Friday Eco-Fact: Australia’s Incredible Monotremes

When one thinks of mammals people generally think ones that give birth to live young. These types mammals are known as eutherians, however there actually two more types of mammals; marsupials and monotremes, which are mostly only found in Australia. Marsupials are mammals that give birth to their young in a pocket, such as a kangaroo. The monotremes on the other hand are mammals that give birth to their young by laying eggs. There are only two monotreme species left the duck billed platypus and the echidna which there are actually four different subspecies of. Each of these monotremes can only be found in Australia and New Guinea.

The peculiar way monotremes reproduce is what causes many scientist to believe that the monotremes may be the oldest type of mammal in existence. Many scientists believe that the first mammals evolved from reptiles and that monotremes are left overs from this natural evolution. However, why didn’t these mammals evolve like the rest? It is cannot be proven why the echidna and platypus survived, but many scientists believe it is because these two species had no natural competition for the food sources they rely on. The echidnas eat ants, which are in abundance in Australia while the platypus eats insects, mollusks, and yabbies that are commonly found in Australia’s waterways.

Some other unusual characteristics of monotremes beside egg laying is that they have no teats to nurse their young from like other mammals. These monotremes however do secrete milk from two circular patches on their bellies that their babies lick from. An even more unusual trait is that both the echidna and platypus have a poisonous spur on their hind foot.  In the case of the echidna this spur cannot harm anyone since it is now inactive, but in the case of the platypus it can still use its stinger which has enough poison to kill a small dog and cause severe pain in a human.

The monotremes despite their non-mammalian features actually share plenty of similar characteristics with their mammal cousins. The monotremes can grow fur and regulate their body temperature like other mammals. But it is the differences of the monotremes that will forever make them a unique part of Australia’s incredible biodiversity.