0:00:02 > 0:00:04Australia, home of the possum, cool surfer dudes, strange lingo...
0:00:04 > 0:00:05No worries, mate, fair dinkum.
0:00:05 > 0:00:08..Lots of sunshine and the bonza Barrier Reef.
0:00:08 > 0:00:12It's the biggest, most spectacular coral reef in the world.
0:00:12 > 0:00:14What's more, every creature is linked to another.
0:00:14 > 0:00:18Imagine one huge family tree dating back 18 million years...
0:00:18 > 0:00:22from the miniscule to the mammoth to the miraculous.
0:00:22 > 0:00:25They're all connected in Barney's Barrier Reef.
0:00:45 > 0:00:47Come on, I've got something to show you.
0:00:47 > 0:00:49I don't want it, I'm chilling in my hut.
0:00:49 > 0:00:51- In YOUR hut?- Yes, look.
0:00:51 > 0:00:55Everybody knows that we all need our own space, Barney.
0:00:55 > 0:00:58See this line here? Your space.
0:00:58 > 0:01:01Over here, my space.
0:01:01 > 0:01:02In fact...
0:01:04 > 0:01:07Home is where the heart is.
0:01:07 > 0:01:10You know what, the reef community is no different to this either.
0:01:10 > 0:01:13The reef is like its own very special country
0:01:13 > 0:01:16with each ocean creature competing for their own space.
0:01:16 > 0:01:20From mobile homes to caravans to their own unique rental agreements,
0:01:20 > 0:01:22the reef has every type of accommodation.
0:01:22 > 0:01:24That's yours...
0:01:24 > 0:01:28It's time to dive deep and discover why there's no place like home.
0:01:28 > 0:01:30Yeah, I agree.
0:01:35 > 0:01:38Hah! There we go. Home sweet home.
0:01:47 > 0:01:50Corals are the biggest colonies of living animals in the reef.
0:01:50 > 0:01:54It might look like a plant but there's a lot more to it than that.
0:01:54 > 0:01:56Corals dominate the areas they live in.
0:01:56 > 0:02:00When they set up home, they cover 80% of the reef.
0:02:00 > 0:02:02They're like the big reef landlords
0:02:02 > 0:02:04and provide comfy homes for many creatures.
0:02:04 > 0:02:08So I see. Crabs, shrimps, yellow feathery things, you name it.
0:02:08 > 0:02:12From the colourful to the spiky, cute, funny and...
0:02:12 > 0:02:13ugly.
0:02:13 > 0:02:16Hey, who are you calling ugly?
0:02:16 > 0:02:18Sorry, big guy. No offence.
0:02:18 > 0:02:22Corals are the cities of the reef, like London, New York or Sydney.
0:02:22 > 0:02:26There are high-rises, basement flats and modern deluxe penthouses.
0:02:26 > 0:02:29And they're called loads of different things -
0:02:29 > 0:02:31branching, boulder and brain coral.
0:02:31 > 0:02:33I can see why it's called that.
0:02:33 > 0:02:35Are you sure that didn't belong to a person?
0:02:35 > 0:02:39If coral is a kind of housing estate, what about the tenants?
0:02:41 > 0:02:44Let me introduce our first home-lover, the zooxanthellae.
0:02:44 > 0:02:46The whatathelly?
0:02:46 > 0:02:50Zooxanthellae. They're tiny plants that kind of pay rent to the corals
0:02:50 > 0:02:54by gathering energy from the sun and then passing this on as food
0:02:54 > 0:02:56to their coral landlord.
0:02:56 > 0:02:59In return, the corals provide shelter, protection and food,
0:02:59 > 0:03:01mainly in the form of waste.
0:03:01 > 0:03:05- What kind of waste?- Well, all the stuff the coral doesn't need.
0:03:05 > 0:03:07Their garbage, basically.
0:03:07 > 0:03:09That's not my idea of a good deal.
0:03:09 > 0:03:12So, the Zoothe-thingy is connected to our coral
0:03:12 > 0:03:15by being a coral-dweller, like a kind of tenant.
0:03:15 > 0:03:18Yup, the zooxanthellae is a tenant in the mighty
0:03:18 > 0:03:22coral housing estate and they're connected by their rental agreement.
0:03:22 > 0:03:24Who else lives in our coral housing estate?
0:03:24 > 0:03:25Next connection, please.
0:03:27 > 0:03:30More coral? Hang on, what's that blue toilet-brush?
0:03:30 > 0:03:35It's called a Christmas tree worm and it also lives in the coral
0:03:35 > 0:03:37which creates a soft and safe home for the worm.
0:03:37 > 0:03:41Christmas tree worm, cos it's shaped like a Christmas tree. Clever.
0:03:41 > 0:03:42That's not a worm though!
0:03:42 > 0:03:45I've got loads in my garden that don't look like that.
0:03:45 > 0:03:47although I'd be quite happy if they did.
0:03:47 > 0:03:51Well, worms are everywhere and the ocean's no different.
0:03:51 > 0:03:55When they're little, the Christmas tree worm swims around till it finds
0:03:55 > 0:03:59a bare patch to live on live coral, like where a fish has had a chomp.
