:00:00. > :00:09.No matter how well we think we know our planet, the natural world still
:00:10. > :00:16.has the ability to surprise us, to shock us and to maybe sometimes even
:00:17. > :00:21.to scare us. With its extraordinary events and bizarre behaviour. New
:00:22. > :00:24.technology means that nature's weirdest phenomenon are being caught
:00:25. > :00:31.Evermore readily on camera. So we're going to bring you the strangest
:00:32. > :00:39.stories our world has to offer. I've never seen anything like that
:00:40. > :00:47.before. From bizarre body snatchers. And a butterfly blizzard. Do you see
:00:48. > :00:50.that, guys? With the help of scientists, experts and eyewitnesses
:00:51. > :01:16.we're going to try and unravel exactly what on earth is going on.
:01:17. > :01:25.So let's get cracking. First up, we reveal some astonishing super
:01:26. > :01:31.powers, specialist skills that help animals succeed in the toughest of
:01:32. > :01:34.environments. Our next group of extreme jet-setters proof when it
:01:35. > :01:44.comes to super powers, size isn't everything. In early October 2011
:01:45. > :01:50.the Denning family were hiking through woodland in central Mexico.
:01:51. > :01:54.When they became part of one of the most extraordinary events in the
:01:55. > :02:05.natural world. Look at them all. Do you see that, guys? Millions of
:02:06. > :02:18.butterflies. A vision in orange. Carpeting small stands of pines.
:02:19. > :02:28.This is awesome! They were at the centre of a butterfly blizzard.
:02:29. > :02:35.Butterflies in their millions that descend on certain areas of trees in
:02:36. > :02:47.Mexico and California like clockwork every year. Days before these trees
:02:48. > :02:54.would have been bare. So where have all of these swathes of better flies
:02:55. > :03:02.come from and why are they here? They can be found throughout the
:03:03. > :03:06.United States where ever their staple food, milkweed is flentyful.
:03:07. > :03:11.This food source can take them as far north as Canada. Which, when the
:03:12. > :03:20.seasons change, can be a brutal place for a butterfly. Richard Fox
:03:21. > :03:24.has spent years studying the intricacies of butterfly behaviour.
:03:25. > :03:27.Basically, it's too cold in the winter time across most of the
:03:28. > :03:34.United States and certainly in Canada for these butterflies to
:03:35. > :03:41.survive. They have to move or die. The monarchs are flying for their
:03:42. > :03:45.lives away from the cold north. But to reach these warm winter hideouts,
:03:46. > :03:55.well that's a seriously long-haul flight. These butterflies cover over
:03:56. > :04:02.2,000 miles. They fly for anything up to 10 weeks to reach these winter
:04:03. > :04:07.roosts. It's the kind of journey usually undertaken by birds or great
:04:08. > :04:15.herds of mammals. So how does a tiny insect manage it? Well, these are
:04:16. > :04:19.butterflies with super powers. We tend to think of butterflies as
:04:20. > :04:24.delicate creatures blown around by the wind. These monarchs are serious
:04:25. > :04:29.flying machines. They have the brain the side size of a pinhead, yet they
:04:30. > :04:33.can navigate across a continent. They can fly at high altitude.
:04:34. > :04:41.People have seen them from aeroplane windows. They are not flying blind.
:04:42. > :04:46.Monarchs come equipped with some serious inbuilt GPS. They have a
:04:47. > :04:57.time serious inbuilt GPS. They have a
:04:58. > :05:03.working out north and south. In their ant ten nigh, their feelers,
:05:04. > :05:10.they have a clock which enables them to take account for the passage of
:05:11. > :05:13.the sun across the sky -- antennae. As they travel south the millions of
:05:14. > :05:17.monarchs from all over the United States are funneled together by the
:05:18. > :05:25.Gulf coast and the rocky mountains. In a good year, it might be 150
:05:26. > :05:30.million monarchs. Rather than spread throughout the forest, they huddle
:05:31. > :05:38.close together, warmth in numbers against the cooler nights. But as
:05:39. > :05:41.the sunrises, and the day heats up, the butterflies leave the branches
:05:42. > :06:00.in an orange explosion. Not surprisingly, these winter
:06:01. > :06:04.roosts have become tourist hotspots. For the people that live in these
:06:05. > :06:13.special areas, the arrival of the monarchs is cause for celebration.
