0:00:04 > 0:00:06Planet Earth...
0:00:06 > 0:00:09millions of different species...
0:00:10 > 0:00:13..but a few are special...
0:00:16 > 0:00:20..thriving, dominating.
0:00:25 > 0:00:30The key to their success lies in their opportunism.
0:00:32 > 0:00:36For others, it's down to their ability to collaborate.
0:00:36 > 0:00:40And for some, it's all about surviving where others can't.
0:00:42 > 0:00:45So, what is their secret?
0:00:45 > 0:00:49By delving deep beneath the skin, we'll reveal the unique
0:00:49 > 0:00:52features that set some species apart.
0:00:59 > 0:01:04In this series, new behaviour and the very latest scientific
0:01:04 > 0:01:09research will throw fresh insight into The Wonder Of Animals.
0:01:24 > 0:01:28Tropical waters, murky lagoons...
0:01:35 > 0:01:38..the frigid polar seas.
0:01:43 > 0:01:4632 species of dolphin thrive in
0:01:46 > 0:01:49a vast array of underwater worlds.
0:01:58 > 0:02:02These highly social animals spend their lives roaming
0:02:02 > 0:02:04the oceanic highways.
0:02:09 > 0:02:13They're the most widespread of all marine mammals.
0:02:17 > 0:02:22So, what exactly is the secret to their success?
0:02:32 > 0:02:36Despite their cheerful and charismatic appearance,
0:02:36 > 0:02:39every member of the dolphin family
0:02:39 > 0:02:42is, in fact, a ruthless predator.
0:02:52 > 0:02:57From the 50 kilogram Hector's dolphin to the ten tonne orca.
0:03:04 > 0:03:07They all share a highly adapted anatomy...
0:03:10 > 0:03:11..complex communication...
0:03:13 > 0:03:16..and a big brain.
0:03:19 > 0:03:22And it's these three characteristics
0:03:22 > 0:03:24which have enabled them to become
0:03:24 > 0:03:27the ocean's most versatile predators.
0:03:33 > 0:03:36First up is that incredible anatomy.
0:03:38 > 0:03:40In their constant search for food,
0:03:40 > 0:03:44dolphins spend their lives racing through the world's oceans.
0:03:46 > 0:03:49Some can reach 30 miles an hour,
0:03:49 > 0:03:53that's six times faster than an Olympic swimmer.
0:03:55 > 0:04:00And in a medium that's 800 times denser than air,
0:04:00 > 0:04:02efficiency rules.
0:04:04 > 0:04:08Tail muscles are surrounded by blocks of fibrous fat,
0:04:08 > 0:04:13that compress and store energy at the end of each stroke.
0:04:13 > 0:04:18And then release it like a spring as the tail changes direction.
0:04:21 > 0:04:24A torpedo-like body reduces drag.
0:04:26 > 0:04:30While pectoral fins act like wings to give lift.
0:04:33 > 0:04:38Allowing these hydrodynamic bullets to effectively fly through
0:04:38 > 0:04:40the water with the minimum of effort.
0:04:51 > 0:04:56Thanks to their super streamlined bodies, a pod of dolphins can travel
0:04:56 > 0:05:01up to 120 kilometres in a single day.
0:05:01 > 0:05:03So, saving energy is crucial.
0:05:07 > 0:05:12At top speeds, leaping out of the water burns 50 percent fewer
0:05:12 > 0:05:14calories than swimming beneath it.
0:05:17 > 0:05:21And explosive ventilation through the blowhole can fill ten litre
0:05:21 > 0:05:24lungs in just a third of a second.
0:05:29 > 0:05:33But it's what's underneath this modified set of nostrils that
0:05:33 > 0:05:36makes a dolphin such a proficient hunter.
0:05:41 > 0:05:46Two pairs of phonic lips, one set for each nostril,
0:05:46 > 0:05:49serve a similar function to our vocal cords.
0:05:51 > 0:05:54By passing air over these lips independently,
0:05:54 > 0:05:58a dolphin can produce both clicks and whistles simultaneously.
0:06:01 > 0:06:04Whilst both are used in communication, the clicks
0:06:04 > 0:06:09produced by the first set of phonic lips are also used to find food.
0:06:11 > 0:06:16Due to their ultrasonic frequency, these clicks are normally
0:06:16 > 0:06:21inaudible to us but to a dolphin they're as loud as a jet engine.
0:06:23 > 0:06:26By changing the shape of a fat-filled
0:06:26 > 0:06:27structure, called the melon,
0:06:27 > 0:06:31they can focus this sound in to a narrow beam.
0:06:35 > 0:06:39Up to 500 clicks a second hit the prey,
0:06:39 > 0:06:41and echo back towards the dolphin.
