Episode 1 Nature's Weirdest Events

However well we think we know our planet,

the natural world still has the ability to surprise us,

to shock us, and sometimes even to scare us

with its extraordinary events and bizarre behaviour.

And given modern technology,

nature's weirdest phenomena are now frequently caught on camera

wherever and whenever they occur.

So this means that we can now bring you the strangest

stories our world has to offer.

From a marine mammal causing total gridlock...

to canine commuters joining the nine to five.

And a prickly problem invading America.

With the help of eyewitnesses, experts and scientists

we are going to try and explain what on earth is going on.

Nature has the ability to delight and amaze us, but it's also

a powerful, even unstoppable force to be reckoned with and in these

astonishing events it really does appear that nature has taken over.

We start with animals oddly out of place.

Species so shockingly in the wrong place at the wrong time, they

stop us in our tracks.

From a creature creating a lethal handicap on the 14th hole,

to an unlikely hitchhiker that's crossed continents.

But we start in Brazil where an out of town visitor was causing

trouble in paradise.

Life on Brazil's idyllic coastline

of white sandy beaches is usually laid back and lively.

But in March 2013,

an astonishing animal appeared out of the blue.

Emerging from the Atlantic was a 4m, three tonne elephant seal.

The appearance of a massive marine mammal more often

found in Antarctica took everyone by surprise.

But that was nothing compared to what the seal did next.

Oblivious to the crowds, it headed up the beach and onto

the busiest street in town.

Well, at least he used the crossing.

But bizarrely, this traffic stopping event isn't unique.

Back in 2000 an elephant seal in New Zealand

created mayhem by wrecking

any parked car in its path.

So why are these enormous seals turning up in new territory

and creating utter chaos?

Well, these events even surprise elephant seal experts

like Patrick Robinson.

Going into a busy area especially with traffic

and people is quite rare.

It's not abnormal for a seal to venture away from the coast -

they do that frequently -

but they typically do not enter populated areas like that.

So why had this seal taken against the traffic?

The answer lies in the time of year that he appeared.

In the elephant seal's calendar, October is when this happens.

The elephant seal breeding season.

When adult males are fired up by hormones and fight for females.

The stakes in these gladiatorial battles are high.

Fights often result in serious injury

or even death.

The seal in New Zealand had chosen an unusual arena for battle

but he was suffering from the same raging hormones as the males

back on the beach.

He was primed to fight anything in his path.

And he was relatively close to his usual breeding beaches.

But the elephant seal in Brazil was

over 1,300 miles from his nearest breeding beach.

Could he really have travelled so far looking for love?

Well, it's unlikely, actually, because he arrived in March

so six months away from the mating season.

Perhaps the answer lies in the more secretive part of their lives?

Elephant seals only spend about three months of year out of water,

to breed or to moult.

The rest of the year is spent thousands of miles out to sea.

They can travel upwards of four or 5,000 kilometres away from their

colonies during a typical migration and they have two migrations

per year so that adds up to quite a bit of distance in swimming per year.

They make these epic journeys for just one thing, food.

Their favourite hunting grounds are the rich waters off of Antarctica.

This is where our seal should have been in March 2013.

So how had he got it so wrong?

Well, first we need to understand how they learn to navigate.

There is no inherited navigation ability.

We've looked at individuals that have never been to sea before

and compared those to their mothers' satellite tracks that we've collected

and we see no correlation there.

So we think it's just a bit of a random choice in the very

beginning during their first migration.

Young seals hone their skills by trial and error.

Their first few years are spent cruising the oceans

and given they can cover vast distances, one wrong turn

can take them way off course.

Just like our seal in Brazil.

The seal is approximately four or five years old.

It probably hadn't locked into the adult pattern yet.

It may have still been exploring and trying to find a good strategy.

In the future he's likely to learn his sense of direction...

..and avoid the odd city break getting in the way of finding food.

A few hours later, he headed back out to sea.

For the seal, this will be a case of practice makes perfect.

But for us this unexpected encounter was very strange indeed.

But even here in the UK, the odd lost marine mammal

makes a surprising appearance.

Islanders on Orkney, off the coast of Scotland,

were astounded when they woke up one morning in March 2013

to find a one and a half tonne walrus.

Given that in spring he was supposed to be 1,300 miles

away at the North Pole, he was definitely more than a little lost.

But after a relaxing rest on the Scottish Riviera,

he got back on track and headed north.

But some out of place animals aren't just surprising,

they can be terrifying.

For our next story we head to Brisbane, Australia.

Where at Carbrook Golf Course, members soak up the Queensland sunshine

whilst playing a satisfying, and usually

uneventful, round of golf.

Uneventful that is,

until players became suspicious

that the water hazard might be a lot more hazardous

than anyone had intended.

