08. Creatures Of The Deep
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00:00The ocean, the largest habitat on earth, and an inhospitable place,
00:29for those of us who live on land.
00:35Yet, for a billion years, this was the only place on the planet where life existed.
00:49Today, descendants of those early life forms continue to thrive.
00:59They share the sea with fish, but outnumber them by ten to one.
01:07They have no backbones, and have evolved into countless different forms.
01:16Some are huge, large-brained, and intelligent.
01:21Others are minuscule, yet build the largest natural structures on the planet.
01:46They are marine invertebrates, the creatures of the deep.
01:51They have colonized every corner of the ocean, and have a mind-boggling range of solutions to the problem of staying alive.
02:22The Ocean
02:32The ocean is by no means uniform.
02:35Differences in depth, temperature, sunlight, and currents pose particular challenges.
02:43One and a half miles down, these hydrothermal vents spew out superheated water at 450 degrees centigrade from cracks in the earth's crust.
02:58Despite the enormous pressure, the total darkness, and the scaldingly high temperatures, the ancestors of all life may have evolved in a place just like this.
03:12Pompeii worms, so named for their ability to survive volcanic heat.
03:23They share the vents with crabs and two-meter-long tube worms.
03:30They can only survive here because they're able to feed on bacteria that thrive around the vents.
03:43These colonies are extremely rare.
03:50Not surprisingly, most life thrives nearer the surface, where feeding is considerably easier.
04:05These are krill, tiny shrimp-like crustaceans.
04:10Swarms can reach astounding numbers, 60,000 per cubic meter.
04:19During the night, they rise towards the surface to feed on plankton.
04:27Here, in the Sea of Cortez, off Mexico, the swarms attract hunters of all kinds, from humpback whales to shoals of predatory fish.
04:40Yet another hunter arrives. It's one from the deep.
04:48A humboldt squid.
04:53Two meters long, they have a local reputation as man-eaters.
05:02Alone, they're forced to hide in the depths of the sea.
05:09Formidable enough, but this is a pack of hundreds.
05:20They're highly intelligent hunters. Their eyesight is exceptional.
05:24They have powerful tentacles, suckers ringed with 70,000 hooks, and a razor-sharp beak for tearing through flesh.
05:39Now the fish find that they are under attack, and so group together for safety.
05:50But the humboldt squid work as a team, herding the fish against the rocks.
06:09It's thought that the squid flash red and white, not only to confuse their prey, but also to signal to each other when they are about to attack.
06:39Humboldt squid numbers are growing rapidly.
06:43They're getting bigger and bigger.
06:46The fish are more and more aware of their surroundings.
06:50They're becoming more and more aware of their surroundings.
06:54Their prey is getting closer and closer.
06:58They're becoming more and more aware of their surroundings.
07:03Humboldt squid numbers are growing rapidly.
07:09But they remain mysterious.
07:13As fast as they arrived, they disappear back into the deep.
07:19800 miles from the South Pole, in the shadow of a smouldering Mount Erebus.
07:25800 miles from the South Pole, in the shadow of a smouldering Mount Erebus.
07:44Winter temperatures are a punishing minus 40.
07:49This, perhaps, is the last place you might expect to find marine life.
07:55This, perhaps, is the last place you might expect to find marine life.
08:16Now, it's the beginning of the polar spring.
08:20And for the first time in months, light reaches the sea beneath the ice.
08:34It's extremely cold and completely dark for much of the year.
08:38So, conditions are not unlike those of the deep ocean.
08:43Yet, in McMurdo Sound, life flourishes.
08:48Yet, in McMurdo Sound, life flourishes.
09:10The creatures here grow extremely slowly.
09:14But that does mean they can reach a great age and great size.
09:19And they occur in surprisingly large numbers.
09:24Three-metre-long carnivorous nematine worms, red sea stars, and urchins carpet the seafloor.
09:30Three-metre-long carnivorous nematine worms, red sea stars, and urchins carpet the seafloor.
09:54This monster worm will eat almost anything
09:58and is constantly scanning the seafloor for food.
10:14Animals are swarming here in such numbers because of this.
10:20A dead seal pup.
10:23Such a great quantity of food may only arrive once in ten years.
10:27Such a great quantity of food may only arrive once in ten years.
