Narrator: Why would a shark give someone a hug?
Most sharks would never do that.
Riskin: If I saw a big tiger shark coming toward me,
I would wet my wet suit.
Narrator: What's with these piggies paddling in paradise?
Why, in an uninhabited island in the bahamas,
Are pigs suddenly swimming?
Narrator: And is this plastic pollution...
Seeing that on that big a scale is amazing.
Narrator: ...Or something else?
These are living creatures.
Narrator: Nature is awe-inspiring,
But, sometimes, it just doesn't make sense.
I have never seen anything like this!
Our team of experts investigate
The weirdest animal behavior...
That's amazing.
...And the most unexpected events...
What is causing that?
...Ever caught on camera.
Man #2: My god!
These are nature's strangest mysteries, solved.
♪
Grand bahama.
Known for its abundant marine life,
This caribbean island is a magnet for divers
Who visit to explore its spectacular reefs.
♪
It's also home to one of the ocean's most fearsome killers,
A tiger shark.
Sharks are scary, and for good reason.
They're giant fish with huge teeth
That can really take a bite out of you.
Narrator: With a reputation
For eating almost anything in its path,
The tiger shark is among the largest and deadliest predators
In the ocean,
Second only to the great white in fatal attacks on humans.
♪
November 2014.
A diving tour guide, jim abernethy,
Gets an unexpected visit from a female tiger shark.
What happens next is extraordinary.
The predator comes in...
...For a snuggle.
♪
I've been diving with large predatory sharks --
Tigers, great hammerheads, bulls, oceanic whitetips --
For decades.
I had no idea of the things that I would discover.
Narrator: Our experts are equally surprised.
This is very strange because most sharks would never do that.
♪
This is weird.
I mean, if I saw a big tiger shark like that
Coming toward me out of the depths,
I would wet my wet suit.
But it's not aggressive, and it's swimming up to this guy
And letting him rub its nose,
And then going away for a minute,
And then coming back and getting more nose rubs.
What is going on?
Narrator: This shark returned six times
For more rubbing.
She chases me down, as you can see,
In anticipation of getting her head rubbed.
Conley: Why would the shark want to do this?
Why would it interact in such a friendly, playful manner
With this human?
Narrator: What could be behind this bizarre behavior
From one of the ocean's most dangerous predators?
Does the shark think the diver could provide
Some personal maintenance?
So, there are a few different reasons
That this might be happening.
One is that the shark might be just getting clean.
Fish have these things called "cleaner stations,"
Where a big fish swims into an area
And a bunch of little fish come and clean it off.
Nosal: So, sometimes,
A shark may come to one of these cleaning stations,
Stay there, maybe even open its mouth,
And allow fish to pick little parasites out of its gums.
Riskin: Basically, the big fish promises not to bite anybody,
And the little fish, you know, clean off the gills
And then go away, and then the big fish swims on.
So there's a theory that maybe the shark is using the diver
As some sort of cleaning station,
Thinking that he's going to come and rub off
Any kind of parasite on his nose.
The cleaning theory I like and I want to believe it,
But I don't think that's what's happening.
Nosal: Typically, a big shark would just wait
While the fish or the little shrimp
Do their cleaning job.
Riskin: The shark keeps moving,
And that's not what big fish do.
This fish is coming up,
It's rubbing against the guy, it's interacting,
And then it's swimming off and then coming back.
It's acting like a dog at a dog park.
It's not acting like a fish at a cleaner station.
[ beeps ]
Narrator: If the tiger shark isn't coming to get groomed,
Could it be stimulating one of its unique senses?
Riskin: Sharks can sense the electrical signals
That come out of the muscles of fish,
So the nose of a shark
Has all these crazy little holes in it
Filled with gel,
And they're electroreceptors.
♪
Conley: They can actually sense heartbeats
Since the heartbeat creates a current of electricity,
And rubbing the nose where these organs are found
Can be stimulant to those organs.
