0:00:10 > 0:00:14Let's face it - our world is downright weird.
0:00:14 > 0:00:17Aaaaaah!
0:00:17 > 0:00:21Crawling with creatures you've never heard of.
0:00:21 > 0:00:23I can't believe that's a living thing.
0:00:23 > 0:00:26Full of the unexpected,
0:00:26 > 0:00:31like freak weather exploding out of the blue.
0:00:31 > 0:00:33I thought I was going to die.
0:00:33 > 0:00:36And rocks that spontaneously combust.
0:00:36 > 0:00:38I thought it was dynamite going off.
0:00:38 > 0:00:41And the unexplained.
0:00:42 > 0:00:44An unborn twin...
0:00:44 > 0:00:46discovered inside a brain.
0:00:46 > 0:00:50There was multiple hair follicles, bone and teeth.
0:00:54 > 0:00:58We scoured the globe to bring you the very weirdest stories.
0:00:58 > 0:00:59Yeaaaahhhhhhh!
0:00:59 > 0:01:01Ha-ha-ha-ha-ha!
0:01:01 > 0:01:03I could feel this intense pain,
0:01:03 > 0:01:07as if you were being stabbed by hundreds of syringes.
0:01:12 > 0:01:15In this series, we're going to examine the evidence,
0:01:15 > 0:01:19test the science and unravel the mysteries.
0:01:19 > 0:01:24We're going to discover what in the weird world is going on.
0:01:36 > 0:01:39In this episode, we'll uncover the mysteries
0:01:39 > 0:01:42behind some of the natural world's strangest stories.
0:01:45 > 0:01:48What could have caused this shadow in the sea?
0:01:48 > 0:01:53Immediately, we thought it was an oil slick. What else could it have been?
0:01:53 > 0:01:57And what is making this lemming so angry?
0:01:58 > 0:02:03How could a shoal of fish almost cause an international incident?
0:02:03 > 0:02:07And how can a man see with his ears?
0:02:07 > 0:02:13I am a man who uses the techniques of a bat to navigate.
0:02:27 > 0:02:32Out here in the desert, people often report seeing mysterious things -
0:02:32 > 0:02:36mirages, strange lights in the sky, UFOs.
0:02:36 > 0:02:38But it does seem wherever we are,
0:02:38 > 0:02:42our surroundings are capable of playing tricks on us.
0:02:45 > 0:02:50July 8th, 2014 - La Jolla, California.
0:02:50 > 0:02:53So it was a stereotypical sunny San Diego kind of day -
0:02:53 > 0:02:56the sun was out, the water was clear,
0:02:56 > 0:03:00tourists everywhere enjoying the beautiful weather we normally have.
0:03:05 > 0:03:08But all was not well in paradise.
0:03:08 > 0:03:12There was just something really unusual going on.
0:03:12 > 0:03:15We looked out and saw this black blob in the water.
0:03:15 > 0:03:21A huge, oily black mass had appeared along the coast,
0:03:21 > 0:03:23stretching for miles up the beach.
0:03:25 > 0:03:28I left my office and ran towards the pier
0:03:28 > 0:03:30so I could see first-hand what was going on.
0:03:31 > 0:03:35Immediately, we thought it was an oil slick. What else could it have been?
0:03:38 > 0:03:43This wouldn't be the first time that an oil slick has hit California.
0:03:43 > 0:03:46Just off the coast, there are some really rich wells
0:03:46 > 0:03:50so oil's been washing up on the beaches since the 1950s.
0:03:51 > 0:03:54But from above, there was something very fishy
0:03:54 > 0:03:56about this particular oil slick.
0:03:58 > 0:04:04It looked like oil, but it wasn't behaving like oil.
0:04:04 > 0:04:07We didn't see any oil residue on the sand,
0:04:07 > 0:04:09which, for that big an amount of black,
0:04:09 > 0:04:13we definitely should have seen oil on our surface.
0:04:14 > 0:04:18Even stranger, it seemed that the oily blob
0:04:18 > 0:04:19was actually being repelled away
0:04:19 > 0:04:22from people and animals in the ocean.
0:04:25 > 0:04:28So what exactly was this suspicious slick
0:04:28 > 0:04:30and why wasn't it washing ashore?
0:04:32 > 0:04:36From the pier, the truth suddenly became clear.
0:04:38 > 0:04:40Once we were able to look down, we realised,
0:04:40 > 0:04:43"Oh, my gosh, this is just a huge school of fish!"
0:04:45 > 0:04:50Amazingly, the giant black mass in the ocean wasn't oil.
0:04:50 > 0:04:55The coastline had been invaded by an immense silvery shoal of fish.
0:04:59 > 0:05:03From below the waves, it was clear what had swamped the shoreline.
0:05:04 > 0:05:08Anchovies - perhaps as many as 100 million of them.
0:05:08 > 0:05:11It was quite phenomenal.
0:05:11 > 0:05:13I've seen pictures of schools like this,
0:05:13 > 0:05:15but I've never got in the water with them.
0:05:21 > 0:05:26It was like diving into a large dark blob
0:05:26 > 0:05:30and having it separate as you went inside of it and create a cavity.
0:05:30 > 0:05:32It had a life of its own, you might say.
0:05:32 > 0:05:38For a shoal of this size to be so close to shore was truly strange.
0:05:39 > 0:05:42I've never seen anything like this before in the 30 odd years
0:05:42 > 0:05:44that I've been in this area.
0:05:44 > 0:05:47We don't know exactly why the anchovies were here,
0:05:47 > 0:05:51but anchovies tend to school in order to avoid predators.
0:05:54 > 0:05:58Anchovies are part of a group of fish called obligate shoalers
0:05:58 > 0:06:02that live almost exclusively in deep waters.
0:06:02 > 0:06:06However, a large group of predators could have forced them inshore.
0:06:07 > 0:06:11But with all the swimmers in the water, this seemed unlikely.
0:06:14 > 0:06:17And it was about to get weirder
0:06:17 > 0:06:22because it wasn't just fish that were being driven inshore.
0:06:25 > 0:06:28Look at these guys! Just absolutely crazy.
0:06:29 > 0:06:31Just a short distance down the coast,
0:06:31 > 0:06:35the surf turned to an eerie red.
0:06:35 > 0:06:40Not with blood, but with a plague of red tuna crabs.
0:06:40 > 0:06:45The whole beach is covered with them.
0:06:45 > 0:06:50Hundreds of thousands of tiny red crustaceans carpeted the beaches,
0:06:50 > 0:06:56littering the landscape with stinking piles of seafood.
0:06:56 > 0:06:58And this wasn't the only stranding.
0:06:59 > 0:07:03All across the state, abandoned sea lion pups were washing up
0:07:03 > 0:07:08in unexpected places and one scientist thinks she knows why.
0:07:08 > 0:07:10Something really weird is happening
0:07:10 > 0:07:12off the coast of California at the moment.
0:07:14 > 0:07:17So we've detected this anomaly out in the ocean
0:07:17 > 0:07:18and we've called it The Blob.
0:07:20 > 0:07:25It's enormous, thousands of miles across, hundreds of metres deep
0:07:25 > 0:07:27and we think it's getting better.
0:07:27 > 0:07:32What scientists had discovered was an immense blob
0:07:32 > 0:07:36of abnormally warm water, squatting off the Californian coast.
0:07:36 > 0:07:41It was so large that it could be detected by satellites in space.
0:07:41 > 0:07:45It's water that's about four degrees Celsius warmer than it should be.
0:07:45 > 0:07:49It began off the coast of California and it's moved inland,
0:07:49 > 0:07:52it's invaded the beaches all along the coast.
