Their playground, the Pacific Ocean. Lording it over such a vast kingdom,
they cut an all-too-familiar silhouette. Their popular reputation
as fierce predators is understandable. Yet, what are they
but common scavengers? The humble dustmen of the seas, and all too often,
outsmarted by their juniors. Here are sharks in their true colors. The Pacific is by far
the largest body of water on the planet. Covering 70 million square miles, it accounts
for half the world's ocean surface. Lost in this blue kingdom,
pinpricks of land where young seabirds are about to leave their nests
for the first time. A fact not lost on life below the reef
that encircles the tiny islands of the French Frigate Shoals
in northwestern Hawaii. After weeks of training, black-footed albatross chicks
are ready for the big day. Their parents have already left
the nesting ground. Even the strong wind
blowing off the lagoon can't help this one. It's fair game for the most opportunistic
predator in the lagoon, the tiger shark. It's both unpredictable
and extremely aggressive. Unlike other species of sharks out to sea,
the tiger shark is generally a loner whose favorite hunting grounds
are the shallows. Nothing like a nudge
in the right direction to get airborne. It wasn't to be. The chicks will try to take off in unison. So the tiger shark
only has a narrow window of opportunity for playing, feasting,
and saving its awesome reputation. In the open sea, sharks and birds
behave in an altogether different way. Every kind of ocean nomad
is drawn by the strong winds and currents that galvanize the sea
into a maelstrom of competing interests, both above and below the surface. How are these pristine opal waters
managed, or serviced, if you like? Like the tiger shark
policing the shallows alone, nomads out here work together
towards a common objective, be it for defense or attack. Schools of baitfish
bunch together for protection. They're being rounded up
by a pod of bottlenose dolphins. The table is laid. Wait a moment. Unexpected guests have shown up, and the dolphins must leave the table. Silky sharks. They've been watching the dolphins
work from a distance. Their vision finely attuned
to the blue gloom because of special pigments in their eyes. The dolphins sensibly wait
for a second sitting, which they'll share
with others on the surface. Gannets and brown petrels
enjoy a bird's-eye view, but their patience is wearing thin. Now that the waters have been tested,
a full aerial bombardment is underway. These feathered torpedoes
must climb to ten meters before executing
their spectacular sorties. This extraordinary assault by shark
and bird against the bewildered baitfish is relentless. Having taken the lion's share, the silky sharks withdraw
as willfully as they came. It's a moment of respite for the baitfish, but not for long. Yellowfin tuna form a third front,
wave after wave of them. This is predation on a massive scale. The remaining baitfish
have one last card to play. They swarm individual silky sharks,
not for revenge, but for protection against the tuna. The baitfish face a dilemma. Should they jump ship from shark to tuna? The silence of this predatory world
speaks for itself. There are areas of the Pacific
where natural predators turn to scavenging for a living. The main island in the archipelago
of New Caledonia is a sliver of land in the South Pacific,
250 miles long and 30 wide. Smaller islands bathe
in the crystal clear waters of a tropical lagoon. The largest lagoon in the world,
9,000 square miles. It's a paradise meticulously tended
by those who inhabit it. No paradise is one without sacrifice. Those who share it
share off each other too. Everywhere life thrives,
death will reap a just reward. The lagoon creates waste
and must dispose of it. One day, the dead and the wounded
will be mopped up by scavengers. The dustmen of the seas. The lagoon is not impenetrable. Cracks are opened up
in this vast ring of coral by the relentless pounding of the ocean. The whitetip reef shark
is an expert dam buster. A red snapper snared in a net. The shark hones in on the distress signals as the snapper emits
a faint electrical charge, even when it's motionless. Literally a millionth of a volt
is enough to stimulate sensory organs called ampullae of Lorenzini
on the shark's snout. In effect, the injured and the weak
sign their own death warrant. A grey reef shark approaches
the industrious whitetips keen to join operation cleanup. Its impressive size does not earn it
the automatic right to muscle in. This is a private party
for whitetips only. Sharks themselves also run the risk
of getting caught in nets, particularly those more used
to inhabiting the open sea. But white tip reef sharks are equipped
with two rows of teeth. The uppers are triangulated and jagged. The lower row, narrow and sharp. A perfect combination for cutting
and tearing their way out of trouble. Damaged teeth will be replaced in 18 days, and they'll grow about 20,000 new teeth
in the course of their lives. As long as whitetip reef shark
move freely and hunt in packs, neither nets nor other sharks
will stop them in their mission to clean up the lagoon
of injured and weak fish. Inadvertently, the sharks will even help
dismantle these destructive nets. This snapper might count itself lucky. If only it could hide its distress. The more it struggles to stay afloat,
the stronger the signal. Thanks to the shark's natural radar and its capacity to detect vibrations
from far, the area is cleared. Pockets of coral and limestone caves
do offer some insulation from this radar, which, it must be said,