10:30But a seal's body won't be easy to eat.
10:40Nematines have a snout like a harpoon
10:43that enables them to puncture the skin of the corpse.
10:53It's harder work for the sea stars.
10:56They feed by pushing out their stomachs through their mouths.
11:05As this sea star presses its stomach against the seal's skin,
11:09it secretes digestive juices that dissolve the seal's tissue.
11:14But that takes time.
11:23These scavengers will feed here throughout the summer
11:27until all that remains of the seal will be a skeleton-stripped bear.
11:40The shallows are only a tiny part of the marine world.
11:4490% of it is open water.
11:53Its currents carry life for thousands of miles.
12:01The masters of this nomadic existence are jellyfish.
12:08A life spent drifting in the empty ocean could be a lonely one,
12:13but not for this jellyfish.
12:18Aurelia.
12:22Swarms like this are not accidental.
12:25These individuals all hatched together
12:28when the temperature and currents were just right.
12:35Their timing has ensured that they can make the most of feeding
12:39on a late-summer plankton bloom.
12:53BUBBLING
13:05Jellyfish have no brain and no blood,
13:09but they do have eye spots
13:11that enable them to tell the difference between light and dark.
13:15And they can move independently of the current
13:18by a simple form of jet propulsion.
13:23BUBBLING
13:29All jellyfish have stinging tentacles with which to catch their food.
13:34As they pulse their bodies, the tentacles trap plankton,
13:38which is then passed towards their mouth in the centre.
13:44BUBBLING
13:52BUBBLING
14:03A swarm of 100,000 stinging jellyfish
14:07might seem a daunting prospect for a predator.
14:13But not for this one.
14:15A huge fried-egg jellyfish.
14:19It is a killer.
14:25Its weapons are harpoon-like cells that cover its tentacles.
14:32When they come into contact with a victim, they spear it.
14:41BUBBLING
14:49BUBBLING
14:51The fried-egg then hauls in its prey.
15:02A few lucky Aurelia do manage to pull themselves free.
15:10BUBBLING
15:13But for the majority, there's only one outcome.
15:18Death.
15:34Jellyfish, like a great many marine invertebrates,
15:38have soft, vulnerable bodies.
15:41BUBBLING
15:45They are protected by stinging cells.
15:53But there are other kinds of defence.
16:01Armour-plating.
16:12BUBBLING
16:18These are spider crabs.
16:21They spend most of their lives in deep water.
16:25But once a year, off the coast of southern Australia,
16:28a quarter of a million crabs set off on a long journey to the shallows.
16:41They're here because they all share a problem.
16:44Each crab has been wearing the same suit of armour for a year now.
16:54And it's getting uncomfortably tight.
17:02So each crab eventually has to shed its shell and produce a bigger one.
17:09Replacing an old shell is understandably a tricky process.
17:17First, the crab grows an entirely new skin within the old shell.
17:26It then flexes its body to force its shell to split along the back...
17:32..before gingerly backing itself out.
17:44The spider crabs are not only here to molt, but to mate.
17:51And they grab the opportunity with considerable enthusiasm.
17:56BUBBLING
18:01Coming together in such numbers does, however, have a drawback.
18:09It attracts predators.
18:15A stingray.
18:18A stingray.
18:35Despite there being so many potential prey,
18:38the stingray seems to ignore them.
18:41Perhaps the safety in numbers.
18:44Although not all the crabs are prepared to rely on it.
18:56Alarm spreads amongst the crabs.
19:08But in fact, most of them are safe.
19:11This ray is being very choosy.
19:13It's only interested in the softest-shelled, most recently molted crabs.
19:31Once a target is singled out, there is no escape.
19:42THUNDER
19:44MUSIC
20:07When their new armour has hardened,
20:09the crabs return to the competitive safety of the deep,
20:13leaving behind only their old, empty shells.
20:21Like spider crabs, the behaviour of most marine creatures
20:25is controlled by a very simple nervous system.
20:29But there are exceptions.
20:37This cuttlefish is one of the cleverest animals in the ocean.
20:43It has a very large brain.
20:45In fact, it's larger for her size than that of most fish or reptiles.
20:53Her life is both complex and full of intrigue.
20:59Giant Australian cuttlefish usually live alone,
21:02but once in their short lives, they must come together to mate.