0:03:59 > 0:04:04It settles onto this patch and waits for the coral to grow around it as it heals.
0:04:04 > 0:04:05They're playing hide and seek.
0:04:05 > 0:04:09Cute! They're very sensitive to disturbances and vibrations
0:04:09 > 0:04:13- and so quickly retract. They're quite shy.- Bless 'em!
0:04:13 > 0:04:14When they think the danger's over,
0:04:14 > 0:04:18they'll reappear and test the water before fully extending.
0:04:18 > 0:04:21Pretty yet clever worms. Now that's a first.
0:04:21 > 0:04:23Poor old coral, it's got heaps of stuff living in it.
0:04:23 > 0:04:26The Zoo-thingies lived in the coral too, didn't they?
0:04:26 > 0:04:29Zooxanthellae, that's right.
0:04:29 > 0:04:32The Christmas tree worms are linked to the zooxan-diddlybum
0:04:32 > 0:04:36because they both make homes in the coral. OK, who's our next contender?
0:04:36 > 0:04:40Hang on, we've had corals. They're the and cities of the ocean,
0:04:40 > 0:04:42towering over everything, blah blah blah...
0:04:42 > 0:04:46That's when they're providing a home for everything else.
0:04:46 > 0:04:48When they need to find their own space, it's different.
0:04:48 > 0:04:51That's when they get really competitive.
0:04:51 > 0:04:54But how can corals be competitive?
0:04:54 > 0:04:58They're just there. It's not like they can run away or anything.
0:04:58 > 0:05:00That's where you're wrong. Once fully-grown,
0:05:00 > 0:05:03- it's every coral for itself. - Yeah but why?
0:05:03 > 0:05:06Cos I mean the seabed's big enough for loads of corals, surely?
0:05:06 > 0:05:08But like anyone looking for a home,
0:05:08 > 0:05:10they want the best spot which in their case
0:05:10 > 0:05:14is the sunniest part away from the force of breaking waves.
0:05:14 > 0:05:17Some corals will simply try to compete with their neighbours
0:05:17 > 0:05:19by growing faster, higher or wider.
0:05:19 > 0:05:22Or, if another coral is moving too close,
0:05:22 > 0:05:26they can send out stinging tentacles to try and fight it off.
0:05:26 > 0:05:27'Alien vessel approaching.'
0:05:27 > 0:05:30Is there anything in this reef that doesn't sting?
0:05:30 > 0:05:34Yeah, most animals, really. But coral certainly can.
0:05:34 > 0:05:36Its other weapon is to push its stomach
0:05:36 > 0:05:41on the outside of their mouth and digest the other coral.
0:05:41 > 0:05:43'Alien vessel approaching.'
0:05:43 > 0:05:48OK, nope. That, I wouldn't do. Even for the sunniest house in Britain.
0:05:48 > 0:05:53- Hang on a minute, though. The sun in Oz is pretty deadly, right?- Yes.
0:05:53 > 0:05:57- So why don't they dry out?- I'm glad you asked that question, Barney.
0:05:57 > 0:05:59They produce their own sun block.
0:05:59 > 0:06:02Cool! Coral sun block. Now that's something I'd like to try.
0:06:02 > 0:06:05Probably not. It comes in the form of a sticky, smelly mucus.
0:06:05 > 0:06:07Ah, that's gross. I like it, though.
0:06:07 > 0:06:11It is pretty amazing. No, no... that's the middle bit, there.
0:06:11 > 0:06:13My side, your side. Very good.
0:06:13 > 0:06:16It is pretty amazing that corals fight each other for space.
0:06:16 > 0:06:18It's a bit like the Christmas tree worm
0:06:18 > 0:06:20cos they fight coral too, for a bit of their turf.
0:06:20 > 0:06:22Now that's my side just there.
0:06:22 > 0:06:25That's it... that's mine, that's yours.
0:06:25 > 0:06:28Competitive corals are linked to our Christmas tree worm
0:06:28 > 0:06:30as they both survive by damaging coral.
0:06:32 > 0:06:34Oh, wow, moving rocks!
0:06:34 > 0:06:35Oh, no, wait... turtles.
0:06:35 > 0:06:38Why do they stick their necks out? It can't be comfortable.
0:06:38 > 0:06:41- Are they stuck? - They're not like tortoises.
0:06:41 > 0:06:43They can't pull their heads back into their shells.
0:06:43 > 0:06:49They're really quite amazing. Do you know they can grow to over 160kg?
0:06:49 > 0:06:52That's like the equivalent of 40 cats.
0:06:52 > 0:06:56Imagine trying to pick up 40 cats or one very big one!
0:06:56 > 0:06:59It's no wonder they can't move very fast.
0:06:59 > 0:07:02Why are they throwing sand everywhere? Are they having fun?
0:07:02 > 0:07:06Well, she is. That is a nesting female digging a hole for her eggs.
0:07:06 > 0:07:10She's not getting very far. She's just flinging sand everywhere.
0:07:10 > 0:07:13I know it looks chaotic but she'll get there in the end
0:07:13 > 0:07:15and end up covered in sand.
