[narrator] Growing up in the wild can be pretty hardcore.

Imagine learning to leap, roar, swim, or fly for the very first time.

You've got to get it right because the faster you are, the stronger you are, or even the better you can camouflage yourself, the greater your chances of surviving and thriving in the wilderness...

When you grow up, that is!

But with all this feral rivalry going on, you've got to wonder, who really is Mother Nature's biggest or smallest , or most dangerous untamed youngling of them all?

The answers will astound you, and we are counting them down from ten to one.

They are cute, they are "wild".

They are the "cover girls and boys" of the animal kingdom and they know it!

They are baby animals.

When the planet is filled with species that want to devour you, you're going to need all the enigmatic superpowers you can muster to live your best life: hiding in plain sight, shapeshifting, and apparently the ability to do this!

So, in a world where evolution has empowered you with the ability to mystify your arch nemesis, just who will make our Top Ten dream team of deception?

Most mysterious baby animals, assemble!

[birds chirp] When it comes to all-star animals of mystery, the kangaroo is iconic.

A living symbol of Australia, famous across the world for its hop and long tail.

But have you ever seen one up a tree?

Well at Number Ten, we have the charmingly enigmatic tree kangaroo.

And though it's hard to tell, this one's got a baby onboard.

Found in Australia, New Guinea, and Indonesia, tree kangaroos are very rarely spotted in the wild, which really cranks their mystery factor up a dial.

Habitat loss and uncontrolled hunting has pushed many of the 14 species of tree kangaroo close to extinction.

So, much of what we know about these elusive creatures is from those that live in zoos and animal sanctuaries, in the hope we can help boost their numbers and their chance of survival here on earth.

Yeah, pretty sure these Goodfellow's tree kangaroos are living their best zoo-lives.

Now - back to that stowaway baby.

Tree kangaroo joeys start their lives in their mother's pouch - giving them ultimate undercover status.

As much of their early lives are spent out of sight, a lot of what goes on in there is still a mystery.

But we do know that a lot of milk gets slurped in a Goodfellow's tree kangaroo pouch, and over the course of about nine to ten months, their living quarters start getting a little bit squashy!

Eugh!

That can't be comfortable.

Inevitably, as a joey gets bigger it will pop out to say hello and steal a bite of Mum's dinner.

Though it's unlikely you'll see a tree kangaroo chow down on broccoli in the wild, greens are always on the menu.

Now that bellies are full, it's time for a climbing lesson.

Mum's off to a flying start, but this joey isn't so sure.

Hopping up a tree must be pretty daunting when you've never done it before.

There's no motivation quite like realising you're on your own all of a sudden.

And it's off!

Their long tail helps them to balance, and rubbery pads and long claws on their paws help them to grip onto branches.

Once this climber-in-training grows up, it'll be able to jump up to nine metres into nearby trees - and a whopping six storeys down to the ground in a single bound!

And the joey's made it to the top.

Looking pretty happy with itself too.

Yep, you nailed it, little one.

Time for a victory lap.

Unlike their ground-dwelling cousins that always hop two legs at a time, tree kangaroos are the only macropods that are able to move their hind legs independently- adding to their mystique and climbing repertoire.

When the fun is over, it's back into the pouch.

How it gets back in there at that size is definitely a mystery.

Every joey knows that the safest place to sleep in the treetops is snuggled up in the pouch behind Mum's very impressive claws.

The Arctic Circle - a cold, inhospitable place.

It's astonishing, but here is where some of the world's hardiest animals make themselves right at home.

Our next mysterious "Baby Animal" will grow up to be one of the most cunning, stealthy creatures roaming the tundra.

Say hello to Number Nine.

The Arctic fox.

Cute, huh?

A face that can melt hearts, an incredibly fluffy tail , adorable scruffy coats.

But it's all a clever disguise- one that these carnivores constantly change throughout their lives.

To start off, baby Arctic foxes come into this chilly part of the world wearing a dark coat.

