0:00:08 > 0:00:11However well we think we know our planet,
0:00:11 > 0:00:16the natural world still has the ability to surprise us,
0:00:16 > 0:00:19to shock us, and sometimes even to scare us
0:00:19 > 0:00:23with its extraordinary events and bizarre behaviour.
0:00:23 > 0:00:25And given modern technology,
0:00:25 > 0:00:30nature's weirdest phenomena are now frequently caught on camera
0:00:30 > 0:00:33wherever and whenever they occur.
0:00:33 > 0:00:37So this means that we can now bring you the strangest
0:00:37 > 0:00:39stories our world has to offer.
0:00:42 > 0:00:46From a marine mammal causing total gridlock...
0:00:46 > 0:00:50to canine commuters joining the nine to five.
0:00:50 > 0:00:54And a prickly problem invading America.
0:00:56 > 0:01:00With the help of eyewitnesses, experts and scientists
0:01:00 > 0:01:05we are going to try and explain what on earth is going on.
0:01:25 > 0:01:30Nature has the ability to delight and amaze us, but it's also
0:01:30 > 0:01:36a powerful, even unstoppable force to be reckoned with and in these
0:01:36 > 0:01:41astonishing events it really does appear that nature has taken over.
0:01:43 > 0:01:46We start with animals oddly out of place.
0:01:46 > 0:01:50Species so shockingly in the wrong place at the wrong time, they
0:01:50 > 0:01:52stop us in our tracks.
0:01:52 > 0:01:57From a creature creating a lethal handicap on the 14th hole,
0:01:57 > 0:02:02to an unlikely hitchhiker that's crossed continents.
0:02:02 > 0:02:06But we start in Brazil where an out of town visitor was causing
0:02:06 > 0:02:08trouble in paradise.
0:02:09 > 0:02:12Life on Brazil's idyllic coastline
0:02:12 > 0:02:16of white sandy beaches is usually laid back and lively.
0:02:18 > 0:02:20But in March 2013,
0:02:20 > 0:02:23an astonishing animal appeared out of the blue.
0:02:25 > 0:02:31Emerging from the Atlantic was a 4m, three tonne elephant seal.
0:02:34 > 0:02:37The appearance of a massive marine mammal more often
0:02:37 > 0:02:41found in Antarctica took everyone by surprise.
0:02:43 > 0:02:47But that was nothing compared to what the seal did next.
0:02:48 > 0:02:52Oblivious to the crowds, it headed up the beach and onto
0:02:52 > 0:02:55the busiest street in town.
0:02:55 > 0:02:57Well, at least he used the crossing.
0:03:00 > 0:03:04But bizarrely, this traffic stopping event isn't unique.
0:03:08 > 0:03:11Back in 2000 an elephant seal in New Zealand
0:03:11 > 0:03:13created mayhem by wrecking
0:03:13 > 0:03:15any parked car in its path.
0:03:21 > 0:03:25So why are these enormous seals turning up in new territory
0:03:25 > 0:03:27and creating utter chaos?
0:03:29 > 0:03:33Well, these events even surprise elephant seal experts
0:03:33 > 0:03:35like Patrick Robinson.
0:03:35 > 0:03:38Going into a busy area especially with traffic
0:03:38 > 0:03:40and people is quite rare.
0:03:40 > 0:03:43It's not abnormal for a seal to venture away from the coast -
0:03:43 > 0:03:45they do that frequently -
0:03:45 > 0:03:49but they typically do not enter populated areas like that.
0:03:51 > 0:03:54So why had this seal taken against the traffic?
0:03:58 > 0:04:01The answer lies in the time of year that he appeared.
0:04:03 > 0:04:07In the elephant seal's calendar, October is when this happens.
0:04:15 > 0:04:19The elephant seal breeding season.
0:04:19 > 0:04:24When adult males are fired up by hormones and fight for females.
0:04:26 > 0:04:30The stakes in these gladiatorial battles are high.
0:04:30 > 0:04:32Fights often result in serious injury
0:04:32 > 0:04:34or even death.
0:04:41 > 0:04:45The seal in New Zealand had chosen an unusual arena for battle
0:04:45 > 0:04:50but he was suffering from the same raging hormones as the males
0:04:50 > 0:04:52back on the beach.
0:04:52 > 0:04:55He was primed to fight anything in his path.
0:04:56 > 0:05:00And he was relatively close to his usual breeding beaches.
0:05:01 > 0:05:04But the elephant seal in Brazil was
0:05:04 > 0:05:08over 1,300 miles from his nearest breeding beach.
0:05:09 > 0:05:13Could he really have travelled so far looking for love?
0:05:15 > 0:05:19Well, it's unlikely, actually, because he arrived in March
0:05:19 > 0:05:22so six months away from the mating season.
0:05:24 > 0:05:28Perhaps the answer lies in the more secretive part of their lives?
0:05:31 > 0:05:35Elephant seals only spend about three months of year out of water,
0:05:35 > 0:05:37to breed or to moult.
0:05:39 > 0:05:43The rest of the year is spent thousands of miles out to sea.
0:05:43 > 0:05:47They can travel upwards of four or 5,000 kilometres away from their
0:05:47 > 0:05:51colonies during a typical migration and they have two migrations
0:05:51 > 0:05:55per year so that adds up to quite a bit of distance in swimming per year.
0:05:56 > 0:06:00They make these epic journeys for just one thing, food.
0:06:02 > 0:06:07Their favourite hunting grounds are the rich waters off of Antarctica.
0:06:09 > 0:06:13This is where our seal should have been in March 2013.
0:06:13 > 0:06:16So how had he got it so wrong?
0:06:17 > 0:06:22Well, first we need to understand how they learn to navigate.
0:06:22 > 0:06:24There is no inherited navigation ability.
0:06:24 > 0:06:29We've looked at individuals that have never been to sea before
0:06:29 > 0:06:34and compared those to their mothers' satellite tracks that we've collected
0:06:34 > 0:06:36and we see no correlation there.
0:06:36 > 0:06:38So we think it's just a bit of a random choice in the very
0:06:38 > 0:06:41beginning during their first migration.
0:06:41 > 0:06:44Young seals hone their skills by trial and error.
0:06:44 > 0:06:47Their first few years are spent cruising the oceans
0:06:47 > 0:06:52and given they can cover vast distances, one wrong turn
0:06:52 > 0:06:54can take them way off course.
0:06:54 > 0:06:57Just like our seal in Brazil.
0:06:57 > 0:07:00The seal is approximately four or five years old.
0:07:00 > 0:07:03It probably hadn't locked into the adult pattern yet.
0:07:03 > 0:07:07It may have still been exploring and trying to find a good strategy.
0:07:09 > 0:07:13In the future he's likely to learn his sense of direction...
0:07:14 > 0:07:19..and avoid the odd city break getting in the way of finding food.
0:07:23 > 0:07:26A few hours later, he headed back out to sea.
0:07:27 > 0:07:32For the seal, this will be a case of practice makes perfect.
0:07:32 > 0:07:37But for us this unexpected encounter was very strange indeed.
0:07:39 > 0:07:42But even here in the UK, the odd lost marine mammal
0:07:42 > 0:07:44makes a surprising appearance.
0:07:45 > 0:07:48Islanders on Orkney, off the coast of Scotland,
0:07:48 > 0:07:53were astounded when they woke up one morning in March 2013
0:07:53 > 0:07:56to find a one and a half tonne walrus.
0:07:57 > 0:08:00Given that in spring he was supposed to be 1,300 miles
0:08:00 > 0:08:05away at the North Pole, he was definitely more than a little lost.
0:08:05 > 0:08:09But after a relaxing rest on the Scottish Riviera,
0:08:09 > 0:08:11he got back on track and headed north.
0:08:13 > 0:08:17But some out of place animals aren't just surprising,
0:08:17 > 0:08:19they can be terrifying.
0:08:19 > 0:08:22For our next story we head to Brisbane, Australia.
0:08:23 > 0:08:28Where at Carbrook Golf Course, members soak up the Queensland sunshine
0:08:28 > 0:08:31whilst playing a satisfying, and usually
0:08:31 > 0:08:33uneventful, round of golf.
0:08:33 > 0:08:35Uneventful that is,
0:08:35 > 0:08:37until players became suspicious
0:08:37 > 0:08:41that the water hazard might be a lot more hazardous
0:08:41 > 0:08:44than anyone had intended.