is only used at short range. But what is this one after? A swimming wrasse
which emits long-range vibrations. Whitetips will go to great lengths
to satisfy their appetite, or is it just curiosity? After all,
they need only feed every other day and a mere three percent
of their body weight is reckoned a good enough meal. Some fetch up at the mouth of a cave
through a break in the reef, a good place for an ambush. Unlike their cousins in the open water, whitetips don't need
to be on the move to breathe. They can lie and wait for their prey
by using muscular contractions to pump water through their gills. These males
aren't hungry for food, but sex. They're waiting for a female. She's hemmed in
on all sides by competing males, but the paramour
must fend off other excited rivals. The lovemaking
will last about five minutes, during which time the suitor must fend off
other rivals drawn into the scene by the vibrations and electrical impulses
radiating from the courtship. The female probably got off lightly. This one is unlikely to survive. Her blood involuntarily signals
her vulnerable condition to every pilferer in the area, including the biggest fish in the world, the whale shark. It's 15 meters long, and quite harmless. Like real whales,
the whale shark is a filterer using its cavernous jaws
to hoover up plankton and other small fry in its path. It too, is a most efficient cleaner, though quite incapable
of cleaning up a dying shark. Commotion, blood, electricity. The telltale distress signals
radiate loud and clear. This silvertip has homed in
from the bottom of the pass. A welcoming committee is awaiting. The red snappers are back, and so are the grey reef sharks. These passing bottlenose dolphins
and their calves steer clear of the danger. A silvertip this size
is also a potential threat to baby dolphins. The shark must be seen off. Indeed, the dolphins take it in turns
to go up to the surface to breathe. The tactic is ingenious. The dolphins spiral around the silvertip
to force him down out of harm's way. Reinforcements are called in
to increase the pressure. It's now five against one
and the silvertip finally gets the point. The dolphins can't disguise their delight. It's time to surface and celebrate. The pass through the reef is now clear and the dolphins are free
to enter the shallows and explore the waters
around the sandy islands. As spring turns to summer
in the Southern Hemisphere, a time-honored pilgrimage
is about to wash up on these shores. Same time, same place. A green turtle scarred by a long journey. The healthy ones
will perpetuate the species as they have done for 15 million years. An annual rendezvous for mating
and for the females to lay eggs. The event is also on the calendar
of the blacktip shark. At high tide, it watches greedily
as the females prepare to beach. The solitary turtles
have crossed the Pacific with pinpoint accuracy. Thanks, it is thought,
to some magnetic minerals in their brain which tap into the Earth's
magnetic field for direction. The tide fills natural pools
around the beachrock, allowing the sharks to get close to shore. A female, all 80 pounds of her,
hauls her eggs far from the high water mark,
more than a kilometer inland. The sharks know the routine. They'll patrol the pools
until the tide flushes them out again. The turtles have 12 hours
to dig and fill their nests before catching the next high tide out. As the tide goes out, sand crabs also dig in
for a night of hunting. As night falls,
blacktips still brush the shoreline. Grey reef sharks
patrol further out at sea. A blockade is on. With the tide now low, some turtles have finished
laying their eggs. A blanket of sand will keep them
at a constant temperature and hide them from predators
during a two-month period of incubation. The females now begin
the arduous return journey. By morning,
most have left on the high tide. Those that have missed it must face
a punishing wall of exposed coral under the baking sun. All after an exhausting night's work. It's the end of the road for this one. Her carcass now reeks
of rich oils and torn flesh. On cue, gray reefs
and blacktips follow their noses. To locate dead prey, these scavengers are guided
by their sense of smell. Reclusive hermit crabs
are left to polish the silver. By mid-summer, the dry season has set in
on the main island of New Caledonia. A mountain range on the Leeward Coast
creates long periods of drought. It's home
to tens of thousands of wild deer who now look elsewhere for green pasture. Some head for the mangroves. Many will leave the island altogether and venture across the bay
in search of food on other islands. Their narrow hooves
are ill-suited for swimming. Hopefully, the natural buoyancy
of their paunch will keep them afloat. The deer can average two knots
over long distances, simply by repeating
the same movements they use on land. Across the lagoon in any direction,
lie dozens of tiny uninhabited islands. They're thick with grasses
and foliage supplied all year-round by soft water
trapped in the limestone subsoil. The crossing has been worthwhile,
even if some of the deer have struggled two miles from the mainland
to find new feeding grounds. They'll spend the entire summer
island hopping to survive the drought. Every day brings new arrivals. This kid is exhausted,
but at least he's made it. Many die in midstream. Waste to be disposed of
by the dustmen of the seas. A mere one part blood
to 100 million parts water is enough to trigger a frenzy. By the end of the summer, the last of the nesting turtles