0:07:15 > 0:07:16Oops!
0:07:16 > 0:07:18So what's she doing now?
0:07:18 > 0:07:22She's laying her eggs into the chamber at the bottom of the pit.
0:07:22 > 0:07:24She's gathering sand using one flipper at a time,
0:07:24 > 0:07:26a bit like us using a cupped hand,
0:07:26 > 0:07:28and throwing the sand away from the chamber
0:07:28 > 0:07:30so it's ready for laying her eggs.
0:07:30 > 0:07:31Whoa! It's like a pinball machine.
0:07:31 > 0:07:34I know what you mean! She's made a safe home for her eggs.
0:07:34 > 0:07:37Now she starts to get paranoid.
0:07:37 > 0:07:39Like any mother, she wants to do the best for her kids.
0:07:39 > 0:07:42No matter what movement or disturbances happen,
0:07:42 > 0:07:45like passing humans, she just carries on finishing the nest.
0:07:45 > 0:07:47Or flinging sand about.
0:07:47 > 0:07:51- Yeah, they do go a bit wild. - It's a bit crowded on that beach.
0:07:51 > 0:07:55Yeah, there's about 20,000 turtles nesting.
0:07:55 > 0:07:57Hang on a minute, hold the film...
0:07:57 > 0:07:59that's 20,000 turtles on an island
0:07:59 > 0:08:03the size of about 32 football pitches? That's mad.
0:08:03 > 0:08:07Yup, about 625 turtles per football pitch all trying
0:08:07 > 0:08:11to find space for their babies, so no wonder they're competitive.
0:08:11 > 0:08:16- Now that is a cute baby turtle! - I know!
0:08:16 > 0:08:19After two months, the babies dig their way out at night and then race
0:08:19 > 0:08:23down to the sea to avoid being eaten by predators and then they're off!
0:08:23 > 0:08:24They're pretty independent.
0:08:24 > 0:08:28They move much quicker in the water. That's almost fast for a turtle.
0:08:28 > 0:08:30I know, clumsy on land, graceful in water.
0:08:30 > 0:08:33So, the connection here, I'm guessing, is competition?
0:08:33 > 0:08:36The corals were competing for a prime spot on the reef
0:08:36 > 0:08:39and the mother turtles competing for the best home for their eggs.
0:08:39 > 0:08:41Absolutely.
0:08:41 > 0:08:43Isn't it lovely how all these ocean creatures
0:08:43 > 0:08:44have their own special place?
0:08:44 > 0:08:46So, Barney, remind me,
0:08:46 > 0:08:50how did we get from the corals to the turtles again?
0:08:57 > 0:08:59We started off with the corals...
0:08:59 > 0:09:01our ultimate housing estate and home provider.
0:09:01 > 0:09:03They're landlords to the zooxanthellae
0:09:03 > 0:09:07and pretty Christmas tree worms who also link to competitive coral,
0:09:07 > 0:09:10who are obsessed with owning the sunniest spot in the reef.
0:09:10 > 0:09:14Nearly as competitive as our mummy turtles whose wild flinging
0:09:14 > 0:09:17of sand is a ploy to put their eggs in the safest housing,
0:09:17 > 0:09:19no matter who else got there first.
0:09:19 > 0:09:23Enter our next contender, looking for a home sweet home.
0:09:27 > 0:09:31So, who connects to our proud mum, the turtle?
0:09:31 > 0:09:35Our friend the shark. Wowsers, those are some pretty big teeth.
0:09:35 > 0:09:37Actually, these are grey nurse sharks.
0:09:37 > 0:09:40They might look scary with their snagging teeth
0:09:40 > 0:09:42but they're pretty placid, really.
0:09:42 > 0:09:46Those teeth are good for holding fish but they're not flesh-rippers
0:09:46 > 0:09:47like other sharks.
0:09:47 > 0:09:48Oh, a friendly shark?
0:09:48 > 0:09:52- That's a new one.- Well, most are pretty harmless to be honest.
0:09:52 > 0:09:53Not convinced just yet.
0:09:53 > 0:09:56Surely they don't have problems looking for a home?
0:09:56 > 0:09:58They're big and look scary.
0:09:58 > 0:10:01No, they don't have problems finding a home to chill in
0:10:01 > 0:10:03but for their babies, it's different.
0:10:04 > 0:10:07- This is the worst case of sibling rivalry you'll ever hear about.
0:10:07 > 0:10:10- Uh-oh.- Brace yourself.
0:10:10 > 0:10:13So, nurse shark eggs hatch inside the mother shark.
0:10:13 > 0:10:15Yeah, not shocked yet.
0:10:15 > 0:10:20When the pups are born, they're only about the size of a small sausage.
0:10:20 > 0:10:23Pups? Like puppies, OK.
0:10:23 > 0:10:26Yup, small but certainly not shy.
0:10:26 > 0:10:29These tiny baby sharks do the unimaginable.
0:10:29 > 0:10:33They start to eat each other.
0:10:33 > 0:10:35Whoa, hang on!
0:10:35 > 0:10:38What, they start to eat their own brothers and sisters?