0:07:52 > 0:07:56Now, a bit of warm water might not seem like much of a big deal,
0:07:56 > 0:08:00but many marine animals are highly sensitive
0:08:00 > 0:08:03to alterations in their environment
0:08:03 > 0:08:07and four degrees warmer is a big shift.
0:08:07 > 0:08:10By changing the temperature of the water beyond what it should be
0:08:10 > 0:08:14at this time of year, it's shifting the whole food web in the oceans.
0:08:14 > 0:08:19This shift has forced many of the local species to find new homes.
0:08:19 > 0:08:22Tuna crabs venturing too close to the shore,
0:08:22 > 0:08:27sea lions pushed further out to hunt, leaving their pups to starve
0:08:27 > 0:08:31and anchovies searching for cooler waters,
0:08:31 > 0:08:34swarming along the shoreline,
0:08:34 > 0:08:38all down to an oceanic abnormality.
0:08:38 > 0:08:40It's still a really big mystery as to what is causing The Blob
0:08:40 > 0:08:43and why we've got this huge area of warm water off the coast
0:08:43 > 0:08:45and scientists are trying to figure it out.
0:08:47 > 0:08:51And while the mystery remains unsolved, it's a safe bet
0:08:51 > 0:08:55that the residents of La Jolla Beach can expect to see
0:08:55 > 0:08:58more weirdness in the waves sometime soon.
0:09:03 > 0:09:07So it appears that a giant shoal of anchovies
0:09:07 > 0:09:10can masquerade as an oil spill. Who'd have thought it?
0:09:10 > 0:09:12But then, what other weirdness
0:09:12 > 0:09:15might result from an aquatic case of mistaken identity?
0:09:16 > 0:09:20How about...a military fallout between countries?
0:09:22 > 0:09:25In the 1980s,
0:09:25 > 0:09:28strange things were happening in the waters around Sweden.
0:09:32 > 0:09:37Nato and the USSR were still locked in the Cold War.
0:09:39 > 0:09:43And Sweden was caught in the middle,
0:09:43 > 0:09:45right next to the Iron Curtain.
0:09:46 > 0:09:49Soviet submarines were on patrol.
0:09:50 > 0:09:53It was a very, very tense situation.
0:09:55 > 0:09:57Everyone was terrified
0:09:57 > 0:10:01because we thought we were being occupied by the Soviet Union.
0:10:01 > 0:10:03Throughout the '80s,
0:10:03 > 0:10:07Soviet subs were reported regularly off the coast of Sweden,
0:10:07 > 0:10:11so the Swedes set out to trap them.
0:10:11 > 0:10:14They started monitoring their coastline
0:10:14 > 0:10:16with underwater microphones.
0:10:22 > 0:10:26The navy drew up a list of signs and sounds
0:10:26 > 0:10:29that might indicate stealthy submarine activity.
0:10:31 > 0:10:34When you listen underwater, it's a whole new world.
0:10:34 > 0:10:36You hear all kinds of things.
0:10:37 > 0:10:39They could hear engine noise, for example,
0:10:39 > 0:10:44boat engine noise or they could hear Russian submarines.
0:10:45 > 0:10:48One of the sounds the navy typically detected
0:10:48 > 0:10:51that indicated a Russian submarine,
0:10:51 > 0:10:54they called, imaginatively, "the typical sound".
0:10:54 > 0:10:59CLICKING AND WHIRRING
0:10:59 > 0:11:02Although civilians weren't allowed to hear it.
0:11:02 > 0:11:05Everyone sort of knew that the typical sound
0:11:05 > 0:11:07was the sound of a Russian submarine.
0:11:07 > 0:11:10We could never hear this sound because it was classified,
0:11:10 > 0:11:11but we all heard about it.
0:11:19 > 0:11:22But when the Cold War finally ended,
0:11:22 > 0:11:25something really weird started to happen.
0:11:26 > 0:11:29The Swedish thought that they could
0:11:29 > 0:11:33still hear Russian submarines in their waters.
0:11:34 > 0:11:37The Swedish navy still consistently reported,
0:11:37 > 0:11:39"We are still intruded by Russian submarines.
0:11:39 > 0:11:41"We hear the typical sound all the time."
0:11:41 > 0:11:46But the Russians claimed they hadn't sent any subs.
0:11:47 > 0:11:50So, were the Russians actually telling the truth?
0:11:50 > 0:11:52And, if they were,
0:11:52 > 0:11:55what was the typical sound that the navy was listening to?
0:11:55 > 0:11:59Clearly the Swedish authorities needed to get to the bottom
0:11:59 > 0:12:02of this marine mystery before it was too late.
0:12:04 > 0:12:07So the Swedes called in acoustic experts like Magnus
0:12:07 > 0:12:10to try and identify the typical sound
0:12:10 > 0:12:13and help defuse the situation.
0:12:13 > 0:12:16This is when we were actually able to hear the sound for the first time
0:12:16 > 0:12:18and we were then the first civilian people
0:12:18 > 0:12:20ever to hear the typical sound.
0:12:23 > 0:12:25Then they played this sound for us
0:12:25 > 0:12:28and we were all sitting quiet in this room, listening carefully.
0:12:28 > 0:12:30HISSING AND POPPING
0:12:30 > 0:12:32It sounded like someone frying bacon.
0:12:36 > 0:12:39And I was like, "When are you going to play the sound?"
0:12:39 > 0:12:40And they were like, "Well, we just did."
0:12:40 > 0:12:43HISSING AND POPPING CONTINUES
0:12:48 > 0:12:51That's an underwhelmingly odd noise.
0:12:52 > 0:12:55I suppose it just about qualifies as a mysterious sound.
0:12:55 > 0:12:59Maybe the Russians had a penchant for undersea stir-fry.
0:12:59 > 0:13:02Or could it be a red herring?
0:13:02 > 0:13:08Weirdly, that's exactly what Magnus thought it was.
0:13:12 > 0:13:17It didn't sound like a submarine at all and he could prove it.
0:13:19 > 0:13:22We recorded this sound and it sounded exactly like this typical sound
0:13:22 > 0:13:25so we sent it back to them and they told us,
0:13:25 > 0:13:28"That's very interesting, where did you get that from?"
0:13:28 > 0:13:31"It's from a herring."
0:13:31 > 0:13:35He used a herring to make the typical sound.
0:13:35 > 0:13:37But how could the noise that a herring makes
0:13:37 > 0:13:42possibly be mistaken for the sound of a Russian submarine?
0:13:42 > 0:13:45Well, probably not how you think.
0:13:46 > 0:13:49There's only one way to produce the typical sound
0:13:49 > 0:13:50and that is to squeeze a herring.
0:13:52 > 0:13:55Yes, that's right, you heard him - squeeze a herring.
0:13:57 > 0:14:01So, herring is a very interesting fish. It has a swim bladder.
0:14:01 > 0:14:04The herring will pump in air into the swim bladder to sort of keep afloat,
0:14:04 > 0:14:07but the funny thing with the herring is that has a canal
0:14:07 > 0:14:10from the swim bladder and out to the anal opening.
0:14:10 > 0:14:13See where this is going yet?
0:14:13 > 0:14:15So they can sort of...fart, if you want.
0:14:17 > 0:14:22And each time they release these bubbles, that will cause sound.
0:14:22 > 0:14:27And although one flatulent fish couldn't cause a crisis,
0:14:27 > 0:14:30a whole farting school could.
0:14:31 > 0:14:34So you can have millions and millions of herring,
0:14:34 > 0:14:37one school could be like several square miles.
