The only known venomous mammal in Australia is the Platypus. It is an egg-laying mammal that spends most of its life underwater.
The Platypus is a true evolutionary survivor and has extraordinary skills from electroreception for orientation to a poisonous spine for defence and breeding purposes.
The duck-billed platypus is one of two mammals alive today that still lay eggs. This so called animal group of ‘monotremes’ was once widespread across the globe but is now limited to Australia and New Guinea where the Platypus and its relative the Echnida have still survived.
Genetic analysis has shown that the echidna diverged from platypuses between 19-48 million years ago, which is much sooner than previously thought.
Researchers believe the main reason the Platypus has survived the competition of live-birth mammals is the ability to permanently live in a semi-aquatic environment.
They live aside freshwater rivers or lakes, and create burrows for shelter and protection. They are active mainly at night time, when they use their webbed feet for swimming and shut their eyes to dive. They are able to stay underwater for up to 10 minutes, before returning to the surface for oxygen.
Another reason for the species’ survival is how skilled they are at hunting in the water.
Duck-billed platypuses use two different types of receptors located in their bill that help them find and catch prey: mechanoreceptors and electroreceptors.
Mechanoreceptors help to detect movement in the water while electroreceptors detect electrical signals emitted from the skin of live prey, just like electroreception found in some fish and sharks.
While hunting, the platypus will even sway its head from side to side to maximize the effectiveness of these two glandular structures which combined enable the Platypus to be able to judge the distance of potential prey while still having its eyes closed underwater.
All adult males have a spur located above the heel which receives venom from the so called ‘crural gland’ in its thigh and is peaking production during the breeding season. For this reason it is assumed that the main purpose of the spike is mainly used for competing for mates or breeding territories.
However, it is understood that these animals will use them for defence as well.
The other extant monotreme, the echidna, also got a spike on its ankle but lacks the gland to produce venom.
The venom produced by the Duck-billed Platypus is quite unique, as it acts on pain receptor cells, which makes it a viable candidate for creating a new type of painkiller.