Damon Mcknight
Australia is home to the world's only living egg-laying mammals, known as monotremes. These include the platypus and four species of echidnas, sometimes known as spiny anteaters. Echidnas are medium-sized, solitary mammals covered with coarse hair and spines, while platypuses are famous for their duck-like bills, webbed feet, and beaver-like tails. These strange creatures are the last survivors of a much larger and more diverse set of species that once roamed the southern continents.
| Characteristics | Values |
|---|---|
| Name | Monotremes |
| Species | Platypus, Echidna |
| Habitat | Australia, New Guinea |
| Diet | Insects, ants, termites, small invertebrates, shrimp, crayfish |
| Reproduction | Egg-laying |
| Gestation | 10-11 days |
| Young | Puggle |
| Lifespan | 14-16 years |
| Weight | Female: 4.5 kg, Male: 6 kg |
| Conservation status | Endangered |
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What You'll Learn
Platypuses and echidnas are the only egg-laying mammals
Platypuses and echidnas are the only surviving members of the order Monotremata, which are the only living mammals that reproduce by laying eggs. These two species are the last survivors of a much larger and more diverse set of species that once roamed the southern continents.
Monotremes are considered some of the most primitive living mammals, having split from other mammalian lineages approximately 150 million years ago during the Jurassic period. Their name comes from the Greek word "monotreme", meaning "single opening", referring to the single duct (the cloaca) for their urinary, defecatory, and reproductive systems. They are also known as "egg-laying mammals".
Platypuses and echidnas exhibit some of the most unusual biological traits among mammals. From their egg-laying reproductive process to their specialised adaptations, these creatures stand out in the mammalian world for blending both ancient and modern features. Platypuses lay between one and three eggs, while echidnas lay a single egg about 22 days after mating. The female echidna deposits the egg directly into her pouch, while the female platypus incubates her eggs in a burrow. After being laid, the eggs are incubated for around 10 to 11 days (in platypuses) or 10 days (in echidnas).
Like all mammals, platypuses and echidnas feed their young on milk, which contains various factors to sustain their growth and development. However, they do not have teats, so the young suckle milk from the pores of two milk patches. Platypuses and echidnas are also known for their venomous spurs, which are located in the ankle region. These spurs contain a powerful venom that can be used for self-defence or to capture prey.
In addition to their egg-laying ability, platypuses and echidnas possess other unique characteristics that set them apart from other mammals. For example, they have webbed feet and a duck-like bill, which make them excellent swimmers. They also have a long, slender snout that functions as both mouth and nose, with electrosensors that help them find prey.
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Monotremes are the only living mammals that lay eggs
The platypus is famous for being one of the world's strangest animals. From its webbed toes to the tip of its fat tail, the platypus is packed with features that whisper of their ancient lineage. Platypuses lay between one and three eggs, which are incubated for around 10 to 11 days.
Echidnas, sometimes known as spiny anteaters, are quill-covered monotremes. They are medium-sized, solitary mammals covered with coarse hair and spines. The female echidna lays a single soft-shelled, leathery egg 22 days after mating, and deposits it directly into her pouch. The egg is about 1.4 centimetres long and weighs 1.5 to 2 grams. It hatches after 10 days of gestation. The young echidna, called a puggle, is born larval and fetus-like, and sucks milk from the pores of the two milk patches.
Monotremes are considered some of the most primitive living mammals, having split from other mammalian lineages approximately 150 million years ago during the Jurassic period. Their evolutionary path diverged significantly from marsupials and placental mammals, resulting in the retention of certain reptilian features, such as egg-laying. However, monotremes also developed key mammalian traits, such as the ability to produce milk, though they do so without the use of nipples. They also have unique reproductive strategies. For instance, monotreme eggs are leathery, similar to those of reptiles, and the young hatch in a relatively underdeveloped state, requiring extensive care.
The presence of vitellogenin genes (a protein necessary for egg yolk formation) is shared with birds, suggesting that the common ancestor of monotremes, marsupials, and placentals was oviparous, and that this trait was retained in monotremes but lost in all other extant mammal groups. DNA analyses suggest that although this trait is shared and is synapomorphic with birds, platypuses are still mammals and that the common ancestor of extant mammals lactated.
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Echidnas are sometimes known as spiny anteaters
Echidnas are sometimes referred to as spiny anteaters because of their resemblance to the anteaters of South America. They are medium-sized mammals covered with coarse hair and spines, which are made of keratin, the same fibrous protein that makes up fur, claws, nails, and horn sheaths in animals. They are usually black or brown in colour, but there have been several reports of albino echidnas with pink eyes and white spines.
Despite their appearance, echidnas are capable swimmers and tree climbers. They inhabit scrubland, desert, and montane forest in Australia, Tasmania, Indonesia, and Papua New Guinea. They are found in forests and woodlands, hiding under vegetation, roots, or piles of debris. They sometimes use the burrows of other animals, such as rabbits and wombats.
