0:00:02 > 0:00:05Australia. Home of the possum, cool surfer dudes, strange lingo,
0:00:05 > 0:00:08lots of sunshine and the bonzer barrier reef.
0:00:08 > 0:00:11It's the biggest, most spectacular coral reef in the world,
0:00:11 > 0:00:14and what's more, every creature is linked to another.
0:00:14 > 0:00:18Just imagine one huge family tree dating back 18 million years.
0:00:18 > 0:00:21From the miniscule to the mammoth to the miraculous,
0:00:21 > 0:00:23they're all connected.
0:00:45 > 0:00:46Oh, wow! I've got a parcel!
0:00:46 > 0:00:50Hang on, how did they know I'm here? I'm on a deserted island
0:00:50 > 0:00:52in the middle of nowhere. Ah...!
0:00:52 > 0:00:55"Deserted Island, Middle of Nowhere." Hey, Gem, look!
0:00:55 > 0:00:58- I've got a parcel from my dad. - Ooh!- I'm so excited.
0:00:58 > 0:01:00Families - What would you do without them?
0:01:00 > 0:01:05I'd have a cheaper phone bill, but I couldn't live without them either(!)
0:01:05 > 0:01:09Cool. Back scratchers. I'll use one of those later. Ah, a grass skirt.
0:01:09 > 0:01:10I'll do the hula for you in a bit.
0:01:10 > 0:01:12Oh, a teddy bear. That can go by the bed.
0:01:12 > 0:01:14A picture of Dad, so I don't forget him.
0:01:14 > 0:01:16Ah, a shirt. Good.
0:01:16 > 0:01:18Yes, I probably won't be wearing that.
0:01:18 > 0:01:20Well, maybe for a fancy dress party.
0:01:20 > 0:01:24Who apart from my dad would send me a parcel on a desert island?
0:01:24 > 0:01:26Well, families are made up of lots of different people.
0:01:26 > 0:01:30Mums, dads, brothers, sisters, step-siblings.
0:01:30 > 0:01:32Yes, and families are just as important here.
0:01:32 > 0:01:37There are different families, but are not always nice to each other.
0:01:37 > 0:01:39I know! There's all kinds of kerfuffles!
0:01:39 > 0:01:40Parents desert their babies,
0:01:40 > 0:01:44fierce sibling rivalry, you've got spoilt only children...
0:01:44 > 0:01:47But at the end of the day, they're all family.
0:01:47 > 0:01:51- FRRRRT! - Ah, love it. My dad rocks.
0:01:57 > 0:02:01- Ah, it's Nemo!- Or clownfish, as they're officially known.
0:02:01 > 0:02:03Hey, why don't sharks eat clownfish?
0:02:03 > 0:02:06- I don't know. - Because they taste funny!
0:02:07 > 0:02:10- A-ha-ha(!)- Clownfish.
0:02:10 > 0:02:12- They're not really very funny, are they?- Not really.
0:02:12 > 0:02:15They're called clownfish as they bob around
0:02:15 > 0:02:17in a clownish fashion when they swim.
0:02:17 > 0:02:19It's like they're playing hide and seek!
0:02:19 > 0:02:22It may look like they're clowning around,
0:02:22 > 0:02:25but they're hanging out with their buddies, the anemones.
0:02:25 > 0:02:27Clownfish coat themselves in the anemones' mucus.
0:02:27 > 0:02:31Ew! I wouldn't coat myself in anyone's mucus.
0:02:31 > 0:02:33But it's for a good reason. It allows them to hide out
0:02:33 > 0:02:36in the anemone's tentacles without getting stung.
0:02:36 > 0:02:39Clownfish are careful parents and when it's time for them
0:02:39 > 0:02:42to have a family, they lay eggs near the anemone,
0:02:42 > 0:02:44so they have a safe nursery to hatch in.
0:02:44 > 0:02:47- Cor, these two look busy! - Yep, that's Mum and Dad.
0:02:47 > 0:02:52- They're cleaning up to lay eggs. - Clean, house-proud. I'm impressed.
0:02:52 > 0:02:57Aw, Mum and Dad are playing in some, um, balloon-type things.
0:02:57 > 0:02:58Those are the eggs, Gem.
0:02:58 > 0:03:02Ah, yeah! Bright orange ones. I can see the family resemblance.
0:03:02 > 0:03:05They're not playing. They're looking after them to help them hatch.
0:03:05 > 0:03:08Ah, you're right. They are good parents, aren't they?
0:03:08 > 0:03:10You haven't seen anything yet.
0:03:10 > 0:03:13Now they fan the eggs, to help remove the waste.
0:03:13 > 0:03:17And that goes on for a long, long, long time...
0:03:17 > 0:03:20BARNEY SNORES
0:03:20 > 0:03:22Oh, sorry. Their dad is very protective.
0:03:22 > 0:03:26- He checks that all the hundreds of eggs are OK.- Hundreds of eggs?
0:03:26 > 0:03:28- Whoa! They must be tired.- Oh, yes.
0:03:28 > 0:03:33But all that hard work has paid off and now they have ickle babies.