0:08:44 > 0:08:47Around '97/'98 we had one of our members come in and tell us that
0:08:47 > 0:08:50he'd seen a fin out on this lake.
0:08:50 > 0:08:53But our members have a tendency to drink a little bit while they play
0:08:53 > 0:08:57so we really just put that down to too much alcohol for that member.
0:08:57 > 0:08:59But as the weeks went by,
0:08:59 > 0:09:03more golfers reported strange activity in the lake.
0:09:03 > 0:09:05I was standing on that green over there
0:09:05 > 0:09:08and I was about to hit my ball and I heard this big splash.
0:09:08 > 0:09:12So I look up like this. Missed the putt by two foot.
0:09:12 > 0:09:16Something was stirring beneath the surface
0:09:16 > 0:09:20and rumours of the problem at the putting green were spreading.
0:09:20 > 0:09:25It was time for course manager Scott Wagstaff to investigate.
0:09:25 > 0:09:27We realised we might have something to deal with here,
0:09:27 > 0:09:30there might be some truth to the mystery, yeah.
0:09:30 > 0:09:34Could one of the lake's many fish be the culprit?
0:09:34 > 0:09:38Or in a country renowned for large and potentially
0:09:38 > 0:09:40lethal snakes and crocodiles,
0:09:40 > 0:09:42could the golfers have something far more
0:09:42 > 0:09:45worrying on their hands?
0:09:45 > 0:09:48Well, what they discovered was far more shocking
0:09:48 > 0:09:50than they'd ever imagined.
0:09:55 > 0:10:00Caught on camera miles from the ocean, was a shark.
0:10:03 > 0:10:06So how on earth was this marine monster
0:10:06 > 0:10:09living in a land-locked golf course?
0:10:10 > 0:10:11On closer inspection,
0:10:11 > 0:10:16this unexpected arrival turned out to be a bull shark.
0:10:18 > 0:10:22And alarmingly, the club realised that more than one
0:10:22 > 0:10:23had moved into the lake.
0:10:25 > 0:10:28This really was a water feature with added bite.
0:10:29 > 0:10:32It was time to delve deeper
0:10:32 > 0:10:35and find out more about these sharks.
0:10:38 > 0:10:42Bull sharks are usually found in warm coastal waters.
0:10:42 > 0:10:45They're skilled hunters that cruise the oceans
0:10:45 > 0:10:51looking for anything they can get their teeth into.
0:10:51 > 0:10:53Shark expert Dr Michael Heithaus
0:10:53 > 0:10:58thinks the golf course has got some challenging new members on its hands.
0:10:58 > 0:11:02Bull sharks have a reputation for being pretty darn aggressive.
0:11:02 > 0:11:05We don't really know why but they can also be really unpredictable.
0:11:05 > 0:11:08They're big predators, they're one of the few species
0:11:08 > 0:11:11that will attack prey almost as big as they are.
0:11:11 > 0:11:15So they are dangerous predators that you need to give a healthy respect.
0:11:15 > 0:11:18Bull sharks are actually one of the few species of shark
0:11:18 > 0:11:21known to be man eaters.
0:11:21 > 0:11:25Straying off the fairway here could have deadly consequences.
0:11:28 > 0:11:33But hang on, just how are these marine sharks living in freshwater?
0:11:33 > 0:11:36Most fish either live in freshwater or sea water,
0:11:36 > 0:11:38they can't move between the two
0:11:38 > 0:11:42because of the dramatic change in the level of salt.
0:11:42 > 0:11:47Yet these sharks seem to have done just that.
0:11:47 > 0:11:49Well, for fish that live in saltwater
0:11:49 > 0:11:51and freshwater, they face really different challenges.
0:11:51 > 0:11:54When fish are in saltwater they've got to hold on to as much
0:11:54 > 0:11:58water in their bodies as they can and keep it from leaking out.
0:11:58 > 0:12:00When they're in freshwater they've got to keep water
0:12:00 > 0:12:03out of their bodies and keep it from kind of flooding in.
0:12:03 > 0:12:07So not many animals can solve both of those problems at once.
0:12:07 > 0:12:09It's really bull sharks
0:12:09 > 0:12:12and a few other species that can do these two things.
0:12:12 > 0:12:16Bull sharks have kidneys that can help them get rid of all that
0:12:16 > 0:12:19extra water that's coming into their body when they're in freshwater,
0:12:19 > 0:12:23a lake really shouldn't be a problem for them physiologically.
0:12:23 > 0:12:26So thanks to some clever bull shark biology,
0:12:26 > 0:12:29these sharks sometimes can be seen very
0:12:29 > 0:12:31close to shore and even swim up rivers.
0:12:33 > 0:12:37So what's the reason for their forays into freshwater?
0:12:37 > 0:12:41The real benefit for an adult to get into freshwater is probably to have their pups.
0:12:41 > 0:12:43It's a good place for them cos there's plenty of food
0:12:43 > 0:12:46and no bigger sharks that would like to eat them.
0:12:46 > 0:12:48Now, it's a little more unusual to find bigger animals
0:12:48 > 0:12:50in freshwater and especially in lakes.
0:12:50 > 0:12:53There's not many places in the world that happens.
0:12:53 > 0:12:56So this really is an extraordinary situation.
0:12:56 > 0:12:58Many of the bull sharks have now grown to
0:12:58 > 0:13:01over 2m in length.
0:13:02 > 0:13:06So what are these voracious predators finding to eat?
0:13:06 > 0:13:10The sharks are very self-sufficient and we've got a number of fish
0:13:10 > 0:13:14species that live in the lake and live quite happily.
0:13:14 > 0:13:16Breams probably the most prevalent, but there's quite a lot
0:13:16 > 0:13:18of variety of fish for the sharks
0:13:18 > 0:13:22to feed off, so it's a bit of a smorgasbord I guess for them.
0:13:24 > 0:13:25With all this food on offer,
0:13:25 > 0:13:30the golf course sharks are clearly feeling well above par.
0:13:30 > 0:13:31There are now 12 in the lake,
0:13:31 > 0:13:35so there's a real suspicion that they're even breeding here.
0:13:36 > 0:13:39But given that the lake is entirely land locked,
0:13:39 > 0:13:42how did the first sharks get here?
0:13:43 > 0:13:47Well, the golf course is bordered by a river and this river
0:13:47 > 0:13:50eventually joins the Pacific Ocean.
0:13:50 > 0:13:53But how did they make the leap between the river and the lake?
0:13:55 > 0:13:58This area is the heart of the Logan River flood plain
0:13:58 > 0:14:00and in the mid '90s the river
0:14:00 > 0:14:03which sits next to the golf course just burst its banks,
0:14:03 > 0:14:05flooded across the golf course.
0:14:05 > 0:14:08And as the water receded, there were some little surprises
0:14:08 > 0:14:09left in the lake.
0:14:10 > 0:14:14The flood waters must have washed in a few young bull sharks,
0:14:14 > 0:14:18which were fully equipped to invade this new freshwater territory.
0:14:18 > 0:14:22Any other species probably wouldn't have survived.
0:14:22 > 0:14:25So how do the golfers feel about teeing off next to
0:14:25 > 0:14:28shark-infested waters?
0:14:28 > 0:14:31The lake is quite well signed, everyone is well aware.
0:14:31 > 0:14:34We don't allow any swimming, no ball fossicking, nothing like that.
0:14:34 > 0:14:36So we do our best, keeping the sharks alive
0:14:36 > 0:14:38and also keeping the golfers safe.
0:14:38 > 0:14:42And in true Aussie style, the club's members seem to have taken
0:14:42 > 0:14:45the new residents in their stride.
0:14:45 > 0:14:48Well we threw some chicken in and two sharks, about eight to nine foot,
0:14:48 > 0:14:51came up, it was just incredible to see.
0:14:51 > 0:14:53Sharks aren't the worry, mate,
0:14:53 > 0:14:56it's the snakes around here that you got to worry about.
0:14:56 > 0:15:00The members absolutely love the fact that we've got sharks here, they've embraced it
0:15:00 > 0:15:02like nothing else, really.
0:15:02 > 0:15:04The monthly Shark Lake Challenge
0:15:04 > 0:15:07must be one of the world's deadliest rounds of golf.
0:15:10 > 0:15:14Certainly not a place to go fishing for your golf balls.
0:15:14 > 0:15:19Now, bull sharks have been responsible for 92 attacks on humans.
