What animal is a mammal, but has the bill of a duck, lays eggs and lives in the water? A platypus – one of the world’s rare and unique creatures. These fascinating animals are only found in freshwater rivers and creeks of eastern and southeastern Australia. Platypuses can be kept in captivity, but they are not very friendly and should not be handled without professional training.
How do these interesting creatures live, and how did they come to be? Let’s find out.
1. Platypuses are monotremes that share genes with reptiles, birds and mammals
The word monotreme means “single hole” – this refers to their genitals, which is a hole that functions as an anus, a urinary opening and a reproductive organ. Platypuses and echidnas are the only surviving monotremes that split from the rest of the mammal family 166 million years ago.
Prehistoric platypuses were gigantic. At nearly 1 meter long, they were nearly double the size of the platypus we know today. Modern platypuses grow to about 50 cm from beak to tail, weighing about 1.5 kg. Platypuses from colder climates are larger than platypuses from warmer habitats.
2. Platypus bills help them to sense their surroundings
Platypus bills function like a sixth sense, because they contain cells that allow for the detection of electric fields. All living things generate electric fields, so a platypus can rely entirely on its bill alone to identify the location of their prey, without the need for sight, hearing or smell.
The bill of a platypus is not solid and bony like most bird beaks. Instead, it is smooth, flexible and rubbery, and it feels like suede when touched. Bird beaks are used for pecking and striking, which are quite different from platypus bills which are used to navigate and sense.
3. Platypuses have evolved to adapt to their surroundings
Platypuses spend most of their time in the water. Although they can only stay underwater for a few minutes, they have other evolutionary traits that make it easier for them to survive in their aquatic habitat. Like otters, they have dense, thick fur that they can groom to add air bubbles, providing extra insulation to keep them warm. They also have retractable webbing on their front claws – this helps them walk around on land when they need to instead of struggling with webbing that would obstruct their movement.
4. Platypuses don’t have stomachs, their food travels directly to their intestines
Platypuses eat invertebrates that live on riverbeds, like worms, shrimp and insect larvae. Once food enters a platypus’s mouth, it travels to the gullet and then to the intestines. Scientists suggest that platypuses don’t have a stomach because their diets contain high levels of calcium carbonate, which neutralizes stomach acid due to its alkalic properties.
Platypuses also have no teeth. When they hunt, they pick up small amounts of gravel along with their prey and keep this prey and gravel mixture in their cheek pouches. Once they are ready to eat, they chew by grinding the gravel and their food together in their mouths using their hard grinding plates.
5. Male platypuses are venomous
Male platypuses have an ankle spur on their back feet that contains venom strong enough to kill a dog. This venom will not kill a human, but it can be very painful and the effects will last for several weeks. During mating season, male platypuses fight using the venom to achieve dominance and find a mate. They also use the spurs to defend themselves from predators.
6. Platypuses have five pairs of chromosomes that determine sex
Mammals have one pair of chromosomes that decide whether their offspring are male or female, but platypuses are the exception. Some of the ten chromosomes have similarities with the sex chromosomes of birds. Like birds, platypuses lay eggs. Unlike birds, platypuses feed their young with milk, but instead of providing milk through nipples, platypuses have mammary gland ducts on their bellies that ooze milk.
Once a female platypus has mated with a male, she creates a nest by burrowing into the riverbank and seals herself into the nest to lay her eggs. She uses her tail to keep the eggs close to her body. In ten days, the eggs hatch, and the baby platypuses nurse for four months until they are weaned and can swim on their own.
7. Platypuses can live for more than 20 years
On average, platypuses grow up to 50 cm in length and 3 kg in weight. They become fully grown at about a year old, but they only become sexually mature in their second year of life. Platypuses live for about 12 years in the wild, but they have been known to live for much longer in captivity or in good environmental conditions.
8. Platypuses are not endangered, but this is due to insufficient data
The International Union for Conservation of Nature has platypuses listed as “Least Concern”. However, this is mostly because there has not been much research conducted on the species, and hence no data on the size of the platypus population. Platypuses face threats from prolonged droughts in Australia creating significant changes in the platypus’s aquatic habitat. Land clearing and climate change have also contributed to habitat loss.
Platypuses are hunted by snakes, crocodiles, water rats, eagles, owls and hawks. They are also hunted by foxes, dingos and large fish. They were even hunted by humans for their fur until they were instated as a protected species in Australia in the early 20th century. Now, it is illegal to capture or kill a platypus unless it is specifically for scientific research.
9. Platypus milk has antibacterial properties
Platypus babies drink milk by sucking on their mothers’ skin, where milk is oozed out of special mammary glands. Due to their habitat and the way they live, platypus milk needs to be protected from environmental bacteria – studies show that platypus milk contains a unique protein that could hold the key to its antibacterial properties. This protein was named the Shirley Temple protein due to its ringlet-like structure.