0:03:33 > 0:03:36- Look at those faces! - Aw, they're so cute!
0:03:36 > 0:03:39They're called clownfish but there's no joking around
0:03:39 > 0:03:41when it comes to being good parents.
0:03:41 > 0:03:45clownfish are great examples of ocean family dedication.
0:03:45 > 0:03:47Both mum and dad are great caring parents.
0:03:47 > 0:03:50So who's the next happy family?
0:03:50 > 0:03:54Five pairs of legs, a super-long antenna,
0:03:54 > 0:03:58a super-hard exoskeleton and - ooh - super-staring eyes.
0:03:58 > 0:04:00It can only be the crayfish.
0:04:00 > 0:04:03Or Mummy crayfish, to be precise.
0:04:03 > 0:04:07Or, as she's also known, the rock lobster.
0:04:08 > 0:04:12Well, she's rock-hard. That's for certain.
0:04:12 > 0:04:14This is a real example of girl power, all right.
0:04:14 > 0:04:18The female carries her eggs around on her own for three weeks.
0:04:18 > 0:04:20Well, it's not that long, is it?
0:04:20 > 0:04:23Well, it is when you can have up to 250,000 eggs.
0:04:23 > 0:04:25250,000?! Where does she put them all?
0:04:25 > 0:04:28Under her skirt, of course, where she looks after them
0:04:28 > 0:04:31by fanning them and keeping them from predators.
0:04:31 > 0:04:34Wow. Now, that is a lot of eggs. I wonder if she has a favourite?
0:04:34 > 0:04:38Maybe number 2,052? One thing's for sure.
0:04:38 > 0:04:41You wouldn't want to mess with a rock lobster in a hurry.
0:04:41 > 0:04:43They can look a little scary.
0:04:43 > 0:04:45- Aw, are these the babies?- Yeah.
0:04:45 > 0:04:50This is their first stage of growing up. A tiny spider-like larva.
0:04:50 > 0:04:53- Completely transparent. - They look like ghost babies.
0:04:53 > 0:04:56Or happy little aliens. Eventually, they lose their transparency
0:04:56 > 0:05:00and look like mini-lobsters. But I think they're cuter
0:05:00 > 0:05:03- when they're see-through. - What a caring Mummy crayfish.
0:05:03 > 0:05:07She doesn't look the motherly type but you can't fault her dedication.
0:05:07 > 0:05:10They clownfish are dedicated parents. They fan and fan and fan,
0:05:10 > 0:05:12and Mummy crayfish does the same.
0:05:12 > 0:05:15The clownfish and crayfish are linked together
0:05:15 > 0:05:17because they both obsessively protect their eggs.
0:05:19 > 0:05:22Ah, little baby fish!
0:05:22 > 0:05:25They're actually spiny chromis babies.
0:05:25 > 0:05:28- They're a species of damselfish. - I think they're cute!
0:05:28 > 0:05:31How come they don't get lost or blown away?
0:05:31 > 0:05:33Mummy and Daddy keep an eye on them.
0:05:33 > 0:05:36Stay together. Stop messing about.
0:05:36 > 0:05:38So parents nag their kids in the ocean, too.
0:05:38 > 0:05:41This species are unusual because the babies,
0:05:41 > 0:05:42officially known as the fry...
0:05:42 > 0:05:45Ah, fry! That's where "small fry" comes from.
0:05:45 > 0:05:49Well, there you go. Cool, eh? As I was saying, this family are unusual
0:05:49 > 0:05:53because the parents stay by their babies, or fry, the whole time.
0:05:53 > 0:05:56Usually, fish abandon their babies once they've hatched.
0:05:56 > 0:05:58did I say they feed off their parents' mucus?
0:05:58 > 0:06:02HORSE NEIGHS Oh, not mucus again?
0:06:02 > 0:06:05Yes, damselfish produce mucus on their scales
0:06:05 > 0:06:08- and the babies feed off it. - Oh, completely gross!
0:06:08 > 0:06:11Although I have seen baby-food that looks similar.
0:06:11 > 0:06:14Crayfish Mummy looks after her thousands of eggs
0:06:14 > 0:06:18and damselfish go one step further and look after their small fry.
0:06:18 > 0:06:22So the crayfish and damselfish are linked by total parental love.
0:06:24 > 0:06:31- Ciao, bella! Kissy-kissy! - Ti amo, you are magnificente!
0:06:31 > 0:06:36Hold the phone. Nudibranchs kissing? Whatever next?
0:06:37 > 0:06:40Oh, nudibranchs, contain yourselves, will you?
0:06:40 > 0:06:43Or go and find a little corner to snog in, please!
0:06:43 > 0:06:47- Apparently, they stay like this for days.- Oh, wow, look at these two.
0:06:47 > 0:06:49They've got a sign between them.
0:06:49 > 0:06:53Those are their eggs. They're stuck together in that shape by mucus.
0:06:53 > 0:06:57- What?!- Yep. It may look like they're just advertising their love for each
0:06:57 > 0:07:01other but actually they're releasing their eggs, which are...