Around '97/'98 we had one of our members come in and tell us that

he'd seen a fin out on this lake.

But our members have a tendency to drink a little bit while they play

so we really just put that down to too much alcohol for that member.

But as the weeks went by,

more golfers reported strange activity in the lake.

I was standing on that green over there

and I was about to hit my ball and I heard this big splash.

So I look up like this. Missed the putt by two foot.

Something was stirring beneath the surface

and rumours of the problem at the putting green were spreading.

It was time for course manager Scott Wagstaff to investigate.

We realised we might have something to deal with here,

there might be some truth to the mystery, yeah.

Could one of the lake's many fish be the culprit?

Or in a country renowned for large and potentially

lethal snakes and crocodiles,

could the golfers have something far more

worrying on their hands?

Well, what they discovered was far more shocking

than they'd ever imagined.

Caught on camera miles from the ocean, was a shark.

So how on earth was this marine monster

living in a land-locked golf course?

On closer inspection,

this unexpected arrival turned out to be a bull shark.

And alarmingly, the club realised that more than one

had moved into the lake.

This really was a water feature with added bite.

It was time to delve deeper

and find out more about these sharks.

Bull sharks are usually found in warm coastal waters.

They're skilled hunters that cruise the oceans

looking for anything they can get their teeth into.

Shark expert Dr Michael Heithaus

thinks the golf course has got some challenging new members on its hands.

Bull sharks have a reputation for being pretty darn aggressive.

We don't really know why but they can also be really unpredictable.

They're big predators, they're one of the few species

that will attack prey almost as big as they are.

So they are dangerous predators that you need to give a healthy respect.

Bull sharks are actually one of the few species of shark

known to be man eaters.

Straying off the fairway here could have deadly consequences.

But hang on, just how are these marine sharks living in freshwater?

Most fish either live in freshwater or sea water,

they can't move between the two

because of the dramatic change in the level of salt.

Yet these sharks seem to have done just that.

Well, for fish that live in saltwater

and freshwater, they face really different challenges.

When fish are in saltwater they've got to hold on to as much

water in their bodies as they can and keep it from leaking out.

When they're in freshwater they've got to keep water

out of their bodies and keep it from kind of flooding in.

So not many animals can solve both of those problems at once.

It's really bull sharks

and a few other species that can do these two things.

Bull sharks have kidneys that can help them get rid of all that

extra water that's coming into their body when they're in freshwater,

a lake really shouldn't be a problem for them physiologically.

So thanks to some clever bull shark biology,

these sharks sometimes can be seen very

close to shore and even swim up rivers.

So what's the reason for their forays into freshwater?

The real benefit for an adult to get into freshwater is probably to have their pups.

It's a good place for them cos there's plenty of food

and no bigger sharks that would like to eat them.

Now, it's a little more unusual to find bigger animals

in freshwater and especially in lakes.

There's not many places in the world that happens.

So this really is an extraordinary situation.

Many of the bull sharks have now grown to

over 2m in length.

So what are these voracious predators finding to eat?

The sharks are very self-sufficient and we've got a number of fish

species that live in the lake and live quite happily.

Breams probably the most prevalent, but there's quite a lot

of variety of fish for the sharks

to feed off, so it's a bit of a smorgasbord I guess for them.

With all this food on offer,

the golf course sharks are clearly feeling well above par.

There are now 12 in the lake,

so there's a real suspicion that they're even breeding here.

But given that the lake is entirely land locked,

how did the first sharks get here?

Well, the golf course is bordered by a river and this river

eventually joins the Pacific Ocean.

But how did they make the leap between the river and the lake?

This area is the heart of the Logan River flood plain

and in the mid '90s the river

which sits next to the golf course just burst its banks,

flooded across the golf course.

And as the water receded, there were some little surprises

left in the lake.

The flood waters must have washed in a few young bull sharks,

which were fully equipped to invade this new freshwater territory.

Any other species probably wouldn't have survived.

So how do the golfers feel about teeing off next to

shark-infested waters?

The lake is quite well signed, everyone is well aware.

We don't allow any swimming, no ball fossicking, nothing like that.

So we do our best, keeping the sharks alive

and also keeping the golfers safe.

And in true Aussie style, the club's members seem to have taken

the new residents in their stride.

Well we threw some chicken in and two sharks, about eight to nine foot,

came up, it was just incredible to see.

Sharks aren't the worry, mate,

it's the snakes around here that you got to worry about.

The members absolutely love the fact that we've got sharks here, they've embraced it

like nothing else, really.

The monthly Shark Lake Challenge

must be one of the world's deadliest rounds of golf.

Certainly not a place to go fishing for your golf balls.

