生命之旅第一集:海洋里的生命 Seas of Life

[00:00.00] [00:02.20] [00:03.20]Since its early origins, there has been a spectacular explosion of life on the planet [00:08.66] [00:17.28]Some creatures have come and gone [00:19.44] [00:26.35]Others have stayed the distance [00:28.25] [00:34.23]All species that have ever lived on the planet are related to each other, [00:38.22] [00:38.43]including us humans - just one result of the journey of life. [00:43.66] [01:01.52]The oceans are teaming with life in all its forms [01:05.25] [01:14.43]This is a journey to discover... [01:16.06] [01:16.27]...how this spectacular diversity came to be [01:19.67] [01:23.21]We'll meet the beautiful... [01:24.57] [01:27.08]...the bizarre... and the extreme... [01:33.68] [01:37.89]...and we'll come face to face with the some of the most feared predators on the planet. [01:43.19] [01:46.33]As we meet these creatures, we'll learn something... [01:48.96] [01:49.17]...of our own aquatic origins... [01:51.23] [01:51.47]...as we journey through the incredible Seas of Life [01:55.07] [02:12.06]There is an enormous variety of life on the planet, [02:15.32] [02:15.73]but how did it come about? [02:17.56] [02:19.73]For a few days each year, [02:21.13] [02:21.37]this remote Pacific beach shed's some light on the answer [02:24.82] [02:27.27]Dawn reveals an epic dramatic struggle... [02:29.54] [02:29.74]...one that's been going on since the time of the dinosaurs. [02:32.84] [02:41.22]It's a battle, fought by all living things, [02:44.12] [02:44.46]only the individuals best suited to the world in which they live stand a chance. [02:48.86] [02:49.33]Its what we know as 'survival of the fittest' [02:52.46] [02:58.17]And at no point in these baby turtles lives is this more critical than [03:02.44] [03:02.64]when they leave the nest [03:04.17] [03:08.81]Hungry predators are waiting. [03:10.71] [03:24.16]Its an instinctive dash from nest to sea [03:26.89] [03:35.47]Some youngsters lag behind. [03:37.34] [03:40.55]The tiniest physical difference determines who lives and who dies... [03:46.21] [03:48.75]Some are weak... others strong [03:51.28] [04:19.28]Chance plays its part too. [04:21.25] [04:24.36]Only a lucky few will make it to the waters edge [04:27.05] [04:33.07]Any trait that increases the odds of a youngster surviving [04:36.73] [04:36.94]will be passed on in its genes [04:39.20] [04:39.94]Its natural selection, and its been going on for billons of years, [04:44.43] [04:44.64]shaping life all over the world. [04:47.11] [05:01.26]You might not think we have much in common with the fish, [05:04.02] [05:04.33]but we actually share the same basic blue print. [05:07.06] [05:07.63]A blue print... formed in the sea [05:09.96] [05:20.18]The seas are life's laboratory where many solutions to the challenges of living... [05:25.01] [05:25.22]were first developed and tested [05:27.24] [05:34.49]Its left its mark on every living thing, including us. [05:38.02] [05:47.01]At one time in our lives we actually had gill slits... and even a tail! [05:52.03] [05:54.58]This is a human being at just 24 days after conception. [05:58.81] [06:00.75]Bathed in a warm, salty sea of amniotic fluid, it's a time of extraordinary growth. [06:06.55] [06:09.36]Here on the head are gill slits or more precisely, 'pharyngeal pouches'... [06:15.70] [06:17.54]Fish embryos have them too, in fish they do turn into gills, [06:22.06] [06:22.31]but in humans they become parts of the face, ear and jaw. [06:26.40] [06:29.35]This tail too suggests that we share ancestors with other animals... [06:34.05] [06:34.25]it's an echo of our own evolutionary past... [06:36.78] [06:41.36]We humans are a tiny shoot on just one branch of a giant family tree [06:46.85] [06:47.20]- the