0:10:38 > 0:10:39They must be hungry!
0:10:39 > 0:10:42No, it's not about their hunger,
0:10:42 > 0:10:45This is an example of sibling rivalry to the extreme.
0:10:45 > 0:10:49Again, it's all about them competing for space in their mum's belly
0:10:49 > 0:10:52because they're a metre long when they're actually born.
0:10:52 > 0:10:56- A metre? That is a big baby. - That's the thing -
0:10:56 > 0:10:58their mum is just over two metres herself,
0:10:58 > 0:11:02so it's like giving birth to something half her size.
0:11:02 > 0:11:03They fight to the death
0:11:03 > 0:11:07because they're basically securing their place in their first home.
0:11:07 > 0:11:12It's survival of the fittest and out of about 80 eggs, only two are born.
0:11:12 > 0:11:16Respect to the sharks. Those are some big babies.
0:11:16 > 0:11:19So, the mother turtle competes fiercely for a home for her eggs
0:11:19 > 0:11:22and the grey nurse pups compete fiercely for their own space
0:11:22 > 0:11:23inside their mum.
0:11:23 > 0:11:26So grey nurse sharks are connected to our turtles
0:11:26 > 0:11:27by what else but competition.
0:11:27 > 0:11:31Step up, our next contender, the hermit crab.
0:11:34 > 0:11:35Ah, I've heard of this guy.
0:11:35 > 0:11:39He carries his shell on his back, like a portable home. Next!
0:11:39 > 0:11:43- As ever, it's not quite as simple as that, Barney.- Of course not.
0:11:43 > 0:11:45As you said, this crab is famous
0:11:45 > 0:11:48for nicking abandoned shells for its home.
0:11:48 > 0:11:50I always thought that was weird.
0:11:50 > 0:11:52- It's like wearing someone else's pants.- I agree.
0:11:52 > 0:11:54They'll go to any extreme.
0:11:54 > 0:11:57Sometimes, when there aren't shells available,
0:11:57 > 0:11:59they have to make do with what they can find.
0:11:59 > 0:12:03Hermit crabs have been found wearing bottle-tops
0:12:03 > 0:12:05or even bits of pipe like this one.
0:12:05 > 0:12:10If he keeps this pipe as his home, he'll end up growing pipe-shaped.
0:12:10 > 0:12:13He'll have a pipe-shaped bottom! I bet the other crabs laugh at him.
0:12:13 > 0:12:16Possibly. Unless they're the ones wearing the bottle tops!
0:12:16 > 0:12:20- Do they stay in the same shell, or bottle top, forever?- No.
0:12:20 > 0:12:23As they grow, they need bigger houses, a bit like us.
0:12:23 > 0:12:26You wouldn't want to stay in your Wendy house forever.
0:12:26 > 0:12:29I'll have you know I've never stayed in a Wendy house.
0:12:29 > 0:12:31Although I did have a friend called Wendy and I stayed with her once.
0:12:31 > 0:12:32You know what I mean.
0:12:32 > 0:12:35Anyway, this is when it gets really competitive.
0:12:35 > 0:12:37Good homes are not always available
0:12:37 > 0:12:40and the crabs really go to war when they need one.
0:12:40 > 0:12:43- Crab wars, great!- Like these two.
0:12:49 > 0:12:51Haw-ya!
0:12:51 > 0:12:54Hai! Hai!
0:12:57 > 0:13:00Firstly, he tries to drown him in sand
0:13:00 > 0:13:03and then go in for the comedy chase option.
0:13:03 > 0:13:06Their life depends on it. A hermit crab without a shell
0:13:06 > 0:13:10or a home of some kind is not going to survive very long in the ocean.
0:13:10 > 0:13:13So, as ever, it's one crab for itself.
0:13:13 > 0:13:15Crabs fight to the death to find new homes.
0:13:15 > 0:13:17I can sense a running theme here.
0:13:17 > 0:13:20You're right, the link is competition again,
0:13:20 > 0:13:22for a decent home to survive.
0:13:22 > 0:13:24Both the grey nurse sharks and hermit crabs
0:13:24 > 0:13:27make sure they do survive, whatever it takes.
0:13:30 > 0:13:32Next, the anemone.
0:13:32 > 0:13:33Ah, one of my favourites.
0:13:33 > 0:13:35# Anemone Ba ba ba da-da... #
0:13:35 > 0:13:38But I've never seen an anemone move like that!
0:13:38 > 0:13:42That's because he's hitching a ride with a hermit crab.
0:13:42 > 0:13:46What a complete freeloader. These anemones get everywhere.
0:13:46 > 0:13:48They encourage the anemone because they know that anemones
0:13:48 > 0:13:52can sting and scare away predators that might want to eat them.
0:13:52 > 0:13:54OK, but what does the sea anemone get out of this?
0:13:54 > 0:13:56A free home for a start.
0:13:56 > 0:13:58A mobile home as well.
0:13:58 > 0:14:01And they're in a good position to gobble up the crab's food.
0:14:01 > 0:14:05Another I'll scratch your back and you scratch mine-relationship.