The babies - or kits - only wear this short, velvety covering, for a couple of weeks.

Then it's time for their first costume change.

Ta da!

Arctic camouflage is so in, a summer fashion statement that all the cool kits wear.

Standing out is not on the agenda for these babies.

Blending in with the lichen-covered rocks is more their game.

And games are something these feisty kits excel at.

Litters can number up to a dozen, sometimes more - meaning someone's always up for a play-fight.

Ganging up on Mum is a bold move.

But experience wins the day!

For the first two to four weeks, this roughhousing is fuelled by their mother's milk.

As fun as it looks, this is serious training.

Here in this outdoor arena is where these boisterous youngsters hone their pouncing techniques and test-drive their sharp teeth with playful nips.

All of this develops their hunting abilities, vital skills the kits need to survive in this beautiful, yet harsh wilderness.

Both parents help to feed their hungry brood, taking down birds and mammals plus scavenging for carrion.

They put on a meaty spread for their offspring for about three months , then these growing babies start to fend for themselves.

An egg is a rich prize for this beginner.

Resting in the sun, these fox kits are making the most of the warm rays while they last.

The change in season is coming and their coats are starting to reflect that.

Soon, their full winter wardrobe will be on show.

This is why these animals have a number of "aliases" - also being known as polar, white, and snow foxes.

No matter what these fluffy changelings are called, it's a clever adaptation.

And here in the frosty terrain is where all that pouncing practice as kits comes to fruition.

Once their keen ears pick up scuffles under the snow, it's on.

This nosediving move has paid off.

It's called "mousing" - a classic hunting technique used by all foxes.

It might take these youngsters a little while to really get the hang of this mysterious talent, but what a fun task to master.

Camouflage and stealth aren't just valuable "superpowers" to have in the Arctic freeze , because our next young masters of mystery are taught from an early age to use the cloak of darkness to cover their never-ending search for the sweet nectars of life.

That's right.

Hanging out at Number Eight is none other than the fruit bat, also known as the flying fox.

Found in subtropical rainforests from Africa to South-East Asia, New Guinea, and Australia.

As members of the bat family, these little pups will grow up to earn the honour of being the only mammal in the world capable of sustained flight.

Baby fruit bats are born in the same way as their cousins, such as the yellow-shouldered bat.

Mum gives birth to a single pup in the treetops, while hanging upside down.

Immediately after delivery, she cradles the infant with her wings and guides it to her teats, in the pits of her wings.

Here the pup will suckle milk for anywhere up to six months, all while wrapped in Mum's leathery embrace.

These young pups must cling to their mothers 24/7 for at least a month until they are able to regulate their own body temperature - and can be left alone while Mum is at "work."

During the daylight hours, fruit bats live in large colonies also known as camps, with populations sometime as high as 200,000.

Designed to spend half their life upside down, bats use this method of roosting to conserve their energy.

Fruit bats are not immune to heat stress.

In extreme conditions they flap their wings, using blood vessels in the membrane to expel excess heat, cooling down their body temperature.

When Mum returns to her pup, she recognises her baby, distinct from all others, by its call and its smell.

The pups progressively learn to fly in camp, and from about 12 weeks of age, they begin to learn how to be a fruit bat, in earnest.

[bats shriek] A day in the life of a fruit bat begins around dusk.

While diurnal, or daytime, animals sleep, these industrious foragers take to the evening skies to work the nightshift.

Gripping onto tree branches with their feet and webbed thumbs, they feed on fruits and flowers.

When they've had their fill, they head back to camp to sleep through the day.

In drier periods, these return trips may involve the search for water.

Flying foxes hydrate themselves by skimming the water surface of a river or pool so they can then drink by licking their wet fur.

But these low-flying missions are not without risk because, as the world's largest bat species, you're going to be noticed.

Saltwater crocodiles, unfortunately, have a thing for fruit bats.

However, mother fruit bats carrying their pups on foraging trips face dangers all of their own.