tree of life. [06:48.43] [06:49.07]We're only one of tens of millions of living tips [06:52.13] [06:52.37]each one representing different species. [06:54.96] [06:59.28]And they way they all connect, reveals how every life form is related. [07:03.51] [07:05.45]To trace our roots, [07:06.85] [07:07.09]we'll have to journey back to when the very first life forms appeared, [07:10.82] [07:11.02]three point eight billion years ago! [07:14.05] [07:30.31]So how did life begin? [07:32.57] [07:33.58]Back then, planet Earth was a pretty unpleasant place. [07:37.21] [07:40.42]The atmosphere was thin, there was no oxygen [07:43.48] [07:43.69]and that meant no protective ozone layer to shield earth from the sun. [07:47.09] [07:49.29]Unfiltered ultra-violet rays would beat down on the young planet, [07:52.73] [07:52.93]with a strength that would be lethal to us today. [07:55.92] [08:05.24]And that's not all, massive volcanic eruptions and meteor impacts shook the land. [08:10.77] [08:21.46]Compared to this mayhem, the forming seas were a safe haven, [08:25.36] [08:25.60]and it was somewhere underwater that life must have first evolved. [08:29.29] [08:38.48]The seas were awash with organic molecules... [08:41.21] [08:41.95]...building blocks of all life formed naturally [08:45.21] [08:45.42]in the primordial soup of the early oceans. [08:48.41] [09:03.13]Somewhere in this cauldron, the recipe for our own DNA appeared. [09:08.37] [09:13.48]And the first sparks of life were ignited. [09:16.57] [09:21.39]Meet the ancestors! Simple cells like these were the first living things. [09:26.79] [09:26.99]The predecessors of all future life on earth [09:30.19] [09:32.56]Over time, these cells diversified and spread around the world. [09:36.90] [09:37.30]And one group in particular would have a devastating impact on the planet. [09:41.53] [09:48.21]Here, off Western Australia, [09:50.41] [09:50.62]colonize of these ancient microbes still exist today. [09:54.38] [09:55.25]They form strange pillars made of lime, called stromatilites. [10:00.16] [10:01.49]This could be a scene from three billion years ago. [10:04.29] [10:16.47]They might look harmless now, but back then the microbes almost [10:20.31] [10:20.51]...snuffed out all life - forever. [10:22.81] [10:27.32]By generating huge amounts of a new, and toxic waste gas, [10:30.76] [10:30.96]they triggered a global pollution crisis. [10:33.36] [10:38.60]This new gas was oxygen. [10:40.89] [10:41.10]And it destroyed primitive cells, poisoning them by the billion. [10:45.13] [10:49.27]Extinction swept the planet [10:51.37] [11:00.65]But a few cells survived and thrived on oxygen. [11:04.78] [11:05.29]And they inherited the earth. [11:07.22] [11:07.43]From now on, oxygen would power all life from the tiniest cell, [11:11.66] [11:11.86]to the biggest creature of all time... [11:13.83] [11:16.70]This is the greatest oxygen breather of them all, [11:19.69] [11:19.94]the largest animal that has ever existed, the blue whale! [11:24.03] [11:31.42]Blue whales can be as long as a 737 passenger jet [11:34.98] [11:35.19]and weigh more than 30 bull elephants! [11:37.78] [11:38.99]Their massive lungs are 400 times bigger than our own. [11:42.22] [11:42.83]That means they can dive for 30 minutes on a single breath [11:46.02] [11:46.30]and when they return to the surface for air, [11:48.20] [11:48.40]blow a... spout of water 12 meters high. [11:51.80] [12:01.35]Every year tourists encounter migrating blue whales [12:04.51] [12:04.72]as they gather together off the coast of California... [12:06.84] [12:07.05]...to hunt tiny little shrimp-like creatures called krill [12:10.18] [12:13.39]There can be up to two thousand of these giants at a time. [12:16.66] [12:16.93]It's