- 2 days ago
Reveals vibrant coral gardens, unique marine species, and vast mysterious depths that cover most of our planet.
温暖明亮的水域，栖息着小丑鱼、海龟和珊瑚礁黑暗的高压区域，动物利用光信号来生存...
温暖明亮的水域，栖息着小丑鱼、海龟和珊瑚礁黑暗的高压区域，动物利用光信号来生存...
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AnimalsTranscript
00:00:02Over half of all animals in the open ocean drift in currents.
00:00:17Jellyfish cross entire oceans, feeding on whatever happens to tangle with their tentacles.
00:00:29Some can go to a metre, even two metres across.
00:00:34And when, by lucky chance, they encounter a patch of sea rich in plankton, their numbers explode.
00:00:54But, be ye here, which is hard to find.
00:01:04The sea is more than onewhich is greater than one.
00:01:08The sea is more than one with the sea.
00:01:10Is this a canary?
00:01:25It's such a successful strategy that jellies are one of the most common life forms on the
00:01:32planet. But among the jellies, and looking somewhat like them, is a rather more complex and sinister
00:01:49creature. The Portuguese man-of-war.
00:02:02It floats with the help of a gastile bladder, topped by a vertical membrane. With that serving
00:02:12as a sail, it maintains a steady course through the waves.
00:02:40Long threads trail behind it, some as much as 30 meters long. Each is armed with many thousands
00:02:51of stinging cells. A single tentacle could kill a fish, or in rare cases, a human. But among
00:03:06its lethal tentacles, lurks a man-of-war fish that feeds by nibbling them.
00:03:18Whilst this fish has some resistance to the stings, it must still be extremely careful.
00:03:28Most other fish are not so lucky.
00:03:52A tentacle has caught this one, and wheels it in.
00:04:06It's already paralysed.
00:04:14Specialised muscular tentacles transfer the victim to others that digest the catch, liquefying
00:04:21it with powerful chemicals.
00:04:30Eventually, all that is left is a scaly husk.
00:04:45This voracious man-of-war may collect over a hundred small fish in a day.
00:05:19The struggle to survive in a day.
00:05:21The struggle to survive in our green seas can have far-reaching consequences.
00:05:26Once a year, one particular meadow in Australia is transformed.
00:05:40Around the first full moon of winter, an army materialises.
00:05:49Spider crabs.
00:05:59To the past year, they'd been feeding in deeper waters.
00:06:13Now they march across the seagrass plains
00:06:35Hundreds of thousands of them
00:06:47They clamber over one another
00:06:55Creating great mounds
00:07:03Nearly a hundred metres long
00:07:09They're not seeking mates
00:07:11Neither are they laying eggs
00:07:13They have come here in order to grow
00:07:21Like all crabs, their bodies are enclosed
00:07:24In a hard, unexpandable shell
00:07:29So to grow, they have to break out of it
00:07:42And that allows the soft one
00:07:45That has developed belief to expand
00:07:56It will take days for the new shell to harden
00:08:11Its legs are so limp
00:08:13That they won't work properly
00:08:19The crab is unprotected
00:08:21And in great danger
00:08:32A smooth stingray
00:08:37It's huge, about four metres long
00:08:43It wants a soft, freshly molted crab
00:08:46That will be easier to eat
00:09:09The crabs try to stick together
00:09:20But now, disturbed by the ray
00:09:23They're scattering
00:09:30A newly molted crab
00:09:33Is too weak to keep up the crowd
00:09:50The safest place
00:09:51Is right in the middle of the pile
00:09:55That is why they have all assembled here
00:10:06There is safety in numbers
00:10:25But the vast majority of the crabs escape
00:10:29And within the next few days
00:10:31They will be ready to return to the depths
00:10:34And resume their lonely wanderings
00:10:36In search of food
00:10:50This is no graveyard
00:10:55But the triumph of a hundred thousand crabs
00:10:58Successfully molted
00:11:06A Sally Lightfoot crab
00:11:11One of thousands of shore crabs
