When we think of mammals, we usually picture animals that give birth to live babies such as dogs, cats, or even humans. But did you know that there’s a small and rare group of mammals in the world that actually lay eggs and feed milk to their babies? (or puggles as they’re known). These special egg laying mammals are called as monotremes in the scientific world.
Egg-laying mammals or monotremes, are a unique group of mammals that produce eggs instead of giving live birth. There are few living monotremes in the world and all are found in Australia or New Guinea.
Only two types of egg-laying mammals are left on the planet today: the platypus and the echidna (also known as the spiny anteater). However, there are five known species of these animals, each with its own unique traits.
Monotremes once dominated Australia until their poach bearing relatives, the marsupials (pouched mammals like kangaroos and koalas) came along and swept them away millions of years ago. It is believed that the platypus and echidna managed to survive because their ancestors taking to the water where they could avoid competition.
So, what makes these mammals so unusual? Let’s take a look at the five species of monotremes that still lay eggs today.
The Platypus
The platypus is one of the most unusual animals on Earth. With its duck-like bill, beaver-like tail, webbed feet and it looks like a mix of different animals. Found in eastern Australia and Tasmania, it’s built for both land and water, spending most of its time swimming in rivers and streams.
The female build a burrow where she lays one to three eggs and keeps them warm by curling around them. After about 10 days, the small babies hatch.
The young platypuses, called puggles are completely helpless when they’re born. They have no fur and are entirely dependent on their mother’s milk to survive. But here’s something really interesting- platypuses don’t have teats like other mammals. Instead of nursing from nipples, their milk seeps through the mother’s skin, and the babies lick it off her fur. It’s a pretty unusual way to feed, but it works perfectly for these unique creatures!
The platypus is the only Australian mammal known to be venomous. Males have a sharp spur above the heel on each hind leg, which is capable of delivering a painful toxin. While this venom won’t kill a human, it can cause severe pain and swelling. Scientists believe this venomous spur is mainly used by males to assert dominance over other males during the breeding season
The Short-beaked Echidna
The short-beaked echidna, also known as the spiny anteater, is one of the few egg-laying mammals left on Earth. This intriguing animal is found throughout Australia and parts of New Guinea.
The Short-beaked Echidna has strong claws for digging and a long, sticky tongue to catch its favorite food- ants and termites. Their sticky tongue is used to catch termite ants and smash them inside their mouths as they don’t have teeth at all. With a keen sense of smell, its not only finds food hidden underground but also tracks down potential mates during breeding season.
The female carries the fertilized egg inside her for about 20 to 30 days and then she lays a single soft, leathery egg, which she carries in a pouch-like fold of skin on her belly. Once the egg hatches, a small, hairless baby called a puggle, emerges. The baby stays in the mother’s pouch feeding on her milk, until it is strong enough to survive on its own.
The Eastern Long-beaked Echidna
The Eastern Long-Beaked Echidna, a fascinating egg-laying mammal native to New Guinea, is one of the largest monotremes alive today. Although it resembles its long-beaked relatives, it different slightly in size and diet. This echidna is covered in brown or black fur and has protective spiny exterior, a compact body without a tail, and a long, slender snout with a tiny mouth at the end.
Unlike most mammals, echidnas don’t have teeth, instead, they use their long, sticky tongue to catch ants, termites, earthworms, and insect larvae, which they swallow whole. Their snout helps them track food by following scent trails, root through mud and dirt for food. Echidnas are mostly nocturnal, foraging at night and hiding during the day under logs, rocks, or by burrowing into the ground to escape the heat.
In contrast to the short-beaked echidna, which mainly eats ants and termites, the Eastern Long-Beaked Echidna primarily consumes earthworms, insects, and larvae. Like other monotremes, female lays eggs, which she keeps in her pouch until they hatch. The eastern long-beaked echidnas are different from their long-beaked cousins and considered vulnerable by the IUCN
The Western Long-beaked Echidna
The western long-beaked echidna is a unique species of monotreme, a small group of mammals that lay eggs instead of giving birth to live young. This rare mammal lives in one of the most isolated and unexplored Foja Mountains of New Guinea. As the largest monotreme, it can weigh up to 40 pounds, making it much larger than other echidna species.
