird and insect numbers around us. The platypus is currently listed as a Threatened species in the states of South Australia and Victoria given declines in distribution and numbers - but remains unlisted nationally. Developing conservation strategies to protect against further degradation and maintain the many ecosystem services we are reliant on is paramount for both the platypus and us. There is much we can do to protect this amazing creature and its freshwater habitats. Even reporting of any platypus sightings you make is important.

For more information on the unique platypus:
·      https://academic.oup.com/jmammal/article/100/2/308/5477503
·      https://ebooks.publish.csiro.au/content/platypus
·      https://www.bees.unsw.edu.au/platypus-conservation-initiative
·      https://www.youtube.com/watch?v=QNoQvjlmGdk
·      https://www.youtube.com/watch?v=OVneqhu9oZk