0:00:30 > 0:00:36Our planet's continents are fringed by shallow seas.
0:00:36 > 0:00:41Rarely more than 200m deep, they lie on the continental shelves
0:00:41 > 0:00:45which may stretch sometimes for hundreds of miles,
0:00:45 > 0:00:49before the sea floor drops into deeper, darker waters.
0:00:55 > 0:00:59Altogether, they constitute a mere 8% of the world's oceans,
0:00:59 > 0:01:04but they contain the vast majority of its marine life.
0:01:23 > 0:01:27DEEP, ECHOING CRIES
0:01:37 > 0:01:42A male humpback whale sings to attract a mate.
0:01:51 > 0:01:54ECHOING WHALE SONG
0:02:02 > 0:02:07The whales have just returned to their breeding grounds
0:02:07 > 0:02:10in the shallow seas of the tropics.
0:02:17 > 0:02:20The calf is no more than a few weeks old.
0:02:26 > 0:02:31Despite being three metres long and weighing nearly a tonne,
0:02:31 > 0:02:33he is nonetheless vulnerable.
0:02:36 > 0:02:41But his mother watches over him and, as he begins to tire,
0:02:41 > 0:02:47she supports him close to the surface so that he can breathe more easily.
0:03:10 > 0:03:14These shallows around the equator are excellent nurseries.
0:03:14 > 0:03:19They're warm, calm, and contain very few predators.
0:03:21 > 0:03:27The playful calf is now drinking 500 litres of milk a day.
0:03:27 > 0:03:30But his mother must starve.
0:03:30 > 0:03:33There is nothing for her to eat here.
0:03:40 > 0:03:42Like many tropical shallow seas,
0:03:42 > 0:03:46these crystal-clear waters are virtually lifeless.
0:03:46 > 0:03:49They receive year-round sunlight,
0:03:49 > 0:03:53but they lack the nutrients essential for the growth of plankton.
0:03:53 > 0:03:56The mother will be trapped here for the next five months
0:03:56 > 0:04:00until her calf is strong enough to make the journey
0:04:00 > 0:04:03to the feeding grounds, near the poles.
0:04:26 > 0:04:30Coral reefs are oases in a watery desert.
0:04:30 > 0:04:36Most tropical shallows are barren, but these coral havens contain
0:04:36 > 0:04:39one quarter of all the marine life on our planet.
0:04:58 > 0:05:00Reefs are the work of polyps -
0:05:00 > 0:05:04tiny colonial animals like minute sea anemones.
0:05:04 > 0:05:10Yet the Great Barrier Reef is so big it can be seen from the moon.
0:05:17 > 0:05:22It's actually 2,000 separate reefs that together form a barrier
0:05:22 > 0:05:27stretching for over 1,000 miles along Australia's north-eastern coast.
0:05:30 > 0:05:34Despite its vast size, this reef does not contain
0:05:34 > 0:05:38the greatest variety of marine life on the planet.
0:05:39 > 0:05:43For that, one must travel north, to Indonesia.
0:06:10 > 0:06:14There are individual reefs in Indonesia that contain
0:06:14 > 0:06:18almost as many kinds of fish as live in the whole of the Caribbean.
0:06:20 > 0:06:24There are also ten times the number of coral species.
0:06:26 > 0:06:31Corals thrive in these waters with the help of microscopic plants -
0:06:31 > 0:06:35algae - that grow within the tissues of the polyps.
0:06:41 > 0:06:46And the polyps feed by snaring passing morsels with their tentacles.
0:06:59 > 0:07:04At night, the algae are inactive, but then the polyps put out
0:07:04 > 0:07:08even more tentacles, so coral, in effect, feeds around the clock.
0:07:26 > 0:07:31This well-balanced alliance brings benefits to both polyps and algae,
0:07:31 > 0:07:37and between them they turn the barren seas into rich gardens.
0:07:47 > 0:07:50The Indonesian reefs contain such a variety of life
0:07:50 > 0:07:53because they lie at a giant crossroads.
0:07:53 > 0:07:57This is the meeting place for different seas,
0:07:57 > 0:08:00the Indian Ocean and the Pacific.
0:08:02 > 0:08:06Here, everything demands a closer look.
0:08:06 > 0:08:12On the surface of this sea fan, there are two polyps that are not polyps.
0:08:12 > 0:08:14They're pygmy seahorses,
0:08:14 > 0:08:18the world's smallest, less than two centimetres high.
0:08:30 > 0:08:36They are males, settling a territorial dispute by head-butting.