the greatest gathering of blue whales anywhere in the world. [12:20.16] [12:40.15]Blue whales have huge appetites, [12:42.45] [12:42.72]they can take in 50 tons of water in a single gulp and eat 40 million krill a day. [12:48.99] [13:08.45]How did evolution ever take such a gigantic leap? [13:11.64] [13:12.28]Could a blue whale really have evolved from a single cell? [13:15.91] [13:17.79]With teamwork and co-operation, yes! [13:20.49] [13:27.30]The first step was for single cells to join together to create a more complex living thing. [13:33.73] [13:37.48]For even a whale is really just a vast group of co-operating cells. [13:41.74] [13:49.19]Co-operating cells - sounds a simple solution, [13:52.62] [13:52.89]but the journey of life took almost three billion years to get this far. [13:57.16] [14:07.34]Among the first creatures to benefit from cells pulling together were the jellyfish. [14:12.37] [14:21.19]Jellyfish fossils have been found in rocks formed 670 million years ago. [14:26.35] [14:34.13]These ancient animals were the first to have muscle fibers and a simple nervous system. [14:39.33] [14:42.44]But a jelly fish doesn't know its front from its back. [14:45.14] [14:45.48]It reaches out in all directions, which can leave you going nowhere fast. [14:49.57] [14:54.09]Luckily, evolution had a new strategy up its sleeve [14:57.11] [14:57.32]which would allow life to move forwards. [14:59.59] [15:13.24]Incredibly, this is one of the most important creatures in the whole [15:16.73] [15:16.94]of the journey of life-the first type of animal to grow a head, the flatworm! [15:21.54] [15:27.19]And this worms head start is the foundation of our basic body plan. [15:31.95] [15:32.39]We share the very same head sprouting genes. [15:35.42] [15:48.24]Flatworms also evolved the first eyes. [15:50.97] [15:53.38]Just a cluster of cells they can't do much more than distinguish light from dark. [15:57.82] [15:59.55]But at least the worm has some idea what's coming when its traveling head first. [16:03.68] [16:07.43]All this new sensory information needed processing... [16:09.79] [16:10.33]it might be small and very simple but this is, nevertheless, the world's first brain! [16:16.10] [16:22.01]So it's thanks to the flatworms that are brains are in our heads [16:25.27] [16:25.61]- and not in our backsides! [16:27.20] [16:33.38]If the evolution of the first brain was a milestone event, [16:36.41] [16:36.62]then so too was the evolution of the first anus! [16:39.78] [16:42.43]The flatworm has an extendable stomach, with just one opening [16:46.19] [16:46.46]and the snag with that is it can't eat and excrete at the same time. [16:50.26] [16:51.04]But as some worms stayed flat, other worms got rounder: [16:54.44] [16:54.64]They developed an internal tube - the 'through-gut'! [16:58.41] [17:03.38]In through the mouth... along the digestive tract... and out through the anus! [17:08.22] [17:10.29]This production line meant worms could feed non-stop. [17:13.55] [17:13.93]The 'through-gut' was such an efficient system [17:16.95] [17:17.16]that since then every living creature has had one, including us. [17:21.89] [17:29.51]At this stage in the planets history all animals were soft bodied, [17:33.31] [17:33.71]but this left them vulnerable to predators [17:36.15] [17:41.45]Then around 570 million years ago, there was a major breakthrough, [17:46.25] [17:46.46]when life chanced upon a winning formula - the softies turned hard! [17:51.62] [17:55.33]The first 'shells' were probably developed by accident. [17:58.53] [17:59.17]The early snails began to store mineral waste from their diet on their back. [18:03.30] [18:03.57]And this hardened into a shell. [18:05.34] [18:14.22]Today there are half a million