0:14:37 > 0:14:40I have seen it sometimes when you're out sailing
0:14:40 > 0:14:44and you can have hundreds of metres covered with just bubbles everywhere.
0:14:44 > 0:14:47You have this cacophony of farts coming
0:14:47 > 0:14:52and you will hear, like, a roar of farts coming
0:14:52 > 0:14:55and it can actually sound quite impressive.
0:14:57 > 0:15:00Impressive indeed! In fact, I wish I'd heard it myself.
0:15:00 > 0:15:02But why on earth would the navy think
0:15:02 > 0:15:05that it was the sound of a submarine?
0:15:05 > 0:15:10Well, the answer lies in the reason why herring make the bubbles.
0:15:11 > 0:15:15They use this as what we call an anti-predator defence,
0:15:15 > 0:15:18so if you have a killer whale or a dolphin chasing a herring school,
0:15:18 > 0:15:22they can release a lot of air and a dolphin is like,
0:15:22 > 0:15:25"Hey, where did the herring go? I can just see bubbles now."
0:15:25 > 0:15:31And to a school of herring, an underwater sub can be just as scary.
0:15:31 > 0:15:34During the Cold War, Russian subs had been cruising past
0:15:34 > 0:15:39schools of herring and causing them to panic,
0:15:39 > 0:15:41causing them to make the typical sound.
0:15:42 > 0:15:45If one of those guys enters a herring school,
0:15:45 > 0:15:47they will probably scare off the herring
0:15:47 > 0:15:49and you will hear a lot of those sounds.
0:15:51 > 0:15:53And after the Cold War ended,
0:15:53 > 0:15:57the herring continue to make these panic sounds,
0:15:57 > 0:16:00but this time, they were scared by predators.
0:16:00 > 0:16:04Or, embarrassingly, by Sweden's own submarines.
0:16:06 > 0:16:09If you think about this guy moving through the water,
0:16:09 > 0:16:11all the herring will be scared
0:16:11 > 0:16:13and probably release all these bubbles
0:16:13 > 0:16:16and the sonar operator inside here, he will be like,
0:16:16 > 0:16:19"I can hear the Soviet submarines just next to us."
0:16:21 > 0:16:24So instead of tracking Russian submarines,
0:16:24 > 0:16:27the Swedish navy had instead been eavesdropping
0:16:27 > 0:16:30on the anal alarm calls of Baltic herring.
0:16:31 > 0:16:35Now, that's an embarrassing incident for all concerned.
0:16:42 > 0:16:44So, misidentifying a shoal of herring
0:16:44 > 0:16:48nearly caused an international incident, which is a bit worrying.
0:16:48 > 0:16:51But then, sometimes, if you mistake the identity
0:16:51 > 0:16:54of another species of animal, you can end up in a world of pain.
0:16:57 > 0:17:01Take a look at this weird video that surfaced online.
0:17:02 > 0:17:04It shows something very strange.
0:17:06 > 0:17:10It's a cat being attacked by a lemming.
0:17:10 > 0:17:13But hold on, shouldn't that be the other way round?
0:17:16 > 0:17:20Lemmings, like most rodents,
0:17:20 > 0:17:24have a reputation for being timid, fearful creatures.
0:17:26 > 0:17:29Top of the menu for a host of predators.
0:17:31 > 0:17:35So, most lemmings have the sense to hide from everything.
0:17:38 > 0:17:40So, just what was going on here?
0:17:40 > 0:17:46Why was this lemming behaving so out of character?
0:17:46 > 0:17:48Weirdly, zoologist Nick Crumpton
0:17:48 > 0:17:51doesn't think it's acting out of character at all.
0:17:51 > 0:17:56Ha! Wow, that is very, very brave.
0:17:58 > 0:18:01He thinks the clue to this weird behaviour
0:18:01 > 0:18:03lies in the lemming's appearance.
0:18:03 > 0:18:06Usually, small mammals are quite dull.
0:18:06 > 0:18:08They are brown or grey and that's what the American,
0:18:08 > 0:18:10the common lemmings, look like.
0:18:12 > 0:18:17But the lemming in this video is brightly coloured and stripy,
0:18:17 > 0:18:21and that tells Nick that it isn't a common lemming.
0:18:21 > 0:18:23This is its Norwegian cousin.
0:18:25 > 0:18:29Those black lines and those very light colourations
0:18:29 > 0:18:32on the Norwegian lemming's coat tells us something interesting.
0:18:32 > 0:18:36It says that, rather than hiding from their predators,
0:18:36 > 0:18:38they are actually advertising themselves.
0:18:38 > 0:18:39They are very clear to see,
0:18:39 > 0:18:41especially when the ground is covered in snow.
0:18:45 > 0:18:47It's something we see a lot in nature,
0:18:47 > 0:18:50bright colours being used to warn off predators,
0:18:50 > 0:18:52and it's known as aposematic colouration.
0:18:54 > 0:18:58You see it in insects when they advertise their stings and bites.
0:18:58 > 0:19:02In amphibians, warning of their toxic skin.
0:19:02 > 0:19:06Even in other mammals, like stinky skunks.
0:19:07 > 0:19:11And the fact that this lemming is so brightly coloured
0:19:11 > 0:19:13tells you something about its temperament.
0:19:15 > 0:19:18Norwegian lemmings are different to other lemmings
0:19:18 > 0:19:22and other voles in that they are very, very aggressive.
0:19:22 > 0:19:23LEMMING SNARLS ANGRILY
0:19:23 > 0:19:26Like the Vikings, these Nordic inhabitants
0:19:26 > 0:19:28are bloodthirsty, hairy berserkers.
0:19:33 > 0:19:38Norwegian lemmings have been known to kill weasels and fight off skuas.
0:19:38 > 0:19:43In fact, the Norwegian lemming will take on perceived predators
0:19:43 > 0:19:47of almost any size, including us.
0:19:48 > 0:19:53It looks like this cat picked on the wrong type of lemming.
0:19:53 > 0:19:55Yeah, my money is on the lemming.
0:20:00 > 0:20:05From fishy oil slicks to flatulent herring,
0:20:05 > 0:20:08the world is a weird place.
0:20:08 > 0:20:13But, whatever you do, don't pick a fight with the wrong lemming!
0:20:29 > 0:20:34Right, next up, we go from some oddly aligned animals
0:20:34 > 0:20:39to some truly astonishing supersonic sensory abilities.
0:20:39 > 0:20:42So, let's start with some cows.
0:20:42 > 0:20:44Yeah, cows.
0:20:47 > 0:20:51Not an animal normally associated with the weird.
0:20:54 > 0:20:57I mean, they're a bit odd looking, but they're not that strange.
0:20:58 > 0:21:03So, why, in 2008, were a bunch of scientists really, really excited
0:21:03 > 0:21:09about a group of - and I really shouldn't say this - boring bovines?
0:21:09 > 0:21:13Well, just like so many good, weird mysteries,
0:21:13 > 0:21:17this one started up with some really grainy satellite images.
0:21:17 > 0:21:20And they showed something rather odd.
0:21:22 > 0:21:26All the cows in a field were facing exactly the same way.
0:21:27 > 0:21:29And not just in one paddock.
0:21:32 > 0:21:36We looked for pastures all over the world, in all continents
0:21:36 > 0:21:40and we randomly selected more than 300 pastures.
0:21:43 > 0:21:45So we used satellite images
0:21:45 > 0:21:50and, yeah, found a strong preference for the north-south direction.
0:21:51 > 0:21:56Sabine and her team had discovered a bizarre bovine pattern
0:21:56 > 0:21:58stretching across the globe.
0:22:01 > 0:22:03So, what was going on here?