0:08:45 > 0:08:48An electric flash?
0:08:48 > 0:08:52No, the display of a file clam.
0:08:56 > 0:09:01Perhaps this extraordinary pulsation of the clam's fleshy mantle
0:09:01 > 0:09:05is a warning to frighten away nibbling fish,
0:09:05 > 0:09:06but no-one really knows.
0:09:21 > 0:09:24And there are snakes here too.
0:09:24 > 0:09:25Lots of them!
0:09:31 > 0:09:34These are banded sea kraits.
0:09:34 > 0:09:39They lay their eggs on land, but they hunt here in the water.
0:09:43 > 0:09:47They're too slow to catch fish in a straight chase.
0:09:47 > 0:09:52So they seek prey that is hiding in the nooks and crannies of the coral.
0:09:54 > 0:09:59Their bite is highly venomous and paralyses their victims.
0:10:03 > 0:10:08And on this reef, the snakes do not hunt alone.
0:10:13 > 0:10:19Shoals of yellow goatfish and trevally are seeking similar prey
0:10:19 > 0:10:22and they attract the snakes' attention.
0:10:22 > 0:10:26As one group of hunters searches the reef, they're joined by the other.
0:10:35 > 0:10:39At least 30 snakes have now joined the caravan.
0:10:44 > 0:10:48The big fish scare the prey into cracks,
0:10:48 > 0:10:51and there the snakes can catch them.
0:10:51 > 0:10:54And anything fleeing from the kraits
0:10:54 > 0:10:58will swim straight in to the mouths of the waiting trevally.
0:10:58 > 0:11:00There's nowhere to hide.
0:11:06 > 0:11:11As the raiders scour the reef, more and more snakes join the hunt.
0:11:32 > 0:11:35This co-operation between snakes and fish,
0:11:35 > 0:11:40spectacular though it is, has only recently been observed,
0:11:40 > 0:11:44for it only happens on the most remote reefs in Indonesia.
0:11:53 > 0:11:57Perhaps such hunting alliances were once a common sight, but today
0:11:57 > 0:12:03no more than 6% of Indonesia's reefs are in their pristine state.
0:12:30 > 0:12:35Beyond the coral, stretches a world of shifting sand.
0:12:35 > 0:12:38Out there, with nowhere to hide,
0:12:38 > 0:12:42survival is not easy and camouflage can be crucial.
0:12:45 > 0:12:49If this wasn't moving, you might think it was a shell or a rock.
0:12:49 > 0:12:51In fact, it's an octopus.
0:12:53 > 0:12:55A gurnard -
0:12:55 > 0:12:58its huge pectoral fins disguise its shape,
0:12:58 > 0:13:02and they can also help in clearing away sand when searching for food.
0:13:07 > 0:13:10The jawfish hides underground.
0:13:12 > 0:13:16The wonderpus octopus on the other hand, has such a powerful bite that
0:13:16 > 0:13:21it has a special warning display to tell others to keep out of its way.
0:13:33 > 0:13:36Here and there, plants manage to take root,
0:13:36 > 0:13:40and they're cropped by green turtles.
0:13:40 > 0:13:42Sea grasses are the only flowering plants
0:13:42 > 0:13:45that have managed to grow in the sea.
0:13:45 > 0:13:48Although they put out a few ribbon-like leaves,
0:13:48 > 0:13:51they produce very extensive networks of fleshy stems -
0:13:51 > 0:13:54rhizomes - that are buried in the sand.
0:14:01 > 0:14:02At their lushest,
0:14:02 > 0:14:07they can transform the sea bed into an underwater meadow.
0:14:07 > 0:14:11The largest expanse grows in the shallow waters
0:14:11 > 0:14:13of Shark Bay in Western Australia.
0:14:16 > 0:14:21These vast aquatic grasslands stretch for 1,500 square miles.
0:14:21 > 0:14:29And like terrestrial prairies, they support herds of grazers - dugongs.
0:14:42 > 0:14:45Dugongs are the largest herbivores in the sea.
0:14:45 > 0:14:48They can be three metres long and weigh half a tonne,
0:14:48 > 0:14:51and they eat nothing but sea grass,
0:14:51 > 0:14:55mostly the fleshy rhizomes, which they excavate with their mobile lips.
0:15:10 > 0:15:13A herd can clear a patch of sea grass
0:15:13 > 0:15:16the size of a football pitch in a single day.
0:15:40 > 0:15:44Food is not evenly distributed in the tropical shallow seas
0:15:44 > 0:15:47and it can take a lot of finding.