0:15:19 > 0:15:22Principally because of their tolerance of fresh water.
0:15:22 > 0:15:24It means that they can swim further up rivers
0:15:24 > 0:15:27and come into contact with more people.
0:15:27 > 0:15:30So if you're overseas you might want to think twice about taking
0:15:30 > 0:15:32a freshwater dip.
0:15:32 > 0:15:34They've been seen right up into the Mississippi
0:15:34 > 0:15:37and right up into the Amazon too.
0:15:37 > 0:15:39Coming to the Thames some time soon?
0:15:39 > 0:15:40Let's hope not.
0:15:42 > 0:15:46And with today's technology, more and more of these shocking
0:15:46 > 0:15:48appearances are being captured on camera.
0:15:48 > 0:15:50All right.
0:15:50 > 0:15:53Take this family, having a lovely day out fishing
0:15:53 > 0:15:55on a South Carolina river.
0:15:55 > 0:15:57Until this happened.
0:16:01 > 0:16:04Oh, Jesus Christ! There's a shark!
0:16:04 > 0:16:07It's a shark! A shark!
0:16:07 > 0:16:10There's a big ass shark!
0:16:10 > 0:16:13Another bull shark turning up where it's least expected.
0:16:15 > 0:16:17So it's certainly worth keeping your eyes peeled
0:16:17 > 0:16:21and your camera running, you just never know what might show up.
0:16:23 > 0:16:27But some unexpected animals don't travel under their own steam,
0:16:27 > 0:16:29they hitch a lift.
0:16:30 > 0:16:32For our next story,
0:16:32 > 0:16:36we travel to Washington State on America's west coast.
0:16:39 > 0:16:44In March 2013, a mysterious boat washed in on the morning tide.
0:16:47 > 0:16:50Crusted with barnacles and draped in seaweed,
0:16:50 > 0:16:54this vessel had clearly spent many months at sea.
0:16:57 > 0:17:01Fisheries officer Allen Pleus was one of the first people to see
0:17:01 > 0:17:05the unusual boat, which on closer inspection
0:17:05 > 0:17:07wasn't quite as empty as it looked.
0:17:09 > 0:17:11I found lots of different kinds of mussels.
0:17:11 > 0:17:13I found several different kinds of crab.
0:17:13 > 0:17:16There was actually a sea cucumber, which is a type of species
0:17:16 > 0:17:18we've never seen associated with marine debris before.
0:17:18 > 0:17:20It had a very rich
0:17:20 > 0:17:23diversity of species on there which gave us the first
0:17:23 > 0:17:26clue of course that there was something unique here.
0:17:26 > 0:17:30But then the boat revealed something astonishing.
0:17:30 > 0:17:33Hidden by seaweeds and barnacles was a tank,
0:17:33 > 0:17:37an old bait box, where a stowaway was hiding.
0:17:41 > 0:17:43I saw a fish come right up to the surface
0:17:43 > 0:17:46and you know, look around and then go back down.
0:17:46 > 0:17:50So I assumed that if there's one fish there could be more.
0:17:50 > 0:17:54It turned out that five fish had hitched a ride on board,
0:17:54 > 0:17:57this is the sole survivor.
0:17:57 > 0:18:02It's definitely not something you would see in our area here and
0:18:02 > 0:18:06it looks like some of the fish that you would see snorkelling
0:18:06 > 0:18:08in a tropical area.
0:18:10 > 0:18:14So how had a tropical fish ended up shipwrecked on the chilly
0:18:14 > 0:18:15shores of Washington state?
0:18:17 > 0:18:20The first job was to cast the net wide
0:18:20 > 0:18:24and find the identity of the mystery traveller.
0:18:24 > 0:18:27The fish was transferred to experts at a local aquarium
0:18:27 > 0:18:32where Keith Chandler settled it into its new home.
0:18:32 > 0:18:33We drove over there
0:18:33 > 0:18:37and found this incredible fish that I'd never seen before.
0:18:37 > 0:18:40The water that it was in when we got there was kind of sketchy,
0:18:40 > 0:18:42so we got it in clean water and it perked up.
0:18:42 > 0:18:44We were concerned about what to feed it
0:18:44 > 0:18:47so we tried different things and we found
0:18:47 > 0:18:50that it really liked little pieces of cut up razor clam
0:18:50 > 0:18:53and it also liked salmon. So it eats better than I do.
0:18:53 > 0:18:55It's a very spoiled fish.
0:18:57 > 0:19:01They trawled the web to find out more about their unexpected guest.
0:19:01 > 0:19:06Until they found something that took everyone by surprise.
0:19:07 > 0:19:11The fish was a striped beakfish.
0:19:11 > 0:19:14A baffling discovery because striped beakfish
0:19:14 > 0:19:18live in the coral reefs of China, Japan, and Korea.
0:19:18 > 0:19:22They don't migrate away from warm seas, so our fish
0:19:22 > 0:19:25was definitely more of an accidental tourist
0:19:25 > 0:19:27than a seasoned traveller.
0:19:29 > 0:19:32So how had it ended up shipwrecked over 4,000
0:19:32 > 0:19:36miles from home? It was time to turn
0:19:36 > 0:19:40to the only other evidence that they had, the boat.
0:19:40 > 0:19:44This is a piece of the information that's important to identify a boat.
0:19:44 > 0:19:46This area was heavily encrusted with
0:19:46 > 0:19:50organisms, we scrape off whatever vegetation is there
0:19:50 > 0:19:54and we were really lucky, that the lettering was in good shape,
0:19:54 > 0:19:56so that you could actually read it.
0:19:56 > 0:19:58This is the name here,
0:19:58 > 0:20:00Saisho Muro.
0:20:00 > 0:20:05The name and registration number led to the astonishing truth.
0:20:05 > 0:20:08The boat was from Japan.
0:20:08 > 0:20:12The same country that's also home to striped beakfish.
0:20:14 > 0:20:17But ocean currents alone would be unlikely to carry
0:20:17 > 0:20:21an object of this size such a vast distance.
0:20:21 > 0:20:26Something extraordinary must have pushed the boat across the Pacific.
0:20:28 > 0:20:32And just over two years beforehand, something completely
0:20:32 > 0:20:37unprecedented and catastrophic had happened on the shores of Japan.
0:20:41 > 0:20:43In March 2011
0:20:43 > 0:20:46a tsunami hit the coast of Japan.
0:20:46 > 0:20:49The devastation it caused dragged some
0:20:49 > 0:20:52five million tonnes of debris into the Pacific Ocean.
0:20:53 > 0:20:55Now, most of this would
0:20:55 > 0:20:58have sunk without trace, but around one and a half million tonnes
0:20:58 > 0:21:01of it floated away from Japan's coastlines.
0:21:04 > 0:21:08And although it's not the first time this material has washed up
0:21:08 > 0:21:12on the coast of America, no-one thought an animal like a fish
0:21:12 > 0:21:15could ever have survived the journey.
0:21:15 > 0:21:19I've never seen anything like this in the 34 years that I've been here.
0:21:19 > 0:21:21a fish that came all the way from Japan
0:21:21 > 0:21:25and is still alive on our coast was fascinating.
0:21:25 > 0:21:29As it turned out, there were more than 30 different Japanese
0:21:29 > 0:21:31species on board.
0:21:31 > 0:21:36A veritable Noah's Ark sailing the high seas for a staggering two years.
0:21:38 > 0:21:41So just how did they all survive this incredible journey?
0:21:43 > 0:21:47Well, this hole may well have provided a lifeline.
0:21:47 > 0:21:52It meant that the boat was travelling partially submerged in the water.
0:21:52 > 0:21:55The stowaways had the full run of the ship.
0:21:55 > 0:21:59Obviously this is a deep recessed area.
0:21:59 > 0:22:03The growth that came around it again helped protect it from other
0:22:03 > 0:22:05species that would be after the fish.
0:22:05 > 0:22:08So it had a really good area to escape
0:22:08 > 0:22:11and when it was hungry it would
0:22:11 > 0:22:14basically have this whole boat as a buffet.
0:22:15 > 0:22:19The boat had become a floating aquarium, a mini ecosystem
0:22:19 > 0:22:24of predators and prey and this held the key to the survival of the group.
0:22:26 > 0:22:29But then, a puzzling new discovery emerged.
0:22:30 > 0:22:33The fish was only one year old.