0:22:03 > 0:22:07Why would hundreds of herds of heifers all prefer
0:22:07 > 0:22:10to face in exactly same direction?
0:22:12 > 0:22:17It might be the ancestors of the cattle migrated long distances
0:22:17 > 0:22:21and that is still in the cattle and another hypothesis
0:22:21 > 0:22:26is that cattle use it as a common escape direction
0:22:26 > 0:22:30so if a predator is approaching, it would be a mess
0:22:30 > 0:22:35if all the cattle are lying in random order and crash into each other.
0:22:37 > 0:22:42But how were they doing it? Sabine wasn't sure.
0:22:44 > 0:22:48Some animals navigate using the sun or the stars
0:22:48 > 0:22:54and a few can even use their sense of smell to home, but cows -
0:22:54 > 0:22:57they're not known for their keen eyesight
0:22:57 > 0:22:59or known for their sense of smell.
0:22:59 > 0:23:01Sabine was stumped.
0:23:05 > 0:23:08That was until she stumbled upon another clue in the images.
0:23:08 > 0:23:15Under high-voltage power lines, the cattle are in random order
0:23:15 > 0:23:18so they are not aligned in the north-south direction,
0:23:18 > 0:23:22but their body orientation is in all directions.
0:23:25 > 0:23:29So the power lines were throwing out the cows' alignment,
0:23:29 > 0:23:31but there's one thing
0:23:31 > 0:23:34that goes hand-in-hand with electricity, isn't there?
0:23:34 > 0:23:36Magnetism.
0:23:46 > 0:23:51Magnets have two poles - north and south.
0:23:51 > 0:23:55Lines of magnetic force radiate out from pole to pole.
0:23:58 > 0:24:02But these magnetic fields aren't just flat, in 2D.
0:24:04 > 0:24:09Using magnetic fluid, tiny particles of iron suspended in oil...
0:24:13 > 0:24:18..you can see those fields radiating out in three-dimensional space.
0:24:20 > 0:24:25And one of the largest magnets we know of is the one were standing on.
0:24:27 > 0:24:30So you can think of the Earth magnetic field
0:24:30 > 0:24:31like a huge bar magnet,
0:24:31 > 0:24:35where the field lines go out at the southern hemisphere,
0:24:35 > 0:24:38go around in invisible lines all over the world
0:24:38 > 0:24:43and re-enter the Earth at the northern hemisphere.
0:24:43 > 0:24:44And it is invisible to us,
0:24:44 > 0:24:48but many animals can sense the Earth's magnetic field.
0:24:48 > 0:24:53And Sabine thinks that cows may be one of them.
0:24:53 > 0:24:57So the high-voltage power lines obviously disturbed
0:24:57 > 0:25:01the magnetic sense of the cattle so that they are in random order.
0:25:04 > 0:25:07So if these cows had a sort of hidden sixth sense,
0:25:07 > 0:25:11what Sabine was wondering was, did other animals too?
0:25:11 > 0:25:13Perhaps ones closer to home.
0:25:15 > 0:25:20She thinks that dogs have a similar secret, but it's well hidden.
0:25:20 > 0:25:26In fact, they only give it away at a very specific moment.
0:25:26 > 0:25:30I would say, on average, about twice a day.
0:25:30 > 0:25:33How you ever noticed your dog spinning around
0:25:33 > 0:25:36before they stop to do their business?
0:25:36 > 0:25:39What are they doing?
0:25:39 > 0:25:43Well, it turns out that dogs are picky poopers.
0:25:43 > 0:25:50After studying nearly 2,000 squats, Sabine had discovered a pattern.
0:25:50 > 0:25:54So they like to defecate facing in the same direction.
0:25:54 > 0:25:59Rover, Fido, certainly my poodles Itchy and Scratchy,
0:25:59 > 0:26:03they know their magnetic north from their magnetic south.
0:26:03 > 0:26:07Sabine has discovered that dogs, like cows,
0:26:07 > 0:26:09can sense magnetic fields.
0:26:11 > 0:26:14They poo facing north.
0:26:14 > 0:26:17But they don't show this behaviour all the time.
0:26:19 > 0:26:23Some days and walks, the dogs were aligned perfectly
0:26:23 > 0:26:29and on other days, they were doing it in a random direction.
0:26:31 > 0:26:36It seems that sometimes they get distracted, but not by squirrels.
0:26:37 > 0:26:41It turned out that, on some of these days, there were solar flares,
0:26:41 > 0:26:43magnetic storms.
0:26:43 > 0:26:47The dogs are very sensitive to slight changes
0:26:47 > 0:26:50of the Earth's magnetic field.
0:26:50 > 0:26:53That squatting must be pretty sensitive
0:26:53 > 0:27:00to be disrupted by sunshine and the reason they do it is even stranger.
0:27:02 > 0:27:07Weirdly, the key lies in the fact that dogs usually only spin
0:27:07 > 0:27:10when they're somewhere unfamiliar.
0:27:12 > 0:27:16So, if the dogs have not been in that territory before,
0:27:16 > 0:27:21they start to establish a mental map by aligning themselves
0:27:21 > 0:27:24with the magnetic field lines and using that
0:27:24 > 0:27:26if they return to this place later on.
0:27:39 > 0:27:42So it turns out that dogs might not just be man's best friend,
0:27:42 > 0:27:45they might also be master map makers, too.
0:27:45 > 0:27:47You see, when they're spinning,
0:27:47 > 0:27:52they're looking at visual landmarks, like these mountaintops here,
0:27:52 > 0:27:57and they're using those to calibrate their internal compass.
0:27:57 > 0:27:59And once they've done that, they then put down
0:27:59 > 0:28:03one of their stinky Xs on the ground.
0:28:04 > 0:28:08In fact, though, they don't just put one down.
0:28:08 > 0:28:11They put lots down and this enables them
0:28:11 > 0:28:14to produce an accurately orientated,
0:28:14 > 0:28:17internal mental map of their environment
0:28:17 > 0:28:19so the next time they come back,
0:28:19 > 0:28:23they can see - or probably SMELL - exactly where they are.
0:28:25 > 0:28:28So perhaps the next time you go for a stroll in the countryside,
0:28:28 > 0:28:31you should take your bearings from the cows
0:28:31 > 0:28:33or even let your dogs take the lead.
0:28:33 > 0:28:36They probably have a better sense of where to go
0:28:36 > 0:28:39and which direction to go in.
0:28:41 > 0:28:44Now, I'm not one to brag, I'm not that sort of bloke,
0:28:44 > 0:28:47but I've got to say that my sense of direction is pretty good.
0:28:47 > 0:28:49I've got lost twice in my life - curiously,
0:28:49 > 0:28:53both times in the same place. And therefore,
0:28:53 > 0:28:56I have to consider myself as lucky, because some people
0:28:56 > 0:28:59can't even follow a satellite navigation machine.
0:29:03 > 0:29:05But could there be a weird reason
0:29:05 > 0:29:09why some people's sense of direction is so much better than others?
0:29:11 > 0:29:13You'd never believe it if I told you,
0:29:13 > 0:29:16but there are intriguing hints
0:29:16 > 0:29:19that some of us might have a sixth sense too.
0:29:19 > 0:29:22In humans, we do not know if we can sense magnetic fields.
0:29:22 > 0:29:26Some people say they can, some people obviously can't.
0:29:28 > 0:29:32So, currently, there are two possible mechanisms that are currently debated
0:29:32 > 0:29:37and the research is for animals, how they might sense this magnetic field.
0:29:37 > 0:29:40So on the one hand, we have magnetite and on the other hand,
0:29:40 > 0:29:42we have a chemical cryptochrome-based system.