Now, bull sharks have been responsible for 92 attacks on humans.

Principally because of their tolerance of fresh water.

It means that they can swim further up rivers

and come into contact with more people.

So if you're overseas you might want to think twice about taking

a freshwater dip.

They've been seen right up into the Mississippi

and right up into the Amazon too.

Coming to the Thames some time soon?

Let's hope not.

And with today's technology, more and more of these shocking

appearances are being captured on camera.

All right.

Take this family, having a lovely day out fishing

on a South Carolina river.

Until this happened.

Oh, Jesus Christ! There's a shark!

It's a shark! A shark!

There's a big ass shark!

Another bull shark turning up where it's least expected.

So it's certainly worth keeping your eyes peeled

and your camera running, you just never know what might show up.

But some unexpected animals don't travel under their own steam,

they hitch a lift.

For our next story,

we travel to Washington State on America's west coast.

In March 2013, a mysterious boat washed in on the morning tide.

Crusted with barnacles and draped in seaweed,

this vessel had clearly spent many months at sea.

Fisheries officer Allen Pleus was one of the first people to see

the unusual boat, which on closer inspection

wasn't quite as empty as it looked.

I found lots of different kinds of mussels.

I found several different kinds of crab.

There was actually a sea cucumber, which is a type of species

we've never seen associated with marine debris before.

It had a very rich

diversity of species on there which gave us the first

clue of course that there was something unique here.

But then the boat revealed something astonishing.

Hidden by seaweeds and barnacles was a tank,

an old bait box, where a stowaway was hiding.

I saw a fish come right up to the surface

and you know, look around and then go back down.

So I assumed that if there's one fish there could be more.

It turned out that five fish had hitched a ride on board,

this is the sole survivor.

It's definitely not something you would see in our area here and

it looks like some of the fish that you would see snorkelling

in a tropical area.

So how had a tropical fish ended up shipwrecked on the chilly

shores of Washington state?

The first job was to cast the net wide

and find the identity of the mystery traveller.

The fish was transferred to experts at a local aquarium

where Keith Chandler settled it into its new home.

We drove over there

and found this incredible fish that I'd never seen before.

The water that it was in when we got there was kind of sketchy,

so we got it in clean water and it perked up.

We were concerned about what to feed it

so we tried different things and we found

that it really liked little pieces of cut up razor clam

and it also liked salmon. So it eats better than I do.

It's a very spoiled fish.

They trawled the web to find out more about their unexpected guest.

Until they found something that took everyone by surprise.

The fish was a striped beakfish.

A baffling discovery because striped beakfish

live in the coral reefs of China, Japan, and Korea.

They don't migrate away from warm seas, so our fish

was definitely more of an accidental tourist

than a seasoned traveller.

So how had it ended up shipwrecked over 4,000

miles from home? It was time to turn

to the only other evidence that they had, the boat.

This is a piece of the information that's important to identify a boat.

This area was heavily encrusted with

organisms, we scrape off whatever vegetation is there

and we were really lucky, that the lettering was in good shape,

so that you could actually read it.

This is the name here,

Saisho Muro.

The name and registration number led to the astonishing truth.

The boat was from Japan.

The same country that's also home to striped beakfish.

But ocean currents alone would be unlikely to carry

an object of this size such a vast distance.

Something extraordinary must have pushed the boat across the Pacific.

And just over two years beforehand, something completely

unprecedented and catastrophic had happened on the shores of Japan.

In March 2011

a tsunami hit the coast of Japan.

The devastation it caused dragged some

five million tonnes of debris into the Pacific Ocean.

Now, most of this would

have sunk without trace, but around one and a half million tonnes

of it floated away from Japan's coastlines.

And although it's not the first time this material has washed up

on the coast of America, no-one thought an animal like a fish

could ever have survived the journey.

I've never seen anything like this in the 34 years that I've been here.

a fish that came all the way from Japan

and is still alive on our coast was fascinating.

As it turned out, there were more than 30 different Japanese

species on board.

A veritable Noah's Ark sailing the high seas for a staggering two years.

So just how did they all survive this incredible journey?

Well, this hole may well have provided a lifeline.

It meant that the boat was travelling partially submerged in the water.

The stowaways had the full run of the ship.

Obviously this is a deep recessed area.

The growth that came around it again helped protect it from other

species that would be after the fish.

So it had a really good area to escape

and when it was hungry it would

basically have this whole boat as a buffet.

The boat had become a floating aquarium, a mini ecosystem

of predators and prey and this held the key to the survival of the group.

But then, a puzzling new discovery emerged.

The fish was only one year old.

Born long after the tsunami had set the boat adrift.

How on earth was this possible?