0:06:43 > 0:06:47Fat pads in their lower jaw act as a receiver,
0:06:47 > 0:06:52and the echoes are transmitted along the bone and into the inner ear.
0:06:56 > 0:07:02Echolocation is an anatomical marvel that helps a dolphin detect
0:07:02 > 0:07:05and even stun its prey beneath the sand.
0:07:14 > 0:07:19A single dolphin is a highly efficient predator,
0:07:19 > 0:07:23but what makes these incredible animals so effective is their
0:07:23 > 0:07:26ability to work together.
0:07:26 > 0:07:30And to do that, they need to be able to communicate.
0:07:38 > 0:07:42All dolphins use non-vocal communication as part
0:07:42 > 0:07:43of their repertoire.
0:07:48 > 0:07:52Somersaults, breaches...
0:07:56 > 0:08:00..and lob-tailing
0:08:00 > 0:08:02all indicate levels of excitement.
0:08:04 > 0:08:07But they also convey information about the direction of travel
0:08:07 > 0:08:10and location of potential food.
0:08:17 > 0:08:20A spinner dolphin's three metre leaps
0:08:20 > 0:08:24are generated by muscles ten times more powerful than our own.
0:08:26 > 0:08:31And on exit, torque created by a single tail fluke gives the twist.
0:08:33 > 0:08:36The sounds of the slap rip through the water
0:08:36 > 0:08:39at over 3,000 miles an hour
0:08:39 > 0:08:42and can be heard by other dolphin pods eight kilometres away.
0:08:44 > 0:08:46Attracted by this sound,
0:08:46 > 0:08:49spinner dolphins join forces to hunt
0:08:49 > 0:08:52in super-pods over 1,000 strong.
0:08:56 > 0:08:59The combination of leaps and splashes
0:08:59 > 0:09:04not only serves to corral the bait fish beneath them
0:09:04 > 0:09:08but it also allows other dolphins in the pod to build up a mental picture
0:09:08 > 0:09:12of what's happening well beyond their line of sight.
0:09:20 > 0:09:22Of course, non-vocal communication
0:09:22 > 0:09:26can convey much more complex information.
0:09:27 > 0:09:30Body rubbing,
0:09:30 > 0:09:32blowing bubbles
0:09:32 > 0:09:35and touching of fins
0:09:35 > 0:09:38all help to maintain the close
0:09:38 > 0:09:41relationships that bond the pod together.
0:09:46 > 0:09:49Dolphins also communicate with each other using their second
0:09:49 > 0:09:51set of phonic lips.
0:09:56 > 0:09:58Unlike echolocation clicks,
0:09:58 > 0:10:02this rich repertoire of low-frequency whistles
0:10:02 > 0:10:03is audible to humans.
0:10:07 > 0:10:09HIGH PITCHED CLICKING
0:10:14 > 0:10:16The meaning of each of these whistles can be
0:10:16 > 0:10:20altered by the accompanying body position which further
0:10:20 > 0:10:24enhances the complexity of their communication.
0:10:26 > 0:10:29But to coordinate a hunt effectively,
0:10:29 > 0:10:33dolphins need to know not just what is being said
0:10:33 > 0:10:35but who is saying it.
0:10:37 > 0:10:41They do this by using what is known as a signature whistle.
0:10:43 > 0:10:47This short sound of between four and 20 kilohertz,
0:10:47 > 0:10:52is unique to each individual, much like our names.
0:10:54 > 0:10:56All dolphins live in a fission,
0:10:56 > 0:11:01fusion society, where members of a pod will come and go constantly.
0:11:01 > 0:11:06So, when one dolphin meets another, it whistles its own name.
0:11:12 > 0:11:16Scientists have found that individuals can
0:11:16 > 0:11:20remember their pod mate's whistle for over 20 years.
0:11:21 > 0:11:26This long-term memory allows each dolphin to adapt its behaviour
0:11:26 > 0:11:31to suit any situation, and that includes hunting.
0:11:35 > 0:11:37By knowing who they're hunting with,
0:11:37 > 0:11:42and by communicating constantly, a pod can work as a team.
0:11:51 > 0:11:56Together, they herd the bait fish, forcing them to the
0:11:56 > 0:11:59surface to cut off their escape route.
0:12:03 > 0:12:07Burst pulses and click trains allow each dolphin to communicate
0:12:07 > 0:12:10and echolocate simultaneously.
0:12:13 > 0:12:16This way, a group of intelligent
0:12:16 > 0:12:19individuals can coordinate their behaviour perfectly.
0:12:45 > 0:12:50Working together like one giant super-organism.