00:11:14Just waiting for their moment
00:11:19Every day, they gather on the tropical shores of Brazil
00:11:26Waiting for the tide to go out
00:11:37Which exposes their feeding grounds
00:11:41Seaweed-covered rocks
00:11:43A hundred metres from the shore
00:11:54Getting there is a race against the tide
00:12:05They leap from rock to rock
00:12:21These crabs seem to be afraid of the water
00:12:37And for good reason
00:12:50The moray eel
00:12:54The chain moray is a specialist crab hunter
00:13:04Its blunt teeth can easily grip and crush a crab's shell
00:13:09Its blunt teeth can easily grip and crush a crab's shell
00:13:14It's the crab's deadliest enemy
00:13:28But the crab's feeding grounds are still a long way off
00:13:38They must press on
00:14:02Halfway
00:14:09But their enemy has other ideas
00:14:12But their enemy has other ideas
00:14:17Crossing the land
00:14:25To reset the ambush
00:14:31To feed, the crabs must keep going
00:14:41But nowhere is safe
00:14:47An octopus
00:14:48Also a crab killer
00:15:15The crabs make a dash for it
00:15:44Made it
00:15:55Risking life and limb
00:15:57Risking life and limb
00:15:57To graze on these seaweed pastures
00:16:03But in two hours' time
00:16:05When the tide starts to turn
00:16:08They will have to run the gauntlet all over again
00:16:24In a far corner of Southeast Asia
00:16:27Lies the Coral Triangle
00:16:33A cluster of the richest coral reefs in the world
00:16:42Undersea cities crammed full of life
00:16:52As in any crowded metropolis
00:16:55There is fierce rivalry for space
00:17:03For food
00:17:04For food
00:17:09And for a partner
00:17:12But the reef is also a place full of opportunity
00:17:29A cuttlefish
00:17:47It specializes in hunting crabs
00:18:00But a large crab
00:18:02But a large crab is a dangerous quarry
00:18:11It has powerful claws
00:18:13It has powerful claws
00:18:16The cuttlefish however
00:18:19Has a remarkable talent
00:18:26Its skin contains millions of pigment cells
00:18:30With which it can create ever-changing colors and patterns
00:18:43And that apparently hypnotizes the crab
00:19:09A cuttlefish may be clever
00:19:11But a shark is bigger
00:19:16And it eats cuttlefish
00:19:20Time to disappear
00:19:37Back to the hunt
00:19:43A new target
00:19:44But the same mesmerizing technique
00:20:03For those that manage to establish themselves
00:20:06In these bustling undersea cities
00:20:09There can be great rewards
00:20:15During the dry season
00:20:17Over half a million terns
00:20:19Crowd onto this remote atoll
00:20:21In the Indian Ocean
00:20:30Their chicks are still in their dark juvenile plumage
00:20:38They vary in age
00:20:49Whilst the more advanced chicks take to the air
00:20:59Others aren't quite ready yet
00:21:22Those just starting to learn to fly
00:21:25Use the shallow lagoon
00:21:27And it occupies the center of the atoll
00:21:29As their training ground
00:21:33It's difficult for some of them
00:21:35To stay aloft for long
00:22:00Giant tree valleys
00:22:02Giant tree valleys
00:22:15Usually they are solitary hunters
00:22:18Usually they are solitary hunters
00:22:18But about 50 of them
00:22:20Have come here from neighboring reefs
00:22:22Attracted by this abundance
00:22:24Of potential prey
00:22:34The fledglings stay out of the water
00:22:36If they can
00:22:39They easily drink on the wing
00:22:59If the juvenile are to catch one now
00:23:01They have to up their game
00:23:14So there is a fish here
00:23:16That amazingly
00:23:17Has a brain
00:23:19Capable of calculating
00:23:20The airspeed
00:23:21Altitude
00:23:22And trajectory
00:23:24Of a bird
00:23:50The airspeed
00:23:56The time comes
00:23:57When every fledgling
00:23:58Has to take to the air
00:24:00And collect food
00:24:01For itself
00:24:25Their parents
00:24:27Lead them to the training grounds
00:24:29After the ferry
00:24:31The airspeed
00:24:41How about the airspeed
00:24:55The airspeed
00:24:58I don't know.