0:29:46 > 0:29:49The really weird thing is that we have both of these
0:29:49 > 0:29:52magnetism-sensing compounds in our bodies.
0:29:53 > 0:29:58Magnetite is a special iron compound found in certain cells
0:29:58 > 0:30:00in an animal's nose or beak.
0:30:01 > 0:30:06It acts like a tiny compass, spinning to face magnetic north.
0:30:06 > 0:30:11Cryptochrome is a light-sensitive chemical found in animals' eyes.
0:30:11 > 0:30:15It also reacts to magnetism and we think it might allow
0:30:15 > 0:30:20some animals, like birds, to actually see magnetic fields.
0:30:20 > 0:30:24The jury is out whether humans can use these receptors
0:30:24 > 0:30:28like other animals do, but we certainly have them.
0:30:28 > 0:30:30We have magnetite in our bones.
0:30:30 > 0:30:32It was found in bones of the nose and the brain.
0:30:32 > 0:30:36We also have cryptochrome in our eyes.
0:30:36 > 0:30:41Weirder still, the compounds are actually functional.
0:30:42 > 0:30:46If you replace the cryptochrome in the eye of a fly
0:30:46 > 0:30:51with the cryptochrome from a human's eyes, it works
0:30:51 > 0:30:53and the fly can sense magnetism,
0:30:53 > 0:30:58proving that our own magnetic compounds actually function,
0:30:58 > 0:31:03although we may - or may not - be able to use them.
0:31:05 > 0:31:08So, the next time you're lost, turn off the GPS
0:31:08 > 0:31:13and follow your natural instincts all the way home.
0:31:13 > 0:31:15You never know, you might actually get there.
0:31:23 > 0:31:27Now, even if we can't sense the Earth's magnetic field,
0:31:27 > 0:31:32there are some people who have extraordinary animal abilities.
0:31:35 > 0:31:37This is Daniel Kish...
0:31:38 > 0:31:41..and he is totally blind.
0:31:43 > 0:31:46I lost my first eye at the age of seven months
0:31:46 > 0:31:50and the second at 13 months from retinoblastoma.
0:31:50 > 0:31:54I have no recollection of ever having seen.
0:31:56 > 0:31:59I got my first bicycle when I was six.
0:32:00 > 0:32:04I go hiking alone, I've travelled to nearly 40 countries,
0:32:04 > 0:32:07mostly on my own.
0:32:08 > 0:32:11So, how does Daniel manage to do all these things
0:32:11 > 0:32:13with such apparent ease?
0:32:13 > 0:32:19I tend to think of challenges as puzzles,
0:32:19 > 0:32:23as opportunities for discovery.
0:32:24 > 0:32:29The clue to Daniel's incredible abilities lies in his nickname.
0:32:33 > 0:32:36I seem to be known the world over as the real-life Batman.
0:32:38 > 0:32:42No, Daniel isn't a superhero, but, weirdly,
0:32:42 > 0:32:45he does share something in common with actual bats.
0:32:46 > 0:32:53I am a man who uses the techniques of a bat to navigate.
0:32:56 > 0:32:59That's right - Daniel has actually learned to echolocate,
0:32:59 > 0:33:01just like a bat.
0:33:03 > 0:33:05And he does it with a single sound.
0:33:05 > 0:33:08HE CLICKS WITH HIS TONGUE
0:33:08 > 0:33:12So, I learned at a very early age that when I click my tongue...
0:33:12 > 0:33:15HE CLICKS WITH HIS TONGUE
0:33:15 > 0:33:18..I get feedback from the environment all around me.
0:33:21 > 0:33:24But how can sound be used to navigate?
0:33:25 > 0:33:28Now, sound travels through air,
0:33:28 > 0:33:31a bit like the way ripples travel through water.
0:33:31 > 0:33:35So, if I make a single sharp sound in this pool, just watch the waves.
0:33:37 > 0:33:40The waves spread out into the pool
0:33:40 > 0:33:44and then bounce back from the rim in a uniform way to their source.
0:33:44 > 0:33:48But let's put an object in that environment,
0:33:48 > 0:33:50something big and hard like this.
0:33:52 > 0:33:53When the waves hit the object,
0:33:53 > 0:33:57they reflect back sooner than the waves hitting the rim
0:33:57 > 0:34:00so that when they reach their source, they sound different.
0:34:02 > 0:34:05A skilful listener can locate objects
0:34:05 > 0:34:09by the way that sounds are reflected differently.
0:34:09 > 0:34:13HE CLICKS WITH HIS TONGUE
0:34:13 > 0:34:16Here we've got a stairway.
0:34:16 > 0:34:21And Daniel is a very good listener.
0:34:21 > 0:34:24So we have a structure here that has a roof.
0:34:24 > 0:34:27He's never been to this park before,
0:34:27 > 0:34:31but he can quickly determine its layout.
0:34:31 > 0:34:34A pavilion.
0:34:34 > 0:34:37And it's got places to sit underneath
0:34:37 > 0:34:41and the roof is held up by poles.
0:34:41 > 0:34:44Here's a pole.
0:34:50 > 0:34:52So this park has lots of trees and pavilions,
0:34:52 > 0:34:58although you have a building on the far side, but it's pretty open.
0:34:58 > 0:35:03Daniel doesn't see the world in the same way we do.
0:35:03 > 0:35:06You can think of it as a kind of fuzzy geometry.
0:35:06 > 0:35:10It does not have the degree of definition
0:35:10 > 0:35:12that is available to vision.
0:35:12 > 0:35:17But, incredibly, he can still make out textures.
0:35:17 > 0:35:22This tree is a total oddball in terms of its shape.
0:35:26 > 0:35:31So it starts out quite low here
0:35:31 > 0:35:33and then, as you approach it,
0:35:33 > 0:35:36it quickly comes up, but it doesn't ever get very tall.
0:35:38 > 0:35:45And it's a highly irregular kind of structure here,
0:35:45 > 0:35:50it kind of swings out a little bit and then it curves around.
0:35:51 > 0:35:54Daniel's abilities are so remarkable
0:35:54 > 0:35:57that it drove one scientist to find out more.
0:35:57 > 0:36:01Daniel is not only exceptionally good at echolocation,
0:36:01 > 0:36:04he's also exceptionally good at verbalising how he does it.
0:36:09 > 0:36:11Having Daniel here around
0:36:11 > 0:36:14is like almost being able to talk to a bat.
0:36:15 > 0:36:19To find out what's happening inside Daniel's brain
0:36:19 > 0:36:24whilst he's echolocating, Lutz is conducting a series of MRI scans.
0:36:25 > 0:36:29Inside the scanner, Daniel is listening to virtual echoes
0:36:29 > 0:36:35and Lutz is watching how his brain reacts.
0:36:35 > 0:36:37The results are astonishing.
0:36:40 > 0:36:41He can really see with his ears
0:36:41 > 0:36:46and it's not only that he can process spatial information
0:36:46 > 0:36:48acquired with his auditory system,
0:36:48 > 0:36:53but he can also recruit parts of his visual cortex to do this task.
0:36:55 > 0:36:59Put simply, Daniel is using the part of his brain
0:36:59 > 0:37:02that would normally deal with sight
0:37:02 > 0:37:05to help process sound into spatial images.
0:37:07 > 0:37:10But here's the truly weird thing -
0:37:10 > 0:37:16the scans also show there is nothing unique about Daniel's brain.
0:37:16 > 0:37:20If one part of the brain has really no input any more
0:37:20 > 0:37:23because of a sensory deprivation,
0:37:23 > 0:37:27then this part can be taken over by other modalities.