Often during spring in the southern hemisphere, mother bats become entangled in power lines or fences, leaving young bats, like these ones, orphaned.

When they come into care, they are fed four or five times a day.

Then, at ten to twelve weeks of age, they are weaned off milk formula and introduced to a fruit-only diet.

Next, they are sent to a bat creche for a few weeks before finally being released to start their lives back in the wild as some our planet's cutest creatures of the night.

If there's one smile in the animal kingdom to rival all others, it surely belongs to Number Seven, the quokka.

Primarily found on a small island off Australia's western coast, this small, rare species of wallaby is known by visiting tourists as one of the happiest animals on earth.

And you can see why its "selfie game" is strong.

But there's a lot more to the quokka than its famous smile.

Just like our friend, the tree kangaroo, quokka mums raise their young in a pouch, away from the prying eyes of the world.

But here's where quokkas turn the mystery factor up a dial.

Mum has a top-secret baby back-up plan.

One day after a female quokka gives birth, she will mate again and put the new fertilised embryo inside of her on pause, just in case a tragedy were to befall her newborn.

If the worst does happen and her first joey is lost, quite remarkably, the fertilised egg inside of her resumes development and is born in under a month.

A quokka joey will spend about six to seven months in the pouch, unless of course it gets thrown out by its mother first.

When confronted by a predator, quokka mums have been known to toss their innocent joey out of their pouch and bound away!

While it sounds harsh, she does it because the reality is - one quokka being eaten is better than two.

Fortunately for this little joey, life here on Rottnest Island is relatively predator-free.

Back in the pouch you go.

These quokkas are indeed masters of deception.

Nocturnal by nature, they love to snooze and shelter in dense vegetation by day.

Adding to their mystique, they create their own secret tunnels through the under scrub to different feeding spots.

This helps quokkas remain hidden from their predators, or any humans who might want to get a selfie with them when they're not feeling camera-ready.

Quokkas are herbivores, eating native grasses and leaves, stems and bark from a myriad of plant-life.

Their favourite though is new, young growth.

It's official - these elusive babies, set to be masters of survival, are so much more than just a happy face.

At any given time, there are more than 200 million insects for every person on planet earth.

Fortunately, some of them look like this.

Number Six is one of the most famous creatures that employ the mysterious process of metamorphosis.

The butterfly.

So, how does this enigma change its form over the course of its life?

And have you ever stopped to wonder why?

Hot tip - they're not just "winging it."

These tiny eggs have big ol' butterfly-shaped dreams.

It's not going to be easy, with physical changes over the course of a butterfly's lifetime so hardcore, they make puberty seem like a walk in the park.

But where's Mum?

Well, she just lays her eggs and flies off, but at least she's thoughtful about where she deposits them.

Most butterflies attach their eggs to the leaves and stems of plants that will be perfect food for these babies to start munching on when they hatch.

And once they do, the foliage feast is on.

By eating as much of the good stuff as possible, these babies will have all the nutrients they need to enter their next stage of life.

This might just be their most mysterious phase - when the caterpillar attaches itself to something sturdy and becomes a chrysalis.

Inside the chrysalis, the caterpillar's body is breaking down into a tissue cell soup.

Yum.

From this "soup", new body parts are built: wings, legs, and new eyes, to name a few.

When the time comes, the chrysalis splits open and metamorphosis is complete.

That curly thing is called a proboscis - a long straw-like device used for feeding.

No more leaves.

There's a new food source on the menu for the butterfly in its fourth and final life stage - the nectar of flowers, the juice of overripe fruits, sometimes even poo.

And herein lies a secret strategy of creatures that metamorphosise.

Because adult butterflies and their caterpillars don't eat the same thing, they don't have to compete for food.

A baby that can turn itself into a tissue cell soup and come out on top looking this good is pretty mysterious in our books.

Let's wing our way back to Australia: the home of the second largest living bird on the planet and our fifth "Most Mysterious Young Animal."

Say g'day to the emu.