snail species, each with a different kind of shell. [18:19.32] [18:32.34]As these shells became thicker or more spiny, they became predator proof. [18:37.87] [18:43.55]This scallop can clam up if it sees danger coming... [18:46.68] [18:48.02]...but its simple eyes haven't detected this slow moving... [18:51.25] [18:51.46]...scallop eating starfish! [18:53.32] [19:01.27]Once it feels the danger though, the scallop pulls a fast one. [19:05.13] [19:17.22]It's a great escape, but with a heavy shell the scallop soon runs out of steam. [19:21.81] [19:27.73]Half a billion years ago, [19:29.12] [19:29.39]some snails escaped the danger of the sea bed altogether. [19:32.89] [19:33.90]But how did they do that, weighed down by their heavy shells? [19:37.60] [19:39.44]The solution - a buoyancy aid! [19:42.17] [19:45.34]Snails filled their shells with gas... which marked the rise of super-snails. [19:50.30] [19:50.55]The nautiloids [19:51.74] [20:00.32]Later the nautiloids cousins rolled up their shells and became the ammonites. [20:05.19] [20:12.30]Ammonites thrived for over 300 million years [20:16.03] [20:20.11]This ammonite graveyard in southern England was created by a single shoal. [20:24.88] [20:30.45]Its part of a huge fossil bed that stretches for several miles inland [20:34.36] [20:34.63]and shows how prolific these creatures were. [20:37.03] [20:47.07]With their gas filled shelled, these primitive cephalopods ruled the open seas. [20:52.41] [20:54.48]But a rigid shell wasn't the only possible form of protection [20:57.91] [21:01.95]Evolving down another branch on the tree of life was a flexible, [21:05.35] [21:05.56]lightweight suit of armor: As worn by the very first bugs. [21:09.46] [21:11.70]This is the most famous of them all - the Trilobite. [21:15.43] [21:16.70]Its flexible armor allowed body segments to be specialized for different tasks. [21:21.26] [21:24.24]With the first jointed limbs animals could move faster than ever before. [21:28.14] [21:30.72]The Trilobite's real trump card was its eyes. [21:33.81] [21:34.15]The first to see detail well. This was an evolutionary bombshell. [21:38.99] [21:42.39]For the first time predators and prey could see each other coming. [21:45.99] [21:46.46]Eyes became a hunting tool and first line of defense. [21:50.42] [21:50.97]With them arose the super bugs. [21:53.16] [21:55.41]Eyes triggered a deadly arms race, as hunter and hunted struggled to outdo each other. [22:00.71] [22:14.33]And this rush to stay ahead, sparked an explosion of new life [22:18.39] [22:25.57]This competition has resulted in the some extreme bugs. [22:28.80] [22:32.88]These eyes are the most sophisticated of any creature on the planet. [22:36.78] [22:37.18]And they belong to the mantis shrimp. [22:39.24] [22:47.12]Whereas our vision uses just three color pigments [22:49.92] [22:50.13]- red, blue and yellow - mantis shrimps use at least eight. [22:53.72] [23:01.47]Mantis shrimps need this high tech gear, not just to hunt their prey [23:05.37] [23:05.61]but more importantly to avoid each other in this colorful coral world. [23:10.60] [23:17.25]For the mantis shrimp is armed with earth's most earth-shattering weapon... [23:21.12] [23:24.33]...a thickened claw, turned club! [23:26.52] [23:29.30]It's a smash and grab attack. [23:31.10] [23:41.28]Armored animals were and still are very successful, [23:44.58] [23:44.92]but our ancestor was built very differently. [23:47.75] [23:54.33]Something a bit like this - a sea squirt... nothing more than a bag of jelly. [23:59.39] [24:14.35]The incredible thing is 80% of squirt genes are inside us too [24:19.28] [24:19.48]- including those that form the human heart! [24:21.88] [24:22.95]But where's our backbone. [24:24.55] [24:32.30]The