0:37:31 > 0:37:34In essence, our brains are flexible.
0:37:34 > 0:37:37They can adapt to meet new challenges
0:37:37 > 0:37:39in the most incredible ways.
0:37:39 > 0:37:43Daniel has recruited part of his unused visual system
0:37:43 > 0:37:47to improve his echolocation.
0:37:47 > 0:37:51Anyone can improve their ability to echolocate.
0:37:52 > 0:37:58So, with some dedicated practice, even you could learn to do it.
0:38:00 > 0:38:03But before you try riding your bike blindfolded,
0:38:03 > 0:38:06perhaps practise your skills at home first?
0:38:12 > 0:38:15From oddly aligned ungulates
0:38:15 > 0:38:18to dogs that will only poo facing north,
0:38:18 > 0:38:21our world is full of hidden oddities.
0:38:21 > 0:38:27We may or may not have a sixth sense, but with practice,
0:38:27 > 0:38:32we can train ourselves to see with our ears.
0:38:46 > 0:38:50Next, to get from some very fancy fairy rings
0:38:50 > 0:38:52to some very mucky gold,
0:38:52 > 0:38:54we have to take a trip to the other side of the world.
0:39:00 > 0:39:03One of the world's weirdest landscapes is in Namibia.
0:39:06 > 0:39:11A vast scrubland, pockmarked with thousands of shallow circles.
0:39:13 > 0:39:18Rings of grass surrounding barren soil, about five metres across.
0:39:20 > 0:39:27One local myth holds that these rings are the footprints of gods.
0:39:27 > 0:39:31But it's not just the locals that were intrigued by these rings.
0:39:32 > 0:39:35So the interesting thing about the Namibian rings,
0:39:35 > 0:39:37they don't have any human origin to them.
0:39:40 > 0:39:43They extend over such a vast area.
0:39:43 > 0:39:45You can travel hundreds of kilometres
0:39:45 > 0:39:47and you'll find exactly the same patterns.
0:39:50 > 0:39:54So what's causing these elliptical oddities?
0:39:54 > 0:39:57Well, generally, if you've got a weird mystery,
0:39:57 > 0:40:00you've got some pretty weird theories to go with it.
0:40:02 > 0:40:05Over the years, there's been many scientists
0:40:05 > 0:40:06who've seen the fairy rings
0:40:06 > 0:40:09and puzzled over what might have been causing them.
0:40:09 > 0:40:11Some of the earlier ideas suggested
0:40:11 > 0:40:15that maybe there was gas seeping from underground
0:40:15 > 0:40:18or perhaps they were the remnants of toxic bushes
0:40:18 > 0:40:21that had previously lived there and had poisoned the soil
0:40:21 > 0:40:24and then nothing could live around them any more.
0:40:26 > 0:40:29But that's not all. Some scientists thought
0:40:29 > 0:40:32that radioactivity could be causing the circles.
0:40:32 > 0:40:35Others favoured fungi.
0:40:35 > 0:40:39Some even thought they might be made by rutting ostriches.
0:40:41 > 0:40:43So, which of these odd theories
0:40:43 > 0:40:47was the correct answer to this circular conundrum?
0:40:49 > 0:40:52As it turned out, actually, none of them.
0:40:52 > 0:40:54You see, when the scientists got down on the ground,
0:40:54 > 0:40:58inside the fairy rings, they found...
0:40:58 > 0:41:01Well, not much.
0:41:01 > 0:41:05Each ring was formed from a patch of bare earth
0:41:05 > 0:41:09surrounded by some tall grasses.
0:41:09 > 0:41:14Inside were no gases, no toxic plants, no radioactivity,
0:41:14 > 0:41:19no fungi and absolutely no ostriches.
0:41:21 > 0:41:23But they did find something else.
0:41:25 > 0:41:29Every one of the fairy rings is colonised by ants and termites
0:41:29 > 0:41:32and there are nests around the edges of the rings.
0:41:32 > 0:41:39Were these hive-minded harvesters the real cause of the fairy rings?
0:41:39 > 0:41:40There are other parts of the world
0:41:40 > 0:41:43where leafcutter ants clear patches of vegetation
0:41:43 > 0:41:45and leave bare ground
0:41:45 > 0:41:48or where termites clear the areas around their nests.
0:41:48 > 0:41:52Well, it looked promising and termites are master architects,
0:41:52 > 0:41:56building complex mound structures all around Africa.
0:41:56 > 0:42:00They certainly seemed like the perfect fit,
0:42:00 > 0:42:02but there was a problem.
0:42:03 > 0:42:05Understanding how you get cleared patches,
0:42:05 > 0:42:07that's relatively simple.
0:42:07 > 0:42:11But understanding how you get these patches to be spaced regularly,
0:42:11 > 0:42:14that's the really tricky part.
0:42:14 > 0:42:17Ants and termites don't clear perfect circles
0:42:17 > 0:42:21and, even if they did, it's unlikely that they'd be the same diameter
0:42:21 > 0:42:23and the same distance apart.
0:42:23 > 0:42:26They'd have to be pretty obsessively compulsive colonies
0:42:26 > 0:42:32to achieve that. The termite theory? No. It's another dud.
0:42:35 > 0:42:38One scientist believed that the answer
0:42:38 > 0:42:41lay in a change of perspective.
0:42:41 > 0:42:46None of these different researchers has so far found an ultimate answer.
0:42:50 > 0:42:53So I thought that we should maybe not only look at fieldwork,
0:42:53 > 0:42:56but we should also look at remote sensing applications
0:42:56 > 0:42:58and area images.
0:42:59 > 0:43:03Stephan realised that everyone was looking
0:43:03 > 0:43:06at what caused individual rings
0:43:06 > 0:43:09and not what had caused the large-scale pattern.
0:43:11 > 0:43:13It's a bit like looking at a pimple
0:43:13 > 0:43:16and trying to describe a whole disease.
0:43:16 > 0:43:20Fairy circles, if you look at those in area images,
0:43:20 > 0:43:23they have clearly a very distinct pattern.
0:43:23 > 0:43:25It's actually a very, very unique pattern.
0:43:27 > 0:43:31After studying thousands of fairy rings from above,
0:43:31 > 0:43:35Stephan realised that the rings were roughly the same size
0:43:35 > 0:43:37and the same distance apart.
0:43:38 > 0:43:42But critically, they were only ever found in very specific areas.
0:43:44 > 0:43:48The fairy circles typically occur in the transition
0:43:48 > 0:43:51from very arid grassland to desert,
0:43:51 > 0:43:57so we believe that gaps emerged due to competition for moisture.
0:43:57 > 0:43:58Yes!
0:43:58 > 0:44:01He realised that the fairy rings only form
0:44:01 > 0:44:04with exactly the right amount of rain.
0:44:04 > 0:44:08Any more water and they would simply be grassland savanna.
0:44:08 > 0:44:11Any less and it would all be desert.
0:44:12 > 0:44:17And this realisation led Stephan to a truly weird conclusion.
0:44:20 > 0:44:21What we now think
0:44:21 > 0:44:25is that fairy circles are actually creating themselves.
0:44:27 > 0:44:31The fairy rings develop as a way for the plants
0:44:31 > 0:44:37to organise themselves, to survive in an area with very limited water.
0:44:42 > 0:44:47Imagine this coin is one of those fairy rings
0:44:47 > 0:44:49growing out in Namibia.
0:44:49 > 0:44:53The long grasses that grow around the edge of the rim here
0:44:53 > 0:44:56are competing for scarce water.
0:44:56 > 0:45:00Their roots are radiating inwards, taking away all that water
0:45:00 > 0:45:04so it's barren inside the ring there.