0:22:33 > 0:22:37Born long after the tsunami had set the boat adrift.
0:22:37 > 0:22:39How on earth was this possible?
0:22:40 > 0:22:44One theory is that the fish was born inside the boat,
0:22:44 > 0:22:47to parents that sadly didn't survive the trip.
0:22:47 > 0:22:50The other, that it hitched a lift at some point
0:22:50 > 0:22:53during the course of that boat's journey.
0:22:53 > 0:22:57Now, one of the few other places that we know that striped beakfish occur
0:22:57 > 0:23:00is here in the Hawaiian islands.
0:23:00 > 0:23:04So could it be that after the tsunami, the ocean currents
0:23:04 > 0:23:10carried that little boat all the way from here in Japan across to Hawaii
0:23:10 > 0:23:15where the fish quite literally jumped ship and then
0:23:15 > 0:23:18a further 2,500 miles all the way across here
0:23:18 > 0:23:20to Washington state.
0:23:20 > 0:23:24But whatever happened, there's no doubt that this globetrotting fish
0:23:24 > 0:23:28had an incredible adventure on the high seas.
0:23:29 > 0:23:32A truly astonishing story of survival.
0:23:32 > 0:23:34But...
0:23:34 > 0:23:37as remarkable as this story is, we also have to admit that animal
0:23:37 > 0:23:42stowaways frequently cause absolute devastation in their new homes.
0:23:42 > 0:23:45Boats have unwittingly transported many species to new
0:23:45 > 0:23:49territories, where they've wreaked havoc with the local wildlife
0:23:49 > 0:23:52and perhaps the greatest culprits of all are rats.
0:23:52 > 0:23:56These animals have been sailing the seven seas for centuries and they
0:23:56 > 0:24:00adapt very well to new environments. And as a consequence of this,
0:24:00 > 0:24:03they alone have been responsible
0:24:03 > 0:24:06for between 40 and 60%
0:24:06 > 0:24:09of all reptile and bird extinctions.
0:24:10 > 0:24:14What these unexpected visitors show us is that when it comes to
0:24:14 > 0:24:19survival, nature has the power to rise to any challenge, anywhere.
0:24:20 > 0:24:24Whether it's a seal scoping out hot new travel destinations,
0:24:24 > 0:24:28sharks surviving and thriving in uncharted territory,
0:24:28 > 0:24:32or a fish cast adrift far from home.
0:24:32 > 0:24:37When these animals turn up on our turf, they're impossible to ignore.
0:24:40 > 0:24:42Next, we'll be looking at what happens
0:24:42 > 0:24:47when nature does the unexpected and suddenly takes over our lives.
0:24:47 > 0:24:52From a stealthy invader with a death defying secret,
0:24:52 > 0:24:57to a shattering wave of ice that smashed up whole houses.
0:25:00 > 0:25:03But we start in the American West, in California.
0:25:07 > 0:25:09For most of the time life is pretty laid back
0:25:09 > 0:25:12in this hot and hazy state.
0:25:12 > 0:25:15Apart from a few days every year,
0:25:15 > 0:25:18when America's West gets very wild indeed.
0:25:21 > 0:25:24In a matter of minutes, driving anywhere becomes
0:25:24 > 0:25:26a dangerous game of dodgems.
0:25:26 > 0:25:27Oh, my God.
0:25:29 > 0:25:32This full scale invasion is worthy of Day of the Triffids.
0:25:33 > 0:25:36And the plant responsible?
0:25:36 > 0:25:38Tumbleweed.
0:25:38 > 0:25:40This is an attack of the tumbleweed.
0:25:40 > 0:25:44It's almost like a fog that's come through. So you got the dust in the air,
0:25:44 > 0:25:46so all of a sudden you see cars appear out of nowhere.
0:25:46 > 0:25:48They hit a car, you just see them just scatter
0:25:48 > 0:25:50and smash all of a sudden they just go...
0:25:50 > 0:25:52and it just disintegrates.
0:25:52 > 0:25:55Traffic gets a little bit crazy because they'll end up braking
0:25:55 > 0:25:58and letting the tumbleweed cross and it's like, so all of a sudden
0:25:58 > 0:25:59you're, like, slamming on your brakes.
0:25:59 > 0:26:03Even on the ground, standing up to a plant the size of a human
0:26:03 > 0:26:05is easier said than done.
0:26:05 > 0:26:07SHE SCREAMS
0:26:10 > 0:26:13But wait a moment, this is the same
0:26:13 > 0:26:16plant famous for its cameo appearances in American Westerns?
0:26:16 > 0:26:18The lonely rambling weed?
0:26:20 > 0:26:23Well, don't believe everything you see in the movies.
0:26:24 > 0:26:27Because these wayward weeds
0:26:27 > 0:26:31can charge across the landscape in vast numbers.
0:26:31 > 0:26:34It's crazy look at it! It is, look out!
0:26:37 > 0:26:40And this is just the start of the problem - just look at what
0:26:40 > 0:26:43happens when something blocks the plants' path.
0:26:47 > 0:26:52The town of Bakersfield seems to bear the brunt of the problem.
0:26:52 > 0:26:56So they're, they're like huge snowdrifts. We have a long fence
0:26:56 > 0:26:59and they were just covered down the whole side,
0:26:59 > 0:27:03almost an eighth of a mile of just fence and nothing but tumbleweeds.
0:27:03 > 0:27:06When I drove in I thought, "Oh, my!"
0:27:06 > 0:27:08Tumbleweeds were everywhere.
0:27:08 > 0:27:11My employees have to be out there getting tumbleweeds, they had
0:27:11 > 0:27:14to take pitch forks and rakes and everything.
0:27:14 > 0:27:20So why has the tumbleweed staged such a spectacular takeover?
0:27:20 > 0:27:23And how has so much of it ended up in Bakersfield?
0:27:24 > 0:27:27Well, to get to the root of this prickly problem
0:27:27 > 0:27:31we need to start on California's dry and dusty roadsides.
0:27:33 > 0:27:37These unassuming green shrubs look perfectly innocent now
0:27:37 > 0:27:42but this is what tumbleweed looks like when it's not moving at 50mph.
0:27:43 > 0:27:46The plant grows here all year round without
0:27:46 > 0:27:49causing any trouble at all. So what makes
0:27:49 > 0:27:53them such a menace on just a few days of the year?
0:27:55 > 0:27:58As winter arrives the tumbleweed begins to dry out
0:27:58 > 0:28:01and it looks pretty dead and done for.
0:28:01 > 0:28:05But it's not, in fact, this is just the start.
0:28:05 > 0:28:08As it dries, it begins to fold in on itself,
0:28:08 > 0:28:10forming this characteristic shape.
0:28:10 > 0:28:14But it's also about the fact that it's becoming more fragile and
0:28:14 > 0:28:18particularly down here in the root, which becomes really brittle.
0:28:18 > 0:28:20To the extent that in the end,
0:28:20 > 0:28:23all it takes is a good gust of wind for this to snap
0:28:23 > 0:28:27and then the plant begins to tumble.
0:28:29 > 0:28:33So seasonal changes transform the tumbleweeds
0:28:33 > 0:28:35then all they need is a push.
0:28:38 > 0:28:42When the Santa Anna winds come, they rock the tumbleweeds
0:28:42 > 0:28:46and they snap off their bases and then they start tumbling and
0:28:46 > 0:28:50this last year we had a lot of tumbleweeds, thousands and thousands.
0:28:50 > 0:28:54Now, Bakersfield is set in miles of open land and trapped between
0:28:54 > 0:28:56two mountain ranges.
0:28:56 > 0:28:59So the prevailing winds funnel the tumbleweed
0:28:59 > 0:29:02straight towards the town.
0:29:02 > 0:29:05But being in the firing line is only part of the problem.
0:29:05 > 0:29:08Year on year, these unruly weeds
0:29:08 > 0:29:13increase in number, tightening their stranglehold on Bakersfield.
0:29:13 > 0:29:17We tend to think of plants as being very benign or passive organisms
0:29:17 > 0:29:19but in fact they're incredible invaders.
0:29:19 > 0:29:22Ruthlessly trying to colonise new environments
0:29:22 > 0:29:27and perhaps the most aggressive of all is the tumbleweed.
0:29:27 > 0:29:29And the secret of its success is not
0:29:29 > 0:29:32the fact that it rolls over vast distances,
0:29:32 > 0:29:35it's what it's doing when it's rolling. Listen to this.