0:07:01 > 0:07:03well, snotted together.
0:07:03 > 0:07:05Yeah, doesn't seem as romantic now.
0:07:05 > 0:07:09- Especially when you hear this. They lay their eggs...- Not in snot?
0:07:09 > 0:07:12Well, yes, in snot, and then leave them alone.
0:07:12 > 0:07:15I always said they weren't to be trusted.
0:07:15 > 0:07:18They're left to fend for themselves in a snot-ring.
0:07:18 > 0:07:20Too much snogging and not enough caring.
0:07:20 > 0:07:22And way too much snot!
0:07:22 > 0:07:24Our spiny chromis, or baby damselfish
0:07:24 > 0:07:27as they're more fondly known, feed on their parents' mucus,
0:07:27 > 0:07:30and the nudibranchs wrap their babies in a ring of mucus.
0:07:30 > 0:07:34So, the damselfish and nudibranchs are linked with mucus.
0:07:36 > 0:07:38Look! They're play-fighting.
0:07:38 > 0:07:41- Either that or playing Twister. - These are two epaulette sharks.
0:07:41 > 0:07:44They're also called the long-tailed carpet sharks.
0:07:44 > 0:07:47Is that because they have long tails and are flat like a carpet?
0:07:47 > 0:07:52- I'm not sure if they're play- fighting now.- They're mating.
0:07:52 > 0:07:54But he's biting her fin. That's not romantic.
0:07:54 > 0:07:57I know, but in the epaulette world, it's quite acceptable.
0:07:57 > 0:07:59Oh. Oh, and here's the egg.
0:07:59 > 0:08:02And a baby epaulette... ah! Hang on a minute, sharks lay eggs?
0:08:02 > 0:08:05Well, not all sharks. But the epaulette sharks do.
0:08:05 > 0:08:08They lay them on the ocean floor and disguise them
0:08:08 > 0:08:11- by covering them with algae. - I love it. Egg-laying shark.
0:08:11 > 0:08:15- What happens next?- They leave them. - What? They lay and go?
0:08:15 > 0:08:18- What about the babies?- The pup is on its own, and I mean on its own.
0:08:18 > 0:08:21They have a one in three chance of surviving.
0:08:21 > 0:08:24- It's every pup for themselves. - Cute baby, though.
0:08:24 > 0:08:28But is it meant to have that white ball? Someone should tell it.
0:08:28 > 0:08:30The baby shark, or pup, as it's called,
0:08:30 > 0:08:32is still inside the egg case but survives
0:08:32 > 0:08:35by eating the yolk of the egg until he hatches,
0:08:35 > 0:08:38- while he readies himself for the outside world.- Here he comes.
0:08:38 > 0:08:42I think he's ready for the outside world. Go on, mate, push.
0:08:43 > 0:08:44And he's off.
0:08:44 > 0:08:48No thanks to Mum and Dad who had a play-fight and abandoned him.
0:08:48 > 0:08:50Yes. Those nudibranchs didn't put much love
0:08:50 > 0:08:52into looking after their babies.
0:08:52 > 0:08:56Nudibranchs and epaulette sharks are connected by parental indifference.
0:08:56 > 0:09:00In other words, their mums and dads are rubbish.
0:09:00 > 0:09:02Barrier reef. Not just about underwater.
0:09:02 > 0:09:05There's lots of animals on land as well.
0:09:05 > 0:09:07BIRD CALLS, FOLLOWED BY SQUELCH
0:09:07 > 0:09:10Yeah, like seabirds.
0:09:13 > 0:09:18- Meet the boobies.- Are you serious? - Yes. Silly name, silly face.
0:09:18 > 0:09:21They're known for, well, looking a bit stupid.
0:09:21 > 0:09:25- Wow, that is a big baby. - And so it should be.
0:09:25 > 0:09:28This baby has fought hard to be here.
0:09:28 > 0:09:31Although Mum lays more than one egg, the strongest will usually
0:09:31 > 0:09:34push the others out of the nest to ensure he gets the food.
0:09:34 > 0:09:36Not much brotherly love going on, then?
0:09:36 > 0:09:39I know! It seems harsh but maybe it's nature's way
0:09:39 > 0:09:42of making sure at least one chick always survives.
0:09:42 > 0:09:45And once they've done that, boy are they demanding!
0:09:45 > 0:09:48Feed me! I want some more! I'm still hungry!
0:09:48 > 0:09:51They're greedy all right. And by getting rid of their siblings,
0:09:51 > 0:09:54they've made sure they get all the attention.
0:09:54 > 0:09:56Not to be recommended in the real world.
0:09:56 > 0:10:00You need siblings, to play football with and argue over the remote.
0:10:00 > 0:10:03I agree. Once the chick has hatched, Mum stays by the nest and the male
0:10:03 > 0:10:08goes off hunting. As the chick gets stronger, Mum helps out, too.
0:10:08 > 0:10:09But one parent always baby-sits.
0:10:09 > 0:10:12- Have they forgotten to dress? - I think so.