So it's possible that this is some sort of enjoyment
That it's getting from being petted.
Narrator: But there's something fishy about this idea.
The theory that this shark is trying to get its nose rubbed
So that it, you know, sets off the electrical receptors --
It doesn't smell right.
I mean, if that were something that sharks were into,
You would see sharks doing this more often.
You would see sharks doing it to each other.
You would definitely see sharks rubbing up against other people.
Narrator: So why is the shark behaving this way?
It turns out jim had met this fearsome fish before.
Abernethy: I named the shark "tarantino"
Because it had stolen one of my friend's cameras.
Whoa! That's crazy.
These two know each other.
♪
Narrator: Two years earlier,
The pair had their first encounter.
Abernethy: I was underwater with 10 divers.
When tarantino first swam into my area,
I noticed that she had this huge hook
Going through the top of her jaw.
Oh, god, I just felt so sad for this poor shark
That I thought, "I've got to try to help her."
I was able to remove that hook.
She actually left, and I didn't see her for quite some time.
Narrator: Then, in 2014, something amazing happens --
They meet up again.
Abernethy: Suddenly, a tiger shark was coming in,
And I quickly realized that this is my friend
That I hadn't seen in two years, tarantino.
♪
With tarantino, if you look at very closely at her scars,
It's very easy to recognize this shark.
I rubbed her head, smothering her with affection.
Riskin: This shark remembers
That something good happened there,
And...Whatever's going on and its shark brain
Tells it to come over and rub this guy's hands with its nose.
Narrator: The very fact that tarantino remembers abernethy
Brings up all kinds of new questions.
Riskin: That means the shark recognizes not a diver,
But it recognizes him.
Do the electroreceptors pick up something about him
That's different from other people?
Nosal: There could actually be some sensory signature
That they're cueing into.
It could actually be using the combination
Of electrical signals, smells, and sight
To recognize individual people.
Riskin: It brings up the whole question
Of how sharks perceive the world,
Which I think is a really neat thing to think about.
Narrator: Sharks are often thought to have tiny brains.
The truth is, for a fish of their size,
They have one of the biggest brain-to-body ratios.
♪
Sharks are certainly smarter
Than most humans would give them credit for.
And it's not beyond reason that, in the wild,
They could make certain connections.
Narrator: So, should this encounter
Change the way we interact with sharks?
Abernethy: By making friends with the shark
And actually allowing the shark to gain a sense of trust,
They swim right up to me.
People think of them as these killing machines,
And that's just not the case.
Narrator: However...
Experts agree it pays to remain extremely cautious.
I would never recommend touching a shark.
Riskin: They don't want to bite people,
But, sometimes, they make mistakes.
And the problem is that that little bite it took
Leaves you bleeding terribly, and you die from your wounds.
That's why they're kind of dangerous.
[ beeping ]
Narrator: Elsewhere in the bahamas,
In exuma cays...
♪
...There's a creature swimming in the turquoise water
That seems better suited to the farmyard than the caribbean sea.
[ snorts ]
♪
Schreiber: So, we all know that pigs can fly.
Citation needed.
But why, in an uninhabited island in the bahamas,
Are pigs suddenly swimming?
I mean, what is going on there?
Why on earth are they doing this?
♪
Narrator: In exuma cays,
There are dozens of paddling pigs.
But swine are not usually seen swimming.
♪
So, what's going on?
♪
Wildlife biologist
And host of animal planet's "extinct or alive?"
Forrest galante
Has seen these porcine wonders firsthand
And thinks he knows how they ended up here.
♪
These pigs were dropped off on this one particular cay
In the exumas for food,
And the idea was sailors would come by
And go on the island, hunt a pig,
Throw it on the ship, and eat it.
Narrator: Over time, legend has it
The pigs were forgotten by the sailors
And began swimming on the island.
This piggy paradise charmed forrest so much,
He brought his future wife, jessica, here to say "I do."