21:13MUSIC
21:18As she approaches the traditional mating grounds,
21:21one of the largest males starts to show interest in her.
21:32She moves him away from his rivals to a quieter spot,
21:36a place where she will be able to lay her eggs in safety.
21:44MUSIC
21:51The male takes the female in his arms and turns her to face him,
21:56before using one of his arms to pass sacks of sperm
22:00to an opening near her mouth.
22:04MUSIC
22:14MUSIC
22:18MUSIC
22:39Once mated, he hovers over her,
22:42standing guard until she's laid her eggs.
22:47MUSIC
22:52But he's got a problem.
22:54Males outnumber females four to one,
22:57so keeping her to himself is a constant battle.
23:03MUSIC
23:18MUSIC
23:24This larger rival is more difficult to intimidate.
23:30Cuttlefish can make very dramatic changes to their skin pattern
23:34in order to signal their moods.
23:42Flushes of bright colour and stripes that pulse along his side
23:46tell the rival to keep off.
23:59Most rivals back down at this stage, but not this one.
24:06Although the male's flashing signals get more and more emphatic,
24:10in the end, he has no choice but to fight.
24:13MUSIC
24:44MUSIC
24:51Victory, and the male can return to guard his female.
24:59Cuttlefish are great communicators, but there is a flip side.
25:03They can also be masters of deception.
25:07MUSIC
25:14MUSIC
25:16This male is too small to fight for a mate,
25:19but he has another plan, and it's sneaky.
25:25He approaches the couple cautiously,
25:28holding his tentacles tucked up at the front,
25:31mimicking a female that wants to mate.
25:34To complete his disguise, he changes colour
25:37to appear even more like a female.
25:41The guarding male seems convinced.
25:43Maybe he thinks his luck is in.
25:46Another female to add to his conquests.
25:50MUSIC
26:05The sly cross-dressing male edges closer and closer to the female,
26:09holding his nerve.
26:11As long as he avoids being grabbed in a mating embrace,
26:15the sneak is safe.
26:19MUSIC
26:29At what point the female guesses his true identity is unclear,
26:33but she isn't choosy,
26:35and surreptitiously mates with him right under the larger male's tentacles.
26:42MUSIC
26:50MUSIC
27:06It's time for the female to lay her eggs.
27:09Using the sperm from both males,
27:12she fertilises her eggs one by one
27:15and glues them to a rock in a hidden crevice.
27:20With luck, she will now have a mix of offspring.
27:24Some may become masterful males and others little sneaks.
27:29She'll have all the bases covered.
27:37The coastal waters of British Columbia.
27:41Home to this four-metre-long Pacific giant octopus.
27:53She is a formidable predator,
27:56but at the moment hunting isn't on her mind.
28:11She has just mated for the first time.
28:16And now she's searching for a safe refuge.
28:33She makes her choice carefully.
28:35This is going to be her home for many months to come.
28:41MUSIC
28:53It's her nursery den.
28:58100,000 eggs hang from its ceiling
29:01and she's guarding them with her life.
29:05Without her to protect them,
29:07they will be eaten by predators or become diseased.
29:13She caresses them with her tentacles,
29:16ensuring that algae don't grow on them
29:19and that fish don't eat them.
29:23She constantly keeps the water moving around them
29:26so they're well supplied with oxygen.
29:30MUSIC
29:37She cares for them for six months
29:40and during all this time she doesn't eat a thing.
29:52And now she's ready to go.
29:59As they are hatching, she is dying.
30:13One night, as the baby octopus emerge,
30:17she jets water over them for the last time,
30:20helping them on their way.
30:22MUSIC
30:27This will be her final act.
30:35This is the only time she will reproduce
30:39and to give her young their best chance,
30:42she sacrifices her life.
30:52MUSIC
30:55Out of the depths comes one of the largest
30:58and most aggressive starfish in the ocean.
31:02Picnopodia, a giant sun star the size of a dustbin lid.
31:15It's a hunter.
31:17Each arm is covered by super-sensitive tube feet
31:20that can detect prey by touch and smell.
31:30But the sun star is also partial to carrion
31:33and it detects the carcass of the giant octopus mother.
31:38MUSIC
31:46The miniature suckers on its feet clamp onto the corpse
31:50and drag it out of the cave.