One theory is that the fish was born inside the boat,

to parents that sadly didn't survive the trip.

The other, that it hitched a lift at some point

during the course of that boat's journey.

Now, one of the few other places that we know that striped beakfish occur

is here in the Hawaiian islands.

So could it be that after the tsunami, the ocean currents

carried that little boat all the way from here in Japan across to Hawaii

where the fish quite literally jumped ship and then

a further 2,500 miles all the way across here

to Washington state.

But whatever happened, there's no doubt that this globetrotting fish

had an incredible adventure on the high seas.

A truly astonishing story of survival.

But...

as remarkable as this story is, we also have to admit that animal

stowaways frequently cause absolute devastation in their new homes.

Boats have unwittingly transported many species to new

territories, where they've wreaked havoc with the local wildlife

and perhaps the greatest culprits of all are rats.

These animals have been sailing the seven seas for centuries and they

adapt very well to new environments. And as a consequence of this,

they alone have been responsible

for between 40 and 60%

of all reptile and bird extinctions.

What these unexpected visitors show us is that when it comes to

survival, nature has the power to rise to any challenge, anywhere.

Whether it's a seal scoping out hot new travel destinations,

sharks surviving and thriving in uncharted territory,

or a fish cast adrift far from home.

When these animals turn up on our turf, they're impossible to ignore.

Next, we'll be looking at what happens

when nature does the unexpected and suddenly takes over our lives.

From a stealthy invader with a death defying secret,

to a shattering wave of ice that smashed up whole houses.

But we start in the American West, in California.

For most of the time life is pretty laid back

in this hot and hazy state.

Apart from a few days every year,

when America's West gets very wild indeed.

In a matter of minutes, driving anywhere becomes

a dangerous game of dodgems.

Oh, my God.

This full scale invasion is worthy of Day of the Triffids.

And the plant responsible?

Tumbleweed.

This is an attack of the tumbleweed.

It's almost like a fog that's come through. So you got the dust in the air,

so all of a sudden you see cars appear out of nowhere.

They hit a car, you just see them just scatter

and smash all of a sudden they just go...

and it just disintegrates.

Traffic gets a little bit crazy because they'll end up braking

and letting the tumbleweed cross and it's like, so all of a sudden

you're, like, slamming on your brakes.

Even on the ground, standing up to a plant the size of a human

is easier said than done.

SHE SCREAMS

But wait a moment, this is the same

plant famous for its cameo appearances in American Westerns?

The lonely rambling weed?

Well, don't believe everything you see in the movies.

Because these wayward weeds

can charge across the landscape in vast numbers.

It's crazy look at it! It is, look out!

And this is just the start of the problem - just look at what

happens when something blocks the plants' path.

The town of Bakersfield seems to bear the brunt of the problem.

So they're, they're like huge snowdrifts. We have a long fence

and they were just covered down the whole side,

almost an eighth of a mile of just fence and nothing but tumbleweeds.

When I drove in I thought, "Oh, my!"

Tumbleweeds were everywhere.

My employees have to be out there getting tumbleweeds, they had

to take pitch forks and rakes and everything.

So why has the tumbleweed staged such a spectacular takeover?

And how has so much of it ended up in Bakersfield?

Well, to get to the root of this prickly problem

we need to start on California's dry and dusty roadsides.

These unassuming green shrubs look perfectly innocent now

but this is what tumbleweed looks like when it's not moving at 50mph.

The plant grows here all year round without

causing any trouble at all. So what makes

them such a menace on just a few days of the year?

As winter arrives the tumbleweed begins to dry out

and it looks pretty dead and done for.

But it's not, in fact, this is just the start.

As it dries, it begins to fold in on itself,

forming this characteristic shape.

But it's also about the fact that it's becoming more fragile and

particularly down here in the root, which becomes really brittle.

To the extent that in the end,

all it takes is a good gust of wind for this to snap

and then the plant begins to tumble.

So seasonal changes transform the tumbleweeds

then all they need is a push.

When the Santa Anna winds come, they rock the tumbleweeds

and they snap off their bases and then they start tumbling and

this last year we had a lot of tumbleweeds, thousands and thousands.

Now, Bakersfield is set in miles of open land and trapped between

two mountain ranges.

So the prevailing winds funnel the tumbleweed

straight towards the town.

But being in the firing line is only part of the problem.

Year on year, these unruly weeds

increase in number, tightening their stranglehold on Bakersfield.

We tend to think of plants as being very benign or passive organisms

but in fact they're incredible invaders.

Ruthlessly trying to colonise new environments

and perhaps the most aggressive of all is the tumbleweed.

And the secret of its success is not

the fact that it rolls over vast distances,

it's what it's doing when it's rolling. Listen to this.