0:15:47 > 0:15:51But bottlenose dolphins are inquisitive, energetic
0:15:51 > 0:15:56and very intelligent, and they have discovered a shoal of bait fish.
0:16:04 > 0:16:09Together they ride a wave, using it to carry them into the shallows,
0:16:09 > 0:16:12and there it will be easier to make the catch.
0:16:38 > 0:16:40In Western Australia,
0:16:40 > 0:16:44these dolphins have taken on an even tougher challenge.
0:16:44 > 0:16:48The fish have taken refuge close to the beach,
0:16:48 > 0:16:51where the water is only a few centimetres deep.
0:16:55 > 0:17:00Tail-slapping is a method dolphins often use to stun their prey,
0:17:00 > 0:17:03but it doesn't seem to work here.
0:17:13 > 0:17:16The fish are tantalisingly close,
0:17:16 > 0:17:18but they're still out of reach.
0:17:18 > 0:17:21So the dolphins try another technique.
0:17:25 > 0:17:30Vigorously pumping their tails, they work up some speed.
0:17:30 > 0:17:33And then they hydroplane!
0:18:00 > 0:18:04Their momentum carries them right through the shallowest waters
0:18:04 > 0:18:06and on to the fish.
0:18:16 > 0:18:20Now, they're in real danger of being stranded,
0:18:20 > 0:18:23but fortune favours the brave.
0:18:31 > 0:18:34Younger dolphins lie alongside watching.
0:18:34 > 0:18:37But, so far, only eight individuals here
0:18:37 > 0:18:40have mastered this daring technique.
0:19:29 > 0:19:32Although most life in tropical waters
0:19:32 > 0:19:36is concentrated around the coral reefs and the sea grass meadows,
0:19:36 > 0:19:40there are some spectacular exceptions.
0:19:46 > 0:19:50The desert of Bahrain seems a very unlikely place
0:19:50 > 0:19:53to find a crowded, bustling colony of seabirds,
0:19:53 > 0:19:59but every year 100,000 Socotra Cormorants gather here to breed.
0:20:01 > 0:20:04CROAKING
0:20:06 > 0:20:10It's swelteringly hot and only vigorous panting
0:20:10 > 0:20:14can prevent the birds from fatal overheating.
0:20:14 > 0:20:17This hardly seems a good place to rear young.
0:20:19 > 0:20:23But at least there are no land-based predators here.
0:20:23 > 0:20:27The only source of trouble is likely to be the neighbours.
0:20:27 > 0:20:31So each nest is built just beyond pecking reach.
0:20:47 > 0:20:49But what about food?
0:20:49 > 0:20:53There's only bare sand and the warm, shallow sea beyond.
0:20:53 > 0:20:57Neither seem likely to produce enough nourishment
0:20:57 > 0:20:59to support bird life on this scale.
0:21:02 > 0:21:06The answer is blowing in the wind.
0:21:08 > 0:21:11Sand, whipped up by shamals,
0:21:11 > 0:21:16offshore winds, blows into the seas of the Arabian Gulf.
0:21:16 > 0:21:20With the grains come nutrients which act as fertilizer
0:21:20 > 0:21:24and they transform the shallow sea into a rich fishing ground.
0:21:30 > 0:21:34So, paradoxically, it's the roasted sands of Arabia
0:21:34 > 0:21:38that prevent the Gulf from being another desert in the sea.
0:21:52 > 0:21:55The whale calf is now five months old.
0:21:55 > 0:21:57He's almost doubled in size
0:21:57 > 0:22:01and his days in his tropical nursery are coming to an end.
0:22:01 > 0:22:05It has been a warm and safe place in which to grow up,
0:22:05 > 0:22:09but there's nothing to eat here for his mother.
0:22:09 > 0:22:12She has been living off her fat reserves
0:22:12 > 0:22:17for the last eight months and she's close to starving.
0:22:17 > 0:22:21She must leave now while she still has enough energy to guide
0:22:21 > 0:22:25and protect her calf on the long voyage ahead.
0:22:41 > 0:22:47All across the tropics, humpbacks are heading away from the equator
0:22:47 > 0:22:49towards the rich temperate seas
0:22:49 > 0:22:52of both the Southern and the Northern Hemispheres.
0:22:55 > 0:23:01These are colder, rougher and more dangerous waters.
0:23:12 > 0:23:15Mother and calf must stay close.
0:23:18 > 0:23:21FINS SLAP
0:23:34 > 0:23:38They can send sound signals to one another above the roar of the ocean,
0:23:38 > 0:23:41by slapping fins on the surface.