An expert in camouflage that curiously bucks the trend when it comes to parenting in the animal world.

If you're an emu baby, you get raised by your dad.

And here he is - a doting dad to a clutch of giant eggs.

So, where did Mum go?

Well, as soon as incubation begins, the male of a mating pair becomes aggressive towards other emus.

Emu mums will often head off and find another mate and breed again.

During the incubation period, Dad rarely leaves the nest.

He will go without drinking, eating, and pooping.

He survives only on stored body fat for around eight weeks.

This is one protective Papa and for good reason.

Snakes, lizards, and other nest-thieves love the taste of emu eggs.

FYI humans are on that list.

Luckily, emu eggs also have a little camouflage mystique about them, just to keep those hungry predators guessing.

When emu chicks emerge from their eggs and crack on with life, they strangely don't look a lot like their parents.

Their stealthy stripes help baby emus to blend into their surroundings while they're still finding their feet in the world.

When you've got the likes of dingoes and wedge-tailed eagles hunting you, you've got to be sneaky to survive.

A classic "helicopter parent," Dad is never too far away from his young.

He will protect them at all costs and introduce them to all the fine delicacies of the wild as they grow.

They like to eat a range of fruits, seeds, plant shoots, insects, small animals, and even animal droppings.

While you might see other animals take cover in the heat of the day, emus bizarrely remain active, foraging and wandering in extreme conditions.

So, how do they keep their cool?

The secret lies in their two-toned feathers.

The black tips absorb large amounts of heat from the sun, while the rest of its lighter plumage keeps the heat away from the emu's skin.

This, combined with the fact their feathers are also great camouflage, makes this chick the future owner of one of the coolest and most mysterious outfits out back.

When you're a tiny bug-eyed gecko like Number Four on our countdown, the planet is full of creatures that can and will swallow you in a single gulp.

If you like the idea of not being someone's breakfast, you'll need to develop a seriously sly game plan.

There are over a thousand different species of gecko across the planet, with mad skills like defying gravity, regenerating lost body parts, and the ability to lick their own eyeballs.

The mysterious gecko is tiny, and mighty, if not a little bit quirky.

And their babies are no exception to that rule.

Female geckos lay their eggs in leaves and bark, so they're safe and out of sight.

While a hard calcified shell provides a safe home for baby geckos to develop, the time comes when it poses a problem.

The first challenge these miniscule munchkins have to overcome is escaping their egg.

Their mission is to crack through the shell using as little energy as possible.

Over the course of evolution, different adaptations have developed and one of those is a pair of purpose-built "egg teeth" on the tip of their snout.

Horn-like, and used only for their great egg escape, baby geckos will tap, tap, tap with these teeth until they finally make a breakthrough and enter a brave new world, well and truly on their own.

Lucky these little lizards are born ready.

What they might lack in size, geckos make up for with mysterious skills.

Found in all corners of the world, except for Antarctica, geckos laugh in the face of gravity.

The pads of their long toes are covered with thousands of microscopic hair-like hooks that enable them to traverse vertical terrain.

Spoiler alert: if you ever get challenged to a stare-off with a gecko, the odds aren't in your favour for the win.

Most geckos don't have eyelids they can blink.

Instead, some have transparent eyelids that can require a clean from time to time and what better thing for it, than your long, slimy tongue.

Eugh!

There it is, folks!

Just so you know, no matter how many times you see it, it doesn't get any less gross.

Okay, that's enough.

Maybe just a few more?

And we're done.

Just when you thought geckos couldn't get any weirder, did we mention their tails?

Across the many species of gecko, tails come in all shapes and sizes.

Camouflage?

Yeah, their tails can do that, and it's a pretty common feature on our countdown so, no biggie.

Using it as a fuel tank?

That's kind of new - and a creative place to store your fat.

Using your tail as a decoy by dropping it off when you run into a predator, and then regrowing a new one?

That's where the humble gecko really takes our "Most Mysterious Countdown" to the next level.

Just don't tell this baby that it might lose its tail one day.