0:14:05 > 0:14:06Except this one is,
0:14:06 > 0:14:10"I'll hitch a ride on your back and gobble up your crumbs."
0:14:10 > 0:14:12And sting your enemies, so it works well.
0:14:12 > 0:14:14So the anemone is connected to the hermit crab
0:14:14 > 0:14:16which steals other animal's shells to live in
0:14:16 > 0:14:17because they both have mobile homes.
0:14:17 > 0:14:21Correct. Enter our next entrant in our home-sweet-home category.
0:14:23 > 0:14:26What's so special about this geezer?
0:14:26 > 0:14:30Apart from the fact that he's got a leopard-skin top and domino bottom.
0:14:30 > 0:14:33Let me introduce Mr Triggerfish.
0:14:33 > 0:14:35Wow, he's got a big mouth.
0:14:35 > 0:14:36Hello!
0:14:36 > 0:14:40He's got rat-like sharp teeth and a spiny dorsal fin.
0:14:40 > 0:14:44The first spine is very long and then they go down in size.
0:14:44 > 0:14:47When the fish is in his home, the first of his spines
0:14:47 > 0:14:48is locked upright by the second
0:14:48 > 0:14:52and drops only when the second is pressed like a trigger.
0:14:52 > 0:14:53Hence the name. Clever.
0:14:53 > 0:14:57They do this so they can lock themselves firmly in a mass of coral
0:14:57 > 0:15:00and that will be their home for the night or till danger has passed.
0:15:00 > 0:15:03So they can sleep anywhere and lock themselves in
0:15:03 > 0:15:04using their spiny fin?
0:15:04 > 0:15:07Yeah. They're like the hotel-dwellers of the reef
0:15:07 > 0:15:11staying wherever is convenient or safe for the night.
0:15:11 > 0:15:15- Don't forget to lock yourself in nice and tight.- Righty-o.
0:15:15 > 0:15:18They're a bit like the anemone that lives on the hermit crab
0:15:18 > 0:15:21because they can move house whenever they fancy .
0:15:21 > 0:15:24Right, triggerfish are linked to the anemones
0:15:24 > 0:15:26because they can change their home. Next?
0:15:26 > 0:15:29Who links to our hotel guest the triggerfish?
0:15:29 > 0:15:31Our friend the parrotfish.
0:15:31 > 0:15:34Ah, yes, ordinary-looking fish with a mouth of steel.
0:15:34 > 0:15:37And, let's not forget, a sand-blasted bottom.
0:15:37 > 0:15:39Trust you to remember they poo sand.
0:15:39 > 0:15:43Yes, the parrotfish spend the day in schools, chomping algae off rocks
0:15:43 > 0:15:46but at night they separate and search for somewhere to sleep.
0:15:46 > 0:15:49So where do they go? Under rocks and stuff?
0:15:49 > 0:15:52Yeah, in coral mainly. But, like the triggerfish,
0:15:52 > 0:15:54they choose different places each night.
0:15:54 > 0:15:58The difference with these guys is they make their own sleeping bag
0:15:58 > 0:16:01or tent and kind of camp out for the night.
0:16:01 > 0:16:02Could you run that past me again?
0:16:02 > 0:16:04Let's start with the word "how"?
0:16:04 > 0:16:08- It's another fascinating use of mucus.- Snot?
0:16:08 > 0:16:11Yes, they release mucus and wrap it around themselves
0:16:11 > 0:16:13before they sleep.
0:16:13 > 0:16:16OK, well this is an obvious question - why?
0:16:16 > 0:16:20It protects them from predators that hunt by smell, like sharks.
0:16:20 > 0:16:24So it's kind of a mixture of sleeping bag and armour.
0:16:24 > 0:16:27Another ingenious use of bodily excretions to create a bed
0:16:27 > 0:16:31- for the night.- Hehe! A sleeping bag made out of snot. I love it.
0:16:31 > 0:16:35And it snot, I mean, it's not a quick process either.
0:16:35 > 0:16:37It takes half an hour to make the cocoon
0:16:37 > 0:16:39and almost as long to get out.
0:16:39 > 0:16:42And, they eat their way out.
0:16:42 > 0:16:43What?
0:16:43 > 0:16:47Ho ho! They eat their own snot.
0:16:47 > 0:16:49That is gross!
0:16:49 > 0:16:51It's another clever way of camping out on the reef.
0:16:51 > 0:16:55So, the triggerfish and the parrotfish are both reef campers.
0:16:55 > 0:16:58That's another solid creature connection.
0:16:58 > 0:17:02Hang on a minute, I need a reef-cap.
0:17:10 > 0:17:13So, our competitive mother turtles connected us
0:17:13 > 0:17:16to the grey nurse shark pups who eat each other to make more space.
0:17:16 > 0:17:22That is so gross! Competition also links us to our hermit crabs.
0:17:22 > 0:17:26These guys argue over who has to have the biggest shell. Thank you.
0:17:32 > 0:17:35The hermit crab's mobile home also links him
0:17:35 > 0:17:37to the piggy-backing anemone
0:17:37 > 0:17:40who grabs a free ride and can move house whenever he wants...