♪
[ laughs ]
[ camera shutter clicks ]
I mean, to go to the perfect tropical island destination
And have swimming pigs and men and speedos at your wedding
Is a pretty good... [ laughs ]
...That's a pretty good way to start.
It's pretty cool that we got to go
Swim with pigs on our wedding day.
[ both laugh ]
♪
I think the thing that kind of struck me
Is pigs are typically farm animals --
That's how you think of them.
[ pigs squealing ]
So, to see these pigs running along the beach
Is strange enough.
Then, actually, to see them venture in the water,
It's just -- it's kind of mind-blowing.
You don't really expect it.
♪
Narrator: So, why are the pigs taking to the water?
Maybe these hogs can't take the heat.
Cooke: Could it be to cool down?
Well, this is the bahamas.
It does get extremely hot.
While they're walking on the sand,
Their trotters might be boiling,
The sun might be blasting down on them --
Jump in the ocean, and you can cool down.
[ snorting ]
Narrator: With an average annual temperature
Of almost 80 degrees fahrenheit,
Swimming sounds like an ideal way to cool off.
So, is that what they're doing?
Schreiber: That's a very plausible theory,
Except for the fact that that particular island in the bahamas
Is packed with puddles of mud, lots of shade.
There are plenty of places to go if they're boiling.
Cooke: So they don't have to go into the salty sea
In order to stay cool.
♪
Narrator: Maybe they're swimming in search of supper.
Could the pigs be scavenging for food or even fishing?
Well, pigs are opportunistic omnivores.
[ snorting ]
They will eat
Pretty much anything they can fit into their mouths --
Vegetable roots, fruits, seeds, berries, vegetation --
More or less, anything digestible.
Narrator: And, of course, being pigs,
They aren't picky.
Insects, seaweed, and even snakes
Will all serve as mealtime munchies.
[ pig snorts ]
So, could fresh seafood be behind these aquatic adventures?
That's a particular favorite theory of mine
Because it would suggest that they're scuba-diving pigs.
But can they catch live fish?
♪
They've never been observed doing that,
So, unh-unh -- I don't think so.
So we're gonna have to knock that theory out, as well.
♪
Narrator: Maybe they're swimming to pastures new.
Well, they're not the only surprising animal to do it.
Kangaroos are also in the act.
They've been seen crossing water.
♪
Interesting fact -- they swim using doggy-paddle style.
And that's true. [ chuckles ]
Narrator: Well, kind of.
They also used their long tail to propel themselves forward,
All in an effort to find new terrain.
♪
So, are these pigs swimming to another island?
It seems farfetched, but it could happen.
That's a very exciting theory because, contrary to belief,
Pigs are actually really good at swimming.
You don't think it,
But they have the ability to go quite far.
Narrator: It turns out their close relatives,
The wild boar, are olympic swimmers
And can land up in the most unexpected places.
♪
In July 2016, one emerged from the baltic sea.
Much to the surprise of beachgoers.
♪
Boar are also seen swimming in the ionian islands in greece
Between the islands to get food.
Cooke: So it's possible that a pig could swim the distance
From one island to another.
But what would be the motivation?
Narrator: Well, for a pig,
There's only ever one motivation.
So the solution, it turns out, actually is food,
But not quite how we've been thinking.
There's a food source that's a lot closer than another island.
Narrator: In exuma cays, these pigs are in hog heaven.
But swine aren't often seen swimming.
So, what's the reason for this behavior?
Turns out, these piggies have figured out
A little water aerobics
Will lead to their favorite reward --
Food.
♪
Cooke: Tourists, you see, come up to the island on boats
And like to feed the pigs.
Schreiber: What they've, in fact, done
Is they've turned themselves
Into an incredible tourist attraction
'cause they go into the water
And all the tourists come around,
Going, "oh, my god! A swimming pig!"
Cooke: Pigs are extremely smart,
And they've learnt the behavior of the tourists.
