0:00:02 > 0:00:04# Wormy fish-killers Convoys of caterpillars
0:00:04 > 0:00:06- # Super-clever, brainless slime... # - Ugh!
0:00:06 > 0:00:08# Bunny rabbit swarms, raging storms
0:00:08 > 0:00:10# And pigs that swim at dinner time
0:00:10 > 0:00:13# Tornadoes of fire Starfish going haywire
0:00:13 > 0:00:15- # Algae balls from space! # - What?!
0:00:15 > 0:00:17# Prairie dogs that chat Birds going splat
0:00:17 > 0:00:19# And fish slapping in your face
0:00:19 > 0:00:21# They're wild and weird Wild and weird
0:00:21 > 0:00:23# Really, really wild and really, really weird
0:00:23 > 0:00:25# They're wild and weird Wild and weird
0:00:25 > 0:00:27# They're really, really wild
0:00:27 > 0:00:30# They're really, really wild and weird... #
0:00:30 > 0:00:32On today's show, we meet the monster
0:00:32 > 0:00:34that could be living in your fish tank...
0:00:34 > 0:00:36While, that thing is massive.
0:00:36 > 0:00:38..an island infested with bunny rabbits...
0:00:38 > 0:00:40HE LAUGHS
0:00:40 > 0:00:42..and rats with a death wish.
0:00:49 > 0:00:52# You will have a fishy on a little dishy
0:00:52 > 0:00:54# You will have a fishy on... #
0:00:54 > 0:00:56Mr Tibbles! Come out, come out, wherever you are.
0:00:56 > 0:01:00- Talking to yourself again, Tim? - No. Strangest thing, though.
0:01:00 > 0:01:04- I've lost my fish. - What are you talking about?
0:01:04 > 0:01:06Well, he was in there are swimming around all happy as a clam
0:01:06 > 0:01:09and now Mr Tibbles has vanished.
0:01:09 > 0:01:13- What are you eating?- Fish and chips.
0:01:13 > 0:01:15HE GASPS
0:01:15 > 0:01:16You monster!
0:01:16 > 0:01:18Tim, I'm not eating your fish.
0:01:18 > 0:01:21- Oh, phew!- Eurgh.
0:01:21 > 0:01:24- I wonder where he's gone, then. - Yeah, it's a bit of a mystery.
0:01:24 > 0:01:26And not for the first time, by all accounts.
0:01:26 > 0:01:28To America!
0:01:28 > 0:01:30STAR-SPANGLED BANNER PLAYS
0:01:30 > 0:01:31Miami, in the USA.
0:01:31 > 0:01:34Where an invisible killer is on the loose.
0:01:36 > 0:01:40- What, him?- No, that's Brian.
0:01:40 > 0:01:43He's the owner of a tropical fish and living coral aquarium shop
0:01:43 > 0:01:46and he's seen a lot of strange things in his time.
0:01:46 > 0:01:49We've had fish give birth, a shark hatch out of an egg,
0:01:49 > 0:01:51blue-ringed octopus,
0:01:51 > 0:01:55but I've never seen anything as mind-blowing as this.
0:01:55 > 0:02:00In January of 2013, Brian noticed something pretty unusual.
0:02:00 > 0:02:02I noticed when I came in in the morning,
0:02:02 > 0:02:04all the corals were pulled to the middle of the rocks.
0:02:04 > 0:02:07So I put them all back out and I explained to everybody,
0:02:07 > 0:02:09if you're going to clean the glass,
0:02:09 > 0:02:12to please move the corals back when you're done.
0:02:12 > 0:02:15Everybody had kind of denied it and said they didn't do it.
0:02:15 > 0:02:19The finger of blame pointed at some of Brian's colleagues,
0:02:19 > 0:02:22so he really wasn't happy when it happened again.
0:02:22 > 0:02:24The following day we got a coral shipment in.
0:02:24 > 0:02:26There's a coral called the Finger of Leather,
0:02:26 > 0:02:27which is a soft coral.
0:02:27 > 0:02:30I put it in, came back the next morning
0:02:30 > 0:02:32and it was only about a half-inch on each tentacle.