0:29:36 > 0:29:43That rattling is the sound of 200,000 seeds contained
0:29:43 > 0:29:45within this tumbleweed and all the while
0:29:45 > 0:29:49it's rolling, it's scattering those seeds by the thousands
0:29:49 > 0:29:51and thousands.
0:29:51 > 0:29:54So when tumbleweeds roll in to town,
0:29:54 > 0:29:58so do billions and billions of seeds.
0:29:58 > 0:30:01And it's not just getting worse in Bakersfield.
0:30:01 > 0:30:06Throughout North America, tumbleweed is growing completely out of control.
0:30:06 > 0:30:09It's little wonder we've come to associate tumbleweed
0:30:09 > 0:30:13with the pioneering spirit of the American Wild West.
0:30:15 > 0:30:18But surprisingly, tumbleweed isn't
0:30:18 > 0:30:22actually American at all! It was accidently brought over
0:30:22 > 0:30:26by Ukrainian farmers in the 1800s.
0:30:26 > 0:30:30And America is now facing a tumbleweed takeover.
0:30:37 > 0:30:41But now, Bakersfield entrepreneur John Solorio is
0:30:41 > 0:30:44heading for a showdown with this problematic plant.
0:30:46 > 0:30:50He's designed the world's first Tumblegator.
0:30:53 > 0:30:55John's machine gathers up to
0:30:55 > 0:30:5810 tonnes of tumbleweed a day.
0:30:58 > 0:31:01It shreds and compacts the weed before
0:31:01 > 0:31:04it has the chance to run and shake its seeds.
0:31:07 > 0:31:09Had to have something done with these
0:31:09 > 0:31:12tumbleweeds in the Bakersfield area and they thought well,
0:31:12 > 0:31:13it just makes sense.
0:31:14 > 0:31:17John's invention is just one part
0:31:17 > 0:31:18of a national programme to
0:31:18 > 0:31:22halt the plants' seemingly unstoppable spread.
0:31:22 > 0:31:26Because when a plant finds itself in unchartered new territories,
0:31:26 > 0:31:31these leafy invaders can become almost impossible to control.
0:31:32 > 0:31:38Take knotweed, the UK's own runaway plant.
0:31:38 > 0:31:41The Victorians brought this delicate little flower over from Japan,
0:31:41 > 0:31:45thinking that it might make a pretty addition to their collections.
0:31:45 > 0:31:50But it didn't take long for the knotweed to show its true colours.
0:31:50 > 0:31:54This ruthless invader got out into the countryside
0:31:54 > 0:31:56and started to spread.
0:31:56 > 0:32:00Decades later and it's still on the loose.
0:32:00 > 0:32:02It grows so vigorously that it
0:32:02 > 0:32:06can crack concrete, roads and solid walls.
0:32:06 > 0:32:08It's a nightmare for homeowners,
0:32:08 > 0:32:14who can find their bricks and mortar devalued by a tiny, green weed.
0:32:14 > 0:32:17Stopping this relentless green invasion is proving to be
0:32:17 > 0:32:19an almost impossible challenge.
0:32:22 > 0:32:26But some invaders take a more stealthy approach to their attack.
0:32:27 > 0:32:32Our next animal has been staging a secret invasion all thanks to
0:32:32 > 0:32:33a rather remarkable talent.
0:32:35 > 0:32:38From its original home in the Caribbean,
0:32:38 > 0:32:42a tiny jellyfish has now spread into all of the world's oceans.
0:32:43 > 0:32:47It's likely to have been helped on its way by shipping activities,
0:32:47 > 0:32:51catching a ride in the ballast water of travelling vessels.
0:32:52 > 0:32:55But that alone can't fully explain its success.
0:32:57 > 0:32:59As scientists investigated,
0:32:59 > 0:33:03they were astonished by what they discovered.
0:33:03 > 0:33:08This jellyfish can do the seemingly impossible.
0:33:08 > 0:33:11It's found a way to cheat death,
0:33:11 > 0:33:14to live forever
0:33:14 > 0:33:17and that's something that's helped its global takeover.
0:33:20 > 0:33:23But just how is the jellyfish doing it?
0:33:23 > 0:33:27What's its sought-after secret to eternal life?
0:33:29 > 0:33:32Well, to understand this animal's death-defying feat
0:33:32 > 0:33:36we need to get to grips with the two main stages of a jellyfish.
0:33:40 > 0:33:44The tiny polyp and the larger, full grown Medusa.
0:33:45 > 0:33:52The young polyps form huge colonies, like a jellyfish creche.
0:33:52 > 0:33:55Amongst the group, they grow until it's time for them to form
0:33:55 > 0:33:57an independent Medusa.
0:33:59 > 0:34:02Now, normally the adult Medusa would swim
0:34:02 > 0:34:05around for anything between a few days to a year depending on the
0:34:05 > 0:34:07species of the jellyfish.
0:34:09 > 0:34:14But in the immortal jellyfish, something very strange happens.
0:34:14 > 0:34:18Instead of growing old gracefully the adult does something
0:34:18 > 0:34:20completely mind-blowing.
0:34:22 > 0:34:27The immortal jellyfish has found a means of turning back time.
0:34:27 > 0:34:32The adult can reverse the ageing process and turn back into a polyp
0:34:32 > 0:34:36and that's a feat no less amazing than a caterpillar turning into
0:34:36 > 0:34:42a butterfly and then that butterfly turning back into a caterpillar.
0:34:42 > 0:34:46But the thing is, that doesn't happen just once.
0:34:46 > 0:34:49As far as we know the process can keep going backwards
0:34:49 > 0:34:51and forwards indefinitely.
0:34:52 > 0:34:56Anything stressful like injury or lack of food will send
0:34:56 > 0:34:59the adult back in time to a polyp.
0:34:59 > 0:35:03And in that state, it's easier for it to survive.
0:35:03 > 0:35:07Until eventually, the animal grows a new Medusa
0:35:07 > 0:35:09and turns back into an adult.
0:35:09 > 0:35:16This ingenious trick has helped fuel their stealthy global invasion.
0:35:16 > 0:35:19The jellyfish doesn't just take over new territory,
0:35:19 > 0:35:22it never leaves.
0:35:22 > 0:35:25Now scientists are trying to find out which of the jellyfish's
0:35:25 > 0:35:29genes are controlling its bizarre biological clock.
0:35:29 > 0:35:32Because whether it's sacred waters or hi tech
0:35:32 > 0:35:35beauty serums, throughout history us humans
0:35:35 > 0:35:39have strived to halt the ageing process.
0:35:39 > 0:35:43But it seems that one extraordinary animal is well ahead of us
0:35:43 > 0:35:48and could one day maybe even share its secrets of living forever.
0:35:50 > 0:35:54But unlike the gradual takeover of the immortal jellyfish,
0:35:54 > 0:35:59some invasions cause mass devastation in one fateful moment.
0:36:01 > 0:36:05Our next story takes us to Winnipeg in Canada.
0:36:07 > 0:36:10With stunning scenery and a view over
0:36:10 > 0:36:13a tranquil lake, it's easy to see why people
0:36:13 > 0:36:17choose to live on the peaceful shores of Ochre Beach.
0:36:19 > 0:36:23But in May 2013, at the end of a hard winter,
0:36:23 > 0:36:29all the peace and quiet was quite literally shattered.
0:36:31 > 0:36:33Oh, no.
0:36:33 > 0:36:35This is absolutely crazy.
0:36:38 > 0:36:43From nowhere a 9m high wall of ice rose up
0:36:43 > 0:36:47and threatened to engulf an entire street.
0:36:47 > 0:36:50Residents like Myles Haverluck could only stand back
0:36:50 > 0:36:56and watch in horror as their homes faced a tsunami of ice.
0:36:56 > 0:36:58I like to use the analogy of a freight train
0:36:58 > 0:37:01sort of coming at you because it almost seemed like that.
0:37:01 > 0:37:03It's happened in a matter of...
0:37:03 > 0:37:05five minutes?
0:37:05 > 0:37:07It was probably coming about the same as you would walk
0:37:07 > 0:37:09and it just kept on moving.
0:37:09 > 0:37:13And you're looking at it and you're thinking "Oh, this has got to stop." But it didn't.
0:37:13 > 0:37:17Myles' friend was filming as second by second
0:37:17 > 0:37:20the ice surged towards the house.