key to that inheritance is found inside the sea squirts tiny young. [24:36.76] [24:41.14]This little squirts have... [24:42.57] [24:42.77]...a tail with a thin flexible rod inside, its the earliest hint of a backbone. [24:47.68] [24:53.45]And from this flimsy start, the first true vertebrates emerged, [24:57.61] [24:57.82]including jawless fish. [24:59.91] [25:01.96]These jawless hagfish, are deep sea dwellers that usually live way beyond our reach. [25:07.16] [25:13.14]Here, more than a mile below the surface, [25:15.54] [25:15.74]they're scavenging on the carcass of a dead whale. [25:18.21] [25:23.61]They might look more worms than a fish but 500 million years ago, [25:27.91] [25:28.12]jawless wonders like these ruled the seas. [25:31.35] [25:46.17]Today, they sometimes rise to the shallows and in Sweden's cold dark fjords [25:51.20] [25:51.41]they may come face-to-face with fishermen. [25:53.60] [26:06.29]And if they think they're in trouble, just watch what they can do. [26:09.75] [26:16.17]It's a unique defensive mechanism. [26:18.10] [26:18.57]The hagfish secretes mucus from glands along both sides of its body [26:22.60] [26:22.84]and it swells on contact with sea water. [26:25.17] [26:25.78]The mucus also contains these hi-tensile fibers that create a shield of slime. [26:30.61] [26:36.39]One hagfish could jellify a whole... bucket full of sea water and [26:40.08] [26:40.29]...that's not its only trick. [26:42.05] [26:42.59]Its primitive backbone is so flexible it can literally tie itself in knots. [26:47.46] [26:47.90]And a slipknot can sometimes be a life saver! [26:50.56] [26:55.47]But about 400 million years ago hagfish were sidelined by an new and deadly trend. [27:01.21] [27:05.58]Somewhere out there a new kind of fish was evolving. [27:09.07] [27:09.49]Its front two gill arches gradually grew and encircled the mouth - [27:13.86] [27:14.12]- becoming the very first biting jaws. [27:17.12] [27:18.16]As possessed by the very first sharks. [27:20.76] [27:30.21]And this was one development the sharks have taken full advantage of. [27:34.11] [27:39.72]Sharks teeth are adapted to the diet of their owner. [27:42.71] [27:44.76]Sharks like the sand tiger, [27:46.25] [27:46.46]have narrow biting teeth for seizing slippery fish and squid [27:50.22] [27:52.63]Other teeth, like those of seal sharks, [27:55.10] [27:55.30]are multi pointed for feeding on the ocean floor, [27:57.73] [27:57.97]picking up crabs and shell fish. [27:59.77] [28:01.47]The snaggle tooth's varied diet requires generalized cutting teeth. [28:05.84] [28:09.31]While the tiger shark's are more like a chain saw [28:12.51] [28:12.72]used to tackle turtle shell and fish bone. [28:15.18] [28:18.59]These belong to the biggest meat eating shark alive today, the great white. [28:23.08] [28:23.29]They slice through the flesh of sea mammals. [28:26.06] [29:17.05]The great white, is one of the biggest success stories in the seas of life. [29:20.92] [29:25.16]But other sharks evolved along a very different track, they even lost their teeth. [29:30.53] [29:39.14]These are the sting rays, and here in the Caribbean off the Caiman Islands, [29:43.27] [29:43.47]they gather in large numbers to be fed by divers. [29:46.57] [30:11.40]Rays are the sharks cousins. [30:13.16] [30:13.44]But their body plan has flattened out to make the most of a life on the sea bed. [30:17.93] [30:21.25]Most are bottom feeders, hunting crabs and fish hidden in the sand. [30:25.08] [30:28.12]Their mouth is underneath their head, so they can't see exactly what they are eating. [30:32.18] [30:32.49]But they can rely on an armory of other senses... [30:34.98] [30:35.19]...which rays and sharks have developed to a whole new level. [30:38.59] [30:39.50]To