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Did you know that today there are 5 species of mammals that lay eggs? It is strange to say that there are oviparous mammals, since one of the main characteristics that define mammals is the presence of breasts and nipples to suckle the young after birth. However, in the distant continent of Oceania, a group of oviparous mammals represent the exception within the viviparous reproduction of mammals.
If you want to know the name of this intriguing group of animals, as well as their main characteristics, list of species and their state of conservation, in this Green Ecologist article we will tell you what are the mammals that lay eggs.
What are egg-laying mammals called?
Monotremes is the name that the science of taxonomy has attributed to the curious and small group of mammals that lay eggs. Monotremes have inhabited the Earth since early Cretaceous, about 110 million years ago, being considered today one of the strangest and most enigmatic groups of animals. If we analyze the evolutionary history of monotremes (Prototheria subclass) we will discover that they share the same origin with two very prominent groups of mammals: the marsupials (subclass Metatheria) and placental mammals (subclass Eutheria).
However, the main characteristic that defines and differentiates monotremes from other mammals is their ability to lay eggs, thus lacking body organs associated with suckling their young, such as breasts or nipples. Once the young hatch the protective egg, the monotreme females feed them with nutritional substances that they excrete through their own skin pores.
Learn more about these curious mammalian animals that lay eggs, in this other Green Ecologist article in which we talk about Monotremes: characteristics and examples.
What are the mammals that lay eggs - list
Now that we already know what is the peculiar group of mammals whose young hatch from eggs, let's put first and last names to the species that currently belong to this group, the monotremes. These are the egg-laying mammal species that still exist:
- Platypus (Ornithorhynchus anatinus).
- Short-nosed echidna (Tachyglossus aculeatus).
- Western long-beaked echidna (Zaglossus bruijni).
- Eastern long-beaked echidna (Zaglossus bartoni).
- Long-nosed Echidna of Attenborough, or of the Cyclops Mountains (Zaglossus attenboroughi).
Below, we present detailed information on each of these species, in order to learn more about the main characteristics and the current state of conservation of each one of them.
Platypus (Ornithorhynchus anatinus), the best-known egg-laying mammals
This is probably the best known monotreme in the world. These are the main characteristics of the platypus:
- Its characteristic duck snout, as well as its curious otter and beaver tail legs, make it one of the Stranger-looking mammals.
- This curious combination of limbs and beak, is perfectly designed for platypus to live in aquatic habitats. In this way, the interdigital membranes of its legs and its beaver tail allow it to be great swimmers, while its duckbill is really useful to catch small aquatic invertebrates on which they feed.
- Another of the surprising characteristics of platypus is the presence in males of dewclaws with poisonous glands on their hind legs, making them one of the few poisonous mammals of the world.
- At present, platypus inhabit only and exclusively in the eastern part of Australia and on the island of Tasmania, their conservation status being near threatened (NT).
Short-nosed Echidna (Tachyglossus aculeatus)
The short-nosed echidnasUnlike the platypus, they are monotremes of terrestrial habitats and these are their characteristics:
- They are small in size, between 50 and 75 centimeters in length and their appearance can be assimilated to that of hedgehogs, since they have an entire coating of thorns on their body.
- The main characteristic of this species of terrestrial monotremes is the presence of a short thin muzzle, devoid of teeth, which they use to feed on ants and termites, their favorite food diet.
- To find short-beaked echidnas in their natural habitat, we should visit the islands of New Guinea, Tasmania or Australia, where these monotremes inhabit tropical and subtropical forests and grasslands.
- The current conservation status of short-beaked echidnas is of Least Concern (LC).
Long-nosed echidnas (genus Zaglossus)
The last three species included in the monotreme group belong to the genus Zaglossus. They are commonly known as long-snouted echidnas and, according to their distribution within the island of Nueva Guinea, there are 3 species different:
- Eastern long-beaked echidna (Zaglossus bartoni).
- Western long-beaked echidna (Zaglossus bruijni).
- Long-nosed Echidna of Attenborough, or of the Cyclops Mountains (Zaglossus attenboroughi).
These are the main characteristics of long-snouted echidnas:
- Like the short-snouted echidnas, described above, the long-snouted echidna's body features numerous spines or quills, as well as with a muzzle without teeth suitable for the insectivorous feeding of the animal.
- As their name suggests, these three species of the genus Zaglossus are characterized by a longer and finer snout than that of their short-snouted relatives (Tachyglossus aculeatus).
- These egg-laying mammals they usually have 1 single brood per clutch, and their life expectancy is usually between 30 to 50 years.
- Currently, long-snouted echidnas suffer the loss and degradation of their natural habitat, due to the occupation of activities such as agriculture, hunting or even sporting activities within the natural range of these species. In addition, many are hunted for their meat consumption.
- For all this, the species Zaglossus attenboroughi Y Zaglossus bruijni are critically endangered (CR) for conservation, while Zaglossus bartoni presents a vulnerable state (VU).
If you want to read more articles similar to What are the mammals that lay eggs, we recommend that you enter our category of Animal Curiosities.
Bibliography- Flores, D. (2015) Handbook of the Mammals of the World: Monotremes and Marsupials. Lynx Editions, Argentine Society for the Study of Mammals of Tucumán, Argentina. Volume 22 (2), pp: 423-424.
- Martinelli, A., Forasiepi, A. & Rougier, G. (2008) Australosphenids: Close relatives of the enigmatic monotremes. Science Today Magazine, Volume 18 (104).