We don't want to kill its vibe.

Somewhere out here in the Australian bush is an animal so elusive, endangered, and mysterious, it's almost never seen in the wild.

Meet Number Three on our "Most Mysterious Countdown."

The quoll.

But before you say, "Aw, cute" - be on your guard.

This little critter has razor-sharp teeth and super-strong jaws to tear up meat and crush bones.

This is one baby animal with some serious mysterious qualities.

There are four species of quoll in Australia, and they are all listed as either "endangered" or "near-threatened."

A lot of what we know about these nocturnal enigmas is through quolls that live in sanctuaries and zoos.

Considering their rapid decline in the wild has had a lot to do with humans clearing the native vegetation quolls live in , it's a good thing we can help to boost their numbers back up at protected sanctuaries.

These little freshies are beacons of hope for the spotted-tail quoll species.

Like the quokka and tree kangaroo, quolls are marsupials and their joeys spend the start of their lives in a pouch.

It's a phase of quoll life that's so mysterious, we don't even have footage of it to show you.

But there are plenty of cute joeys though.

A litter of spotted-tailed quolls is usually around five babies , and when they're too big for the pouch, they live in a den or hollow log with their mum who will leave them to amuse themselves while she heads out to track down their dinner.

Quolls are known to be ferocious hunters in the wild and that feisty attitude starts young.

The spotted-tail quoll is also known as the tiger quoll - and you can see why.

Relative to its body weight, it has the second strongest bite of a predatory mammal in the world.

This is one sibling scrap you definitely don't want to get involved in.

Quolls like to hunt their prey at night, using darkness as their cloak.

These carnivorous marsupials love meat with a side of meat, followed by - you guessed it - meat.

Devouring birds, reptiles, and animal carcasses, is what they live for, but this quoll has hit the jackpot.

As you can see, quolls will not shy away from eating animals much bigger than them.

Quolls are as determined as they are mysterious, some climbing high up into the trees to catch their next snack.

Most quolls have a lifespan of only two to four years in the wild, and they aren't especially social creatures except, of course, when it comes to breeding.

Bizarrely, quolls will frequent their own communal "nature" toilets.

Here, they'll mark their territory and maybe even meet the future mother or father of their children.

How mysteriously romantic.

These joeys sure do have a top secret life ahead of them.

Here's hoping we can save these mysterious wonder-babies from the jaws of extinction.

[gentle music plays] Okay, from chilly tundra-based wrestling matches to forests full of those masters of metamorphosis, the butterflies, we are eight "Mysterious Animals" in now.

And at the sharp-end of our countdown.

So, how about a sharp-ended creature?

Say hello to Number Two, the dragonfly.

But these famous flyers actually spend most of their lives out of sight, underwater.

This dragonfly mum isn't checking to see if the water's warm enough for a swim, she's laying her eggs.

You see, dragonfly babies start their lives below the waterline.

When the eggs hatch, what emerges is called a naiad, or nymph.

These babies will stay in the water for between two and six years, becoming fierce predators.

They'll seek out aquatic insects, small fish, and mosquito larvae.

Eugh, sucks to be you, little fella!

Emphasis on the "sucks."

Dragonfly nymphs have also been known to cannibalise their own kind.

As they dine, they grow, and have a mysterious transformation process where they moult, breaking through their outer layer to reveal new and improved body parts.

During this gradual metamorphosis, nymphs will go through between 6 and 15 moults until they emerge as an adult dragonfly.

With four new wings to play with, fully-formed dragonflies live life in the fast lane.

Only living for a few months, they might feel like their life is flashing before their eyes and it's probably because it is!

Flying at speeds of up to 56 kilometres per hour, they're one of the fastest aerial insects on the planet.

Their speed and agility make them one of the most effective aerial predators.

Dragonflies are helping humans keep tabs on the environment.

As a keen predator - but also prey to birds and fish, they are an integral part of the ecosystems they live in.