demonstrate, how finely tuned these senses are we can run a little experiment. [30:44.59] [30:51.34]In the open ocean, sound is usually the first cue [30:54.31] [30:54.51]that alerts a predator to a potential meal. [30:56.95] [30:57.35]It travels four times faster in water than in air. [31:00.54] [31:08.16]Sharks like this Caribbean reef shark... [31:10.32] [31:10.53]...can hear the commotion from at least a kilometer away. [31:13.66] [31:15.13]They have excellent hearing, but instead of having ear flaps like us, [31:20.13] [31:20.34]a tiny duct carries sound waves to the inner ear. [31:23.90] [31:29.61]Next comes the sense of smell. [31:31.67] [31:33.48]Blood and fish oil from this bait box can be detected from 400 meters away. [31:38.48] [31:40.86]Just one drop of blood in 25 million drops sea water is enough to turn a shark's head. [31:46.99] [31:47.53]Then to pinpoint exactly where the smell is coming from, [31:50.09] [31:50.30]it zig zags to pick up the trail. [31:52.56] [32:02.21]100 meters away is still too far away to see the target. [32:05.44] [32:05.68]But a shark can feel it by the pressure waves created in the water. [32:09.41] [32:09.95]These are picked by the lateral line. [32:12.15] [32:12.36]A form of sensory perception all fish have. [32:15.12] [32:23.27]Its only now from 10 meters or less that sight comes into play. [32:27.50] [32:28.17]In daylight, the shark's vision is as good as ours. [32:31.11] [32:31.31]But by night, its much more sensitive. [32:33.47] [32:37.68]The structure of their eye, suggests that sharks might be far sighted. [32:41.58] [32:41.79]They see better at distance than close up. [32:44.05] [32:46.36]But once they get this close, another sense kicks in. They can detect electricity. [32:51.29] [32:51.76]Tiny pores on the snout can register as little as half a billionth of a vault. [32:56.10] [33:03.91]That's the electrical field around a live fish. [33:06.38] [33:06.61]...Or in our test here, a metal feeding pole. [33:09.31] [33:17.02]In the final seconds of attack the shark goes in blind so as to protect its eyes, [33:21.51] [33:21.73]closing them just before it bites. [33:23.56] [33:25.70]That's when the last two sense, touch and taste finally come into play. [33:30.00] [33:34.04]Its this combination of sensory systems [33:36.47] [33:36.67]that makes the shark such an effective, high tech predator. [33:40.47] [33:47.18]You might think such sophisticated animals might dominate the seas forever. [33:51.28] [33:51.72]But the journey of life is never an easy ride. [33:54.35] [33:57.33]Several times over the millennia, meteors shattered the world order, [34:01.06] [34:01.26]and sparked mass extinctions. [34:03.26] [34:13.21]Many primitive animals were lost. [34:15.24] [34:15.45]Even the hardly ammonites. [34:16.88] [34:17.08]But in the shelter of the deep... many of their relatives survived, [34:20.68] [34:20.95]ready to branch out in a whole new way. [34:23.78] [34:28.26]The super snails rose up and colonized the shallow seas. [34:32.29] [34:32.53]Eventually evolving into the latest member of cephalopod dynasty: [34:36.56] [34:36.77]Cuttlefish, octopus and squid. [34:39.33] [34:46.21]Today, just once a year, millions of... [34:48.47] [34:48.68]...opalescent squid gather together to breed off the coast of California [34:52.58] [35:20.28]At just a year old, [35:21.54] [35:21.75]it's the last act in their short lives... once the eggs are laid, most will die. [35:27.51] [35:31.35]Grow fast, spawn and die young - a winning formula in the seas of life. [35:36.45] [35:55.41]'Cephalopod' means 'head-foot' - not a bad description really! [35:59.71] [36:03.25]This whopper is the Giant Pacific octopus. 