0:17:40 > 0:17:42just like the roaming triggerfish.
0:17:42 > 0:17:45The triggerfish and parrotfish are both expert
0:17:45 > 0:17:46at camping out in the reef.
0:17:46 > 0:17:50So, talking of parrotfish, who on earth are they connected to?
0:17:52 > 0:17:54White-tipped reef sharks. Where do they sleep?
0:17:54 > 0:17:56They're the kings of the ocean.
0:17:56 > 0:18:00They don't need snot sleeping bags or to burrow themselves away.
0:18:00 > 0:18:05Absolutely. The shark is a bit like your millionaire penthouse owner.
0:18:05 > 0:18:09They get the best spot, the best view and very little disturbance.
0:18:09 > 0:18:11I didn't think sharks needed to sleep.
0:18:11 > 0:18:14They're always hunting or scaring things.
0:18:14 > 0:18:15Ay! Har har!
0:18:15 > 0:18:19True, some sharks don't sleep and have to keep moving to stay alive
0:18:19 > 0:18:22because they breathe by passing water over their gills.
0:18:22 > 0:18:25But this species of shark,
0:18:25 > 0:18:28a bottom-dwelling shark, like a snooze whenever they can.
0:18:28 > 0:18:29It looks like it.
0:18:29 > 0:18:33This geezer has all the space he needs in his penthouse spot.
0:18:33 > 0:18:36So, as ever, the shark gets what he wants with no hassle.
0:18:36 > 0:18:38I suppose the parrotfish we saw just now
0:18:38 > 0:18:39have got a pretty good deal too.
0:18:39 > 0:18:42They can build their own rooms wherever they like.
0:18:42 > 0:18:44The shark and the parrotfish are linked
0:18:44 > 0:18:47because they're both lucky enough to pick their own homes for the night.
0:18:51 > 0:18:54- The rock-moving wrasse. - There's a clue in that title.
0:18:54 > 0:18:56Meet the rocking wrasse, as I like to call them.
0:18:56 > 0:18:59Yeah, it just looks like another fish to me.
0:18:59 > 0:19:02Barney, there's no such thing in the reef as, "just another fish."
0:19:02 > 0:19:04These guys are really cool.
0:19:04 > 0:19:07- Yeah, cos they move rocks. - And they do more than that.
0:19:07 > 0:19:09These fish can be seen moving boulders
0:19:09 > 0:19:12- much bigger than themselves.- OK, that's pretty cool.
0:19:12 > 0:19:15It's very cool. It's like you lifting a whole car on your own.
0:19:15 > 0:19:17Yeah, that's a piece of cake.
0:19:17 > 0:19:20- With my muscles, it's a doddle. - Yeah, if you say so.
0:19:20 > 0:19:22Why do they move rocks? It's not just for fun.
0:19:22 > 0:19:25They work in pairs. They choose their space
0:19:25 > 0:19:27and while one fish shifts large pieces of rock,
0:19:27 > 0:19:30revealing their prey, the other grabs it and eats it.
0:19:30 > 0:19:33That sounds like good teamwork. But am I missing something?
0:19:33 > 0:19:34I mean, they're fish.
0:19:34 > 0:19:36How do they pick rocks up?
0:19:36 > 0:19:39They pull it with their mouths and push with their snouts.
0:19:39 > 0:19:42That is impressive, especially if they're moving
0:19:42 > 0:19:44something twice their body weight.
0:19:44 > 0:19:46They must have strong mouths.
0:19:46 > 0:19:50And they can continue to build new homes for themselves every night
0:19:50 > 0:19:52by collecting rubble off the sea floor.
0:19:52 > 0:19:55They construct themselves a mound to stay in for the night
0:19:55 > 0:19:56and then move on,
0:19:56 > 0:19:59just like having a new hotel room every night. How extravagant!
0:19:59 > 0:20:01Yep, they're great landscapers.
0:20:01 > 0:20:03They can rearrange any area to suit them,
0:20:03 > 0:20:05thanks to their strong teeth and flexible frame.
0:20:05 > 0:20:10So, our rock-moving wrasse pick their homes wherever
0:20:10 > 0:20:12they please, just like our penthouse suite sharks...
0:20:12 > 0:20:15except the wrasse works a lot harder for it.
0:20:15 > 0:20:16Next, the soldier crab.
0:20:16 > 0:20:19Is it me, or are crabs just quite comical?
0:20:19 > 0:20:21They walk sideways but quickly.
0:20:21 > 0:20:23There's loads of them running together.
0:20:23 > 0:20:26That's how they get their name - the soldier crab.
0:20:26 > 0:20:30- They come out at low tide and troop about.- Why so many?
0:20:30 > 0:20:32They're like ants in a way.
0:20:32 > 0:20:35They come out in their thousands and dig their homes in the sand.
0:20:35 > 0:20:38Is that what those squiggly bits are?
0:20:38 > 0:20:41They dig in a corkscrew pattern so you can see clearly
0:20:41 > 0:20:42where their homes are.
0:20:42 > 0:20:43But they're quite safe.
0:20:43 > 0:20:46Let me guess, they link back to the rock-moving wrasse
0:20:46 > 0:20:48because they're also workmen.
