Australia is a world of pure wonder. It houses countless species found nowhere else of earth. Australia’s unique fauna can be traced back to the supercontinent Gondwana. 140 million years ago, Gondwana began to break up. 50 million years ago, Australia separated from Antarctica and became a lone, drifting island. Whilst placental mammals began to dominate in the rest of the world, the species that were left marooned on this island, including marsupials and monotremes, thrived. They adapted and evolved to become some of the most fascinating species on our planet.
One such species is the egg-laying, beaver-tailed, otter-footed, duck-billed platypus. The platypus is an exceedingly unusual mammal yet somewhat familiar. The first scientists to examine a platypus body believed it was fake – they assumed it was made of several animal parts stuck together. However, since then, we have learned so much more about the behaviours and adaptations of this Australian monotreme (egg-laying mammal).
The platypus is semi-aquatic, inhabiting small streams and rivers across eastern Australia as well as Tasmania. They hunt underwater, using their streamlined body, webbed feet and beaver-like to tail to glide through the water with ease. They also use their tail to store fat. Their fur is dense (to help them keep warm) and waterproof. The platypus is a carnivore, using their soft bill, covered in electroreceptors, to seek out invertebrates on the river floor. They are one of the only mammals known to use electroreception – the detection of electrical fields generated by muscle contractions. Their senses of sight, hearing and smell are almost entirely shut down when underwater but their electroreceptors allow them to navigate through their habitat and locate prey effortlessly.
This creature’s list of adaptations does not stop there. The platypus is also one of the few species of venomous mammals. Males possess a horny spur on each hind foot that is capable of causing excruciating pain. The function of this tool is not fully understood – maybe it’s used to assert dominance over other males during the breeding season. One thing that surprised me about the platypus was their size; from the pictures I’d seen, I imagined them being rather large animals. However, they only reach a maximum length of 50cm from head to tail – around the same size as a domestic cat.
Along with the four species of echidna, the platypus is one of five mammal species that lays eggs. Females lay their eggs in a burrow and curl around them to keep them warm. Their eggs only take around 10 days to hatch, compared with 21 days for a chicken egg. However, platypus babies are born blind, hairless and generally quite helpless. For the next three to four months they survive on their mother’s milk which is released from pores in the platypus’ skin.
Australia was once home to an even more diverse array of wildlife including the diprotodon (the largest marsupial ever to have lived), giant kangaroos weighing over 200kg and the thylacine (commonly known as the Tasmanian tiger). The latter was a large carnivorous marsupial that only became extinct in the 1930s due to hunting, disease and habitat loss. Today, the majority of Australia’s megafauna is extinct, and humans undoubtedly had a role in their demise. With the platypus and hundreds of other species being endemic to Australia, it is vital that we protect the weird and wonderful wildlife that still survives in this extraordinary land.
Seven Worlds, One Planet returns to BBC One tonight at 6:15pm in the UK where we will learn more about the remarkable species found in Australia.
Hennessy, K., Wiggins, V. (2014) Animal Encyclopedia: The Definitive Visual Guide. 2nd edn. London. Dorling Kindersley.
Seven Worlds, One Planet Trailer: https://www.youtube.com/watch?v=nm5XasUl7HM