0:24:01 > 0:24:06In winter, the temperate seas are lashed by violent storms.
0:24:24 > 0:24:30The turbulence stirs the water and draws nutrients up from the depths.
0:24:38 > 0:24:42But nutrients alone cannot support life.
0:24:42 > 0:24:45There must also be sunlight.
0:24:48 > 0:24:53In the spring, as the sun daily climbs higher in the sky,
0:24:53 > 0:24:55the algae start to grow.
0:24:55 > 0:25:00Blooms the size of the Amazon Rainforest turn the seas green.
0:25:03 > 0:25:09Individually, the algae are tiny, but together they produce three-quarters
0:25:09 > 0:25:12of all the oxygen in our atmosphere.
0:25:16 > 0:25:20They're eaten by an array of bewildering creatures.
0:25:20 > 0:25:23Salps appear in the plankton soup.
0:25:29 > 0:25:32Individuals link together to form chains,
0:25:32 > 0:25:35which can stretch for 15 metres.
0:25:45 > 0:25:47Pumping water through their bodies,
0:25:47 > 0:25:51they strain out algae and other edible particles.
0:26:01 > 0:26:05Comb jellies cruise through the water.
0:26:05 > 0:26:10They too flourish in this seasonal soup and for short periods,
0:26:10 > 0:26:13they appear in astounding numbers.
0:26:13 > 0:26:16Krill, shrimp-like creatures.
0:26:16 > 0:26:19By weight, they're the most abundant animals on the planet.
0:26:19 > 0:26:23A single swarm can contain two million tonnes of them.
0:26:33 > 0:26:35And that is a lot of fish food.
0:26:45 > 0:26:46The shallow temperate seas
0:26:46 > 0:26:50support the greatest concentrations of fish on our planet.
0:26:50 > 0:26:54Huge shoals migrate from their over-wintering grounds in the depths
0:26:54 > 0:26:57to feed in these rich waters.
0:27:05 > 0:27:12It's these shoals that support most of the world's sea mammals.
0:27:12 > 0:27:15Sea lions have all the agility and speed needed
0:27:15 > 0:27:18to collect what they want,
0:27:18 > 0:27:21and seemingly delight in doing so.
0:27:54 > 0:27:58Dusky dolphin, often in pods 200 strong,
0:27:58 > 0:28:02work together to reap the harvest.
0:28:04 > 0:28:08They break-up the shoals into smaller, more manageable balls,
0:28:08 > 0:28:10and all the hunters benefit.
0:28:10 > 0:28:11WHIRRING
0:28:36 > 0:28:41By mid-summer, the surface nutrients have all been absorbed.
0:28:41 > 0:28:45The algae die and the food chain collapses.
0:28:50 > 0:28:52In a few special places, however,
0:28:52 > 0:28:57the temperate seas sustain these levels of life throughout the summer.
0:28:57 > 0:29:02Along the coast of California, ocean currents carry a constant
0:29:02 > 0:29:06supply of nutrients up from the depths to the surface layers.
0:29:06 > 0:29:08These upwellings
0:29:08 > 0:29:13fertilise forests of giant kelp that thrive in the summer sunshine.
0:29:20 > 0:29:24The algal towers are as high as a three-story house
0:29:24 > 0:29:27and they can grow by half a metre a day.
0:29:42 > 0:29:47Life in the kelp is as full of drama as in any other forest,
0:29:47 > 0:29:50but the cast is less familiar.
0:29:50 > 0:29:54An army of sea urchins is mounting an attack.
0:29:56 > 0:30:00The urchin plague strikes at the kelps' holdfasts,
0:30:00 > 0:30:03their crucial attachments to the rock.
0:30:17 > 0:30:20Holdfasts are extremely tough,
0:30:20 > 0:30:22but each urchin has five teeth,
0:30:22 > 0:30:27which are self-sharpening and are replaced every few months.
0:30:34 > 0:30:38Urchins fell vast areas of kelp forest,
0:30:38 > 0:30:42creating clearings known as urchin barrens.
0:30:45 > 0:30:49Yet barrens is a poor description.
0:30:53 > 0:30:57Millions of invertebrates invade the sea bed.
0:31:11 > 0:31:14The most fearsome predator here is a giant.
0:31:14 > 0:31:18The sunflower starfish is a metre across
0:31:18 > 0:31:21with an appetite for brittle stars.
0:31:38 > 0:31:43It uses its feet to taste for prey.