That rattling is the sound of 200,000 seeds contained

within this tumbleweed and all the while

it's rolling, it's scattering those seeds by the thousands

and thousands.

So when tumbleweeds roll in to town,

so do billions and billions of seeds.

And it's not just getting worse in Bakersfield.

Throughout North America, tumbleweed is growing completely out of control.

It's little wonder we've come to associate tumbleweed

with the pioneering spirit of the American Wild West.

But surprisingly, tumbleweed isn't

actually American at all! It was accidently brought over

by Ukrainian farmers in the 1800s.

And America is now facing a tumbleweed takeover.

But now, Bakersfield entrepreneur John Solorio is

heading for a showdown with this problematic plant.

He's designed the world's first Tumblegator.

John's machine gathers up to

10 tonnes of tumbleweed a day.

It shreds and compacts the weed before

it has the chance to run and shake its seeds.

Had to have something done with these

tumbleweeds in the Bakersfield area and they thought well,

it just makes sense.

John's invention is just one part

of a national programme to

halt the plants' seemingly unstoppable spread.

Because when a plant finds itself in unchartered new territories,

these leafy invaders can become almost impossible to control.

Take knotweed, the UK's own runaway plant.

The Victorians brought this delicate little flower over from Japan,

thinking that it might make a pretty addition to their collections.

But it didn't take long for the knotweed to show its true colours.

This ruthless invader got out into the countryside

and started to spread.

Decades later and it's still on the loose.

It grows so vigorously that it

can crack concrete, roads and solid walls.

It's a nightmare for homeowners,

who can find their bricks and mortar devalued by a tiny, green weed.

Stopping this relentless green invasion is proving to be

an almost impossible challenge.

But some invaders take a more stealthy approach to their attack.

Our next animal has been staging a secret invasion all thanks to

a rather remarkable talent.

From its original home in the Caribbean,

a tiny jellyfish has now spread into all of the world's oceans.

It's likely to have been helped on its way by shipping activities,

catching a ride in the ballast water of travelling vessels.

But that alone can't fully explain its success.

As scientists investigated,

they were astonished by what they discovered.

This jellyfish can do the seemingly impossible.

It's found a way to cheat death,

to live forever

and that's something that's helped its global takeover.

But just how is the jellyfish doing it?

What's its sought-after secret to eternal life?

Well, to understand this animal's death-defying feat

we need to get to grips with the two main stages of a jellyfish.

The tiny polyp and the larger, full grown Medusa.

The young polyps form huge colonies, like a jellyfish creche.

Amongst the group, they grow until it's time for them to form

an independent Medusa.

Now, normally the adult Medusa would swim

around for anything between a few days to a year depending on the

species of the jellyfish.

But in the immortal jellyfish, something very strange happens.

Instead of growing old gracefully the adult does something

completely mind-blowing.

The immortal jellyfish has found a means of turning back time.

The adult can reverse the ageing process and turn back into a polyp

and that's a feat no less amazing than a caterpillar turning into

a butterfly and then that butterfly turning back into a caterpillar.

But the thing is, that doesn't happen just once.

As far as we know the process can keep going backwards

and forwards indefinitely.

Anything stressful like injury or lack of food will send

the adult back in time to a polyp.

And in that state, it's easier for it to survive.

Until eventually, the animal grows a new Medusa

and turns back into an adult.

This ingenious trick has helped fuel their stealthy global invasion.

The jellyfish doesn't just take over new territory,

it never leaves.

Now scientists are trying to find out which of the jellyfish's

genes are controlling its bizarre biological clock.

Because whether it's sacred waters or hi tech

beauty serums, throughout history us humans

have strived to halt the ageing process.

But it seems that one extraordinary animal is well ahead of us

and could one day maybe even share its secrets of living forever.

But unlike the gradual takeover of the immortal jellyfish,

some invasions cause mass devastation in one fateful moment.

Our next story takes us to Winnipeg in Canada.

With stunning scenery and a view over

a tranquil lake, it's easy to see why people

choose to live on the peaceful shores of Ochre Beach.

But in May 2013, at the end of a hard winter,

all the peace and quiet was quite literally shattered.

Oh, no.

This is absolutely crazy.

From nowhere a 9m high wall of ice rose up

and threatened to engulf an entire street.

Residents like Myles Haverluck could only stand back

and watch in horror as their homes faced a tsunami of ice.

I like to use the analogy of a freight train

sort of coming at you because it almost seemed like that.

It's happened in a matter of...

five minutes?

It was probably coming about the same as you would walk

and it just kept on moving.

And you're looking at it and you're thinking "Oh, this has got to stop." But it didn't.

Myles' friend was filming as second by second

the ice surged towards the house.