32:02Other scavengers rush to join the feast.
32:08MUSIC
32:21Although it's a fearsome predator,
32:23Picnopodia doesn't have it all its own way.
32:28These sea urchins aren't speedy enough to escape,
32:31but they do have a formidable defence.
32:35The sharp spines are hard to get past
32:38and what's more, the urchins can move each spine independently,
32:42pinching the starfish's probing arms.
32:57Trapped by an army of urchins,
32:59Picnopodia is spotted by an enormous king crab.
33:05MUSIC
33:11Picnopodia has more than met its match
33:14and within seconds the crab rips off one of its arms.
33:28But that is just a temporary inconvenience.
33:32Starfish are able to quickly regrow a lost limb.
33:42The most impressive invertebrates may seem to be the giants,
33:45but in fact it's some of the smallest that can make the biggest impact.
33:53Every square inch of this island
33:55has been created by an ever-growing living superstructure,
33:59a coral reef.
34:03It's taken thousands of years to reach this size
34:06and it all began with creatures smaller than a pinhead.
34:32A reef can't be built just anywhere.
34:35It needs something to give it a firm footing.
34:42A wreck like this provides an excellent foundation.
34:48MUSIC
35:00As soon as it settles on the seabed,
35:02the wreck comes under attack from invaders.
35:05Plankton, carried here by ocean currents.
35:13These are the microscopic larvae of barnacles,
35:16sponges and, most importantly, corals.
35:30The larvae must attach themselves to the wreck.
35:33Once there, they can develop into young corals called polyps.
35:41But the polyps are very slow growing
35:43and there is lots of competition from other invaders.
35:55Algae quickly cover the wreck
35:57and that's a problem for the young coral.
36:14Algae attract grazers.
36:23The polyps are in danger of being eaten
36:26before they've even got a proper foothold.
36:31If conditions are right, the survivors can go on to build a reef.
36:40Position is critical.
36:43Too deep and not enough light will reach the corals for them to grow.
36:48Too shallow and they risk being exposed to the air at low tide.
36:55For the reef to really flourish,
36:57it also needs to be in the path of currents carrying food.
37:02FAST FORWARD
37:12Fast forward half a dozen years or so
37:15and the wreck will begin to show the first signs of corals visible to the naked eye.
37:27A decade later and the wreck will be transformed.
37:32FAST FORWARD
37:37Thousands of polyps will form coral heads that encrust its surface.
37:46This ship was sunk during the Second World War
37:50and there has been enough time for a substantial reef to develop.
37:56FAST FORWARD
37:58After decades of growth,
38:00different species of corals dominate particular areas of the wreck.
38:12The fastest-growing types grow best on the edges and overhangs,
38:16reaching far out into the water and up to the light.
38:21They need only a small area to establish themselves,
38:25yet they can rapidly grow dozens of plates or branches crammed with polyps
38:30to gather as much light as possible.
38:43FAST FORWARD
38:51Slower-growing, much more robust corals, like these brain corals,
38:56are better suited to the heart of the developing reef.
39:02It's these that give the reef their structure and permanence.
39:10There could be nearly 500 different species here,
39:13each striving to win a foothold on the rusting hulk.
39:21The pace of life for corals may seem to be so slow
39:25that it's hard to imagine that there is any conflict here.
39:33But as night falls, the mood on the reef changes.
39:40Corals are, in fact, extremely aggressive
39:44and will fight to the death to expand their territory.
39:48There can be no honourable retreat.
39:51A winner will literally eat its enemy alive.
39:58Along the battlefront, the polyps of both competents extrude their guts,
40:03long thread-like filaments, over their opponents.
40:09At the fringe, all that remains of the destroyed polyps are their skeletons.
40:17The coral that can digest fastest wins.
40:26Corals constantly grow over the skeletons of their dead comrades,
40:31building a bigger and bigger reef.
40:35Then, just once a year, a few days after the November full moon,
40:40the corals take part in a mass spawning event.
40:48Millions of eggs and sperm are released into the water
40:52and join to develop into larvae that drift in search of a place to settle.
41:18Corals are the only living species on the reef.
41:38Eventually, every inch of the wreck's surface will be colonised.
41:43The coral will rust away and the reef will be on its own.
41:57Most reefs grow without the help of a wreck to start them off.