:06:14. > :06:21.Lowry is the director of the The museum of Natural History in Pacific
:06:22. > :06:35.Groove California. Also known as Butterfly Town, USA. Pacific Groove
:06:36. > :06:40.takes its monarchs very seriously. -- Crove. All the school children
:06:41. > :06:50.gather together to welcome the monarchs back to the town. The
:06:51. > :06:58.butterflies are the cultural icon of this town. Just how they find the
:06:59. > :07:04.exact spot that their family member travelled to the year before is
:07:05. > :07:12.still not fully understood. Nor is why they choose these particular
:07:13. > :07:16.stands of trees. When it comes to these extraordinary migrators, there
:07:17. > :07:27.are still more super powers left to be discovered. That monarch
:07:28. > :07:37.migration is truly remarkable. Did you know that you can witness a
:07:38. > :07:42.similar effort in the UK. Painted ladies end up in our gardens. We
:07:43. > :07:46.used to think they died here. Recently, however, we have spotted
:07:47. > :07:51.them flying back to Africa. When you take in all of the generations,
:07:52. > :07:59.that's a round trip of more than 9,000 miles. Not bad for an insect
:08:00. > :08:07.that weighs less than a gram. This next strange substance is unlikely
:08:08. > :08:12.to win any popularity contests. It there is a very sticky situation
:08:13. > :08:16.facing fishermen in the Atlantic. How do you get rid of all that
:08:17. > :08:25.slime? They are pulling up their nets and pods to find them covered
:08:26. > :08:35.in slime. Does it ruin... An ooze is clogging their nets and having to be
:08:36. > :08:40.bailed from boats. Oh. Armfuls of this colourless gloom is appearing
:08:41. > :08:48.any one catch. With often more slime than fish, removing it from a haul
:08:49. > :08:54.is an absolute nightmare. Now, it's too common a complaint to be
:08:55. > :08:59.attributed to some freak event or rare natural phenomenon. Something
:09:00. > :09:06.is creating enough of this substance to drive fishermen crazy. The
:09:07. > :09:17.question is - what? Well, the source of this mystery mucus can be found
:09:18. > :09:23.on the deep sea floor. The perpetrator is the hagfish. It's the
:09:24. > :09:35.undertaker of the deep, searching the murky bed for corpses. It uses a
:09:36. > :09:40.tongue to pull flesh from bone. It will even wriggle inside a rotting
:09:41. > :09:48.corpse to Dee row the soft flesh under the skin -- devour. Literally,
:09:49. > :09:53.eating the victim inside out. Nasty eating habits aside, the question
:09:54. > :10:01.remains - why would a creature that lives on the seabed need to produce
:10:02. > :10:05.slime? Well, aside from its willingness to eat sea floor scraps,
:10:06. > :10:11.the hagfish doesn't seem to have very much going for. It's pretty
:10:12. > :10:18.much blind, has no jaws or tough scales, it looks vulnerable. But, in
:10:19. > :10:24.fact, the hagfish really is quite a success story. It's been around for
:10:25. > :10:31.a whopping 300 million years, which makes it one of the oldest fishes in
:10:32. > :10:40.the sea. The secret to its success is slime. It's a defensive strategy
:10:41. > :10:49.so brilliant that it makes the hagfish quite literally,
:10:50. > :10:55.untouchable. Professor Doug Fudge studies these master slimers. So the
:10:56. > :11:00.hag fish is essentially covered with slime glands. The when an animal is
:11:01. > :11:04.attacked by a predator there is muscle in the area where it's
:11:05. > :11:09.touched that cause those slime glands to release their contents.
:11:10. > :11:12.There is actually a little mini volume cape be owe of slime that
:11:13. > :11:18.comes out of the gland. It's reinforced with tens of thousands of
:11:19. > :11:24.silk-like protein fibres we call slime treads. It mixes with sea
:11:25. > :11:29.water and forms this large volume of very unusual fibre reinforced slime.
:11:30. > :11:39.A single hagfish can turn a bucket of water into slime in seconds. That
:11:40. > :11:43.is so gross. It is proves to be a pretty fantastic under water weapon.
:11:44. > :11:47.In a recent study, that was published by a group in New Zealand,
:11:48. > :11:57.they showed hagfish using their slime in a wild situation. The mucus
:11:58. > :12:04.is designed to choke a predator by clogging up its airways much the
:12:05. > :12:12.shark is left gagging as its gills fill with mucus. Every assayant is
:12:13. > :12:23.repulsed by a wall of slime. Is -- assailant. The technique is
:12:24. > :12:28.effective that thehag fish is unpreterribled. How does the hagfish
:12:29. > :12:36.prevent itself from becoming the victim of its own slimy strategy?