They're super-sensitive to the oxygen levels in the air, as well as the cleanliness of the water.

So scientists look to dragonflies as bioindicators of the health of an ecosystem.

If you catch a glimpse of one, you might see it hanging out on a branch, reed, or leaf, not appearing to be doing much, but there is something mysterious going on.

Their wing muscles have to be warm to function at their best - so a little bit of basking in the glorious sun is just what they need.

When it comes to mating, the dragonfly is highly mysterious.

It's not unusual to see a mating pair clinging to each other in full flight giving a whole new meaning to the phrase "love is in the air."

But when they land, that's where it gets truly bizarre, contorting into all sorts of unusual positions.

Afterwards, the female will dart off to lay her eggs, and their mysterious circle of life will start all over again.

It's official.

These dragonfly babies are just as, if not more mysterious, than their parents.

We know by now that Australia, also known as the land "Down Under" is home to a myriad of mysterious creatures.

But, if you thought the others were mysterious - newsflash!

They've got nothing on our Number One.

Our "Most Mysterious Baby Animal" will grow up to be in a league of its own.

Meet the echidna, an unpredictable spiky enigma from the elusive monotreme family.

A group that remain the least understood mammals alive on earth today.

And did we mention echidna babies are called puggles?

With features both mammalian and reptilian, this is one animal that will not be put in a box.

Even though they look a little like a hedgehog, they're not at all related.

Echidnas are monotremes, the only living mammals that lay soft, reptilian-like eggs, along with their close relative, the platypus, a creature so unusual that when European naturalists first encountered them in the late 1700s, they thought it was some kind of hoax.

With an artillery of bamboozling qualities, the echidna has mystery down pat.

Nearly nothing was known about the short- beaked echidna's biology until about three decades ago, a very elusive feat for Australia's most widespread native mammal.

Nocturnal?

Not really.

Diurnal?

Nope, not 100 percent that either.

It's not the likes of mere daylight that dictates an echidna's schedule - it's the temperature.

They're most active on warm days, but if it's too hot, they'll switch things up and come out at night instead.

Their bodies are covered with a combination of fur and spines - which are actually modified hairs.

Though echidnas certainly keep us guessing in the wild, puggles - like these at an animal sanctuary - are helping us to crack the echidna code so we can understand them better and learn how to best look after them, to ensure they have a bright future.

Puggles hatch from a leathery egg that's around the size of a grape.

When they're about 50 days old, their spines begin to grow.

They start their lives in a pouch, drinking milk - a secretive strategy we've seen before on this countdown.

But here's where things get a little peculiar.

Its mother doesn't have nipples.

Instead, a few mammary hairs that a puggle will suckle on.

This puggle in care seems pretty happy with a bowl too.

Baby echidnas live in a special "nursery burrow" with their mother.

Once the youngster has grown its spiny coat and can find food on its own, it sets out into the world - solo.

From what is known about echidna life expectancy, it can be a very long life, with one wild echidna being recorded at 45 years of age.

Found all across Australia and some parts of New Guinea, these discreet creatures frequent habitats with hollow logs, underbrush, and caves to hide in.

They spend their days digging around for ants, termites, and other invertebrates.

It's thought that electroreceptors in their beak may help echidnas sense the movements of their prey.

That's not the only feeding tool they wield.

They catch their meals using a long, sticky tongue.

These crafty creatures are expert diggers, burrowing into the ground quickly, at a moment's notice, to hide when they get disturbed.

This natural excavation technique isn't completely self-serving.

It benefits the environment too - helping seeds to germinate when they get mixed up with soil and water.

When you learn that one echidna alone can move about seven tonnes of soil in a year, you get a sense of how prolific they really are.

Their spines also make for cunning camouflage.

This, combined with their strength and strategy, makes the mysterious echidna extremely difficult to prey on, or even see.

When you're Australia's most widespread native mammal, yet scientists have to spend around 300 hours in the field just to catch a glimpse of you, the "mysterious factor" of a baby echidna is strong.