0:02:32 > 0:02:35Something had eaten about 3 to 4 inches.
0:02:35 > 0:02:38So Brian's fish shop staff were eating the coral?
0:02:38 > 0:02:41OH! I don't see the appeal myself.
0:02:41 > 0:02:46No, the staff weren't eating them but something else was.
0:02:47 > 0:02:52And not just coral but entire fish eaten alive!
0:02:55 > 0:02:58No, no!
0:02:58 > 0:02:59THEY GASP
0:02:59 > 0:03:01Fishy!
0:03:01 > 0:03:04Brian decided to investigate.
0:03:04 > 0:03:05Oh, I can't look!
0:03:07 > 0:03:09I decided to take all the rock out of the aquarium
0:03:09 > 0:03:12and out of nowhere, this giant thing
0:03:12 > 0:03:13just started swimming around the tank.
0:03:13 > 0:03:15The reaction was crazy.
0:03:15 > 0:03:17"Oh, my God, get a net! What is that?"
0:03:20 > 0:03:23And this is what Brian caught. It's a bobbit worm.
0:03:23 > 0:03:27This bizarre-looking creature usually lives in the waters
0:03:27 > 0:03:29of the Indo-Pacific ocean.
0:03:29 > 0:03:32In the wild, they hide in the sediment on the ocean floor
0:03:32 > 0:03:35using their highly tuned antennae to sense prey.
0:03:35 > 0:03:37When an unfortunate fish comes by,
0:03:37 > 0:03:41it strikes in a split second as if from nowhere.
0:03:45 > 0:03:46Ouch!
0:03:47 > 0:03:51Hmm. This is a job for Sherlock.
0:03:51 > 0:03:53It is. But not you.
0:03:55 > 0:03:57- Who then?- Emma Sherlock.
0:03:57 > 0:03:58She's the curator of invertebrates
0:03:58 > 0:04:00at the Natural History Museum in London.
0:04:00 > 0:04:01Ah. Good choice.
0:04:01 > 0:04:05They are really, really powerful animals.
0:04:05 > 0:04:08They will attack with their jaws and it can be so fast
0:04:08 > 0:04:12and so vicious, they can actually snap fish in two.
0:04:12 > 0:04:16Definitely wouldn't want to get your fingers too close to these guys.
0:04:16 > 0:04:20This is a highly weaponised worm, not to be messed with.
0:04:20 > 0:04:23But there's still one thing that doesn't add up.
0:04:23 > 0:04:25It's something that's been in this aquarium
0:04:25 > 0:04:27for a very long time that we'd never noticed
0:04:27 > 0:04:30and we're in and out of the aquarium probably about 30 times a day,
0:04:30 > 0:04:33- 20 times a day. - Make your mind up, Brian.
0:04:33 > 0:04:36Shockingly, other people are finding them in their fish tanks too.
0:04:36 > 0:04:38Wow! That thing's massive!
0:04:38 > 0:04:42- It is quite revolting.- It's huge!
0:04:42 > 0:04:44I can't believe I've never seen him, though.
0:04:44 > 0:04:49Believe it or not, this mega-worm can grow up to 3 metres in length.
0:04:50 > 0:04:52Here, hold this.
0:04:52 > 0:04:55So... Oh, no. Keep going, that's one. Yeah, that's one.
0:04:55 > 0:04:59Oh, hang on. 1.6, yeah, keep going. Keep going. Oh, there you go.
0:04:59 > 0:05:02How does something that big fit in my fish tank?
0:05:02 > 0:05:05I don't know, let's find out.
0:05:05 > 0:05:06Ow!
0:05:06 > 0:05:11It seems staggering to people but actually what's happening,
0:05:11 > 0:05:15is that when these animals are very small, they can fit
0:05:15 > 0:05:18very easily into little crevices in rocks and corals
0:05:18 > 0:05:21and when you're making up your aquarium,
0:05:21 > 0:05:26you put in these bits of coral unknowing of what's lurking inside.
0:05:27 > 0:05:31As the bobbit worm grows, it hides under the sand and rocks.
0:05:31 > 0:05:34The only sign of its presence is the ever-increasing list
0:05:34 > 0:05:36of missing aquarium animals.