0:37:20 > 0:37:23We're about to get engulfed by ice. It's going to come through the house.
0:37:27 > 0:37:30All these houses are getting engulfed by ice.
0:37:35 > 0:37:37Donna Billows was at home with her husband Elmer
0:37:37 > 0:37:39at the moment that the ice struck.
0:37:41 > 0:37:45We stood and watched in amazement as the ice crawled up
0:37:45 > 0:37:48our window and boom, the whole thing broke
0:37:48 > 0:37:50and ice started pouring into the living room.
0:37:50 > 0:37:56It came over the top of our roof, and up over top of the chimney which
0:37:56 > 0:37:59is at least 6 feet above the roof line
0:37:59 > 0:38:04so it was at least 25 feet of ice.
0:38:04 > 0:38:07We just grabbed our keys and got out.
0:38:07 > 0:38:10But just when it seemed that nothing could stop it,
0:38:10 > 0:38:12everything went quiet.
0:38:15 > 0:38:17Please!
0:38:18 > 0:38:22The ice tsunami stopped as suddenly as it had started.
0:38:24 > 0:38:29In just 10 terrifying minutes, most of the street had been wiped out.
0:38:32 > 0:38:36So what had the residents of Ochre Beach just witnessed?
0:38:36 > 0:38:40What had caused a giant wave of ice to break over the houses?
0:38:42 > 0:38:47Now, there's no doubt ice can be a very powerful force.
0:38:47 > 0:38:49It's sculpted much of our planet.
0:38:49 > 0:38:54When layers of snow build up they compress and create a glacier.
0:38:55 > 0:38:59Their sheer mass makes them flow down through the landscape,
0:38:59 > 0:39:02carving up the solid rock below.
0:39:02 > 0:39:05It might travel just a few metres a year
0:39:05 > 0:39:08but as this sped up footage shows, over time
0:39:08 > 0:39:11this movement makes quite an impact.
0:39:11 > 0:39:16But these processes often take millennia, not minutes.
0:39:19 > 0:39:22So what caused such a dramatic and quick change
0:39:22 > 0:39:24in the ice at Ochre Beach?
0:39:25 > 0:39:29With temperatures dropping as low as minus 20 degrees over the winter,
0:39:29 > 0:39:33by May, the lake had been frozen and still for five months.
0:39:36 > 0:39:39So what happened to create such a catastrophe?
0:39:40 > 0:39:43Glacier expert Michelle Koppes...
0:39:45 > 0:39:49..thinks that some very particular conditions may have been at work.
0:39:51 > 0:39:53In the middle of winter the ice is all stuck together
0:39:53 > 0:39:56and it's very resistant to motion. But once it
0:39:56 > 0:39:59starts to break up in the spring time,
0:39:59 > 0:40:01it can start to move.
0:40:01 > 0:40:04By May, the cracks were starting to show
0:40:04 > 0:40:09and 200 square miles of lake ice was melting and moving around.
0:40:12 > 0:40:16But as the ice was thawing to its usual springtime schedule,
0:40:16 > 0:40:19other forces must have been at work.
0:40:19 > 0:40:22So was there anything else unusual about that
0:40:22 > 0:40:24fateful day in Spring?
0:40:24 > 0:40:29Well, that afternoon the weather changed dramatically.
0:40:29 > 0:40:33They were predicting high winds but at four o'clock in the afternoon
0:40:33 > 0:40:37it was as calm as calm could be and at six o'clock at night
0:40:37 > 0:40:39it was absolutely unbelievable.
0:40:39 > 0:40:41So my daughter said "Look at the trees, Dad."
0:40:41 > 0:40:44and our trees in our front lawn, they were doubled down,
0:40:44 > 0:40:48looked like they were touching the ground, I'm surprised they didn't break.
0:40:48 > 0:40:51It was the sudden start of a storm that would completely
0:40:51 > 0:40:53change how the ice behaved.
0:40:55 > 0:40:58Often times when you have rapid warming in the spring time
0:40:58 > 0:41:00you'll also have stormy conditions.
0:41:00 > 0:41:04So as the ice starts to break up if you have a big wind gust or
0:41:04 > 0:41:07a storm event it will start to push on that ice
0:41:07 > 0:41:10and it'll get it to raft onto the shore.
0:41:12 > 0:41:16That wall is probably 15 feet up in the air.
0:41:18 > 0:41:21When it hits the land, the land has friction
0:41:21 > 0:41:24so the ice that is the first to hit the land stops
0:41:24 > 0:41:27and all the ice that's piled up behind it
0:41:27 > 0:41:29kind of crumbles on top of it.
0:41:29 > 0:41:33So it looks like a slow wave that's coming ashore
0:41:33 > 0:41:35but it's basically all the ice tumbling
0:41:35 > 0:41:37over the ice that has stopped.
0:41:39 > 0:41:43The perfect storm of miles of thawing ice and gale force winds
0:41:43 > 0:41:48blowing towards the shore created a terrifying ice tsunami
0:41:48 > 0:41:52so powerful it literally knocked the community sideways.
0:41:52 > 0:41:54So many homes that were just knocked
0:41:54 > 0:41:57right off their foundations. There was one sitting back
0:41:57 > 0:42:00and it was almost on its back it had been tilted up pushed over
0:42:00 > 0:42:02and other ones were just destroyed and crushed.
0:42:02 > 0:42:07I guess you're more in shock. At least I was because I just didn't...
0:42:08 > 0:42:12..think, you know, it was going to get that bad but it did.
0:42:12 > 0:42:17Thankfully, events like this have only been documented in a handful of other places.
0:42:20 > 0:42:23Nobody in Ochre Beach was hurt
0:42:23 > 0:42:26but it's taken a lot of hard graft and community spirit
0:42:26 > 0:42:29to slowly repair the damage.
0:42:29 > 0:42:34A staggering display of nature in its most powerful form
0:42:34 > 0:42:37and of course, a truly horrific event for those homeowners.
0:42:37 > 0:42:40Also - I suppose - proof that as much as we've learned to live
0:42:40 > 0:42:46alongside nature it can still catch us out with its unpredictable force.
0:42:47 > 0:42:49Shocking stories like these
0:42:49 > 0:42:53remind us of the true power of nature.
0:42:53 > 0:42:55Whether it's introducing an aggressive plant
0:42:55 > 0:42:57that overstays its welcome...
0:42:57 > 0:43:02A jellyfish invader with a surprising secret,
0:43:02 > 0:43:06or an icy storm of events triggering a terrifying ordeal.
0:43:06 > 0:43:10When nature takes over, there really is no way of stopping it.
0:43:13 > 0:43:18Next, we meet unstoppable animals with superpowers.
0:43:18 > 0:43:21Specialist skills to survive any situation.
0:43:23 > 0:43:25From an amphibian assassin,
0:43:25 > 0:43:28to an escape artist extraordinaire.
0:43:30 > 0:43:33But we start in Russia in the rush hour.
0:43:36 > 0:43:40The Moscow Metro is one of the world's busiest.
0:43:40 > 0:43:43Every day it carries around 7 million people
0:43:43 > 0:43:45in and out of the city.
0:43:46 > 0:43:49But in amongst the crowd, making their way through
0:43:49 > 0:43:53trains and tunnels are a new team of city slickers.
0:43:53 > 0:43:56A selective band of remarkable...
0:43:56 > 0:43:58dogs.
0:43:58 > 0:44:01There's not an owner or a lead in sight,
0:44:01 > 0:44:04but every day for the last 25 years,
0:44:04 > 0:44:07these animals join the local commute.
0:44:07 > 0:44:10They share their seats with passengers,
0:44:10 > 0:44:14queue for trains and carefully mind the gap.
0:44:14 > 0:44:16and they never miss their stop.
0:44:16 > 0:44:20Because strange as it might seem, their behaviour appears to
0:44:20 > 0:44:22be entirely deliberate.
0:44:25 > 0:44:28So what's bringing these dogs onto the trains?
0:44:28 > 0:44:31And where are they all going?
0:44:31 > 0:44:34Suzanne MacDonald has been studying how animals
0:44:34 > 0:44:36adapt to city life.
0:44:36 > 0:44:41She thinks the dogs' background might help explain their behaviour.
0:44:41 > 0:44:44It only makes sense for dogs to do this if they're feral
0:44:44 > 0:44:46so they don't have owners, so clearly they must be homeless dogs.