5 meters long, and all head and feet. [36:09.19] [36:13.46]It's a gentle giant, with an alien physiology - blue blood, [36:17.92] [36:18.13]three hearts and an incredible nine brains! [36:21.59] [36:22.14]That's one big central brain plus eight mini-brains, one in each tentacle! [36:27.08] [36:40.62]If Cephalopods were really to compete in the seas, [36:43.25] [36:43.46]brainpower would be their big advantage. [36:45.79] [36:54.17]These are Caribbean reef squid. [36:56.33] [37:02.21]When a barracuda's on the scene, [37:03.91] [37:04.11]their best chance is to think themselves out of a tight spot. [37:07.81] [37:11.55]They cleverly alter their appearance to match their immediate surroundings [37:14.58] [37:14.79]- both in texture and color. [37:16.35] [37:16.56]An instant transformation, directly controlled by the brain. [37:20.39] [37:24.07]To the predator, it seems they've simply disappeared. [37:26.97] [37:52.30]The squid also communicate to tell each other when the danger's passed... [37:56.60] [37:57.13]they have an entire language based on skin tones. [38:00.16] [38:07.34]For modern cephalopods, brainpower had overcome the need for a protective shell. [38:12.04] [38:12.72]They're simply smarter than the average fish. [38:14.71] [38:16.19]So why didn't our seas become dominated by the cephalopods? [38:19.85] [38:20.36]But just when it looked like brain had triumphed over braun. [38:23.95] [38:24.16]Fish chanced upon a masterstroke. [38:26.49] [38:26.86]A skeleton made of a new material, bone! [38:30.32] [38:34.47]With it, new bony fish diversified like never before! [38:38.60] [39:06.34]The bony skeleton was a landmark development - one that provided structural support, [39:11.71] [39:11.94]greater protection, more effective gills and improved agility. [39:16.28] [39:22.42]Then for even more subtle maneuvers, fish evolved two sets of paired fins, [39:28.19] [39:28.39]joined to both sides of their body by bones. [39:31.29] [39:31.93]It was a winning combination and its legacy would stick. [39:36.63] [39:41.37]It's why we humans have a pair of arms and a pair of legs! [39:45.40] [39:53.35]Other bony fish, have turned to a more sedentary life. [39:56.28] [40:05.63]The frogfish has come up with a novel use for one of its bones. [40:08.89] [40:09.10]This is no wiggly worm. [40:10.83] [40:11.03]It's a fleshy lure, operated by a modified fin bone. [40:14.83] [40:22.21]But all these damsel fish see is a tempting morsel. [40:25.61] [40:32.29]Not only is the frogfish a master of deception, he's also perfectly camouflaged. [40:37.35] [40:39.73]This shrimp is unlikely to see him until he moves, and by then it's too late [40:44.46] [40:45.57]Because frogfish jaws move faster the muscle. [40:48.50] [40:56.35]How? Well, that's down to bones again. [40:59.41] [41:04.62]It's an elastic 'trap-jaw' that is pre-set at full tension. [41:08.49] [41:09.46]When triggered... the trap snaps open, increasing the mouth volume 10 times, [41:13.86] [41:14.06]and sucking the prey inside. [41:15.86] [41:24.24]Incredible, but when it comes to bone structure, [41:27.30] [41:27.51]these small fry are the most extreme of all. [41:30.60] [41:33.32]For the first two weeks of their lives, they look like any other baby fish. [41:37.18] [41:38.72]Then something begins to go awry... [41:40.81] [41:48.30]The face distorts, and one eye starts to shift, [41:51.76] [41:51.97]moving across to join the other on the opposite side of the head. [41:55.34] [41:56.31]The beginning of an extraordinary transformation. [41:59.07] [42:05.88]The full make over takes less than a week and the results are fixed for life. [42:09.98] [42:11.65]This flatfish are now perfectly adapted for life on the sea bed. [42:16.06] [42:16.43]Its shape and coloring mean it can keep a