0:31:47 > 0:31:50When its actions are speeded up, it becomes clear
0:31:50 > 0:31:54that the predator's fondness for the brittle stars
0:31:54 > 0:31:59is almost matched by the brittle stars' ability to get out of the way.
0:32:11 > 0:32:17Sand dollars, flat sea urchins, cluster together as a defence.
0:32:22 > 0:32:26But it doesn't seem to work against the sunflower star fish.
0:32:26 > 0:32:31The predator extrudes its stomach and wraps it around its victims,
0:32:31 > 0:32:33liquefying their soft parts.
0:32:34 > 0:32:37Nothing is left of them except their white skeletons.
0:32:45 > 0:32:49The Californian upwellings are seasonal and relatively small.
0:32:49 > 0:32:54But in Southern Africa, they're so big they create seas
0:32:54 > 0:32:58rich enough to support colonies of over a million seals.
0:33:03 > 0:33:08The Benguela Current sweeps along the western coastline of Southern Africa,
0:33:08 > 0:33:11driving nutrient-rich waters up to the surface.
0:33:13 > 0:33:16And then, at the southern tip of Africa,
0:33:16 > 0:33:20it meets the Agulhas Current arriving from the East.
0:33:20 > 0:33:24The result, even richer waters.
0:33:35 > 0:33:40The seals here thrive on a diet of fish and squid.
0:33:42 > 0:33:47In temperate seas, there may actually be more squid than fish.
0:33:54 > 0:34:00These are chokka squid and they lay their egg capsules in sandy shallows
0:34:00 > 0:34:03bathed by the warmer Agulhas Current.
0:34:12 > 0:34:16Each capsule contains 100 tiny squid.
0:34:21 > 0:34:26Within a few days, they develop spots of pigment which, when they're adult,
0:34:26 > 0:34:28they will use to communicate with one another.
0:34:40 > 0:34:46With females continuing to lay eggs, and males still preoccupied
0:34:46 > 0:34:50with repelling rivals, the squid drop their guard.
0:34:54 > 0:34:56Stingray!
0:35:02 > 0:35:07Short-tail stingray can be up to two metres across.
0:35:13 > 0:35:15They're the largest of all the stingrays
0:35:15 > 0:35:17and they have appetites to match.
0:35:46 > 0:35:49Another predator is on the prowl...
0:35:51 > 0:35:54..the aptly named ragged-tooth shark.
0:35:59 > 0:36:01Raggies grow to three metres long,
0:36:01 > 0:36:05but they share these waters with a shark twice their size.
0:36:21 > 0:36:23The great white...
0:36:25 > 0:36:29..the largest predatory fish on the planet.
0:36:36 > 0:36:41Each dawn, Cape fur seals leave their colony to go fishing.
0:36:41 > 0:36:46To reach the open sea, they must cross a narrow strip of water,
0:36:46 > 0:36:50and that is patrolled by great whites.
0:36:59 > 0:37:03Each seal is indeed swimming for its life.
0:37:26 > 0:37:29The shark relies on surprise.
0:38:27 > 0:38:33The great white's turn of speed is powered by a high metabolism.
0:38:33 > 0:38:37They only thrive in cold temperate seas, for only these waters contain
0:38:37 > 0:38:42sufficient food necessary to fuel such a ravenous predator.
0:39:14 > 0:39:16As you travel towards the poles,
0:39:16 > 0:39:21north or south, the colder, stormier seas can become even richer.
0:39:23 > 0:39:27Midway between South Africa and the South Pole
0:39:27 > 0:39:31lies the isolated island of Marion.
0:39:36 > 0:39:41The island sits in the infamous Roaring Forties, where incessant
0:39:41 > 0:39:45gale force winds draw nutrients up from the depths,
0:39:45 > 0:39:49ensuring plenty of food for king penguins.
0:39:51 > 0:39:55The kings are returning from a three day fishing trip
0:39:55 > 0:39:57with food for their chicks.
0:39:57 > 0:40:00But first they must cross a crowded beach,
0:40:00 > 0:40:05threading their way between gigantic and bad-tempered elephant seals.
0:40:05 > 0:40:08SEAL SNORTS
0:40:08 > 0:40:10PENGUINS CAW
0:40:17 > 0:40:19The 200,000 penguins breeding here
0:40:19 > 0:40:23are testament to the richness of the fishing.
0:40:27 > 0:40:31King chicks are dependent on their mothers for over a year and
0:40:31 > 0:40:34this puts a great deal of pressure on the parents.