0:10:12 > 0:10:14They're so greedy! They're as large as their parents
0:10:14 > 0:10:19before they grow feathers, so they may look grown-up but they're not.
0:10:19 > 0:10:23It takes a long time before boobies are allowed out on their own,
0:10:23 > 0:10:26because they need to learn how to fly and plunge-dive.
0:10:26 > 0:10:30And as you can see, it might take a while.
0:10:30 > 0:10:32Ah, they actually fly quite gracefully.
0:10:32 > 0:10:34Not bad for a bird called "stupid".
0:10:37 > 0:10:42So boobies are linked to epaulette sharks as they're both only children.
0:10:42 > 0:10:44You've got to love family.
0:10:44 > 0:10:46Let's catch up on our reef family connections.
0:10:50 > 0:10:52So, how did we get from the caring clownfish
0:10:52 > 0:10:55all the way to the boisterous boobies?
0:10:55 > 0:11:00Our first family tie was our loving parents, the clownfish.
0:11:00 > 0:11:03They juggle jobs between them to look after their babies.
0:11:03 > 0:11:05Just like the spiky crayfish.
0:11:05 > 0:11:08She may not look the motherly type but she's very dedicated.
0:11:08 > 0:11:11What about the mucus-chomping spiny chromis damselfish?
0:11:11 > 0:11:14Mucus connects them to the nudibranch,
0:11:14 > 0:11:16- with their heart-shaped eggs. - They're kissy-kissy
0:11:16 > 0:11:20when they meet but they abandon their eggs without a thought.
0:11:20 > 0:11:23Like epaulette sharks. They hide the eggs,
0:11:23 > 0:11:25but they leave their babies to hatch alone.
0:11:25 > 0:11:30Unlike our baby booby, an only child who gets lots of loving, tender care.
0:11:36 > 0:11:39Enter our distinguished officer, the mandarin fish.
0:11:39 > 0:11:41What are you talking about?
0:11:41 > 0:11:44The mandarin fish is named so because of its bizarre colouring
0:11:44 > 0:11:47and head-dress. It looks like a Chinese Imperial officer.
0:11:47 > 0:11:49Ooh, he's quite majestic.
0:11:49 > 0:11:52Digging his colours! And what a fine head-dress.
0:11:52 > 0:11:54- Good morning, sir.- Hello.
0:11:54 > 0:11:57Wow, that is some cool fin-action.
0:11:57 > 0:12:00- Thank you.- Another distinguishing feature of our regal mandarin,
0:12:00 > 0:12:04- he can move his fins like a sideways helicopter.- He's quite a dude.
0:12:04 > 0:12:07- Thank you. - They're a bit like reef celebrities.
0:12:07 > 0:12:11They like to preen, strut and have very fussy eating habits.
0:12:11 > 0:12:14Only the best will do. Five-star, or they turn their nose up.
0:12:14 > 0:12:17Fussy-eating fish, outrageous outfits
0:12:17 > 0:12:20and they obviously like being the centre of attention.
0:12:20 > 0:12:22They really are like celebrities.
0:12:22 > 0:12:26- But they're not as lovely as they look.- OK, tell me more.
0:12:26 > 0:12:29Well, these guys have no parental skills at all.
0:12:29 > 0:12:32The minute the eggs are released, their parents disappear in a flash.
0:12:32 > 0:12:35What?! They don't look after their kids?
0:12:35 > 0:12:38- They don't even hire a nanny? - No, not even a backward glance.
0:12:38 > 0:12:41They're like the glamorous showbiz couple of the reef
0:12:41 > 0:12:45- who just want to party and show off their fancy outfits.- Well, I never!
0:12:45 > 0:12:48Boobies and mandarin fish both lay eggs,
0:12:48 > 0:12:49but boobies care for theirs
0:12:49 > 0:12:53while mandarin fish leave without a backwards glance.
0:12:55 > 0:13:00Spooky things happen around the full moon, and this is one of them.
0:13:00 > 0:13:04Wow! What are those little balls? It's like an ocean snowstorm.
0:13:04 > 0:13:08This is one of the most amazing sights in the ocean.
0:13:08 > 0:13:11It's called coral spawning. It happens only once a year.
0:13:11 > 0:13:16No-one actually knows why, but it's mainly dependent on the full moon.
0:13:16 > 0:13:19- It's very pretty. What is it?- The coral is laying eggs into the water,
0:13:19 > 0:13:22for the eggs to be fertilised by other corals.
0:13:22 > 0:13:24It's quite spooky, really.
0:13:24 > 0:13:28Loads of the corals in the reef all spawn together.
0:13:28 > 0:13:31On that particular day, most corals decide to all lay eggs
0:13:31 > 0:13:35within a few hours of each other, and some even at exactly the same time.
0:13:35 > 0:13:37Ah, so that's why the reef keeps on living?
0:13:37 > 0:13:41Because the moon, sun, tides and corals somehow let each other know
0:13:41 > 0:13:45- it's spawning-time?- Yep. Coral have an incredible ability to conquer,
0:13:45 > 0:13:49settle and outgrow, and spawning is a large part of that process.