low profile - handy for hiding from predators [42:21.83] [42:22.03]or creeping up on prey! [42:23.69] [42:32.54]But if you don't have what it takes to make yourself invisible, [42:35.41] [42:35.61]your best bet is safety in numbers. [42:38.74] [42:42.52]Living in a shoal is a great way to minimize ones chances of being eaten. [42:46.61] [42:56.43]Throughout their evolutionary history, [42:58.23] [42:58.43]shoals of bony fish have come under fire from all sides. [43:02.06] [43:05.01]They've survived the age of the dinosaurs! [43:07.20] [43:17.35]And since a blitz of aerial attacks ever since. [43:19.91] [43:31.33]And all that time they've been hunted from below as well. [43:34.36] [44:10.31]This is predation pressure at its most extreme. [44:13.40] [44:13.84]Any fish that can avoid this kind of onslaught will have genes worth passing on. [44:18.71] [44:29.96]And pushed to the limit... [44:31.15] [44:31.36]...some fish eventually sought refuge out of water, with spectacular results. [44:36.89] [44:56.25]The flying fish - with the most extreme means of escape for any fish. [45:00.92] [45:08.40]Its a tactic designed to confuse any predator. [45:11.20] [45:15.44]Flying fish have evolved extraordinarily long pectoral fins. [45:19.14] [45:19.74]They don't flap, and are used to glide instead. [45:22.51] [45:27.58]Its the tail that does all the work, [45:29.02] [45:29.22]powering the fish along like an outboard motor. [45:31.74] [45:32.16]The fish can glide for up to 100 meters at a time. [45:36.46] [45:39.20]Flying fish perhaps the most extraordinary bony fish of all. [45:43.00] [45:44.17]It just goes to show that anything can happen in the pressure cooker... [45:46.83] [45:47.04]...that is the crowded seas of life [45:49.30] [45:54.11]And that's not the end of life's long journey through the seas. [45:56.98] [46:04.25]Descendants of some bony fish, eventually became the whales and dolphins. [46:08.19] [46:18.17]What kind of extraordinary evolutionary journey [46:21.03] [46:21.24]could have lead to these mammals of the sea. [46:23.54] [46:37.05]The first step was to leave the water altogether. [46:40.18] [46:57.11]By default, these fugitives have hit the jackpot. [47:00.51] [47:01.14]After some three and a half billion years of evolution in the oceans, [47:04.94] [47:05.18]it was their descendants that would go ahead and colonize the land. [47:08.91] [47:11.05]They evolved into all amphibians, reptiles, birds and mammals. Including us. [47:17.32] [47:20.63]Ultimately, some land mammals were to develop a taste for sea food. [47:24.03] [47:24.23]They returned to the oceans to hunt. [47:26.50] [47:38.41]Over time, their legs gradually turned into flippers... [47:41.58] [47:41.88]...and they became the most charismatic creatures of the seas. [47:45.08] [47:51.49]This is the bottlenose dolphin, the most wide spread dolphin in the planet. [47:55.90] [48:04.44]People admire, and identify more closely with this animal than any other sea creature. [48:09.88] [48:17.39]To swim with one is an exhilarating experience. [48:20.51] [48:40.94]But although we love dolphins... [48:42.71] [48:42.91]...perhaps we should identify more closely with the small, colder sea creatures. [48:47.87] [48:48.08]Because its directly down to them, [48:49.88] [48:50.09]and the way they evolved that we are the creatures we are. [48:53.95] [48:54.89]We are just a tiny part of the remarkable richness of our planet. [48:58.76] [48:59.03]And like all the other land animals around us, [49:01.59] [49:01.80]we owe our existence to three and a half billion years... [49:05.36] [49:05.57]...of evolution, in the spectacular seas of life. [49:09.83] [49:11.83]The End [50:01.83]

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