0:40:34 > 0:40:37CALLING AND CHIRPING
0:40:48 > 0:40:50Being flightless,
0:40:50 > 0:40:54the returning penguins must cross the open beach on foot.
0:41:26 > 0:41:30Fur seals, that have come to the beach to breed, are waiting for them.
0:41:39 > 0:41:43Fur seals normally live on krill, but these have now acquired
0:41:43 > 0:41:47an unexpected taste for blubber-rich penguins.
0:41:47 > 0:41:48SEAL ROARS
0:42:37 > 0:42:41Penguins may be featherweights by comparison,
0:42:41 > 0:42:45but they have razor sharp bills and a feisty character.
0:42:47 > 0:42:50The seal could easily lose an eye.
0:42:50 > 0:42:52The only safe way to grab a penguin
0:42:52 > 0:42:56is from behind and the birds are well aware of that.
0:43:01 > 0:43:04PENGUIN CHIRPS, SEAL SNORTS
0:43:05 > 0:43:08SEAL GRUNTS
0:43:18 > 0:43:20Both animals are clumsy on this terrain.
0:43:20 > 0:43:23But the penguin has the more to lose.
0:43:25 > 0:43:27SEAL ROARS
0:43:35 > 0:43:37Made it!
0:43:37 > 0:43:40Two out of three penguins survive the seal attacks
0:43:40 > 0:43:44and succeed in reaching their ever-hungry chicks.
0:44:14 > 0:44:18The humpbacks are nearing the end of their epic journeys.
0:44:23 > 0:44:26After two months and thousands of miles,
0:44:26 > 0:44:32they're entering the Polar Seas, both in the north and the south.
0:44:41 > 0:44:43In the far north,
0:44:43 > 0:44:48winter is over at last and the ice is starting to melt.
0:44:52 > 0:44:56The Aleutian Island Chain, running west from Alaska,
0:44:56 > 0:44:59is the gateway to the Bering Sea.
0:44:59 > 0:45:00With the retreating ice,
0:45:00 > 0:45:05rough weather and ferocious currents stir-up these shallow seas.
0:45:05 > 0:45:10Add sunshine and the mix is spectacularly productive.
0:45:20 > 0:45:24Five million shearwaters have flown almost 10,000 miles
0:45:24 > 0:45:26from Australia to get here.
0:45:26 > 0:45:31In all, 80 million seabirds, come here for the summer.
0:45:31 > 0:45:34The greatest concentration to be found anywhere on Earth.
0:45:48 > 0:45:51The humpbacks have finally arrived!
0:46:10 > 0:46:14The giant shearwater flocks hunt the krill swarms,
0:46:14 > 0:46:18sometimes diving to depths of 40 metres to reach them.
0:46:41 > 0:46:46A large humpback eats three tonnes of krill a day.
0:46:58 > 0:47:02The Polar Seas in summer are the most productive on the planet
0:47:02 > 0:47:06and the whales gorge themselves round the clock.
0:47:13 > 0:47:15The fat reserves they lay down now
0:47:15 > 0:47:19will keep them alive during the year to come.
0:47:19 > 0:47:22But it may not always be this way.
0:47:22 > 0:47:25Fish and krill stocks are declining so rapidly
0:47:25 > 0:47:29that spectacles like this may soon be part of history.
0:47:39 > 0:47:43Once the mother and calf have reached their feeding grounds,
0:47:43 > 0:47:44they will separate.
0:47:47 > 0:47:53With luck, the calf will make the epic journey across the oceans,
0:47:53 > 0:47:56from equator to pole, another 70 times,
0:47:56 > 0:48:00cruising back and forth between the shallow seas,
0:48:00 > 0:48:05where life proliferates so abundantly on our planet.
0:48:29 > 0:48:35A one-tonne great white shark, captured in ultra slow motion.
0:48:35 > 0:48:40To a record a breach like this, which in real-time lasts just a second,
0:48:40 > 0:48:44was certainly Shallow Sea's greatest filming challenge.
0:48:50 > 0:48:55Simon's Town in South Africa is a thriving seaside resort.
0:48:57 > 0:48:59Yet just a few miles offshore
0:48:59 > 0:49:03is a major gathering of great white sharks.
0:49:07 > 0:49:09Cameraman Simon King and his crew arrived
0:49:09 > 0:49:14with an assortment of cameras, including an ultra slow motion unit.
0:49:14 > 0:49:18And for support while filming out in the rolling high seas,
0:49:18 > 0:49:23the rim of a bicycle wheel, to keep Simon firmly on board.