:12:37. > :12:41.They have a way of getting out of the slime. They will tie their body
:12:42. > :12:46.in a knot and then they'll pass their body through the knot and that
:12:47. > :12:59.will wipe the slime off of their body. A necessary skill for the
:13:00. > :13:07.ocean's most slippery character. Now, you may not like this, but
:13:08. > :13:17.humans produce slime too. In the form of snot. What's remarkable is
:13:18. > :13:24.that hagflush slimed and human snot are composed of similar proteins. --
:13:25. > :13:27.hagfish. Humans use their snot to trap harmful substances and expel
:13:28. > :13:34.them from the body. When you think about it, hag fish and humans are
:13:35. > :13:39.using slime as a frontline defence. These animals have proved that in
:13:40. > :13:46.the natural world, it pays to be a master craftsman. Whether you are a
:13:47. > :13:54.silk spinner, escaping the rising tide, a slime producer, defending
:13:55. > :14:06.yourself from attack, or a sand sculptor, looking for love. A super
:14:07. > :14:11.structure is crucial to success. So a specialist skill with help an
:14:12. > :14:17.animal get ahead. What if you can't survive on your own? Rather than
:14:18. > :14:26.admit defeat, this next selection of weirdness shows enlisting some help
:14:27. > :14:32.can hold the key. There is a strange subterranean structure created by
:14:33. > :14:38.remarkable team work. But first a chilling tale of some real-life
:14:39. > :14:42.zombies. Eric Williams from Delaware was mopping his kitchen floor when a
:14:43. > :14:56.dead beetle began to mutate in front of his eyes. From its body something
:14:57. > :15:01.long and worm-like was emerging. Eric wasn't the only one to witness
:15:02. > :15:06.this miniature horror. No idea what those things are. I see all these
:15:07. > :15:12.strange hairs moving around. What do you think that is? It's a cockroach.
:15:13. > :15:17.Look at the stringy bit coming out of it. All the records had one thing
:15:18. > :15:22.in come, a mopped floor or nearby puddle, the presence of water was
:15:23. > :15:28.triggering these writhing worms. That's disgusting. But what were
:15:29. > :15:35.they and how had they got into the bodies of these insects?
:15:36. > :15:43.Biologist Janice Moore has spent a lifetime fascinated by this
:15:44. > :15:50.particular weird event. Whenever I was a child I'd used to see these
:15:51. > :15:54.long worms squiggle in around at my grandfather's. I was told they were
:15:55. > :16:01.horsehair worms and that is a common name because legend says that these
:16:02. > :16:10.worms come from horsehair. In reality, they are parasites. These
:16:11. > :16:14.parasites live inside say the cricket and grow up to be huge
:16:15. > :16:21.compared to the cricket, all called up. The cricket is almost total
:16:22. > :16:31.parasite. The hare worm lover develops inside the body but it has
:16:32. > :16:41.to breed and to do that it has to find water. -- the hare worm lava.
:16:42. > :16:49.It has no qualms about making the lava do all of the legwork. The
:16:50. > :16:56.cricket becomes almost suicidally attracted to water and they have
:16:57. > :17:00.been reported to jump into toilets, into dog water bowls. And if the
:17:01. > :17:06.hairworm is big enough, the merest hint of moisture could be enough to
:17:07. > :17:11.tempt it out. I have never seen anything like that before. Keep an
:17:12. > :17:16.eye out for these miniature body snatchers because they are found
:17:17. > :17:21.here in the UK as well. In fact, in every corner of the globe, super
:17:22. > :17:28.sneaky parasite species have found ways to get the others to do the
:17:29. > :17:37.hard work for them. For example, the mind control that lurks in German
:17:38. > :17:44.gardens. There is a parasite which lives inside the intestinal tract of
:17:45. > :17:48.a variety of songbirds. The parasitic flatworm reaches materia
:17:49. > :17:52.tea inside the digestive system of the bird and casts out its eggs in
:17:53. > :17:59.the bird's droppings. This would be the end of the cycle if it were not
:18:00. > :18:04.for the garden snail that finds bird droppings irresistible. When the
:18:05. > :18:14.these eggs, the egg hatches and a little larval parasite, a flatworm,
:18:15. > :18:19.moves in and there it grows up into a striped Mass. The snail's tentacle
:18:20. > :18:24.is now one enormous a striped Mass. The snail's tentacle
:18:25. > :18:30.flatworm brood sack. But a striped Mass. The snail's tentacle
:18:31. > :18:33.parasitic mastermind encounters a problem. Just like the hairworm
:18:34. > :18:38.cannot breed inside the snail. Delay problem. Just like the hairworm
:18:39. > :18:45.its eggs it has to be once again inside a bird's intestinal tract.