42:02But given time, they can create something as huge as this,
42:06the Great Barrier Reef, the largest living structure on Earth.
42:14MUSIC PLAYS
42:27A coral reef rivals even a rainforest for its diversity of life.
42:33Yet corals like this are found in waters where food is very scarce.
42:38All the creatures here have had to adopt
42:41a different and highly specialised way to gather every nourishing scrap.
42:52Christmas tree worms bore into the coral skeleton for protection,
42:57swirling out and grabbing food particles with their feathery gills.
43:01Coral barnacles are, in fact, related to lobsters.
43:04They lie on their backs, waving their feet to gather any food floating past.
43:18Crabs have evolved many different ways of gathering food.
43:23This porcelain crab has a fan of filament,
43:27This porcelain crab has a fan of filaments on his front legs.
43:37A boxer crab attaches a tiny sea anemone to each fist.
43:41As well as for defence,
43:43he uses their sticky tentacles to gather passing plankton.
43:51This orangutan crab's whole body is coated with sticky hairs.
43:56In this case, perhaps just a bit too sticky.
43:59This strange creature is a sea cucumber.
44:28It uses its tentacles to grab food from the sediment.
44:34There are hunters here too, like these nudibranchs, or sea slugs.
44:41Their vibrant colours are a warning that they're toxic.
44:44There are over 3,000 species. Many hunt just one specific prey.
44:50Some hunt each other.
44:52This emperor shrimp makes the most of the poisonous nature of its host.
44:58But it's a rather one-sided affair.
45:01As it feeds, the shrimp gets protection and a free ride.
45:12Other shrimps have developed a more balanced relationship.
45:16Some even solicit for partnership.
45:19These dance for their dinner.
45:34And these advertise to passers-by that they are open for business.
45:42They are a parasite removal team,
45:45providing a service for countless fish on the reef,
45:48including those that could happily eat them.
45:59In return for their bravery, they get a meal that comes to them.
46:16Coral reefs, built by the tiniest of creatures,
46:20occupy less than half of one percent of the ocean's floor.
46:27Yet they support a quarter of all marine species.
46:31The coral reefs, built by these giant molluscs,
46:35occupy less than half of one percent of the ocean's floor.
46:39of all marine species.
47:09Marine creatures, all without backbones, from corals to cuttlefish to crabs, make up
47:23the majority of life in the oceans.
47:28But they have also had a surprisingly important impact beyond the marine world.
47:35Their fossilized bodies, shells and skeletons form the limestone and chalk that now covers
47:40huge tracts of Asia, Europe and the Americas.
47:45They may be small, but over their two-billion-year history, they have literally changed the world.
48:02To capture some of the sequences in this episode, the life team had to take underwater filming
48:08into uncharted territory.
48:12One shoot meant spending weeks diving under two meters of ice, another involved laying
48:18the foundation for a new coral reef in the tropics.
48:28A sunken ship can make an ideal location for corals to grow.
48:32So with this in mind, the life team set themselves the challenge, to make their very own shipwreck.
48:42After months of searching, they find a boat in the Bahamas that might be suitable.
48:47But there's a lot to do before it can be sunk to the seabed.
48:50It's been here for how many years, eight years on the jetty?
48:53All this fiberglass insulation, it's all got to be removed, and it's all hands to the pump, Ian.
48:59It is.
49:00They're going to go and get a pair of overalls.
49:02The team have to put away their cameras and get their hands dirty.
49:06I've got a 50-ton boat, and I'm trying to clean it with a paint scraper.
49:12Thoroughly cleaning the boat increases the chance that coral will grow on it, and ensures
49:17it won't pollute the sea.
49:18Like changing rooms, isn't it?
49:21After eight years rusting on the jetty, there's no guarantee that she will even float.
49:26We actually, we do have some holes.
49:29All up!
49:31To get this ship ready in time for the inspectors is a massive task, and they're doing a brilliant
49:37job, and we're putting panels through to let the water rush through when she starts sinking.
49:43Right, in you go.
49:45This is the last bit.
49:46Okay, guys.
49:47Aboose!
49:48Young one, young one.
49:50Ship shape at last.
49:52Oh, she's clean.
49:54She's been inspected.
49:56She's ready to be sunk.
49:57What can go wrong now?