00:25:34I don't know.
00:26:04If they are to survive, they must learn quickly.
00:26:16After a month of practicing over the lagoon, the youngsters start to leave and take their chances out over the
00:26:24open sea.
00:26:33Out here on the sand flats, there is safe accommodation for some.
00:26:47The family of saddleback clownfish have found an excellent home.
00:26:55The tentacles of this carpeted anemone can kill.
00:27:02But the clownfish are immune to the poison.
00:27:11So they can shelter from danger.
00:27:18In return, the fish keep the anemone clean of debris.
00:27:27As with all clownfish, the family is ruled by a big female.
00:27:34Her white face marks her out as the boss.
00:27:43The diminutive male has to prove his worth, so he works tirelessly, removing debris and generally keeping on top of
00:27:52the housework.
00:28:14It's greatest challenge is to find a safe place where the boss can lay her eggs.
00:28:24But there's nothing solid here for the female to lay them on.
00:28:33The nearby shell could be the solution.
00:28:46If only he can move it to the protection of the anemone.
00:28:58Too heavy.
00:29:04Besides, it has a mind of its own.
00:29:10A hermit crab.
00:29:20But out here, twice a day, the anemone is swept by tidal currents.
00:29:27And they bring in new opportunities.
00:29:32An old plastic bottle.
00:29:38Perhaps this will do.
00:29:47Not heavy enough.
00:30:01A coconut shell.
00:30:08It looks just right.
00:30:11But it's a long way from home.
00:30:32And he can't move it by himself.
00:30:47So, prepare.
00:30:48They'll work together.
00:30:50Oh.
00:31:31A little adjustment to the anemones tentacles in order to clear a space for it, and the shell
00:31:40is tucked in.
00:31:46The female lays a safe nursery at last.
00:32:07He has proved himself worthy to father her young, and he fertilizes them.
00:32:17Now, he will meticulously tend the eggs, keeping them clean and healthy until they hatch in
00:32:32ten days' time.
00:32:54The blue shark.
00:33:02It travels over 8,000 kilometers a year, riding on the currents supported by its broad,
00:33:09wing-shaped fins.
00:33:16This one may not have eaten for two months.
00:33:25But the currents can carry promising traces of fatty oils from many kilometers away and
00:33:32will lead it to its next meal.
00:33:41After days of travel, the smell of food gets stronger.
00:34:07A dead whale recently struck by a ship.
00:34:14This could be a real feast, but the blue shark must be cautious.
00:34:29Great white sharks, ten times heavier than a blue, are highly possessive around a whale carcass.
00:35:09Great whites are eager to feed on energy-rich whales.
00:35:12A little blubber, which we now know forms a major part of their diet.
00:35:29Once the great white has had its fill, smaller sharks, like the blue shark, tackle what's left
00:35:35of a carcass.
00:35:46As the oils from this dead whale spread more widely, more and more blue sharks appear.
00:36:13Within days, the carcass will be stripped of its blubber.
00:36:26Then, no longer kept buoyant by its oil, it will sink into the depths below.
00:36:36The blue, with its reserves of fat replenished, can now survive for another two months without eating.
00:36:55But most of the creatures come together for a very different reason.
00:37:01To breed.
00:37:07The giant cuttlefish.
00:37:10The largest of all cuttlefish.
00:37:20They live for just one or two years.
00:37:29Now, as the Australian summer draws to an end, they have one last act complete.
00:37:40To find a mate.
00:37:46Now, there are over 100,000 males competing for the arriving females in this one bay.
00:38:00Among them, a giant, a true goliath.
00:38:04He probably weighs about 10 kilos.
00:38:10Bands of color sweep across his skin.
00:38:13That's how cuttlefish communicate.
00:38:35This smaller male couldn't possibly take him on.
