Why Are Australian Animals So Weird?

3 min read

Morning Aussies!

Kangaroos, koalas, platypuses, wombats, emus, big scary spiders…

Australia has some weird ass animals.

I mean, sure, the world is full of strange creatures…

But why does Australia have so damn many of them?

Well, one of the main reasons is to do with Aussie mammals.

See, across the world, there are actually 3 different types of mammals.

  • Placentals (these guys give birth to babies like us)
  • Monotremes (these guys plop their babies out as eggs).
  • Marsupials (these guys grow their babies in weird sacks on the outside of their body).

Most of the mammals in the world are placentals (like us).

Making up 92 percent of all mammals.

But Australia is special because they are the only continent with all 3.

And they are also the only continent where marsupials are the dominant mammal type.

But why is this?

Well, let’s go back to 250 million years ago.

When the world looked like this:

Sick right?

You can see that Australia actually used to be attached to all the other continents.

Which allowed animals to roam freely between these now separate continents.

So, what we think happened is this:

Marsupials first evolved in South America.

And over time… many of them made their way south into Antarctica and Australia.

But then, something happened.

Over MILLIONS of years, the continents slowly separated apart.

Splitting Antarctica and Australia off from the rest of the world.

Meaning many of the worlds marsupials got trapped on Antarctica and Australia.

Here’s the key point.

The rest of the world had a couple marsupials in South America, but it also had TONS of placentals.

So, over time, the placentals out-competed the marsupials and many of them died out.

Now, there weren't many placentals in Australia, but there were… a TON of marsupials.

And after all the marsupials on Antarctica froze to death, the only place left with lots of them was… Australia.

So, now these animals were completely isolated for tens of MILLIONS of years.

So, over time, the initial marsupials evolved into all manner of weird and wacky creatures.

Creatures you simply can't find anywhere else.

Which is why so many animals in Australia are Endemic

(meaning they can only be found there).

Like 83% of the mammals and 89% of the reptiles found in Australia can ONLY be found in Australia.

Pretty wild!

Stay Cute,
Reece, Henry & Dylan 🌈

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