The Ultimate List of Platypus Facts
The platypus is arguably one of the most remarkable species on earth. This egg-laying, duck-billed, beaver-tailed, otter-footed mammal baffled European naturalists when they first encountered it, with some considering it an elaborate hoax.
1. They are one of the only mammals that lay eggs.
The name given to egg-laying mammals is a ‘monotreme’. There are only five species of monotreme in the world – all found only in Australia and New Guinea – including the platypus, and four species of Echidna. Monotremes are also characterised by a primitive skeleton, very similar to that of long-extinct mammals, which suggests that monotremes are actually very ancient creatures.
2. Their bill is used as a sensory organ to find prey underwater.
The platypus’ bill is similar to that of a duck in appearance, but for the platypus, it is used as a sensory organ. When diving, they close their eyes and block their ears and nose, using only the bill to locate prey underwater. The skin on the bill has ‘push rods’ which detect touch and water movement from 15-20 centimetres away, and is also dotted with electroreceptors which detect the small amounts of electricity produced by muscle movements of prey. As electricity moves through water rapidly, the electroreceptors will often detect prey before the push rods.
3. Males have a venomous spur on their inner-hind ankle.
Males are equipped with a keratin spur about 12-18 millimetres long, tucked away on their inner hind ankle. This spur produces a clear, sticky venom used for protection when attacked by predators and to compete with other males for mates. Their venom is strong enough to kill a dog (their main predators), and while it isn’t fatal to humans, it causes excruciating pain that lasts several weeks and is not effectively relieved by analgesics such as morphine. The venom is made up of 19 different compounds, and is thought to be entirely different in make-up from snakes’ venom.
4. Females don’t have nipples, but glands which secrete milk onto the fur.
Unlike most mammals, female platypuses do not possess nipples or teats for milk production. Instead, their mammary glands, located under the skin on their belly, secrete milk through the skin and into the fur on their underside. The babies then suck the milk from the mother’s belly fur.
5. Rather than teeth, they have plates to grind food.
Whilst the several ancestor species of the platypus possessed teeth, the single living species has evolved without teeth. Instead, they have horned pads unique to their species which they use to grind up food. Their diet consists of invertebrates, such as larvae and worms, which do not require too much chewing, due to their lack of teeth, however, sometimes they still need assistance. They dive down and scoop up their prey from the bottom of the lake, creek or other waterways, and at the same time scoop up some gravel. They grind the food and gravel with their plates and the gravel helps to break up the food.
6. Some hibernate for six days at a time in winter.
Platypuses in captivity and those found in Victoria have been found to enter a state of what is called ‘torpor’ during colder months, in which they drop their body temperature and remain inactive for up to six days at a time, much like hibernation. Strangely, individuals in New South Wales and Tasmania have not been found to enter ‘torpor’ at all, even during winter. This is thought to be caused by cooler temperatures of water in these areas.
7. They can swim a metre per second but aren’t adept at walking on land.
The platypus’ body is streamlined and their fur is waterproof, allowing them to swim quite quickly in moving waters, travelling approximately a metre per second – that is double its body length. However, due to its short legs and webbed feet, it walks very awkwardly on land. The webbing on its feet retracts and there are claws on each foot used for digging burrows, which assist in walking, but they are still much slower on land than in water.
8. When they were first discovered, biologists believed they were a hoax.
In 1799, when the platypus was first discovered, British biologists were convinced that the platypus was an elaborate hoax. At the time, several people had ‘created’ animals by sewing them together and claimed that they were a new species from an exotic place, such as a ‘mermaid’ made by sewing a monkey and a fish together. Biologists were convinced that the platypus was one of these creations, and expected that the bill was sewn on.
9. They dig burrows and create plugs to fool predators.
Platypuses have two types of burrows which they dig with their retractable claws high up on the steep muddy banks; ‘nesting burrows’ are where a mother and her young take shelter for several months and are about three to six metres long, while ‘camping burrows’ are where individuals sleep on any given night and are about one to four metres long. They only stay in camping burrows for a few nights and switch between several different burrows over the space of a few weeks. They are very intelligent – when a mother enters a nesting burrow she creates a ‘plug’ behind her, after the plug the burrow usually veers in another direction. It is thought that the purpose of these plugs is to fool predators into thinking they are at the end of the burrow.
10. They are thought to have evolved from one of Australia’s oldest mammals, the Steropodon Galmani.
Steropodon Galmani lived 110-million years ago and is one of Australia’s oldest mammals, and also the ancestor of the platypus. Steropodon lived during the Cretaceous period, and perhaps even earlier, alongside dinosaurs. They were about the same size as the platypus but the main difference was that they had teeth – three molar teeth on the lower jaw. A fossil was found only of its lower jaw, and nothing else, so the bottom jaw structure is the only anatomical information known about the Steropodon.