We're about to get engulfed by ice. It's going to come through the house.

All these houses are getting engulfed by ice.

Donna Billows was at home with her husband Elmer

at the moment that the ice struck.

We stood and watched in amazement as the ice crawled up

our window and boom, the whole thing broke

and ice started pouring into the living room.

It came over the top of our roof, and up over top of the chimney which

is at least 6 feet above the roof line

so it was at least 25 feet of ice.

We just grabbed our keys and got out.

But just when it seemed that nothing could stop it,

everything went quiet.

Please!

The ice tsunami stopped as suddenly as it had started.

In just 10 terrifying minutes, most of the street had been wiped out.

So what had the residents of Ochre Beach just witnessed?

What had caused a giant wave of ice to break over the houses?

Now, there's no doubt ice can be a very powerful force.

It's sculpted much of our planet.

When layers of snow build up they compress and create a glacier.

Their sheer mass makes them flow down through the landscape,

carving up the solid rock below.

It might travel just a few metres a year

but as this sped up footage shows, over time

this movement makes quite an impact.

But these processes often take millennia, not minutes.

So what caused such a dramatic and quick change

in the ice at Ochre Beach?

With temperatures dropping as low as minus 20 degrees over the winter,

by May, the lake had been frozen and still for five months.

So what happened to create such a catastrophe?

Glacier expert Michelle Koppes...

..thinks that some very particular conditions may have been at work.

In the middle of winter the ice is all stuck together

and it's very resistant to motion. But once it

starts to break up in the spring time,

it can start to move.

By May, the cracks were starting to show

and 200 square miles of lake ice was melting and moving around.

But as the ice was thawing to its usual springtime schedule,

other forces must have been at work.

So was there anything else unusual about that

fateful day in Spring?

Well, that afternoon the weather changed dramatically.

They were predicting high winds but at four o'clock in the afternoon

it was as calm as calm could be and at six o'clock at night

it was absolutely unbelievable.

So my daughter said "Look at the trees, Dad."

and our trees in our front lawn, they were doubled down,

looked like they were touching the ground, I'm surprised they didn't break.

It was the sudden start of a storm that would completely

change how the ice behaved.

Often times when you have rapid warming in the spring time

you'll also have stormy conditions.

So as the ice starts to break up if you have a big wind gust or

a storm event it will start to push on that ice

and it'll get it to raft onto the shore.

That wall is probably 15 feet up in the air.

When it hits the land, the land has friction

so the ice that is the first to hit the land stops

and all the ice that's piled up behind it

kind of crumbles on top of it.

So it looks like a slow wave that's coming ashore

but it's basically all the ice tumbling

over the ice that has stopped.

The perfect storm of miles of thawing ice and gale force winds

blowing towards the shore created a terrifying ice tsunami

so powerful it literally knocked the community sideways.

So many homes that were just knocked

right off their foundations. There was one sitting back

and it was almost on its back it had been tilted up pushed over

and other ones were just destroyed and crushed.

I guess you're more in shock. At least I was because I just didn't...

..think, you know, it was going to get that bad but it did.

Thankfully, events like this have only been documented in a handful of other places.

Nobody in Ochre Beach was hurt

but it's taken a lot of hard graft and community spirit

to slowly repair the damage.

A staggering display of nature in its most powerful form

and of course, a truly horrific event for those homeowners.

Also - I suppose - proof that as much as we've learned to live

alongside nature it can still catch us out with its unpredictable force.

Shocking stories like these

remind us of the true power of nature.

Whether it's introducing an aggressive plant

that overstays its welcome...

A jellyfish invader with a surprising secret,

or an icy storm of events triggering a terrifying ordeal.

When nature takes over, there really is no way of stopping it.

Next, we meet unstoppable animals with superpowers.

Specialist skills to survive any situation.

From an amphibian assassin,

to an escape artist extraordinaire.

But we start in Russia in the rush hour.

The Moscow Metro is one of the world's busiest.

Every day it carries around 7 million people

in and out of the city.

But in amongst the crowd, making their way through

trains and tunnels are a new team of city slickers.

A selective band of remarkable...

dogs.

There's not an owner or a lead in sight,

but every day for the last 25 years,

these animals join the local commute.

They share their seats with passengers,

queue for trains and carefully mind the gap.

and they never miss their stop.

Because strange as it might seem, their behaviour appears to

be entirely deliberate.

So what's bringing these dogs onto the trains?

And where are they all going?

Suzanne MacDonald has been studying how animals

adapt to city life.

She thinks the dogs' background might help explain their behaviour.

It only makes sense for dogs to do this if they're feral

so they don't have owners, so clearly they must be homeless dogs.

They need to find food every day and so this is a great way

to do that, they also get social contact, which is great.