0:49:28 > 0:49:35Guided by shark expert Chris Fallows, the crew headed nine miles offshore,
0:49:35 > 0:49:39to Seal Island, home to 60,000 fur seals.
0:49:42 > 0:49:48They arrive at dawn, just in time for the first wave of shark attacks.
0:49:48 > 0:49:52- Oh!- There. Seal still going!
0:49:52 > 0:49:55Straight away, the action was explosive.
0:49:55 > 0:50:00Wow! And one there and the seal's still here on the right.
0:50:02 > 0:50:04Seals all over the show here.
0:50:04 > 0:50:08Great whites only come to Seal Island for two months of the year,
0:50:08 > 0:50:12coinciding with the seal pupping season, and even then,
0:50:12 > 0:50:14their hunting behaviour is very unpredictable.
0:50:17 > 0:50:20It is non-stop.
0:50:20 > 0:50:22Sharks are attacking seals everywhere.
0:50:22 > 0:50:25The team were lucky to hit such a busy time.
0:50:25 > 0:50:29But the real problem was where to point the camera.
0:50:31 > 0:50:35Extraordinary what these seals have to go through every single day
0:50:35 > 0:50:37if they want to go out to sea to find a meal.
0:50:37 > 0:50:42They go across this relatively small patch of water, which is just
0:50:42 > 0:50:46heaving with these enormous predators.
0:50:47 > 0:50:49OK, what we're gonna do...
0:50:49 > 0:50:52It really requires all of our attention.
0:50:52 > 0:50:55Chris has studied shark attacks around Seal Island
0:50:55 > 0:50:56for the last ten years.
0:50:56 > 0:50:58To record a leaping strike,
0:50:58 > 0:51:02it was essential to understand the daily movements of the seals.
0:51:06 > 0:51:10Simon had no way of knowing where the sharks lay in wait.
0:51:10 > 0:51:11They patrol close to the island
0:51:11 > 0:51:15at depth looking up at the silhouettes of seals swimming above.
0:51:15 > 0:51:17So Simon could only focus his camera
0:51:17 > 0:51:22on the seals as they porpoised for their lives through this danger zone.
0:51:22 > 0:51:25OK, hold on, hold on, Sean.
0:51:26 > 0:51:30In theory, as long as he kept his camera running on the stream
0:51:30 > 0:51:34of escaping seals, in time a shark would strike in frame.
0:51:38 > 0:51:40Wow, unbelievable!
0:51:40 > 0:51:43At last, a breach on camera.
0:51:43 > 0:51:47If we manage to film that at ultra slow motion - ho, ho, ho!
0:51:48 > 0:51:52To reveal the action, the team had modified a specialised studio camera,
0:51:52 > 0:51:59normally used to analyse car crash safety tests in ultra slow motion.
0:52:01 > 0:52:04Applied to a shark breach, this revolutionary camera
0:52:04 > 0:52:10should slow down a one-second leap into a 40-second shot.
0:52:10 > 0:52:14But the camera also had another important capability.
0:52:14 > 0:52:19This is sending all its information back to a massive computer,
0:52:19 > 0:52:21and every 2½ seconds
0:52:21 > 0:52:24it's going in cycles, storing information the whole time.
0:52:24 > 0:52:29When I press the trigger, which in fact is a door bell that we strapped onto the handle,
0:52:29 > 0:52:32it remembers the image right in the middle.
0:52:32 > 0:52:36That's the trigger, so, one-and-a-bit seconds before,
0:52:36 > 0:52:38one-and-a-bit seconds after,
0:52:38 > 0:52:43it will record everything that happens, and that's how we should
0:52:43 > 0:52:46be able to record the entire breach of the shark from the point
0:52:46 > 0:52:49it leaves the water to the point it enters.
0:52:49 > 0:52:51That's the theory, anyway.
0:52:51 > 0:52:55By firing the camera mid-way or just after the event,
0:52:55 > 0:52:59Simon would be able to record all the previous action -
0:52:59 > 0:53:02an invaluable ability since there could be no warning whatever
0:53:02 > 0:53:05of where or when a shark would strike.
0:53:06 > 0:53:11The camera was primed, but the fish had stopped jumping.
0:53:14 > 0:53:16All went quiet for days.
0:53:24 > 0:53:27Then, suddenly, the sharks were back in action.
0:53:27 > 0:53:31The port side. It's gonna come back to you - seven o'clock!
0:53:31 > 0:53:36And it's really quite extraordinary that already, in so short a time...
0:53:36 > 0:53:40- Oh, hold on!- And again! See, we just had one kick off now.