Narrator: Once these hogs hear the noise of the motorboats,
They hit the water. [ engine rumbling ]
[ pigs squealing ]
Cooke: So the pigs know that,
If they do their little doggy paddle out to the boats
They're gonna get rewarded with a tasty treat,
And that's what's encouraging them to swim.
Narrator: The question is, have we trained the pigs,
Or have they trained us?
It looks like the pigs are in charge.
So, they've totally cracked it.
These are very, very clever pigs.
♪
[ beeping ]
Narrator: April 12, 2017, oregon.
There's a mysterious sighting
On the pacific northwest shoreline.
At first, it looks like another pollution catastrophe.
Daly: These look like pieces of plastic.
Seeing that on that big a scale is amazing.
But when you take a closer look,
It's clear that these are living creatures.
Narrator: Thousands of these strange organisms
Have washed ashore.
The question is, what were they,
And why were they stranding en masse like this?
♪
Narrator: Oregon -- April 12, 2017.
What looks like plastic, the plague of the seas,
Has washed ashore in massive amounts.
But, on closer inspection,
They turn out to be living creatures.
What are these mysterious blue blobs?
Something that does regularly wash up on beaches
Is the mermaid's purse.
♪
So, this is the common name for rays' and skates' egg cases.
They're strong and flexible because the mermaid purse
Is made up of a combination of keratin and collagen,
Providing protection for that single embryo.
The eggs case can rest or drift on the ocean floor
For up to a year before it hatches.
Narrator: But the physical characteristics
Of these egg cases
Don't match what turned up on the beach in oregon.
Burke: Mermaid's purses
Are thick, leathery-like structures.
They look nothing like the blue blobs
That were washed up onshore.
So it's clearly not what these things are.
Narrator: Mermaid's purses are just not the same shape or color
As the blue blobs.
But there is something else
That's a dead ringer for this mysterious organism.
♪
Burke: They look a lot like a portuguese man-of-war,
Which are also known to strand en masse on beaches like this.
Daly: And they're unable to move by themselves,
But, instead, they drift using the winds and the currents,
And they can be found in groups of a thousand or more
As they float through the warm waters in our world's oceans.
So a mass stranding like this absolutely could be possible.
Narrator: If this is what these are,
Beachgoers best beware.
Daly: The portuguese man-of-war have long tentacles,
Which can cause a painful sting,
And it can even be fatal to humans.
It's a common mistake for people to think
That portuguese man-of-war are jellyfish.
But, actually, it's made up of a colony of individual animals
Known as hydrozoans.
♪
Narrator: And just like a blue blob,
The portuguese man-of-war
Has an anatomy that floats on the surface of the water.
They have this gas-failed bladder.
That helps a portuguese man-of-war
Sail through the seas.
Narrator: But there's a key feature
Of this deadly stinger
That doesn't fit with what washed up in oregon.
Burke: Portuguese man-of-war
Have much, much longer tentacles...
So when you take a closer look,
It's a really unlikely solution to what's going on here.
Narrator: So, what is the mysterious creature
That showed up in oregon by the thousands?
Burke: The answer is that this mass stranding
Is of a species called "velella velella."
♪
And they're commonly known as by-the-wind sailors
Because these creatures are perfectly designed
To sail on the ocean surface
With these beautiful, transparent structures.
Daly: And amazingly, the angle at which their sail is bent
Determines which side of the ocean they live on.
Narrator: This is because
Velella velella have evolved a shape
That ensures they are always at sea,
Except when nature throws a curve ball.
It was el niño.
Narrator: El niño is the intensifying
Of temperatures in the pacific
That happens every couple of years,
Which also changes the direction of wind at the ocean's surface.
2016 was the end of an el niño cycle,
But its effects were still being felt months later,
As the winds pushed these sailing jellies off-course.
This resulted in millions of these velella velella
Washing up on the beaches
Simply because the wind caught their sails
In the wrong direction.
Which meant that they were blown ashore,
Rather than out to sea, where they really wanted to be.
♪