So I don't think you would see this kind of behaviour in a city

where there aren't large populations of feral dogs.

And Moscow certainly has that.

Around 35,000 stray dogs live on the city's streets.

It's a tough life where competition

for food and shelter is fierce.

Abandoned pets or born on the streets, these dogs face a dilemma.

They don't have owners to

care for them and years of selective breeding has stripped away the

natural hunting skills of a true wild dog.

There are such an enormous number of stray dogs that Moscow's mutts

need to be incredibly resourceful to survive in their dog-eat-dog world.

So, they've moved into new territory

and are taking advantage of a captive audience.

If you were a dog and you saw a human and humans give you food

and one day you followed the human and the human went down into a

train and the human petted you and told you how great you were

and everybody on the train was nice to you and then

when you got off the train, you followed the humans,

somebody fed you, you might say the train is a good place.

And so you might do that again.

Dogs are really fast learners, so I think it could spread through

a population of stray dogs really quickly.

In fact, when it comes to finding food, several other animals around

the world have also discovered the perks of public transport.

Whether it's monkeys working the crowds on trains in India

or pigeons making a short hop on the London Underground.

UNDERGROUND ANNOUNCER: Great Portland Street. This is a circle line train to Hammersmith.

But what the Moscow metro dogs are doing

is much smarter than scrounging.

When scientists followed the dogs on and off the trains they were

astonished by what they found.

About 20 of the dogs were making a regular commute.

And most remarkable of all, the stations they

were using were no coincidence.

They're coming from a place where they sleep

which would be on the outskirts of the city. They probably

go where it's quiet at night.

They may go somewhere where they can actually sleep with other dogs

and then in the daytime they would go downtown,

where they can hit up tourists for food and look sad eyed.

And get some snacks and you know, that sort of thing. So it's

sort of like they go from the suburbs at night to their day jobs downtown.

This is the first and only place

this incredible behaviour has been seen.

But how are they finding their way through the Metro's maze of tunnels?

surely, they can't be using a map.

Navigating this complex warren of tracks,

platforms and stations is difficult enough for us humans

but how on earth do the dogs do it? They can't read maps.

Well, even in the heart of Moscow city, these stray animals

are using the same instincts and senses as wild species of dogs do.

All dogs, wild or domestic, have a

sense of smell which is over 10,000 times better than ours.

So what somewhere smells like will tell them

more about their location than any map.

Dogs also have a strong biological body clock,

so the dogs on the metro may be using that to time their daily routine.

It's remarkable how well these dogs have adapted their behaviour

to make the most of our human activities.

It's almost as if they know more about us than we know about them.

These dogs have been remarkably resourceful when it comes to

modifying their foraging behaviour in order to survive.

They really are top dogs.

To meet our next animal with superhero skills,

we travel to Alaska in North America.

Where, in August 2010,

a fishing party reeled in more than they had bargained for.

A huge two and a half metre octopus was a surprising enough catch,

but what it did next had people staring in disbelief.

He's going for it.

-No way.

-I'm telling you right now.

To everyone's amazement, it began to disappear in front of their eyes.

Yeah there's his nose, he's just all the way through it now.

-Except for - oh just...

-Just his nose, yeah. There he goes.

-Wow!

-Wow.

How did this sea creature manage to make an exit worthy of Houdini?

And why are octopuses the ultimate escape artists?

The animal on the boat was a giant Pacific octopus.

Tip to tip, they reach up to 9m in length.

Surprisingly, they're molluscs, so related to other sea creatures

like oysters, mussels, and sea snails.

But unlike most other members of the group,

octopuses don't have a hard shell

making them a soft target for predators.

Could this explain why they would need to make such a quick getaway?

Octopus expert James Woods

has been studying their ingenious defence tactics.

An octopus is all the part that predators want to eat.

Sharks eat them, marine mammals like dolphins

and seals eat them, some marine birds eat them.

But if you can't find something

it's pretty hard to eat it. So their primary defence is camouflage.

And the king of camouflage is the aptly named mimic octopus.

This animal can take on the colour of nearly any setting it finds

and remarkably, it also copies the shape of other sea creatures.

Impersonating anything from a flat fish

to a sea snake in order to protect itself.

But even if an octopus can't dazzle its predators with illusions,

it does have another trick.

It resorts to plan B, escape. And this is where

not having a hard outer shell or a skeleton is a real advantage.

For many species of animal, the limit to how small a gap

they can squeeze through is not governed by their skeleton

as a whole but by this, their skull.

But of course octopus don't have skulls, they're soft bodied animals.

The only hard bit in an octopus are its mouth parts,

known as its beak

and they are about 5 cm in diameter.

So if the beak can squeeze through, the rest can follow.