Echidnas have elongated and slender snouts, or proboscises, that function as both mouth and nose, and which have electrosensors to find earthworms, termites, ants, and other burrowing prey. This is similar to the platypus, which has 40,000 electroreceptors on its bill. The long-beaked echidna has only 2,000, while the short-beaked echidna, which lives in a drier environment, has no more than 400 at the tip of its snout.
The diet of some echidna species consists of ants and termites, but they are not closely related to the American true anteaters or to hedgehogs. Their young are called puggles, and they are born from a single, soft-shelled, leathery egg laid by the female about 22 days after mating. After a quick gestation period of about 10 days, the baby echidna, or puggle, hatches and suckles milk from the mother's pouch.
Echidnas are the only living egg-laying mammals, along with the platypus. They evolved between 20 and 50 million years ago, descending from a platypus-like monotreme. This ancestor was aquatic, but echidnas adapted to life on land, and they play an important environmental role by moving large amounts of soil.
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Platypuses are one of the world's strangest animals
Platypuses are found in freshwater systems such as rivers, lakes, ponds, and streams across eastern Australia, including Queensland, New South Wales, Victoria, and Tasmania. They are most active at night and can stay underwater for 30 to 140 seconds. During the day, they shelter in burrows on the shore or under rock ledges and debris. Platypuses have a unique method of chewing their food, using "grinding plates" in their mouths to break it down. They also possess a small pouch-like section in their mouths that contains glands producing a mucus-rich fluid to aid in nutrient uptake.
One of the most unusual facts about platypuses is that they lack a traditional stomach, a strange trait for a vertebrate animal. They also have a single cloaca for their urinary, defecatory, and reproductive systems, a feature more commonly found in birds and reptiles. Platypuses are one of the few mammals that glow under UV light, a phenomenon known as biofluorescence. They also ooze milk through their skin and can sense electricity.
Platypuses are the only living species of monotremes, an ancient order of animals with primitive traits, that lay eggs. Monotremes are believed to have originated in the chilly polar forests of an ancient world, with the oldest-known monotreme, Teinolophos trusleri, living around 130 million years ago in what is now south-eastern Australia. Platypuses are under threat due to human-induced habitat degradation, and it is crucial to protect them to preserve their uniqueness for future generations.
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The first mammals were almost certainly egg-layers
The platypus and the echidna are the only two surviving species of egg-laying mammals, or monotremes, in the world today. They are native to Australia and New Guinea. However, the first mammals were almost certainly egg-layers, although direct fossil evidence of these fragile structures is yet to be found.
Monotremes are mammals of the order Monotremata. They are the only group of living mammals that lay eggs, rather than bearing live young. The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified by structural differences in their brains, jaws, digestive tract, reproductive tract, and other body parts, compared to the more common mammalian types. Although they are different from other living mammals in that they lay eggs, female monotremes are like other mammals in that they nurse their young with milk.
The sequencing of the platypus genome has also provided insight into the evolution of a number of monotreme traits, such as venom and electroreception. Platypuses and echidnas are in many ways more akin to the original mammal blueprint than other mammals. For example, the platypus has a spur in the ankle region that contains a powerful venom. Male monotremes do not have a prostate or seminal vesicles.
The presence of vitellogenin genes (a protein necessary for egg yolk formation) is shared with birds. The presence of this symplesiomorphy suggests that the common ancestor of monotremes, marsupials, and placentals was oviparous, and that this trait was retained in monotremes but lost in all other extant mammal groups. DNA analyses suggest that although this trait is shared and is synapomorphic with birds, platypuses are still mammals and that the common ancestor of extant mammals lactated.
It has been suggested that lactation's original function was to keep eggs moist. Monotremes do not have nipples, but secrete milk from a hairy patch on their bellies. During incubation, monotreme eggs are covered in a sticky substance whose origin is not known. Before the eggs are laid, their shells have only three layers. Afterwards, a fourth layer appears with a composition different from that of the original three. The sticky substance and the fourth layer may be produced by the mammary glands.
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Frequently asked questions
The platypus and the echidna are the only living mammals that lay eggs. They are the only surviving members of the order Monotremata.
The platypus and the echidna are known for their unusual biological traits. They are furry, warm-blooded, and produce milk. They also have a single duct (the cloaca) for their urinary, defecatory, and reproductive systems. Platypuses lay between 1 to 3 eggs, while echidnas lay a single egg.
The platypus and the echidna are believed to have branched off from the rest of the mammals between 150 and 210 million years ago. They are considered some of the most primitive living mammals, retaining certain reptilian features such as egg-laying. Platypus fossils and DNA suggest that all mammals may have originally been venomous egg-layers.