50:00Here's Kevin.
50:01All right, Christina, here's the very latest with Dean.
50:03As the tail end of Hurricane Dean sweeps through, the team are forced to put their plans on hold.
50:10Wind of 150 miles an hour.
50:14Luck doesn't seem to be on their side.
50:21But two days later, good weather returns.
50:25Here comes a crane.
50:27Finally.
50:31Fingers crossed, arms crossed, legs crossed, everything's crossed.
50:34They urgently need to get the boat into the water, or they won't reach the chosen wreck
50:39site before nightfall.
50:44She's safely in the water.
50:46So far, so good.
50:47It floats!
50:50Her final voyage.
50:54Cameras are mounted around the deck to film her sinking below the surface.
50:59We've spent a week preparing for this, and finally the afternoon's arrived.
51:03But the light's going very quickly, so we have to make a move.
51:08The last few holes are cut.
51:11It's time to pump in water and to abandon ship.
51:20The crew dive in, ready to film her descent, while the support boat moves away to a safe distance.
51:29There's nothing more to do but wait.
51:31Here we go, look at this!
51:33Straighten out, straighten out, straighten out.
51:50She gently comes to rest.
51:52And the right way up, just as they'd hoped.
52:08Now it's time to get back to the ship.
52:11The crew are ready to go.
52:14Now, it's time to let nature take its course.
52:17The crew will be back over the next two years to see how life takes hold.
52:23At this site, the wreck has a very good chance that it'll be colonised by coral.
52:27With luck and time, it will eventually become a full-scale reef.
52:35Meanwhile, at the other end of the world, the life team's challenge is to find out
52:40At the other end of the world, the life team's challenge is very different.
52:48Here in Antarctica, just getting underwater will be tough.
52:57In order to work in such a demanding location, the team needed the help of the National Science Foundation at the McMurdo Polar Research Station.
53:11Everyone here has to be able to cope out on the ice if there's an emergency.
53:16So the life team joins research scientists for survival training to prepare them for any situation.
53:26Even one like this.
53:29A colleague lost in a whiteout is very serious.
53:32This training might mean the difference between rescue or not.
53:37This is supposed to simulate a whiteout.
53:40We've been looking for someone who's been lost.
53:42And you wear the bucket so that you cannot see at all what is going on.
53:46And it does actually work.
53:48It's just, you can't see anything.
53:50It's just, you can't see anything.
53:52You cannot see at all what is going on.
53:54And it does actually work.
53:56It's just, you can't see anything in this.
54:02With the training over, it's time to travel over the ice to the dive site, ready to go beneath the frozen surface of the Ross Sea.
54:13But to get through this ice, thick enough to land a jet on, needs the help of McMurdo's specialist drilling team.
54:23Music
54:46Once the hole is drilled, a specially designed hut is slid into position.
54:52Music
54:56This will be the team's base for the next four weeks of diving.
55:02Look, this is all we need. All we need to go in here.
55:07The door to another world.
55:09All the equipment the team need for the shots must come in and out of this hole.
55:14And this is as far south as it's possible to dive.
55:18The ice is eight feet thick. It's here for eleven and a half months of the year.
55:23And we're going to go down underneath and have a look to see just what it's like underneath here.
55:28Doug and the team venture below the ice.
55:36Music
55:49Music
56:03The under-ice landscape is both surprising and spectacular, but it's the animals they've come to film.
56:10Music
56:14So, specialist time-lapse cameras are moved into position.
56:25The animals move very slowly at these freezing temperatures.
56:29But by using time-lapse to speed up the action 500 times,
56:34the team hopes to reveal the behaviour of these creatures for the first time.
56:40Music
56:51With air and warmth running out for this dive,
56:55Doug makes his way back to the lifeline and the surface.
57:00Music
57:10Music
57:20Oh, that is amazing. It's so beautiful down there.
57:25All sorts of colours, beautiful stalactites made of ice crystals hanging down from the top of the ice.
57:32All sorts of things on the bottom, starfish, urchins, just an amazing profusion of life.
57:37Really lovely, totally unique, unlike anywhere else.
57:40However, after an hour underwater, it is getting pretty cold.
57:44So, can you give me a hand up please?
57:50There would be another month here and over 100 dives before the sequence was eventually completed.
57:57Music
58:27.