0:20:48 > 0:20:51The wrasse construct their homes and the crabs dig theirs.
0:20:51 > 0:20:54Spot on. Another ocean digger, the soldier crab,
0:20:54 > 0:20:56is linked to our rock-moving wrasse by digging.
0:20:56 > 0:21:00So let's see if you can guess our next homely creature.
0:21:01 > 0:21:03OK, what's going on here?
0:21:03 > 0:21:05Is this another obsessively clean shrimp?
0:21:05 > 0:21:08He is a bit obsessive but he's doing it for a reason.
0:21:08 > 0:21:12Is it because those yellow fish are clearly just lazy?
0:21:12 > 0:21:15No, this is another classic symbiotic relationship.
0:21:15 > 0:21:18Yes, when creatures hook up together to help each other out.
0:21:18 > 0:21:22Exactly. These fish are gobies and, unlikely though it seems,
0:21:22 > 0:21:24they're all flatmates.
0:21:24 > 0:21:26Ah, it's the ocean's version of Friends.
0:21:26 > 0:21:30Kind of... but they're not just hanging around drinking cappuccinos.
0:21:30 > 0:21:33The shrimp makes a burrow in the sand where they all live
0:21:33 > 0:21:34and the gobies kind of keep watch.
0:21:34 > 0:21:38In fact, the goby is sometimes nicknamed the watchman goby.
0:21:38 > 0:21:42- Stay away from my shrimp friend. - Does he ever take a tea break?
0:21:42 > 0:21:44Seems to me like he gets the raw end of the deal.
0:21:44 > 0:21:47Maybe. They keep in touch through the shrimp's antennae
0:21:47 > 0:21:50and the goby flicking its tail when it's alarmed.
0:21:50 > 0:21:52This shrimp hasn't got very good eyesight
0:21:52 > 0:21:53but if he feels the goby's flick,
0:21:53 > 0:21:56he's straight in that burrow followed quickly by the goby.
0:21:56 > 0:21:58At night time, the shrimp will collapse the entrance
0:21:58 > 0:22:01once all the flatmates are inside, for protection.
0:22:01 > 0:22:04But then he'll have to start his digging all over again
0:22:04 > 0:22:04to get them out.
0:22:04 > 0:22:06Remind me not to come back as a shrimp!
0:22:06 > 0:22:09Far too much like hard work.
0:22:09 > 0:22:12I think the shrimp can be awarded the ocean's most house-proud award.
0:22:12 > 0:22:16I wouldn't want to be his flatmate. He'd nag me to put away me pants.
0:22:16 > 0:22:17And that's a bad thing?
0:22:17 > 0:22:20He's even more neat and tidy than the soldier crab,
0:22:20 > 0:22:23with his squiggly, muddy burrow.
0:22:24 > 0:22:27Why are we looking at a load of swaying grass?
0:22:27 > 0:22:30Let's go a little closer.
0:22:30 > 0:22:32Wow, look - the grass is alive.
0:22:32 > 0:22:36These are the garden eels, one of the weirdest sights in the ocean.
0:22:36 > 0:22:40They live in communities of up to several hundred of them.
0:22:40 > 0:22:42Is there a reason why they're dancing?
0:22:42 > 0:22:46They're busting some pretty good moves, actually. Body-popping!
0:22:46 > 0:22:47They're eating plankton,
0:22:47 > 0:22:51although they do look like they're all swaying to the same music.
0:22:51 > 0:22:54It's like they're at one of those silent discos.
0:22:54 > 0:22:58They dig their burrow with their tails and then they just stay there.
0:22:58 > 0:22:59- What, forever?- No.
0:22:59 > 0:23:01The big eyes they have work quite well
0:23:01 > 0:23:03because when they see a predator,
0:23:03 > 0:23:04they can pop down into their burrows.
0:23:04 > 0:23:07They look out for each other too, like a real community should.
0:23:07 > 0:23:10If one eel hasn't seen the danger approaching, they rely
0:23:10 > 0:23:13on the other eels moving to tell them all about it.
0:23:13 > 0:23:16Pretty handy. So they're like a neighbourhood watch scheme.
0:23:16 > 0:23:19It's nice to see some animals looking out for one another.
0:23:19 > 0:23:21Almost as friendly as our shrimp and goby living in the same burrow.
0:23:21 > 0:23:23They're linked to our goby and shrimp
0:23:23 > 0:23:26because they watch each others' backs. Next!
0:23:27 > 0:23:31Whoa, spooky. Is this a shipwreck?
0:23:31 > 0:23:34- I love them.- Yep, this one is called the Yongala Wreck.
0:23:34 > 0:23:39It was a passenger and cargo ship with 122 people on board
0:23:39 > 0:23:41that got lost in a cyclone in 1911.
0:23:41 > 0:23:46It was a mystery where it went but it was found again in 1947.
0:23:46 > 0:23:48Now, it's a world-famous wreck site
0:23:48 > 0:23:51which is home to loads of different animals.
0:23:51 > 0:23:53Look, you can see the port-holes there.
0:23:53 > 0:23:56- That's the stern and the rudder.- It's so eerie.