00:38:48Beside goliath and under his protection, a female who has just mated with him.
00:38:58But other rivals are still interested.
00:39:04It seems a small male wouldn't stand a chance.
00:39:10The female is now displaying a white stripe along her side nearest goliath.
00:39:19It's a clear signal that she no longer wants to mate with him.
00:39:27It's all the encouragement that the little male needs.
00:39:54He's going to have to use trickery.
00:40:11He tones down his colors and tucks in his arms.
00:40:18He's just the right size to mimic a female.
00:40:33Goliath is deceived.
00:40:38The small male now displays a white stripe, just like the real female, to deter his advances.
00:40:51He slips beside her.
00:40:56And they mate.
00:41:09By mating with multiple partners, the female ensures the greatest genetic diversity for her young.
00:41:23The sneaky male leaves.
00:41:27His final act complete.
00:41:34So even among giant cuttlefish, it seems, it's not all about size.
00:41:53In the underwater forests of northern Japan.
00:41:58The residents of this sunken wreck are waiting for the summer temperatures to reach 16 degrees Celsius.
00:42:17That, for some, is the time for mating.
00:42:34A kind of giant wrasse called a gobudai.
00:42:45This is a male.
00:42:51And in female terms, he's particularly handsome.
00:43:02He's a metre long and weighs 15 kilos.
00:43:10Much larger than the diminutive female.
00:43:17And he is ready to breed.
00:43:23He attempts to mate with her.
00:43:26And with any of the other dozen or so females that live in his territory.
00:43:32Whenever he gets the chance.
00:43:48But females from around 10 years old, take little notice of his advances.
00:44:22This is because.
00:44:23When any large female reaches a critical body size.
00:44:27She can begin a dramatic transformation.
00:44:48Over just a few months, particular enzymes inside her body cease to work.
00:44:55And male hormones start to circulate.
00:45:03As time passes, her head expands and her chin gets longer.
00:45:13A she has changed into a he.
00:45:27And with this comes a change in temperament.
00:45:36The old male who ruled all the females here.
00:45:42Is challenged to a face off.
00:45:51The more bulbous the head.
00:45:53The more bulbous the head.
00:45:54The more it intimidates an opponent.
00:45:56The more bulbous the head.
00:46:15Here we go, it's the next.
00:46:38Only the largest females transform themselves in this way, but the change enables them
00:46:50to have more mates, so they will have many more offspring carrying their genes.
00:47:02But a new male can't afford to be complacent.
00:47:07Inside the body of every Kobudai female, there is a new male in waiting.
00:47:24And wave power creates towering fortresses like these cliffs in the Arctic, home to tens
00:47:31of thousands of breeding seabirds.
00:47:38The faces of the cliffs are accessible only from the air, and have plenty of nooks and
00:47:43crannies for those that can get there.
00:47:51But to feed, seabirds must still master the ocean world beyond.
00:48:00A puffin.
00:48:05He's a fisherman and a father.
00:48:14He has a mate for life.
00:48:23Both share the burden of raising their weak old chick, their puffling, who needs five square
00:48:31meals a day.
00:48:34The parents alternate fishing trips.
00:48:37horse?
00:48:38Whisk, whisk, whisk, whisk, whisk, whisk.
00:48:40Whisk, whisk, whisk, whisk, whisk, whisk!
00:48:41It's Dad's turn.
00:48:45Ahyy, ha, ha, ha, ha…
00:49:05When fish stocks are low, huffins must fly as much as 50 kilometres out to sea to reach
00:49:13the good fishing grounds.
00:49:27Once there, they plunge into another world.
00:49:39Good fishing spots are hard to come by, and they have company.
00:49:54Like the puffin, their wings are short and good for diving.
00:50:01Puffins can hold their breath for over a minute and dive as deep as 40 metres.
00:50:11A catch!
00:50:32But it's a long way home.
00:50:48After an exhausting round trip of almost 100 kilometres, this puffins nearly made it.
00:50:57But there are pirates on this coast.
00:51:04Arctic skewers.