:18:46. > :18:51.How does the flatworm complete the cycle? Mind control. It forces the
:18:52. > :19:00.usually reclusive snail upward towards the light. Once exposed, the
:19:01. > :19:05.snail's tentacle is a pulsates in Grub on a plate. Birds will look at
:19:06. > :19:13.snail's tentacle is a pulsates in they will eat it. And in that way
:19:14. > :19:17.the life cycle is complete. Now, the poor snail is
:19:18. > :19:20.the life cycle is complete. Now, the might just get out alive minus
:19:21. > :19:27.tentacle. But other hosts are not so lucky. Our next parasite requires
:19:28. > :19:34.its host to make the ultimate sacrifice. So one of the most
:19:35. > :19:40.spectacular examples of zombie behaviour is and is infected with
:19:41. > :19:44.fungus. If you're battling for space in the rainforest, hitching a ride
:19:45. > :19:52.on the back of an angled would seem to be a clever tactic. -- the back
:19:53. > :19:59.of an ant. It is not clever enough for the type of fungus. The fungus
:20:00. > :20:04.enters the body through the and's windpipe, where it begins to extract
:20:05. > :20:09.nutrients from all but its major organs. As the fungus grows, it eats
:20:10. > :20:17.the ant alive, while leaving it with just enough of its faculties to
:20:18. > :20:26.move. The reason why it does this is brilliantly devious. To cast
:20:27. > :20:30.spores, the fungus needs to be high, so it floods the and's brain with
:20:31. > :20:37.chemicals, forcing it on an upward march. Having reached an optimum
:20:38. > :20:46.height, the ant has served its purpose and called to set devours
:20:47. > :20:50.its brain, before with a final flourish it bursts through the
:20:51. > :20:55.exoskeleton and casts spores into the air. Does a wonderful story if
:20:56. > :21:01.you happen to be reading about it and a really nasty story if you an
:21:02. > :21:05.ant. One of my favourite types of body
:21:06. > :21:14.snatchers actually lives in UK waters. The larvae of a tapeworm in
:21:15. > :21:20.his boots the stickleback. -- inhibits the stickleback.
:21:21. > :21:26.It does not leap out of the mouth of a stickleback into the mouth of a
:21:27. > :21:32.passing bird. It modifies the behaviour causing it to flip over
:21:33. > :21:35.onto its back revealing its bright white belly making it far more
:21:36. > :21:41.obvious to predators like herons. I know it is a sad end for the old
:21:42. > :21:45.stickleback, but you have to admit when it comes to parasites, mind
:21:46. > :21:51.control is a fiendishly effective survival technique.
:21:52. > :21:57.Bending the will of others for your own game is not the most altruistic
:21:58. > :22:00.of survival methods. Thankfully, our next story shows what can be
:22:01. > :22:08.achieved if you choose to work together. In May 2004, a group of
:22:09. > :22:12.scientists gathered in South America, at a very particular spot
:22:13. > :22:21.in rural Brazil. They took up tools and began to dig. Over the next few
:22:22. > :22:28.days, they painstakingly excavated the area. And from the soil,
:22:29. > :22:42.something incredible began to emerge. They uncovered a vast
:22:43. > :22:46.network. Some 50 metres squared. An architectural maze of different
:22:47. > :22:53.shapes and structures, branching out into the ground. This subterranean
:22:54. > :23:02.design was precise and too complex to be created by chance. It had been
:23:03. > :23:04.engineered. But by what? What could have created this underground
:23:05. > :23:17.architecture? What the scientists had uncovered
:23:18. > :23:27.was a secret city. A giant home created for some of the smallest
:23:28. > :23:34.animals on the planet. Ants. And for and biologists like Ross Kirby, this
:23:35. > :23:37.experiment brought Deary to life. This is the first time that we can
:23:38. > :23:51.literally see the bare-bones of what they have built. We poured cement
:23:52. > :23:55.into the empty nest of leafcutter ants. Once the cement had set we
:23:56. > :24:02.could reveal the underground metropolis. This was not your
:24:03. > :24:08.average and nest. This was an entire and city, going as deep as eight
:24:09. > :24:13.metres into the ground. And masterminded by a population of up
:24:14. > :24:21.to 7 million leafcutter ants. But why does an ant need such an