0:13:49 > 0:13:51Once the eggs are released, that's it.
0:13:51 > 0:13:54They're on their own to grow roots and start their own family.
0:13:54 > 0:13:56Now that is one big family.
0:13:56 > 0:14:00Talk about teamwork. Shame they leave their babies alone, though.
0:14:00 > 0:14:03So the mandarin fish and corals are linked together
0:14:03 > 0:14:06as they leave their babies to fend for themselves.
0:14:06 > 0:14:09So freedom at birth connects the mandarin fish and coral.
0:14:12 > 0:14:14The box jellyfish.
0:14:14 > 0:14:17Deadly, highly venomous killers.
0:14:17 > 0:14:20Aw, but surely the babies aren't deadly?
0:14:20 > 0:14:22- They look like mini-jellies. - Don't be fooled.
0:14:22 > 0:14:25They may be babies, but they're still pretty tough.
0:14:25 > 0:14:29And where they come from is as mysterious as their reputation.
0:14:29 > 0:14:33The adults appear out of nowhere just after a full moon,
0:14:33 > 0:14:36nearly invisible with their venom-loaded tentacles.
0:14:36 > 0:14:39A few days later, they mysteriously disappear.
0:14:39 > 0:14:44But they have left something behind... deadly microscopic spawn.
0:14:44 > 0:14:46Deadly microscopic spawn? As if!
0:14:46 > 0:14:49Well, they are once they start feeding off the plankton.
0:14:49 > 0:14:52They have to survive completely on their own.
0:14:52 > 0:14:56Well, if you're going to grow up to be a deadly killer,
0:14:56 > 0:14:58you have to be tough right from the outset.
0:14:58 > 0:15:01Our baby box jellies are connected to corals
0:15:01 > 0:15:04because their children are left to fend for themselves.
0:15:04 > 0:15:08OK, let's not get sidetracked. Who else is linked to the crafty corals?
0:15:10 > 0:15:13Hey! It's the big yellow-mouth spotty leopard-skin fish.
0:15:13 > 0:15:16No, it's not. It's the triggerfish.
0:15:16 > 0:15:18That's a dull name for a fish with style.
0:15:18 > 0:15:21Well, they're not dull parents, that's for sure.
0:15:21 > 0:15:22They're always on the go.
0:15:22 > 0:15:25They're picking up rubble, blowing away dust...
0:15:25 > 0:15:27All in preparation for making a nest.
0:15:27 > 0:15:30When they've made a nest, they really take care of it.
0:15:30 > 0:15:33- They're a bit like the cleaners of the sea world.- Yes.
0:15:33 > 0:15:37And once the eggs are laid, the male fertilises them and the female
0:15:37 > 0:15:40fans and defends them. She's like a proper mummy.
0:15:40 > 0:15:43- And the male fish? - Well, they have it made.
0:15:43 > 0:15:46There's usually one male for several females.
0:15:46 > 0:15:49OK for some. Does he have time for parenting?
0:15:49 > 0:15:52Well, considering he has to share himself between them all,
0:15:52 > 0:15:54he also works pretty hard.
0:15:54 > 0:15:57He guards the nest, protecting the mum and the babies
0:15:57 > 0:15:59until they hatch, then the female takes over.
0:15:59 > 0:16:01It's an equal workload, I'd say.
0:16:01 > 0:16:05They're very busy being parents, Mr and Mrs Triggerfish,
0:16:05 > 0:16:07who work together to look after their kids,
0:16:07 > 0:16:10just like the co-operative corals.
0:16:13 > 0:16:17Reef cuttlefish. They may look comical but are super-intelligent.
0:16:17 > 0:16:20If Y equals 2 x 4 + 3, we can easily conclude
0:16:20 > 0:16:24that by carrying the 1, Y = the second-last letter of the alphabet.
0:16:24 > 0:16:27Er, really? Appearances can be deceptive, I suppose.
0:16:27 > 0:16:30Well, listen to this for a fascinating fact.
0:16:30 > 0:16:3395% of all the animals in the world don't have a spine.
0:16:33 > 0:16:36They're called invertebrates, and cuttlefish are considered
0:16:36 > 0:16:38the most intelligent of them all.
0:16:38 > 0:16:41Fascinating, my dear Barney, but the question is,
0:16:41 > 0:16:45- are cuttlefish good parents? - Why, they are the best, dear Gemma.
0:16:45 > 0:16:48And why are we talking like we're in a costume drama?
0:16:48 > 0:16:51Not sure. Maybe it's the cuttlefish's fetching skirt.
0:16:51 > 0:16:53These two are flirting! See how the skirt
0:16:53 > 0:16:55is twirling and the colour changing?
0:16:55 > 0:16:58That is the cuttlefish's way of saying, "I fancy you".
0:16:58 > 0:17:00But they look identical.
0:17:00 > 0:17:03Why are they copying each other? Is that part of flirting?
0:17:03 > 0:17:05Well, kind of. Get this.
0:17:05 > 0:17:09Some male cuttlefish compete for the affections of the girls by...
0:17:09 > 0:17:11- pretending to BE girls.- What?!