0:05:39 > 0:05:41Do you reckon that's where my fishy's gone?
0:05:41 > 0:05:43Probably not.
0:05:43 > 0:05:46Uh, Tim? We see that castle there?
0:05:46 > 0:05:47Mm. It's fancy, isn't it?
0:05:47 > 0:05:50You don't suppose your fish has gone in there, do you?
0:05:53 > 0:05:55- Oh, yeah! Oh, there he is! - HE LAUGHS
0:05:55 > 0:05:57Oh, fishy, fishy, fishy!
0:05:57 > 0:05:59Tim, why don't you just get yourself a proper pet?
0:05:59 > 0:06:02You know, one that does something interesting. Like a rabbit!
0:06:02 > 0:06:05No, not a rabbit! Anything but!
0:06:05 > 0:06:06What are you talking about, Tim?
0:06:06 > 0:06:09SCREAMING
0:06:09 > 0:06:12Naomi! Naomi!
0:06:13 > 0:06:16No, no! Not a rabbit!
0:06:16 > 0:06:18They are too hellbent on world domination.
0:06:18 > 0:06:23Don't be daft, rabbits are amazing and super cuddly. Look at this!
0:06:23 > 0:06:24WOMAN SCREAMS
0:06:24 > 0:06:28- what was that?- Nothing. Where's the rewind button on this thing?
0:06:30 > 0:06:32We head to Okunoshima.
0:06:32 > 0:06:35A small island off the coast of Japan.
0:06:35 > 0:06:38But, visitors are not coming here for the scenery
0:06:38 > 0:06:40or for the sea air.
0:06:40 > 0:06:44Oh, no. They've come for this.
0:06:44 > 0:06:45SHE SCREAMS
0:06:45 > 0:06:47Welcome to Rabbit Island.
0:06:47 > 0:06:50# Rabbit, Rabbit, rabbit, rabbit, rabbit, rabbit, rabbit,
0:06:50 > 0:06:52# rabbit, rabbit, rabbit, rabbit, rabbit, rabbit, rabbit... #
0:06:52 > 0:06:57Okunoshima is home to hundreds of extraordinary rabbits.
0:06:57 > 0:07:00Those don't look like the shy bunnies of childhood stories.
0:07:00 > 0:07:02They're fearless. They're an army.
0:07:02 > 0:07:04Oh! A bunny rabbit army!
0:07:04 > 0:07:06That would be adorable. All their little ears!
0:07:06 > 0:07:10- Aw!- But aren't rabbits supposed to be scared of everything?
0:07:10 > 0:07:14I'll let wildlife expert Dr Sasha Norris explain.
0:07:14 > 0:07:17A wild rabbit is a classic prey animal.
0:07:17 > 0:07:19So it's a muscular,
0:07:19 > 0:07:23highly nutritious sort of parcel of meat, really.
0:07:23 > 0:07:25I can relate to that.
0:07:25 > 0:07:26Hey!
0:07:28 > 0:07:32As a result, they're top of every predator's hit list.
0:07:32 > 0:07:36By contrast, rabbits on the island seemed to fear nothing.
0:07:36 > 0:07:38They're completely chilled out above the ground with
0:07:38 > 0:07:41no sign of that legendary vigilance.
0:07:41 > 0:07:45In fact, they're relaxed to the point of idiocy.
0:07:45 > 0:07:47Ah! Brilliant!
0:07:47 > 0:07:48Let's watch that again.
0:07:48 > 0:07:50HE LAUGHS
0:07:50 > 0:07:52- OOP!- Tim!
0:07:52 > 0:07:55And rather than fleeing at the first sight of an intruder,
0:07:55 > 0:07:58these rabbits actually chase visitors.
0:07:58 > 0:07:59I knew it.
0:07:59 > 0:08:03- Murderous and violent, the whole lot of them.- How can you say that?
0:08:03 > 0:08:07- Just look at their adorable little faces.- Where did that come from?
0:08:07 > 0:08:11She just wandered in from outside. She's so fluffy!
0:08:11 > 0:08:14So why is the island filled with loads of rabbits, then?
0:08:14 > 0:08:16Well...