0:44:46 > 0:44:50They need to find food every day and so this is a great way
0:44:50 > 0:44:53to do that, they also get social contact, which is great.
0:44:53 > 0:44:56So I don't think you would see this kind of behaviour in a city
0:44:56 > 0:44:59where there aren't large populations of feral dogs.
0:45:01 > 0:45:03And Moscow certainly has that.
0:45:03 > 0:45:08Around 35,000 stray dogs live on the city's streets.
0:45:08 > 0:45:11It's a tough life where competition
0:45:11 > 0:45:14for food and shelter is fierce.
0:45:14 > 0:45:18Abandoned pets or born on the streets, these dogs face a dilemma.
0:45:18 > 0:45:20They don't have owners to
0:45:20 > 0:45:24care for them and years of selective breeding has stripped away the
0:45:24 > 0:45:28natural hunting skills of a true wild dog.
0:45:28 > 0:45:32There are such an enormous number of stray dogs that Moscow's mutts
0:45:32 > 0:45:37need to be incredibly resourceful to survive in their dog-eat-dog world.
0:45:37 > 0:45:40So, they've moved into new territory
0:45:40 > 0:45:44and are taking advantage of a captive audience.
0:45:44 > 0:45:48If you were a dog and you saw a human and humans give you food
0:45:48 > 0:45:51and one day you followed the human and the human went down into a
0:45:51 > 0:45:54train and the human petted you and told you how great you were
0:45:54 > 0:45:56and everybody on the train was nice to you and then
0:45:56 > 0:45:58when you got off the train, you followed the humans,
0:45:58 > 0:46:01somebody fed you, you might say the train is a good place.
0:46:01 > 0:46:03And so you might do that again.
0:46:03 > 0:46:06Dogs are really fast learners, so I think it could spread through
0:46:06 > 0:46:08a population of stray dogs really quickly.
0:46:09 > 0:46:13In fact, when it comes to finding food, several other animals around
0:46:13 > 0:46:17the world have also discovered the perks of public transport.
0:46:17 > 0:46:21Whether it's monkeys working the crowds on trains in India
0:46:21 > 0:46:24or pigeons making a short hop on the London Underground.
0:46:24 > 0:46:30UNDERGROUND ANNOUNCER: Great Portland Street. This is a circle line train to Hammersmith.
0:46:31 > 0:46:35But what the Moscow metro dogs are doing
0:46:35 > 0:46:38is much smarter than scrounging.
0:46:38 > 0:46:42When scientists followed the dogs on and off the trains they were
0:46:42 > 0:46:44astonished by what they found.
0:46:45 > 0:46:50About 20 of the dogs were making a regular commute.
0:46:50 > 0:46:53And most remarkable of all, the stations they
0:46:53 > 0:46:57were using were no coincidence.
0:46:57 > 0:46:59They're coming from a place where they sleep
0:46:59 > 0:47:02which would be on the outskirts of the city. They probably
0:47:02 > 0:47:03go where it's quiet at night.
0:47:03 > 0:47:06They may go somewhere where they can actually sleep with other dogs
0:47:06 > 0:47:08and then in the daytime they would go downtown,
0:47:08 > 0:47:11where they can hit up tourists for food and look sad eyed.
0:47:11 > 0:47:14And get some snacks and you know, that sort of thing. So it's
0:47:14 > 0:47:19sort of like they go from the suburbs at night to their day jobs downtown.
0:47:19 > 0:47:21This is the first and only place
0:47:21 > 0:47:25this incredible behaviour has been seen.
0:47:25 > 0:47:28But how are they finding their way through the Metro's maze of tunnels?
0:47:28 > 0:47:31surely, they can't be using a map.
0:47:31 > 0:47:35Navigating this complex warren of tracks,
0:47:35 > 0:47:39platforms and stations is difficult enough for us humans
0:47:39 > 0:47:42but how on earth do the dogs do it? They can't read maps.
0:47:42 > 0:47:46Well, even in the heart of Moscow city, these stray animals
0:47:46 > 0:47:51are using the same instincts and senses as wild species of dogs do.
0:47:52 > 0:47:55All dogs, wild or domestic, have a
0:47:55 > 0:48:00sense of smell which is over 10,000 times better than ours.
0:48:00 > 0:48:03So what somewhere smells like will tell them
0:48:03 > 0:48:06more about their location than any map.
0:48:06 > 0:48:10Dogs also have a strong biological body clock,
0:48:10 > 0:48:15so the dogs on the metro may be using that to time their daily routine.
0:48:16 > 0:48:20It's remarkable how well these dogs have adapted their behaviour
0:48:20 > 0:48:22to make the most of our human activities.
0:48:22 > 0:48:27It's almost as if they know more about us than we know about them.
0:48:27 > 0:48:30These dogs have been remarkably resourceful when it comes to
0:48:30 > 0:48:34modifying their foraging behaviour in order to survive.
0:48:34 > 0:48:37They really are top dogs.
0:48:37 > 0:48:40To meet our next animal with superhero skills,
0:48:40 > 0:48:43we travel to Alaska in North America.
0:48:45 > 0:48:48Where, in August 2010,
0:48:48 > 0:48:52a fishing party reeled in more than they had bargained for.
0:48:52 > 0:48:56A huge two and a half metre octopus was a surprising enough catch,
0:48:56 > 0:49:01but what it did next had people staring in disbelief.
0:49:01 > 0:49:02He's going for it.
0:49:02 > 0:49:04- No way.- I'm telling you right now.
0:49:04 > 0:49:10To everyone's amazement, it began to disappear in front of their eyes.
0:49:10 > 0:49:14Yeah there's his nose, he's just all the way through it now.
0:49:14 > 0:49:17- Except for - oh just...- Just his nose, yeah. There he goes.
0:49:18 > 0:49:21- Wow!- Wow.
0:49:25 > 0:49:30How did this sea creature manage to make an exit worthy of Houdini?
0:49:30 > 0:49:34And why are octopuses the ultimate escape artists?
0:49:36 > 0:49:39The animal on the boat was a giant Pacific octopus.
0:49:41 > 0:49:44Tip to tip, they reach up to 9m in length.
0:49:47 > 0:49:51Surprisingly, they're molluscs, so related to other sea creatures
0:49:51 > 0:49:53like oysters, mussels, and sea snails.
0:49:56 > 0:49:58But unlike most other members of the group,
0:49:58 > 0:50:01octopuses don't have a hard shell
0:50:01 > 0:50:04making them a soft target for predators.
0:50:06 > 0:50:10Could this explain why they would need to make such a quick getaway?
0:50:12 > 0:50:14Octopus expert James Woods
0:50:14 > 0:50:19has been studying their ingenious defence tactics.
0:50:19 > 0:50:22An octopus is all the part that predators want to eat.
0:50:22 > 0:50:25Sharks eat them, marine mammals like dolphins
0:50:25 > 0:50:27and seals eat them, some marine birds eat them.
0:50:27 > 0:50:29But if you can't find something
0:50:29 > 0:50:34it's pretty hard to eat it. So their primary defence is camouflage.
0:50:35 > 0:50:41And the king of camouflage is the aptly named mimic octopus.
0:50:41 > 0:50:45This animal can take on the colour of nearly any setting it finds
0:50:45 > 0:50:50and remarkably, it also copies the shape of other sea creatures.
0:50:50 > 0:50:53Impersonating anything from a flat fish
0:50:53 > 0:50:57to a sea snake in order to protect itself.
0:50:57 > 0:51:01But even if an octopus can't dazzle its predators with illusions,
0:51:01 > 0:51:03it does have another trick.
0:51:03 > 0:51:08It resorts to plan B, escape. And this is where
0:51:08 > 0:51:13not having a hard outer shell or a skeleton is a real advantage.
0:51:15 > 0:51:19For many species of animal, the limit to how small a gap
0:51:19 > 0:51:22they can squeeze through is not governed by their skeleton
0:51:22 > 0:51:26as a whole but by this, their skull.
0:51:26 > 0:51:30But of course octopus don't have skulls, they're soft bodied animals.
0:51:30 > 0:51:33The only hard bit in an octopus are its mouth parts,
0:51:33 > 0:51:35known as its beak
0:51:35 > 0:51:39and they are about 5 cm in diameter.
0:51:39 > 0:51:42So if the beak can squeeze through, the rest can follow.