0:17:11 > 0:17:14Yes. This allows them to get past the watchful eyes of the big,
0:17:14 > 0:17:16protective males. Sneaky or what?
0:17:16 > 0:17:19Yeah, very sneaky. But you said it still makes them good parents?
0:17:19 > 0:17:22Well, they're the best parents. Cue sad story.
0:17:22 > 0:17:25When ready, the female lays her eggs very carefully
0:17:25 > 0:17:27in the coral, picking the perfect place.
0:17:27 > 0:17:31She lays up to 200 eggs, but not all the eggs survive.
0:17:31 > 0:17:35- So far, not that sad.- Brace yourself.
0:17:35 > 0:17:39Shortly after the egg-laying, the male cuttlefish dies.
0:17:39 > 0:17:43- No!- So Mum is left on her own to cope for a while, but then...
0:17:43 > 0:17:46- the mum dies too.- Oh, that's so sad!
0:17:46 > 0:17:50- Why?- They've used up all their energy and so...so they die.- Oh...!
0:17:50 > 0:17:54I know, but it's just the way of the ocean world. There, there.
0:17:54 > 0:17:57The babies don't know, and have no problem looking after themselves.
0:17:57 > 0:18:00They learn to be independent and instinctively know
0:18:00 > 0:18:02what to eat and how to disguise themselves.
0:18:02 > 0:18:05Good. I couldn't cope with more sadness.
0:18:05 > 0:18:07Triggerfish and cuttlefish are great parents
0:18:07 > 0:18:10and will do what it takes to bring their babies into the world.
0:18:10 > 0:18:15So they are linked because they both have lots of parental care.
0:18:15 > 0:18:17We've seen loads of underwater families.
0:18:17 > 0:18:19Let's run through them again.
0:18:24 > 0:18:27We started back at the colourful mandarin fish.
0:18:27 > 0:18:31They're proud, well-dressed, arrogant, and rubbish parents.
0:18:31 > 0:18:34They abandon their eggs without a backward glance.
0:18:34 > 0:18:37Like corals. Millions of eggs are released all on their own.
0:18:37 > 0:18:41like box jellyfish babies, although I don't feel as sorry for them.
0:18:41 > 0:18:42They are highly venomous.
0:18:42 > 0:18:45But triggerfish are busy and nagging parents,
0:18:45 > 0:18:47but look after their babies with care.
0:18:47 > 0:18:50Just like the cuttlefish, who die for their children.
0:18:50 > 0:18:51Oh, so sad!
0:18:51 > 0:18:53So, who's our next family tie?
0:18:59 > 0:19:02Oh, wow! Look, a turtle piggyback. How cool would that be?
0:19:02 > 0:19:05Um, actually, they're mating.
0:19:05 > 0:19:09Ah. Really? That male turtle's got his work cut out, hasn't he?
0:19:09 > 0:19:12Well, no. The one doing the carrying is the female.
0:19:12 > 0:19:16- No way!- Yes. A female turtle's job is a hard one all right,
0:19:16 > 0:19:19when it comes to families. They do all the work,
0:19:19 > 0:19:22while the male does basically nothing.
0:19:22 > 0:19:24Yes, the women make all the effort
0:19:24 > 0:19:28and carrying around m'Lordship male here is only the beginning.
0:19:28 > 0:19:31They travel up to 3,000km to breed.
0:19:31 > 0:19:35They then drag themselves up the beach on only their front flippers.
0:19:35 > 0:19:39- Well, when you put it like that... - No wonder they're tired.
0:19:39 > 0:19:43But does she get to rest? No way. She then has to dig a hole.
0:19:43 > 0:19:46This sand-flinging? Does she know what she's doing?
0:19:46 > 0:19:49Looks to me like she's just chucking it everywhere.
0:19:49 > 0:19:52When she's working on her own, what do you expect?
0:19:52 > 0:19:53I was only asking.
0:19:53 > 0:19:57It might look like she's randomly flinging sand everywhere,
0:19:57 > 0:19:59- but she'll get it done. - Dare I ask, where's Dad?
0:19:59 > 0:20:03Er, well, once he got his free lift he was nowhere to be seen.
0:20:03 > 0:20:07- Goodbye!- Well, I see your point, but she's nearly done now, isn't she?
0:20:07 > 0:20:10No! Now she lays the eggs into this chamber she's made
0:20:10 > 0:20:13at the bottom of the sandpit. All 120 of them.
0:20:13 > 0:20:17Whoa, that's a lot, I agree.
0:20:17 > 0:20:20I must admit, I have a new respect for the female turtle.
0:20:20 > 0:20:23So you should! There are loads of turtles nesting on this beach.
0:20:23 > 0:20:26Around 20,000, to be precise.
0:20:26 > 0:20:28That's 20,000 turtles on an island
0:20:28 > 0:20:32- the size of about 32 football pitches.- Yes and that's 625 turtles.
0:20:32 > 0:20:36per football pitch, all trying to find space for their babies.
0:20:36 > 0:20:39- It's hard work.- Please tell me she gets to rest now.