So for our octopus on the fishing boat a small gap was all it needed.

But how did it calculate the size

and shape of the environment around it so quickly?

Well, new research is showing that octopuses

are far smarter than you'd think.

Octopuses are the most intelligent of all of the invertebrates.

They have a brain-to-bodyweight ratio that is higher than

some groups of vertebrates like fish and birds.

Octopuses' nervous system is very different than ours.

We have a head and almost all of our nerves are up here

and then there's some nerves that are wiring to our extremities.

Where an octopus does have that centralised brain but two thirds

of its nerves are in its body so it's more of a decentralised system -

sort of like the internet - than something like us,

where it's pretty much all up here.

It's incredible to think that this animal has its brainpower split up

all over its body.

And it means that even if disaster strikes,

they still might be able to think straight.

If an octopus loses its arm, the arm will act as a decoy.

It will still hold on to things with its suckers, it can still

change colour, it can still wiggle, it can still crawl around.

So it acts as a very effective decoy and it might keep the predator

occupied, it's got something to eat, busy, while the rest of

the octopus gets away.

So the octopuses' vulnerability has driven them to become

quick-thinking masters of hide and seek.

But sometimes the only way to survive is to take a more

confrontational approach.

The remote rainforests of Cameroon are a lost world that few

travellers have ever visited.

But some of those who have, tell tales of

a bizarre looking animal more than ready to put up a fight.

A beast capable of drawing blood from its attackers.

Only a few specimens exist

but surprisingly, the culprit is this,

a frog.

So what is this amphibian oddity?

And does it deserve its fierce reputation?

Most amphibians prefer to stay out of trouble

by hiding from danger, using camouflage

to stay under the radar.

Those that take a bolder approach use bright colours

to make a statement, warning predators

that their bodies are loaded with harmful toxins.

But subtle messages aren't enough for this frog.

It may be small, but its violent reputation

has given it the name wolverine frog.

Amphibian expert David Blackman

knows more than most about this elusive

and mysterious animal with its ninja-like skills.

There's no other frog on earth that looks like this.

All around the side of the body on its legs here,

it's covered in what looks like hair. But in fact,

it's actually thin pieces of skin that

project out from the side of the body. Females lack this entirely,

so this is something that's unique to only male hairy frogs.

And it's still not clear why the male frogs would need

all of this excess skin.

And that's not the only thing keeping the experts guessing.

Because this animal is also armed for combat.

One of the remarkable things about this frog is that it has claws

and most amphibians don't have claws. And these aren't claws like

our toenails or fingernails and they're not like claws like you'd

find on a bird, this is actually a claw that's made of naked bone.

Unbelievably when it's threatened, this animal can force its own

bones through its skin.

Arming itself with a sharp claw on its toes.

The animal is actually making its skeleton come through its skin.

Which is a very weird thing.

It's not like there's a natural hole through which these claws are

piercing, it's that there's a complete piece of skin

and the claw's actually puncturing through

and actually causing a little traumatic wound on their toe tips.

We still know very little about whether or not these wounds can heal.

Those claws could sort of be retracted in a sense

and be used again on another day.

Because amphibians and some reptiles really have

remarkable regenerative abilities.

Wolverine frog really is a unique celebration of just how

strange nature can be.

So among the more than 6,200 species of frogs,

of all those thousands of frogs,

these are the only large hairy like frogs

with bones that poke through their toes. They're the only

one in the world that looks like that.

But bizarrely, there are other amphibians who could be

considered their partner in crime.

These little beauties are Iberian newts

and they're remarkable in that when they're attacked by predators

they can push their ribs through their flesh out through their

skin to produce two rows of spines which run the length of their body.

Now, this sounds as if it would be very painful for the newt

but in fact, it does it no harm at all and perhaps what's even

more remarkable is as those ribs pass through the skin,

they pass through some poisonous glands and I can feel them

on the side of the body.

So effectively, they end up with two rows of poison arrows.

Now, of course, if you're a predator, that's pretty nasty

but you've got to admit that it's also very, very clever.

The weird and wonderful creatures

in these stories have developed extraordinary

powers to get what they want.

Whether it's canines commuting to get a square meal,

shape-shifting sea creatures, or highly armed amphibians.

Nature has the never-ending ability to astound us.

So whether it's bizarre adaptations or full scale invasions,

nature survives against the odds.

And often thrives in places where we would least expect it and

when our paths cross, then it proves to be a truly unstoppable force.

Next time on Nature's Weirdest Events.

Freaky fish that walk - yes, walk - down the street...

How weird is that!

..terrifying trees that ooze blood

and alien sounds from the sky.

Me and Tom are hearing noises.

Subtitles by Red Bee Media Ltd