0:23:56 > 0:23:57Do you reckon that's the mast?
0:23:57 > 0:24:01Yeah and wouldn't that be the cabins? Or the cargo holds?
0:24:01 > 0:24:02Look, there's an electric fan.
0:24:02 > 0:24:04And the toilets! How old is that poo?
0:24:04 > 0:24:08Yep, the ocean creatures love to have a new home to play with.
0:24:08 > 0:24:13A shipwreck is just one example of what is known as an artificial reef.
0:24:13 > 0:24:14I bet the fish like it.
0:24:14 > 0:24:17A wreck like this must be like exploring a new playground.
0:24:17 > 0:24:18Some of these false reefs
0:24:18 > 0:24:21give homes to a variety of different animals.
0:24:21 > 0:24:24There's a manta ray, swimming alongside a school of trevally,
0:24:24 > 0:24:27and the odd nosy diver.
0:24:27 > 0:24:31Wrecks are like a ready-made home and there's a space for everyone.
0:24:31 > 0:24:34It's a real community, all bundled into a small space,
0:24:34 > 0:24:35just like our sociable garden eels.
0:24:35 > 0:24:38So garden eels live in communities
0:24:38 > 0:24:42and shipwrecks create communities. That's the connection.
0:24:42 > 0:24:43Trees? In the reef?
0:24:43 > 0:24:47These are mangroves. They're kind of small forests on the coastline
0:24:47 > 0:24:49and on islands of the barrier reef.
0:24:49 > 0:24:51They help hold the earth together
0:24:51 > 0:24:53and stop dirt spilling into the ocean.
0:24:53 > 0:24:56So they're useful but there's not much happening.
0:24:56 > 0:25:00- It's very calm and peaceful. - That's the point, my dear Gemma.
0:25:00 > 0:25:03Uh-oh, why do I have the feeling you're about to go
0:25:03 > 0:25:04all scientific on me?
0:25:04 > 0:25:07'And now for the science.'
0:25:07 > 0:25:11Mangroves, like corals, make up a living community, where all sorts
0:25:11 > 0:25:15of animals choose to live together on a temporary or long-term basis.
0:25:15 > 0:25:18Crabs, jellyfish, lobsters, fish, reptiles and birds.
0:25:18 > 0:25:22Really, Dr Barnacles, it sounds like the reef's getting a bit full.
0:25:22 > 0:25:25Is it like living on the outskirts of a big city?
0:25:25 > 0:25:29Kind of. The mangrove is essentially a nursery for many reef babies.
0:25:29 > 0:25:32I'm surprised it's so peaceful if it's full of babies!
0:25:32 > 0:25:35Baby reef creatures tend to stick together
0:25:35 > 0:25:38or keep quiet as they know there's a chance they might get eaten.
0:25:38 > 0:25:41But in here, they're much safer.
0:25:41 > 0:25:45So the link between wrecks and mangroves must be community.
0:25:45 > 0:25:47In this case it's a special one for babies.
0:25:56 > 0:25:59Well, one thing's clear about the ocean and that is
0:25:59 > 0:26:02that it is home sweet home for many creatures,
0:26:02 > 0:26:04but in lots of different ways.
0:26:10 > 0:26:13From our coral landlords who safely housed the zooxanthellae
0:26:13 > 0:26:15and Christmas tree worms,
0:26:15 > 0:26:18who also fight amongst themselves for the best patch of sunlit ocean.
0:26:18 > 0:26:20To our ultra-competitive contenders -
0:26:20 > 0:26:24our egg-burrowing mother turtle and rather large shark pups competing
0:26:24 > 0:26:25to the death inside their mum.
0:26:25 > 0:26:26And the hermit crabs,
0:26:26 > 0:26:29fighting for the coolest shell in the ocean.
0:26:29 > 0:26:31And of course the cheeky travelling anemone.
0:26:31 > 0:26:33# Da da da da-da Anemone, da da da da... #
0:26:33 > 0:26:36Who links to our snotty hotel guests,
0:26:36 > 0:26:38the triggerfish and parrotfish.
0:26:38 > 0:26:42Nothing compared to our shark with its penchant for penthouse views.
0:26:42 > 0:26:45Then there are the grafters, the rock-moving wrasse.
0:26:45 > 0:26:46And the digging soldier crabs.
0:26:46 > 0:26:49And the shrimp that cleans up after his goby flatmates.
0:26:49 > 0:26:53You can't knock their sense of community, or the garden eels.
0:26:53 > 0:26:55Or the wreck and its artificial reef gang.
0:26:55 > 0:26:59And don't forget the baby day-care in the mangrove forests.
0:26:59 > 0:27:01Which links us back to the coral...
0:27:01 > 0:27:05the original landlord and homeowner. Much like me!
0:27:07 > 0:27:09Ooh, one last thing.
0:27:11 > 0:27:15That's better. Mine, all mine.
0:27:15 > 0:27:17Home sweet home.
0:27:36 > 0:27:39Subtitles by Red Bee Media Ltd
0:27:39 > 0:27:42E-mail subtitling@bbc.co.uk