0:20:39 > 0:20:41Yes. She has to drag herself down to the sea,
0:20:41 > 0:20:46and only then does she rest. If she doesn't meet a hungry tiger shark.
0:20:46 > 0:20:49- I'm gonna get you! - EVIL LAUGH
0:20:49 > 0:20:52She does all the hard work and the bloke turtle does nothing.
0:20:52 > 0:20:54HE SNORES
0:20:54 > 0:20:57Get me a drink, will you, Gem?
0:21:00 > 0:21:02Typical!
0:21:02 > 0:21:04See what I mean?
0:21:11 > 0:21:13Like the mummy cuttlefish, the turtle mums
0:21:13 > 0:21:16are also left to look after their babies on their own.
0:21:16 > 0:21:20So being a single mum is what links the cuttlefish and turtles.
0:21:20 > 0:21:21- Cool. What's next?
0:21:24 > 0:21:26- Ouch!- Ouch! I'm trying to get out of the way!
0:21:26 > 0:21:28- Move out!- I've been here for ten weeks.
0:21:28 > 0:21:31- Who's that?- That's Michelle. - That's MY shell!
0:21:31 > 0:21:36You thought the turtle beach was crowded? It's baby turtle time.
0:21:36 > 0:21:38Whoa, it looks like the school bus rush!
0:21:38 > 0:21:42It may look chaotic but the baby turtles hatch together for a reason.
0:21:42 > 0:21:46- I hope it's a good one. Looks painful.- It's safety in numbers.
0:21:46 > 0:21:49They're vulnerable to predators so they stick together.
0:21:49 > 0:21:52They head straight for the water, despite the fact
0:21:52 > 0:21:56- they've never swam before, and just follow the currents.- Swim!
0:21:56 > 0:21:59Look at them go. Not all of them make it,
0:21:59 > 0:22:02but they learn pretty fast, and once they've hit the water,
0:22:02 > 0:22:06they're not seen again for 30 or 40 years, until they nest.
0:22:06 > 0:22:09Bye, baby turtles. See you again in 2038, or thereabouts.
0:22:09 > 0:22:13Although the competition is fierce, it's safety in numbers
0:22:13 > 0:22:16for the baby turtles, just like their mothers.
0:22:16 > 0:22:18Baby and mother turtles stick together,
0:22:18 > 0:22:22- so our link is safety in numbers. - So, who's next, then?
0:22:24 > 0:22:27Wait until you hear this. This is extreme.
0:22:27 > 0:22:30Oh, why do I have the feeling I'm going to hear something gross?
0:22:30 > 0:22:33The grey nurse shark, with their shaggy teeth,
0:22:33 > 0:22:36look ferocious, but they're actually pretty friendly...
0:22:36 > 0:22:38G'day! How you going?
0:22:38 > 0:22:40..unlike their babies.
0:22:40 > 0:22:45Brace yourself. So, nurse shark eggs hatch inside the mother shark.
0:22:45 > 0:22:48So? I'm not shocked yet.
0:22:48 > 0:22:52When they're born, they're only small, but certainly not shy.
0:22:52 > 0:22:55These tiny baby sharks then do the unimaginable.
0:22:55 > 0:22:59- They start to eat each other. - Whoa, hang on!
0:22:59 > 0:23:03So they eat their own brothers and sisters? They must be hungry!
0:23:03 > 0:23:05No, it's not about their hunger.
0:23:05 > 0:23:08This is an example of sibling rivalry to the extreme.
0:23:08 > 0:23:11It's all about them competing for space in their mum's belly,
0:23:11 > 0:23:14as they're a metre long when they're born.
0:23:14 > 0:23:17A metre?! That's a ma-hoosive bambino! How big are the sharks?
0:23:17 > 0:23:21Well, that's the thing. Their mum is just over two metres herself,
0:23:21 > 0:23:24so it's like giving birth to something half her size.
0:23:24 > 0:23:29They fight to the death to secure their place in their mummy's tummy.
0:23:29 > 0:23:32It's survival of the fittest, and out of about 80 eggs,
0:23:32 > 0:23:36- only two actually make it. - Respect to the sharks.
0:23:36 > 0:23:38Those are some big babies.
0:23:38 > 0:23:40So both the baby turtle and grey nurse
0:23:40 > 0:23:42always start life with siblings,
0:23:42 > 0:23:45even if the baby nurse sharks turn on their brothers and sisters.
0:23:45 > 0:23:49So, siblings link our baby turtles and grey nurse pups.
0:23:49 > 0:23:52But who else is connected to our cute baby turtles?
0:23:52 > 0:23:55From single mummy to single daddy.
0:23:55 > 0:23:59- Eh? Run that past me again. - Meet the magnificent seahorse.
0:23:59 > 0:24:01Legend of the sea, a mystical creature
0:24:01 > 0:24:03that myths are made of. They've been around
0:24:03 > 0:24:09for 40 million years and, well, their daddy is a mummy.
0:24:09 > 0:24:13- Huh?!- Now, this, I don't understand.