0:45:04 > 0:45:08Now, other plants want their share of those resources too,
0:45:08 > 0:45:10so they start to pack themselves in.
0:45:11 > 0:45:14Unfortunately, this means there is a problem
0:45:14 > 0:45:17because the long grasses on the outside of each rim
0:45:17 > 0:45:20are buzzing right up against one another.
0:45:20 > 0:45:22Plants don't like that.
0:45:22 > 0:45:25They want to avoid competition,
0:45:25 > 0:45:30so what they do is they space themselves out equally like this
0:45:30 > 0:45:33and what we see is this regular pattern,
0:45:33 > 0:45:38which is so typical of the vegetation in this area.
0:45:40 > 0:45:43It's a weirdly elegant solution,
0:45:43 > 0:45:50requiring no termites, no gods and absolutely no ostriches.
0:45:56 > 0:45:58So the fairy circles of Namibia
0:45:58 > 0:46:01may be a bit more mathematical than magical,
0:46:01 > 0:46:04but down in the jungles of South America,
0:46:04 > 0:46:08explorers recently discovered another ring-based riddle.
0:46:12 > 0:46:14Found in Peru,
0:46:14 > 0:46:19pictures of this weird structure first surfaced in 2013.
0:46:19 > 0:46:24When they hit the web, they went viral.
0:46:24 > 0:46:26These things were just fascinatingly weird.
0:46:29 > 0:46:32The structure of it, it's like a white picket fence around there
0:46:32 > 0:46:34and then the pole in the middle,
0:46:34 > 0:46:38there's nothing else in biology that looks like this.
0:46:38 > 0:46:43This miniature marvel sparked a furious debate across the net.
0:46:43 > 0:46:45People had a lot of ideas
0:46:45 > 0:46:49and they figured it was something very small making this.
0:46:49 > 0:46:50Nobody was quite sure
0:46:50 > 0:46:53and actually some experts out there said it was probably a hoax.
0:46:53 > 0:46:56They didn't believe anybody had found these things.
0:46:56 > 0:47:00Phil knew he needed to see them first-hand to find out more.
0:47:01 > 0:47:03Armed with the information
0:47:03 > 0:47:06detailing where those first photographs were taken,
0:47:06 > 0:47:09Phil and his team set off into the jungle
0:47:09 > 0:47:11to solve this Peruvian puzzler.
0:47:13 > 0:47:14So, to solve this thing,
0:47:14 > 0:47:17I got together some of my best entomologists
0:47:17 > 0:47:19and we went down to Peru and to get there,
0:47:19 > 0:47:23it took us three plane rides, a bus ride and then two days of canoeing
0:47:23 > 0:47:27up the Tambopata River to get to the Tambopata Research Center.
0:47:27 > 0:47:29Then, every single night for about two weeks,
0:47:29 > 0:47:31we took these canoes out to the island
0:47:31 > 0:47:33where the structures were found
0:47:33 > 0:47:36and we were just really hoping to find a single one.
0:47:36 > 0:47:39We had no idea if we would find any of them at all.
0:47:39 > 0:47:41Working at night and using torches
0:47:41 > 0:47:44to try and cast shadows of these tiny structures,
0:47:44 > 0:47:48they soon discovered that finding a hidden henge
0:47:48 > 0:47:50is a lot harder than it looks.
0:47:50 > 0:47:53We looked up and down trees, looked in the bushes,
0:47:53 > 0:47:56looked in the same places that these things were found before,
0:47:56 > 0:47:59hoping to find a single one because as of then,
0:47:59 > 0:48:01only two had ever been seen, ever.
0:48:01 > 0:48:04When you look at them, they're about that big in diameter
0:48:04 > 0:48:08so this is a very small structure in a very big rainforest.
0:48:08 > 0:48:11We had no idea if we would even see a single one.
0:48:11 > 0:48:16After weeks of hard graft, their efforts finally paid off.
0:48:16 > 0:48:21We looked and we looked and we found one and we were just over the moon.
0:48:21 > 0:48:24But they didn't just find one.
0:48:24 > 0:48:27Over those two weeks, we ended up finding over 50 of them
0:48:27 > 0:48:29in all different conditions.
0:48:29 > 0:48:31Some of them looked like they were completely fresh,
0:48:31 > 0:48:34others looked like they'd been there maybe a few weeks.
0:48:37 > 0:48:41So, Phil and his team had proved that these Amazonian oddities
0:48:41 > 0:48:45were the real deal, not some elaborate internet hoax,
0:48:45 > 0:48:49but they still didn't know exactly what was making them.
0:48:53 > 0:48:57We thought maybe it was a fungus that was growing on these in a circle.
0:48:58 > 0:49:01Then they found one of the structures on a plastic tarpaulin.
0:49:03 > 0:49:06Normally, when you see a fungus, the part that you actually see
0:49:06 > 0:49:08is just the tip of the iceberg of the organism.
0:49:08 > 0:49:12Underneath, there's all these little veins called mycelium.
0:49:12 > 0:49:15And mycelium can't grow through plastic
0:49:15 > 0:49:18and the underside of the tarp was clean,
0:49:18 > 0:49:22so the structure couldn't have been made of fungus.
0:49:23 > 0:49:26Instead, it looked like it was made from silk.
0:49:27 > 0:49:31Incredible? Certainly, but not altogether very helpful.
0:49:31 > 0:49:35You see, in the jungle, there are quite literally thousands,
0:49:35 > 0:49:39perhaps tens of thousands, of silky suspects.
0:49:40 > 0:49:45Some moths create intricate cocoons from silk when they pupate.
0:49:45 > 0:49:50Spiders spin complex webs and egg sacs with their silk.
0:49:50 > 0:49:56And lacewings, well, they lay eggs on top of delicate silk stalks,
0:49:56 > 0:49:58but to find out whodunnit,
0:49:58 > 0:50:03the team first had to establish what these structures really were.
0:50:09 > 0:50:12We put them under a microscope and cut into them
0:50:12 > 0:50:15and, when we looked inside, it look pretty much like an egg.
0:50:17 > 0:50:23So, inside the base of the central spire was an egg, not a pupae.
0:50:23 > 0:50:27That ruled out moths, leaving just spiders
0:50:27 > 0:50:30and lacewings as the mystery silk spinners.
0:50:32 > 0:50:36To unmask which was the evasive egg maker, they put a few
0:50:36 > 0:50:41of the structures into sealed jars in the lab and then simply waited.
0:50:41 > 0:50:43So, finally, after a few days,
0:50:43 > 0:50:49we saw a tiny, tiny thing crawling in one of those jars and it was tiny
0:50:49 > 0:50:51and it was red and we weren't sure what it was,
0:50:51 > 0:50:55but we got out the super macro lenses so we could see very close
0:50:55 > 0:50:58and we realised that it was a tiny spider.
0:51:00 > 0:51:02We found a spider that does all this work,
0:51:02 > 0:51:05builds this beautiful thing, just to lay one egg in there.
0:51:06 > 0:51:10It's an amazing amount of work for an arachnid to do
0:51:10 > 0:51:12for the sake of just a single egg!
0:51:12 > 0:51:15You see, typically, they'll lay tens,
0:51:15 > 0:51:18if not hundreds, inside their silky sacs,
0:51:18 > 0:51:21so the effort that this species is going to
0:51:21 > 0:51:25might yet prove to be even more incredible.
0:51:27 > 0:51:31Phil thinks that the circular fence around the egg spire
0:51:31 > 0:51:34might actually be like a fence to keep predators out.
0:51:36 > 0:51:39And perhaps to keep prey IN, too.