0:08:16 > 0:08:20During World War II, the island was used by the military
0:08:20 > 0:08:24so for secrecy and safety, the civilian population
0:08:24 > 0:08:26and their pets and livestock were evacuated.
0:08:26 > 0:08:32After the war, the island remained uninhabited and has done ever since.
0:08:32 > 0:08:35The theory is that during the 1970s,
0:08:35 > 0:08:37pet rabbits were released here by schoolchildren
0:08:37 > 0:08:41and it's those that are the ancestors of this brood.
0:08:41 > 0:08:42Kids today!
0:08:42 > 0:08:44Well, yesterday.
0:08:44 > 0:08:47Wherever the rabbits came from, one thing is true,
0:08:47 > 0:08:50today there isn't a single predator on the island
0:08:50 > 0:08:53so these bunnies live completely without fear
0:08:53 > 0:08:56and a lack of predators hasn't just made them bold.
0:08:56 > 0:09:00A female rabbit can produce a new litter every month.
0:09:00 > 0:09:03In theory, one female and her offspring
0:09:03 > 0:09:07could produce over 50,000 rabbits in just three years.
0:09:08 > 0:09:11- 50,000?- I know, isn't it amazing?
0:09:11 > 0:09:13It's terrifying!
0:09:13 > 0:09:16Oh, for goodness' sake, will you keep that creature under control!
0:09:16 > 0:09:19You can't just let her run riot all over the place.
0:09:19 > 0:09:20What are you on about, Tim?
0:09:20 > 0:09:22HE GASPS
0:09:25 > 0:09:27Naomi! Naomi!
0:09:31 > 0:09:34Those of you that haven't passed out are probably wondering,
0:09:34 > 0:09:37"Why are these rabbits chasing down the visitors?"
0:09:37 > 0:09:39Well, with so many rabbits on the island,
0:09:39 > 0:09:42edible vegetation can get pretty scarce.
0:09:42 > 0:09:45Luckily for the bunnies, part of the Rabbit Island experience
0:09:45 > 0:09:48is feeding these cuddly critters.
0:09:48 > 0:09:51So when the rabbits spot people, they know there's food to be had
0:09:51 > 0:09:53and they "hare" off in pursuit!
0:09:53 > 0:09:54SHE LAUGHS
0:09:54 > 0:09:58Oi, you! Wake up. You're missing my jokes.
0:09:58 > 0:10:01What follows is a very gentle fluffy mugging.
0:10:01 > 0:10:03HE LAUGHS
0:10:07 > 0:10:11- Naomi, Naomi?- What?
0:10:11 > 0:10:13- Look!- Oh!
0:10:13 > 0:10:15Look, Tim. There's nothing to worry about.
0:10:15 > 0:10:18The only come near you if you've food. Check your pockets.
0:10:18 > 0:10:20Ah...
0:10:20 > 0:10:22I might have something.
0:10:24 > 0:10:29- Why?- Well you never know when you're going to need some spare cabbage.
0:10:30 > 0:10:32RABBITS: MMM...
0:10:33 > 0:10:34Oh, phew!
0:10:36 > 0:10:37Phew.
0:10:40 > 0:10:43You know, Naomi, when it comes to small, fluffy animals,
0:10:43 > 0:10:45there are loads that are better than rabbits.
0:10:45 > 0:10:48- For example?- Rats.- Ew! No.
0:10:48 > 0:10:50Rats are grosser.
0:10:50 > 0:10:52Oh, whatever, you're wronger. I mean, wrong.
0:10:52 > 0:10:54Rats just have a bad reputation.
0:10:54 > 0:10:57They're clean, they're clever, they fight cats...
0:10:57 > 0:11:01What, no? I think you're getting confused, Tim. Cats catch rats.
0:11:01 > 0:11:04Oh, do they? Have a look at this.
0:11:04 > 0:11:11# You better leave my kitten alone... #
0:11:11 > 0:11:15- What? - I told you. Go on, get him!
0:11:15 > 0:11:18This behaviour defies all the rules of nature
0:11:18 > 0:11:20and it's not a one-off case.
0:11:20 > 0:11:24This is not a new species of uber-aggressive, biting rodent.