0:24:13 > 0:24:15Seahorses are the only animal in the world
0:24:15 > 0:24:17where the male gets pregnant and has babies.
0:24:17 > 0:24:20Ah, now this is a lot more like it!
0:24:20 > 0:24:22It's about time the men around here did some work!
0:24:22 > 0:24:25And, might I say, they do it quite uncomplainingly.
0:24:25 > 0:24:28- As if!- Papa seahorse has a brood pouch on the front.
0:24:28 > 0:24:32The female puts their eggs in the pouch and then the male is pregnant
0:24:32 > 0:24:34- for three weeks.- That's not long!
0:24:34 > 0:24:36Well, it is for something size of a small hand.
0:24:36 > 0:24:38But then they go into labour.
0:24:38 > 0:24:40Wait for it... 72 hours!
0:24:40 > 0:24:42- That's three days.- Three days?
0:24:42 > 0:24:45OK, I admit that's quite a while, and it does look like hard work.
0:24:45 > 0:24:49They give birth to as many as 1,000 babies at a time.
0:24:49 > 0:24:52See, sometimes the men in the reef have to work really hard, too.
0:24:52 > 0:24:54OK, OK. I admit they do.
0:24:54 > 0:24:58So the male seahorse works hard but what happens afterwards?
0:24:58 > 0:25:02I bet they rest forever, or leave the female to do everything else.
0:25:02 > 0:25:07Oh, such little faith! Seahorses are completely and utterly romantic.
0:25:07 > 0:25:11During mating, they utter musical sounds. They are completely faithful
0:25:11 > 0:25:14to each other and once they meet, are inseparable.
0:25:14 > 0:25:17Ah, they sound like they'd make the perfect boyfriend.
0:25:17 > 0:25:20Yeah, but there's not much parenting after the daddy gives birth.
0:25:20 > 0:25:23Ah, see! The dad might work hard during the birth
0:25:23 > 0:25:26- but then he deserts the babies. - Well, I'm not so sure I blame him.
0:25:26 > 0:25:281,000 babies is a lot of childcare.
0:25:28 > 0:25:31Imagine making packed lunches for all those every day.
0:25:31 > 0:25:35Turtles and seahorses are both single parents.
0:25:35 > 0:25:38And daddy day-care links us right back to our clownfish,
0:25:38 > 0:25:41as the clownfish daddy is also in charge of looking after the eggs.
0:25:41 > 0:25:43You can't choose your family.
0:25:43 > 0:25:45And in the reef you can sink or swim,
0:25:45 > 0:25:47depending on your family background.
0:25:47 > 0:25:50There's bad parents, obsessive parents,
0:25:50 > 0:25:55and really, really strange parents. Let's refresh with a reef-cap.
0:25:59 > 0:26:03What a cool collection of connections. Let's see those again.
0:26:05 > 0:26:08The clownfish don't joke when it comes to family,
0:26:08 > 0:26:11- protecting their eggs at all cost. - Like the caring crayfish.
0:26:11 > 0:26:15Holding 250,000 eggs under her skirt can't be easy,
0:26:15 > 0:26:17but she'll do anything for her kids.
0:26:17 > 0:26:22What about the baby spiny chromis? They eat their parents' mucus. Yuck!
0:26:22 > 0:26:26Which links them to the nudibranchs, who lay their eggs in mucus rings.
0:26:26 > 0:26:29Egg abandonment links the nudies to the epaulette shark.
0:26:29 > 0:26:32- The kids learn independence the hard way.- Unlike baby boobies
0:26:32 > 0:26:35who, in my opinion, get completely spoilt.
0:26:35 > 0:26:38The mandarins leave their eggs behind them without a glance,
0:26:38 > 0:26:41like the corals, who spawn millions of eggs all through the night.
0:26:41 > 0:26:44Box jellies are left mysteriously by their parents.
0:26:44 > 0:26:47They're not as lucky as trigger fish, very concerned parents,
0:26:47 > 0:26:49like the caring cuttlefish.
0:26:49 > 0:26:53Mum's the word for the turtles. She does everything, including
0:26:53 > 0:26:55carrying around her lazy husband.
0:26:55 > 0:26:59Luckily, the baby turtles stick together. It's a bit of a scramble
0:26:59 > 0:27:02but it helps them survive, unlike the grey nurse shark pups,
0:27:02 > 0:27:04who eat each other to ensure survival.
0:27:04 > 0:27:08Or the seahorse? Who's the daddy? Well, he is.
0:27:08 > 0:27:10Now, that is family dedication for you.
0:27:10 > 0:27:14Seahorses are linked right back to clownfish by daddy day-care.
0:27:14 > 0:27:16Right, a bit more towards me.
0:27:16 > 0:27:17Are you sure I look OK?
0:27:17 > 0:27:19Oh, yeah, you look great.
0:27:19 > 0:27:21Remember, it's for family.
0:27:21 > 0:27:23Your dad's going to love it!
0:27:23 > 0:27:25Smile!
0:27:32 > 0:27:35Subtitles by Red Bee Media Ltd
0:27:35 > 0:27:38E-mail subtitling@bbc.co.uk