What is a monotreme?
Monotremes are egg-laying members of the mammal group. Only two families of animal are included in the group, the platypus and the echidna. There are a total of five species in the group with one species of platypus and four species of echidna.
The name monotreme comes from a word meaning 'one hole' and refers to the cloaca which is a single hole that contains the urinary tract, anus and reproductive tract.
The most unique characteristic of the monotremes is that they lay eggs. Echidnas will carry their egg in a pouch until it hatches while platypus deposit their egg in a burrow. Their eggs have a soft-leathery shell.
Another unique feature of their reproduction is that instead of teats they simply secrete milk from pores of the skin and the young will lick the milk off of these.
Where can you find monotremes?
Monotremes can only be found in Australia and New Zealand. The platypus is restricted to Australia as it the short-beaked echidna. New Guinea is the home of the three species of long-beaked echidna.
Some fossil evidence exists of these animals in Argentina suggesting the group was once more widespread during their early history.
More on Monotremes
Monotremes have a lower body temperature and metabolic rate than other mammals which helps to make them more energy efficient. They are still considered endothermic and can maintain their own body temperature.
All male monotremes have a spur on the back of their legs. This can be used during fights and in defense. In platypus this spur can be used to inject venom.
Monotreme Fact Files
The platypus was thought to be a fake when a specimen was first sent to Europe in the late 1700s. They feature a duck like bill and beaver like tail.
Males have a spur on their back legs which can be used to inject venom.
They spend much of their time foraging for worms, shrimp, insect larvae and more underwater. While foraging they spend 1-2 minutes underwater before surfacing for air but at rest they can remain submerged for up to 11 minutes.
Echidnas are best known for their spines which provide protection. They are also covered with fur and in colder areas such as Tasmania this fur may be almost as long as the spines giving them a furry appearance.
Their long snout helps them to gather up ants and termites. Juvenile echidnas will suckle milk every 5-10 days.
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Slater, P. and Parish, S., 2016. First Field Guide To Australian Mammals. 1st ed. New South Wales: Pascal Press.
Ucmp.berkeley.edu. 2020. Life History And Ecology Of The Monotremata. [online] Available at: <https://ucmp.berkeley.edu/mammal/monotremelh.html> [Accessed 26 December 2020].
The Australian Museum. 2020. What Is A Monotreme?. [online] Available at: <https://australian.museum/learn/species-identification/ask-an-expert/what-is-a-monotreme/> [Accessed 26 December 2020].
Australianwildlifejourneys.com. 2020. Monotremes | Australian Wildlife Journeys. [online] Available at: <https://australianwildlifejourneys.com/wildlife-interest/land-mammals-and-marsupials/animal/monotremes> [Accessed 26 December 2020].
Sorin, A. and P. Myers 2000. "Monotremata" (On-line), Animal Diversity Web. Accessed December 25, 2020 at https://animaldiversity.org/accounts/Monotremata/
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