00:51:30All around, returning parents are being robbed.
00:52:00The skewers' long, raked back wings make them part of the sea.
00:52:04It must have been more maneuverable.
00:52:06It must have been more maneuverable.
00:52:06It must have been more maneuverable.
00:52:43Puffins must choose their moment wisely.
00:53:07A near miss.
00:53:25A last desperate burst of speed.
00:53:29Puffins can hold their moment.
00:53:31And it's made it.
00:53:57And it's made it.
00:53:59safely home after a three-hour round trip
00:54:10where his patient partner is waiting
00:54:29today their puffling will eat
00:54:39but where fish numbers are in decline many puffins now find it hard to get enough food for their chicks
00:54:48in the changing season today it can be even harder to be a successful puffin parent
00:55:05a kilometer from the surface beyond the reach of the sun
00:55:15a giant black void larger than all the rest of the world's habitats combined
00:55:27there's life here but not as we know it
00:55:42alien-like creatures produce dazzling displays of light
00:55:51so
00:55:59nearly all animals need to attract mates and repel predators
00:56:07this language of light is so widespread here
00:56:10that these signals are probably the commonest form of communication
00:56:16on the entire planet
00:56:19and yet we still know little about them
00:56:21so
00:56:46Hunters illuminate themselves and, by doing so, attract inquisitive prey.
00:57:03This is Fang Tooth.
00:57:08It has the largest teeth for its size of any fish.
00:57:14There are pressure sensors all over its head and body which can detect anything moving
00:57:19in the surrounding water.
00:57:28It's the Midnight Zone's most ferricious fish.
00:57:32But prey used light as a distraction.
00:57:40A decoy of luminous ink.
00:57:52Down here, in this blackness, creatures live beyond the normal rules of time.
00:58:07Siphonophores are virtually eternal.
00:58:11They repeatedly clone themselves.
00:58:14Some eventually growing longer than a blue whale.
00:58:42Down here, it snows.
00:58:54Continuous clouds of organic debris drift slowly down from above.
00:59:06This is food, and a whole variety of filter feeders depend on it.
00:59:15And a jellyfish.
00:59:25and delicate sea cucumbers.
00:59:47The 1% of marine snow they miss eventually settles on the sea floor.
01:00:20Over millions of years it forms a layer of mud up to a kilometer thick.
01:00:31It's an empty plane that covers half the surface of our planet.
01:01:01The deep sea bed may at first appear lifeless,
01:01:08but it's home to a unique cast of mud dwellers.
01:01:14The sea toad.
01:01:19It is an ambush predator with an enormous mouth and infinite patience.
01:01:37This fish has been living for so long here that its fins have changed into something more useful.
01:01:51Feet.
01:01:56They help it shuffle about on the sea floor.
01:02:19The flapjack octopus.
01:02:27It hovers just above the surface of the mud as it delicately sifts through it, searching for worms.
01:02:37But it can jet away at the first sight of danger.
01:03:04In the Gulf of Mexico, these eruptions also release a super salty liquid.
01:03:19Brine.
01:03:32It's heavier than sea water, and it accumulates in great pools on the sea floor.
01:03:43It's difficult to make sense of the sight.
01:03:53A lake of concentrated salt water, 15 meters deep, at the bottom of the sea.
01:04:09Around its margin, perhaps even more strangely, there is a profusion of life.
01:04:22Giant mussels that can live and grow for a century or more pack it tightly together,
01:04:28dwarfing the shrimps and squat lobsters that feed around them.
01:04:55A lake of concentrated salt water, 15 meters deep, at the bottom of the sea.
01:05:01Cutthroat eels, scavengers, come to the shores of the brine lake in search of something edible.
01:05:16Some even venture into the brine.
01:05:53Spending too long in it can send an eel into toxic shock.
01:06:08It's only hope is to rise above it.
01:06:26It manages to escape.
01:06:36Others are not so lucky.
01:06:46The brine embalms their bodies, and the casualties of decades accumulate around the margins.
01:06:55The brines.
01:07:02The brines.
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