are leaving the islands. Hundreds of eggs are ready to hatch. Instinctively, the baby turtles
head for the pool. There's no scent of blood this time. Here, the blacktips must use their eyes,
if their patience is to be rewarded. This is a problem
because they're short-sighted and their movements are cramped
by the shallow waters. In the event, the sharks are joined by other, faster
and more efficient predators. Giant trevally. More commonly known as Jack. Pound for pound,
it's the strongest fish in the world, sharks included. It's perfectly suited to the crystal clear
and well-oxygenated shallows. This is the proof. By contrast, it takes two myopic
and clumsy blacktips to hunt down a single baby turtle. Those which survive
the blockade to the open sea must now contend
with predators from the sky. What with these terns,
sharks, and the jacks, it's little wonder that out of 100 eggs,
only one turtle will survive to adulthood. If this is one of them, it will be back
in 15 years to mate or lay eggs. The scavengers will make a point
of being there too. For the most part, life about the lagoon
is entirely predictable. Here is a magnificent exception. An 18-meter blue whale. The largest animal
ever to roam the planet. At the end of the southern summer, this male should be feeding
on krill in the Antarctic, but it's lost its way
and mysteriously fetched up in the lagoon. Never has this been seen before
in New Caledonia. Stretch marks are signs
of severe undernourishment. If the lagoon can't satisfy its needs,
perhaps it can satisfy others'. Forty tons of flesh
emit rapid, low frequency sound waves. The tiger shark has picked up the signal
from several miles away as the whale reaches the bottom
of the bay, exhausted and cornered. In the end, there is only one killer. What a treat. Rare indeed for this tiger shark
to have honed in on so much red meat. It has pushed itself to the limit and has swallowed a tenth
of its own body weight. Other sharks were probably too far off
in the lagoon to make it in time, but the blue whale is going no further. Day after day, the whale's corpse
will radiate a gigantic, oily path. Sharks and their stereoscopic sense
of smell will simply follow this stairway to heaven. This treasure of protein has been bagged
by a whole pack of tigers, and they won't let
any other species of shark near it. Only a few harmless remoras are tolerated. The final cleanup is underway. It has taken a week and counting
to clear all 18 tons of meat. What little evidence is left
of the blue whale will filter through passes in the lagoon
for the final clean in the dark abyss of the open sea. About 85 percent of the Pacific
is more than a mile deep. Plenty of room for other,
more passive scavengers waiting in the dark and cold
and under colossal pressure for the pickings left
by their peers on the surface. Down here, life exists without oxygen. Deep sea hydrothermal vents
sustain an oasis of life. Located on the side of a fault
between two tectonic plates, New Caledonia
is effectively a mountain in the ocean. These gigantic fractures in the crust
belch gases through seafloor chimneys. In this anaerobic and unstable underworld, life is organized
around methane and hydrogen sulfide, highly toxic on land,
but life-sustaining in the abyss. At the bottom of the evolutionary pile
in this ecosystem is the tube worm. It has no mouth,
no digestive tract, and no anus. Everything is passed through its plumes. The thermal vents superheat the water
to 350 degrees Celsius, but at depths of 3,000 meters,
the water does not boil. The pressure is too great. So blind shrimps are free
to scrape the vents for minerals and bacteria. It's remarkable
how marine life can adapt to this hell. Away from the vents, notably at the foot
of the New Caledonian lagoon, there is nothing. Life in these abyssal deserts
depends essentially on what sinks from the surface. When scavengers of the dark
reach their objective, relationships can be
extremely long-lasting. Giant crabs will take several years
to pick a whale carcass clean. Difficult to be spotted
in this dark world, unless like some squid,
you are equipped with photophores, a sort of light-producing organ. They use them to attract prey
or to seduce sexual partners. These luminous cells
can also be seen on dying animals. Others must grope their way
around the ocean floor in their search for organic matter, dead or alive. It's a task made easier
for the birdbeak dogfish, and like its cousins from the lagoon,
its stereoscopic sense of smell. Other scavengers must wait
for the currents to carry food to them. Like this tripod fish. They can also filter organic particles
like this swimming sea cucumber and these crinoids. The vampire squid uses sensory cilia
to detect what's edible in the ocean swells. What do we have here? The most prized dish in the abyss. A whole whale. It's covered with hagfish. These living fossils have been around
for five million years, long before any other fish. They're vertebrates with no eyes,
no skeleton, no scales, not even a mouth. They do have an external circle of teeth
and a strong sense of smell. But a million hagfish can't match this. The Pacific sleeper shark, indolent and sluggish by nature,
but very greedy. Seven meters long and weighing two tons,
it's the largest of all deep water fish and it has an insatiable desire
to keep a 300-liter stomach comfortably full. Most life around the lagoon
in New Caledonia ends up in the abyss. Even the oceanic whitetip sharks
are destined to become a meal for the galatheid crabs. One dustman feeds off another. A fitting end
for the scavengers of the seas.