:24:22. > :24:26.impressively conduct home? There are chambers which are important where
:24:27. > :24:29.the eggs develop. There are waste disposal chambers. There are also
:24:30. > :24:34.many different tunnels, not just to take the ants from chamber to
:24:35. > :24:39.chamber, but to allow air to be completely circulated throughout the
:24:40. > :24:43.nest. And used pheromones to organise construction work and to
:24:44. > :24:47.guide them from foraging sites. These chemical trails help them to
:24:48. > :24:54.work efficiently and stop them from getting lost. They ensure a steady
:24:55. > :25:01.steam of -- stream of grass into the nest. But it is not to eat. The
:25:02. > :25:05.ands cannot digestive grass. They use the blade to feed a fungus,
:25:06. > :25:16.cultivated in special garden chambers. This fungus is the ant's
:25:17. > :25:22.preferred main meal. That is a lot of fungus farming. A nest needs to
:25:23. > :25:28.be this size to support such a large colony. But it is almost
:25:29. > :25:31.inconceivable that something as small and simple as an ant could
:25:32. > :25:38.have created such an amazing structure. When looking at an entire
:25:39. > :25:42.ant colony, you should not be looking at it as 7 million
:25:43. > :25:48.individuals, you should look at it is one great collective unit. A
:25:49. > :25:53.single ant by itself is not up to much. When you have 7 million of
:25:54. > :25:58.them interacting together, their behaviour can be quite complex. All
:25:59. > :26:04.of these ants working together for the good of the whole colony,
:26:05. > :26:13.transform from individuals into a single living being. A super
:26:14. > :26:18.organism. One brain, 7 million ants strong. It is this organisation that
:26:19. > :26:24.makes one of the smallest animals capable of such incredible
:26:25. > :26:32.engineering. So clearly, being part of a super
:26:33. > :26:38.organism is beneficial. But a group mentality can also have its
:26:39. > :26:43.drawbacks. One woman travelling through Peru in
:26:44. > :26:53.2008 came across some ants behaving strangely. They were spinning round
:26:54. > :26:59.and around in a constant circle. One by one they began to collapse and
:27:00. > :27:03.die. She was not the only person to witness these peculiar death
:27:04. > :27:13.circles. Why were they on self-destruct? It is most likely
:27:14. > :27:16.that these ants were out foraging when they got separated from the
:27:17. > :27:21.rest of their party. With the pheromone trail lost, they began to
:27:22. > :27:25.panic and follow each other's pheromones. This confused game
:27:26. > :27:31.follow my leader forced them into a never-ending circle. And because
:27:32. > :27:37.ants are not programmed to think like individuals, they did not save
:27:38. > :27:44.themselves. Instead, the circle became tighter and faster until the
:27:45. > :27:48.ants simply died of exhaustion. Thankfully, these ant death circles
:27:49. > :27:51.are relatively rare events, clearly proving that the benefits of
:27:52. > :27:58.teamwork must outweigh the potential for disaster. Ants are not the only
:27:59. > :28:05.organisms which forms super organisms. Take bees, for example.
:28:06. > :28:10.For high to be successful, thousands of bee brains must work together.
:28:11. > :28:14.The benefits are security, bed and board. When it comes to super
:28:15. > :28:19.organisms, great minds must think alike.
:28:20. > :28:25.These stories show the importance of a listing some help. Whether it is a
:28:26. > :28:31.devious parasite control and a host against its will or an ant colony
:28:32. > :28:37.combining forces to build a subterranean met the Acropolis --
:28:38. > :28:40.mega droplets. Two brains or seven if you can manage it, are better
:28:41. > :28:46.than one. So there we are, we have delved into
:28:47. > :28:50.a catalogue of the most fun, the most foul, the most morbid and
:28:51. > :28:54.marvellous stories our planet has two offer. Whether it has been
:28:55. > :28:59.bizarre animal behaviour or weird natural phenomena, it has had the
:29:00. > :29:04.very best of our brains completely baffled. But then given the natural
:29:05. > :29:06.world's ability to astound, it leaves us with one final and
:29:07. > :29:29.inevitable question, what next? MUSIC: Boombastic
:29:30. > :29:31.by Shaggy