The Western Long-beaked Echidna has a thick coat of fur and protective spines, along with a long snout that helps it track down its primary food source- earthworms. Instead of teeth, it uses a sticky tongue to catch its prey and has three strong, sharp claws for digging and defense. Rather than confronting threats, the western long-beaked echidna usually curls into a tight, spiky ball to shield itself from predators.
These animals are highly solitary, only coming together briefly during the summer mating season. Females typically lay a single egg, which they carry in a pouch-like fold of skin until it hatches. Unfortunately, due to illegal poaching and habitat loss, this already rare species is experiencing a decline in population, making conservation efforts vital for its survival.
Sir David’s Long-beaked Echidna
This echidna is covered in coarse fur and spines and has small spurs on its hind legs, which may serve as a defense mechanism when threatened. It is a solitary and nocturnal animal, spending most of its life alone and only interacting with others during the annual mating season.
After mating, the female prepares for her single egg by creating a well-insulated den or burrow where she will safely keep her offspring. The baby stays in the burrow, nursing until it grows spines and fur and is strong enough to survive independently. Sir David’s long-beaked echidna also has a notably long lifespan, with some related monotremes in captivity living between 45 and 50 years.
Despite its resilience, much about this species remains unknown due to its rarity and remote habitat, making it one of the most intriguing animals still awaiting further scientific exploration.
Frequently Asked Questions (FAQ)
Egg-laying mammals are called monotremes. They are a small, unique group of mammals that lay eggs instead of giving birth to live young.
There are only five known species of egg-laying mammals: the platypus and four species of echidnas (short-beaked echidna, western long-beaked echidna, eastern long-beaked echidna, and Sir David’s long-beaked echidna).
Monotremes are native to Australia, Tasmania, and New Guinea. The platypus inhabits freshwater environments in Australia, whereas echidnas can be found in forests, mountains, and grasslands throughout Australia and New Guinea.
Some mammals, like monotremes, reproduce by laying eggs instead of giving birth because they represent an ancient evolutionary stage between reptiles and modern mammals. Millions of years ago, the ancestors of all mammals likely laid eggs, just like reptiles and birds do today. While most mammals eventually adapted to give birth to live young, monotremes have preserved their ability to lay eggs. Scientists believe this is because monotremes diverged from other mammals very early in evolution, before live birth became before live birth became the dominant reproductive method. Their eggs are similar to reptile eggs, having a soft, leathery shell instead of the hard shell found in bird eggs.
To produce eggs an animal needs vitellogenin genes for the production of egg yolks, there are three vitellogenin genes in total. As humans evolved we lost these genes, but chickens continue to have all three. Platypuses still carry one of the vitellogenin genes, the other two disappeared roughly 130 million years ago. It’s because of this gene that they lay eggs.
Even though they lay eggs, monotremes are able to produce milk to feed their young. The key to this lies in their genetics. In all other mammals, the vitellogenin genes (the genes responsible for producing egg yolk in reptiles and birds) have been replaced by casein genes that are crucial for milk production. Monotremes, like the platypus, still have some vitellogenin genes for laying eggs, but they also have casein genes, enabling them to produce milk. Unlike other mammals, monotremes don’t have teats. instead, they secrete milk through special skin pores and the babies lick it directly from their mother’s fur. This distinctive adaptation helps monotreme young get the necessary nutrients for growth, even though they develop outside the mother’s body in an egg.
Yes, some monotremes are endangered or vulnerable due to habitat loss, poaching, and climate change. The western long-beaked echidna and Sir David’s long-beaked echidna are particularly at risk. Conservation efforts are crucial for their survival.
Platypuses eat small aquatic animals like insects, worms, and crustaceans. Echidnas mainly eat ants, termites, earthworms, and insect larvae, using their long, sticky tongues to catch their food.
Yes! The platypus has electroreception, allowing it to sense underwater prey, and males have venomous spurs on their back legs. Echidnas have sharp spines for protection and strong claws for burrowing.
No, keeping a platypus or echidna as a pet is illegal in most countries. They have specialized diets, unique habitat needs, and are protected wildlife species.