0:51:46 > 0:51:52So for our octopus on the fishing boat a small gap was all it needed.
0:51:52 > 0:51:55But how did it calculate the size
0:51:55 > 0:51:58and shape of the environment around it so quickly?
0:51:58 > 0:52:01Well, new research is showing that octopuses
0:52:01 > 0:52:04are far smarter than you'd think.
0:52:05 > 0:52:09Octopuses are the most intelligent of all of the invertebrates.
0:52:09 > 0:52:13They have a brain-to-bodyweight ratio that is higher than
0:52:13 > 0:52:15some groups of vertebrates like fish and birds.
0:52:15 > 0:52:18Octopuses' nervous system is very different than ours.
0:52:18 > 0:52:22We have a head and almost all of our nerves are up here
0:52:22 > 0:52:25and then there's some nerves that are wiring to our extremities.
0:52:25 > 0:52:29Where an octopus does have that centralised brain but two thirds
0:52:29 > 0:52:33of its nerves are in its body so it's more of a decentralised system -
0:52:33 > 0:52:36sort of like the internet - than something like us,
0:52:36 > 0:52:38where it's pretty much all up here.
0:52:40 > 0:52:44It's incredible to think that this animal has its brainpower split up
0:52:44 > 0:52:46all over its body.
0:52:46 > 0:52:50And it means that even if disaster strikes,
0:52:50 > 0:52:52they still might be able to think straight.
0:52:53 > 0:52:57If an octopus loses its arm, the arm will act as a decoy.
0:52:57 > 0:53:00It will still hold on to things with its suckers, it can still
0:53:00 > 0:53:03change colour, it can still wiggle, it can still crawl around.
0:53:03 > 0:53:06So it acts as a very effective decoy and it might keep the predator
0:53:06 > 0:53:09occupied, it's got something to eat, busy, while the rest of
0:53:09 > 0:53:11the octopus gets away.
0:53:12 > 0:53:15So the octopuses' vulnerability has driven them to become
0:53:15 > 0:53:20quick-thinking masters of hide and seek.
0:53:20 > 0:53:23But sometimes the only way to survive is to take a more
0:53:23 > 0:53:24confrontational approach.
0:53:27 > 0:53:31The remote rainforests of Cameroon are a lost world that few
0:53:31 > 0:53:33travellers have ever visited.
0:53:34 > 0:53:37But some of those who have, tell tales of
0:53:37 > 0:53:42a bizarre looking animal more than ready to put up a fight.
0:53:42 > 0:53:46A beast capable of drawing blood from its attackers.
0:53:48 > 0:53:51Only a few specimens exist
0:53:51 > 0:53:54but surprisingly, the culprit is this,
0:53:54 > 0:53:56a frog.
0:53:58 > 0:54:01So what is this amphibian oddity?
0:54:01 > 0:54:04And does it deserve its fierce reputation?
0:54:06 > 0:54:10Most amphibians prefer to stay out of trouble
0:54:10 > 0:54:13by hiding from danger, using camouflage
0:54:13 > 0:54:15to stay under the radar.
0:54:16 > 0:54:19Those that take a bolder approach use bright colours
0:54:19 > 0:54:22to make a statement, warning predators
0:54:22 > 0:54:25that their bodies are loaded with harmful toxins.
0:54:27 > 0:54:31But subtle messages aren't enough for this frog.
0:54:32 > 0:54:36It may be small, but its violent reputation
0:54:36 > 0:54:39has given it the name wolverine frog.
0:54:39 > 0:54:42Amphibian expert David Blackman
0:54:42 > 0:54:44knows more than most about this elusive
0:54:44 > 0:54:48and mysterious animal with its ninja-like skills.
0:54:48 > 0:54:51There's no other frog on earth that looks like this.
0:54:51 > 0:54:55All around the side of the body on its legs here,
0:54:55 > 0:54:58it's covered in what looks like hair. But in fact,
0:54:58 > 0:55:00it's actually thin pieces of skin that
0:55:00 > 0:55:04project out from the side of the body. Females lack this entirely,
0:55:04 > 0:55:07so this is something that's unique to only male hairy frogs.
0:55:07 > 0:55:10And it's still not clear why the male frogs would need
0:55:10 > 0:55:13all of this excess skin.
0:55:13 > 0:55:16And that's not the only thing keeping the experts guessing.
0:55:16 > 0:55:20Because this animal is also armed for combat.
0:55:20 > 0:55:24One of the remarkable things about this frog is that it has claws
0:55:24 > 0:55:28and most amphibians don't have claws. And these aren't claws like
0:55:28 > 0:55:31our toenails or fingernails and they're not like claws like you'd
0:55:31 > 0:55:35find on a bird, this is actually a claw that's made of naked bone.
0:55:35 > 0:55:40Unbelievably when it's threatened, this animal can force its own
0:55:40 > 0:55:43bones through its skin.
0:55:43 > 0:55:46Arming itself with a sharp claw on its toes.
0:55:46 > 0:55:52The animal is actually making its skeleton come through its skin.
0:55:52 > 0:55:54Which is a very weird thing.
0:55:54 > 0:55:56It's not like there's a natural hole through which these claws are
0:55:56 > 0:55:59piercing, it's that there's a complete piece of skin
0:55:59 > 0:56:02and the claw's actually puncturing through
0:56:02 > 0:56:05and actually causing a little traumatic wound on their toe tips.
0:56:05 > 0:56:09We still know very little about whether or not these wounds can heal.
0:56:09 > 0:56:11Those claws could sort of be retracted in a sense
0:56:11 > 0:56:13and be used again on another day.
0:56:13 > 0:56:16Because amphibians and some reptiles really have
0:56:16 > 0:56:18remarkable regenerative abilities.
0:56:18 > 0:56:23Wolverine frog really is a unique celebration of just how
0:56:23 > 0:56:26strange nature can be.
0:56:26 > 0:56:29So among the more than 6,200 species of frogs,
0:56:29 > 0:56:31of all those thousands of frogs,
0:56:31 > 0:56:34these are the only large hairy like frogs
0:56:34 > 0:56:37with bones that poke through their toes. They're the only
0:56:37 > 0:56:39one in the world that looks like that.
0:56:39 > 0:56:42But bizarrely, there are other amphibians who could be
0:56:42 > 0:56:45considered their partner in crime.
0:56:46 > 0:56:49These little beauties are Iberian newts
0:56:49 > 0:56:52and they're remarkable in that when they're attacked by predators
0:56:52 > 0:56:56they can push their ribs through their flesh out through their
0:56:56 > 0:57:01skin to produce two rows of spines which run the length of their body.
0:57:01 > 0:57:06Now, this sounds as if it would be very painful for the newt
0:57:06 > 0:57:10but in fact, it does it no harm at all and perhaps what's even
0:57:10 > 0:57:13more remarkable is as those ribs pass through the skin,
0:57:13 > 0:57:17they pass through some poisonous glands and I can feel them
0:57:17 > 0:57:18on the side of the body.
0:57:18 > 0:57:23So effectively, they end up with two rows of poison arrows.
0:57:23 > 0:57:27Now, of course, if you're a predator, that's pretty nasty
0:57:27 > 0:57:30but you've got to admit that it's also very, very clever.
0:57:32 > 0:57:34The weird and wonderful creatures
0:57:34 > 0:57:37in these stories have developed extraordinary
0:57:37 > 0:57:39powers to get what they want.
0:57:39 > 0:57:42Whether it's canines commuting to get a square meal,
0:57:42 > 0:57:48shape-shifting sea creatures, or highly armed amphibians.
0:57:48 > 0:57:52Nature has the never-ending ability to astound us.
0:57:53 > 0:57:59So whether it's bizarre adaptations or full scale invasions,
0:57:59 > 0:58:01nature survives against the odds.
0:58:01 > 0:58:05And often thrives in places where we would least expect it and
0:58:05 > 0:58:12when our paths cross, then it proves to be a truly unstoppable force.
0:58:14 > 0:58:17Next time on Nature's Weirdest Events.
0:58:17 > 0:58:21Freaky fish that walk - yes, walk - down the street...
0:58:21 > 0:58:22How weird is that!
0:58:22 > 0:58:26..terrifying trees that ooze blood
0:58:26 > 0:58:29and alien sounds from the sky.
0:58:31 > 0:58:33Me and Tom are hearing noises.
0:58:58 > 0:59:01Subtitles by Red Bee Media Ltd