0:11:24 > 0:11:27These rats weren't born with a death wish. Oh, no.
0:11:27 > 0:11:29Scientists think that this bizarre behaviour
0:11:29 > 0:11:32might be brought about by a parasite.
0:11:32 > 0:11:33Ohh!
0:11:33 > 0:11:37Toxoplasma gondii to be precise.
0:11:37 > 0:11:42A tiny single-celled organism that lives in the rodent's brain.
0:11:42 > 0:11:44Here, it meddles with the neurons
0:11:44 > 0:11:47to render the rat completely fearless.
0:11:49 > 0:11:52But why would a parasite want to give a rat a death wish?
0:11:52 > 0:11:55- Well, this parasite doesn't care too much for rats.- I know the feeling.
0:11:55 > 0:11:57Rats are purely a means to an end.
0:11:57 > 0:12:01You see, for the Toxoplasma, ultimate aim is to get into cats.
0:12:01 > 0:12:03I am well into cats.
0:12:03 > 0:12:06No, no, no. In to cats.
0:12:08 > 0:12:12What's unique about this parasite is that it can only reproduce
0:12:12 > 0:12:14inside the gut of a cat.
0:12:16 > 0:12:19What it needs to do, its life cycle, its evolutionary pressure,
0:12:19 > 0:12:22its need is to get from one cat to another cat.
0:12:22 > 0:12:26And the question is, how does a tiny parasite with no legs,
0:12:26 > 0:12:28no means of moving on its own,
0:12:28 > 0:12:31how does it get all the way from one cat to another cat?
0:12:31 > 0:12:34I don't know. How does a tiny parasite with no legs
0:12:34 > 0:12:36and no means of moving on its own get from one cat to another?
0:12:36 > 0:12:38- It's not a joke.- Oh.
0:12:38 > 0:12:42- No, Toxoplasma makes rats its rodent slaves.- Ew!
0:12:42 > 0:12:44Here's how it works.
0:12:45 > 0:12:49Toxoplasmosis offspring exit the cat in its poo.
0:12:49 > 0:12:52The rat or mouse then eats that poo.
0:12:52 > 0:12:54- Eurgh!- I know, yeah!
0:12:54 > 0:12:56Once inside the rat,
0:12:56 > 0:12:58the parasite moves to the rodent's brain,
0:12:58 > 0:13:00lowering the rat's inhibitions,
0:13:00 > 0:13:04making it less cautious and more likely to get eaten.
0:13:04 > 0:13:05Et voila.
0:13:05 > 0:13:07The life cycle is complete.
0:13:13 > 0:13:16Look at that rat! How about that? He's chasing a cat.
0:13:16 > 0:13:20- Why are you talking in rhyme? - I'm not. At least not a lot.
0:13:20 > 0:13:21Yes, you are. And it's gone too far.
0:13:21 > 0:13:23Oh, now I'm doing it too.
0:13:23 > 0:13:26- Oh, get you. - Seriously. Let's stop now.
0:13:26 > 0:13:28- Yeah, OK.- What have we learnt this week?
0:13:28 > 0:13:32- Oh, uh...pets are weird. - Very good. Anything else?
0:13:32 > 0:13:34Yeah, you don't like light-hearted rhymes.
0:13:34 > 0:13:37- That's true.- Yeah.- What else? - I can't think of anything else.
0:13:37 > 0:13:39Well I've learned the best way to get rid of you
0:13:39 > 0:13:42- if I want a bit of peace and quiet. - Oh, go on.
0:13:42 > 0:13:44Here, bunny, bunny, bunny!
0:13:44 > 0:13:45HE GASPS
0:13:45 > 0:13:49# Rabbit, rabbit, rabbit, rabbit... #
0:13:49 > 0:13:51See you next time!
0:13:51 > 0:13:54# They're wild and weird Wild and weird
0:13:54 > 0:13:56# Really, really wild and really, really weird
0:13:56 > 0:13:58# They're wild and weird, wild and weird
0:13:58 > 0:14:00# They're really, really wild and really, really wild
0:14:00 > 0:14:04# And weird! #
0:14:05 > 0:14:08Wild and weird!