0:51:40 > 0:51:43That fence surrounding it is a trap for tiny mites
0:51:43 > 0:51:47because we kept finding them with mites stuck inside,
0:51:47 > 0:51:50these tiny, tiny things that would be perfect prey size
0:51:50 > 0:51:52for a newly hatched spider.
0:51:54 > 0:51:55If that were the case,
0:51:55 > 0:51:59that would make this even more truly one-of-a-kind.
0:51:59 > 0:52:03As to which super spider species created the silky structure,
0:52:03 > 0:52:09Phil isn't sure, as they've yet to managed to raise one to adult stage.
0:52:09 > 0:52:12But he's already planning a return trip
0:52:12 > 0:52:14to hunt down the proud parents.
0:52:14 > 0:52:18We've got maybe 1% of it solved. There is 99% to go.
0:52:22 > 0:52:26So, strange spiders are producing beautiful rings
0:52:26 > 0:52:28to protect their families.
0:52:28 > 0:52:34But then we like to put rings on the fingers of our loved ones, don't we?
0:52:34 > 0:52:36Although it's my duty tell you that at some stage
0:52:36 > 0:52:40in the pretty new future, the gold that is used to make them
0:52:40 > 0:52:44might come from a less romantic source than you'd ever imagine.
0:52:46 > 0:52:51There's an old saying - where there's muck, there's money.
0:52:51 > 0:52:54And it's something that farmers have known for centuries,
0:52:54 > 0:52:57liberally spreading muck on the fields
0:52:57 > 0:53:00and turning it back into food to sell in our supermarkets.
0:53:02 > 0:53:04Now, I've noticed that recently
0:53:04 > 0:53:07a lot of muck has been hitting the headlines
0:53:07 > 0:53:09and not just in the tabloids, either,
0:53:09 > 0:53:13because apparently it's the new wonder material.
0:53:15 > 0:53:20Scientists have recently worked out how to turn solid waste
0:53:20 > 0:53:22into pure drinkable water.
0:53:22 > 0:53:25They've even managed to collect the gases it gives off
0:53:25 > 0:53:28and use them to power our transport, too.
0:53:29 > 0:53:33So now, you can hop on the number two from Bristol to Bath,
0:53:33 > 0:53:36fuelled by our number twos.
0:53:37 > 0:53:41But, despite all this, one scientist currently thinks
0:53:41 > 0:53:45that we are missing out on our waste's greatest potential.
0:53:45 > 0:53:48We are interested in what goes down the drain.
0:53:51 > 0:53:54Everyone in society gets rid of things down the drain every day.
0:53:54 > 0:53:57They are all flushing away millions of dollars.
0:53:57 > 0:54:00So, Paul has come up with one of the weirdest get-rich-quick schemes
0:54:00 > 0:54:06ever invented and, like all such schemes, it involves gold.
0:54:06 > 0:54:09We thought we could go out and prospect for gold
0:54:09 > 0:54:10and silver in unique places
0:54:10 > 0:54:12and it turns out one of these unique places
0:54:12 > 0:54:15to prospect for gold and silver is poo.
0:54:17 > 0:54:20Yes! You heard him, you heard him correctly!
0:54:20 > 0:54:24Paul wants to get precious metals from poo.
0:54:26 > 0:54:28He's not an alchemist, but, amazingly,
0:54:28 > 0:54:30he may be onto something here.
0:54:32 > 0:54:35There are some truly weird ways
0:54:35 > 0:54:39that precious metals can find their way into our waste,
0:54:39 > 0:54:42some more obvious than others.
0:54:42 > 0:54:44We can find precious metals in everyday items,
0:54:44 > 0:54:48like our make-up, toothpaste and toiletries.
0:54:48 > 0:54:53Manufacturers sometimes put silver particles in our clothing,
0:54:53 > 0:54:56like socks, to reduce odours.
0:54:56 > 0:55:02They even put things like titanium in our foods to keep them fresh.
0:55:03 > 0:55:08And it's not just household waste that ends up in sewage plants.
0:55:08 > 0:55:11Mineral-rich run-offs from farms and industry
0:55:11 > 0:55:12find their way here, too.
0:55:14 > 0:55:16We took pictures of the waste water solids
0:55:16 > 0:55:18using high-powered microscopes
0:55:18 > 0:55:21and we find little particles of gold and silver
0:55:21 > 0:55:25in what are called sewage sludges at waste water treatment plants.
0:55:27 > 0:55:32And when you concentrate the sewerage sludge from entire cities,
0:55:32 > 0:55:34the results are eye-watering.
0:55:34 > 0:55:38Quite literally eye-watering.
0:55:38 > 0:55:41For a city of one million people, every year,
0:55:41 > 0:55:44there's about 13 million worth of precious metals
0:55:44 > 0:55:48and most of that value is actually in gold and silver.
0:55:52 > 0:55:57Now, gold is a lot, lot, rarer than you'd think.
0:55:58 > 0:56:01It's very difficult to mine,
0:56:01 > 0:56:05it's very expensive to get out of the ground indeed
0:56:05 > 0:56:09and that, in turn, makes it incredibly valuable.
0:56:14 > 0:56:15The amount of gold in the solids
0:56:15 > 0:56:18coming out of these waste water treatment plants
0:56:18 > 0:56:21is about the same as what mining companies will blow up mountains for
0:56:21 > 0:56:24in terms of the amount of gold content of rock
0:56:24 > 0:56:27that they'll go and mine, it's the same ore content.
0:56:27 > 0:56:30And rather than saving this mineral-rich muck,
0:56:30 > 0:56:32we're currently just dumping it.
0:56:32 > 0:56:34Every day, there's dump trucks
0:56:34 > 0:56:37that leave waste water treatment plants carrying biosolids.
0:56:37 > 0:56:39They bring it to landfills
0:56:39 > 0:56:41or they burn it or they spread it out on the land
0:56:41 > 0:56:44so each of those dump trucks contain more than enough gold
0:56:44 > 0:56:45to make a gold ring.
0:56:48 > 0:56:51That's an awful lot of gold
0:56:51 > 0:56:56and Paul is working on ways to reclaim his grubby gold for good.
0:56:57 > 0:57:01He's been looking at other places where they are experimenting
0:57:01 > 0:57:06with extracting gold from waste, like the Suwa facility in Japan.
0:57:07 > 0:57:12But to get their gold, they've been crudely burning their waste.
0:57:13 > 0:57:16Paul's working to find a more efficient
0:57:16 > 0:57:21and more environmentally friendly solution to this mucky problem.
0:57:22 > 0:57:26It's a weird world where magical rings
0:57:26 > 0:57:28turn out to be mathematical oddities,
0:57:28 > 0:57:32spiders makes surprising silk henges
0:57:32 > 0:57:37and we all flush away a fortune in gold.
0:57:41 > 0:57:44OK, some of that was pretty strange, a little bit freaky,
0:57:44 > 0:57:46but I've got to tell you -
0:57:46 > 0:57:49we've only just touched down on Planet Weird.
0:57:49 > 0:57:51There's a lot more to come.
0:57:54 > 0:57:58Next time, what caused gigantic hailstones on a sunny summer's day?
0:58:00 > 0:58:06And how could a pop band change the way that music is made forever?
0:58:06 > 0:58:10If we sell one little vial of our new album as DNA,
0:58:10 > 0:58:13we will have sold trillions and trillions of copies.
0:58:13 > 0:58:18Why does this man get legless without drinking any alcohol?
0:58:18 > 0:58:20Have you had anything to drink?
0:58:20 > 0:58:22Nothing.
0:58:22 > 0:58:28And finally, how can a volcano glow bizarrely blue?