0:53:40 > 0:53:42Another attack.
0:53:42 > 0:53:45But it's a big ocean.
0:53:45 > 0:53:49The only way to get there is at full speed,
0:53:49 > 0:53:54to try and keep the spray off the gear,
0:53:55 > 0:53:57and maybe, maybe the attack
0:53:57 > 0:54:01has not finished by the time we reach the scene.
0:54:01 > 0:54:04The shark's first surprise breach is always the most spectacular
0:54:04 > 0:54:09and the team's real challenge was to be there when it happened.
0:54:09 > 0:54:12Oh, so close!
0:54:12 > 0:54:17Just, half a second away, half a second away all the time.
0:54:17 > 0:54:20It's gonna happen.
0:54:20 > 0:54:22Wow, another one! God, hold on!
0:54:32 > 0:54:36Again, just too late and the seal escapes.
0:54:36 > 0:54:41Boy, what a mixed feeling, because every time a seal gets away you go,
0:54:41 > 0:54:42"Yes, to the seal,"
0:54:42 > 0:54:44but it also means....
0:54:44 > 0:54:50no shark attack recorded so, um, persevere.
0:54:52 > 0:54:55- Big shark. He came up on... - Here, here, here, here, here!
0:54:59 > 0:55:04- Fired on it.- Once the high speed camera has fired, it's out of action
0:55:04 > 0:55:08for 15 minutes while the image is downloaded into the computer.
0:55:10 > 0:55:15In the meantime, Simon switches across to a normal speed camera.
0:55:15 > 0:55:18- It was off on the right at first, I know that.- Oh, my god!
0:55:18 > 0:55:20Oh, that was the one, damn it!
0:55:20 > 0:55:23Just their luck - a perfect breach,
0:55:23 > 0:55:26but the high speed camera is still downloading.
0:55:26 > 0:55:28That was the one we should have fired on.
0:55:33 > 0:55:38Be careful. Don't look down, you don't want to look down. Not pretty.
0:55:38 > 0:55:41A seal has been fatally injured.
0:55:41 > 0:55:44No, it's still alive. Shark, yeah.
0:55:46 > 0:55:49For scientists and filmmakers alike,
0:55:49 > 0:55:53recording behaviour like this is always charged with emotion.
0:55:53 > 0:55:54When you have a situation like this,
0:55:54 > 0:55:58we keep the boat in the same position, we don't put it in gear.
0:55:58 > 0:56:01It's unfair on the seal, who's now using the boat as a cover,
0:56:01 > 0:56:03and plus it's a very dangerous situation
0:56:03 > 0:56:06for the shark can come up and catch a seal right next to the boat
0:56:06 > 0:56:10and obviously, if it's a full breach we'll get the shark in the boat with us.
0:56:10 > 0:56:13So, at times like this, we always have to be very cautious
0:56:13 > 0:56:16and do our best to respect both the shark and the seal
0:56:16 > 0:56:20by not changing the situation any more than we have to.
0:56:20 > 0:56:24Filming the predation has all the thrill of a chase.
0:56:24 > 0:56:28At the same time, you can't help but feel sorry for the seal.
0:56:28 > 0:56:30So you can see 1,000 kills,
0:56:30 > 0:56:33and it still doesn't wrench your heart. Every single day
0:56:33 > 0:56:38you watch these little guys joggle and justle for their lives.
0:56:38 > 0:56:40He's coming through, Simon.
0:56:40 > 0:56:42For the next two weeks, the team became more and more
0:56:42 > 0:56:46practised at predicting where the shark breaches would take place.
0:56:46 > 0:56:50- Breach!- And finally their experience paid off.
0:56:50 > 0:56:52Still going.
0:56:54 > 0:56:56Got it. Yes.
0:56:57 > 0:56:59That should be on.
0:57:07 > 0:57:10I should have got it. Oh, man, I think that might be the shot.
0:57:12 > 0:57:15That might be the shot we were hoping for.
0:57:21 > 0:57:25Here it comes, here it comes. Right through the middle, seal first.
0:57:27 > 0:57:28Shark second.
0:57:33 > 0:57:34That's very good.
0:57:34 > 0:57:36Chuffed!
0:57:49 > 0:57:53The high that comes with getting shots like these
0:57:53 > 0:57:57after so much effort is always tempered with respect
0:57:57 > 0:57:59for the predator, and sympathy for the prey.
0:58:35 > 0:58:38Subtitles by Red Bee Media - 2006
0:58:38 > 0:58:41E-mail subtitling@bbc.co.uk