0:12:54 > 0:12:59It's no coincidence that species that live in large social groups
0:12:59 > 0:13:02are amongst the most intelligent animals on the planet.
0:13:05 > 0:13:08Complex communication
0:13:08 > 0:13:12and sophisticated social interaction require a well-developed brain.
0:13:16 > 0:13:20When you're smart and you know what your neighbour's thinking,
0:13:20 > 0:13:26you can develop ever more effective strategies to outwit your prey.
0:13:29 > 0:13:34Key to a dolphin's ability to strategise is this incredible
0:13:34 > 0:13:37brain...and scientists are now beginning to work out
0:13:37 > 0:13:40where its processing power is focused.
0:13:43 > 0:13:45The cerebellum is highly developed.
0:13:48 > 0:13:52It's thought to be involved in the complex tasks of echolocation
0:13:52 > 0:13:56and moving in a three dimensional world.
0:13:57 > 0:13:59And the cerebral cortex, used for planning
0:13:59 > 0:14:04and higher order thinking, is 40% more folded than our own.
0:14:06 > 0:14:11It's thought that this complexity helps a dolphin hunt cooperatively.
0:14:16 > 0:14:21But to power this big brain takes up to 20% of a dolphin's
0:14:21 > 0:14:22metabolic energy.
0:14:26 > 0:14:30So a reliable high calorie diet is important.
0:14:37 > 0:14:42The shallow murky waters of Florida bay are a difficult place to live.
0:14:45 > 0:14:48The fish that live here are fast and manoeuvrable
0:14:48 > 0:14:50and there's no obvious way to corner them.
0:14:52 > 0:14:56But these particular dolphins are not your average hunters.
0:15:00 > 0:15:04Even in murky water their echolocation can detect
0:15:04 > 0:15:08a target shoal from over 80 metres away.
0:15:13 > 0:15:17As they close in on the fish, one key role emerges.
0:15:19 > 0:15:23The chasers' job is to create an artificial barrier to stop
0:15:23 > 0:15:26the fish dead in their tracks.
0:15:31 > 0:15:34They conjure up a net made of mud.
0:15:36 > 0:15:41And the other members drive the fish in to a dead end.
0:15:48 > 0:15:51In panic, the fish take to the air...
0:15:54 > 0:15:56..straight into a trap.
0:16:04 > 0:16:08An innovative feeding strategy allows these particular dolphins
0:16:08 > 0:16:12to thrive in an area of the bay that no other can.
0:16:17 > 0:16:22But in some environments teamwork isn't enough to survive.
0:16:26 > 0:16:30In Western Australia, the resident bottlenose dolphins employ
0:16:30 > 0:16:34a truly ingenious strategy to find hidden food.
0:16:38 > 0:16:40Here a covering of sea grass
0:16:40 > 0:16:43scatters their echolocating clicks...
0:16:46 > 0:16:49..making it difficult to find concealed prey.
0:16:59 > 0:17:02But the key to this pod's hunting prowess
0:17:02 > 0:17:04lies in their power of observation.
0:17:07 > 0:17:12Over time, the dolphins have worked out that a stingray can detect
0:17:12 > 0:17:15food in a way that they can't.
0:17:18 > 0:17:22Electromagnetic sensors on the underside of a stingray allow
0:17:22 > 0:17:25it to sense the tiniest muscle movements of hidden prey.
0:17:29 > 0:17:34And by watching carefully, these wily predators know
0:17:34 > 0:17:36when it's found something.
0:17:37 > 0:17:42Calculating the exact moment to make its move isn't easy...
0:17:46 > 0:17:50..but eventually the quick-witted dolphin gets a free meal.
0:17:56 > 0:18:00Using another animal's senses to overcome
0:18:00 > 0:18:04the limitations of your own is a truly advanced strategy.
0:18:06 > 0:18:10But even greater rewards are to be had by actively cooperating
0:18:10 > 0:18:12with another species.
0:18:18 > 0:18:22In Brazil, around 25 dolphins have learned to do something
0:18:22 > 0:18:25totally counterintuitive.
0:18:31 > 0:18:36Working as a team they drive shoals of fish straight towards
0:18:36 > 0:18:39a line of local fishermen.
0:18:50 > 0:18:54By performing special dives they signal to the fishermen to
0:18:54 > 0:18:55cast their nets.
0:19:00 > 0:19:04But crucially there's something in it for them as well.
0:19:04 > 0:19:06When the nets are cast,
0:19:06 > 0:19:11ensuing panic amongst the shoals of fish make them much easier to catch.
0:19:13 > 0:19:17So, by working hand in hand with humans,
0:19:17 > 0:19:21these dolphins actively increase their food intake.
0:19:25 > 0:19:27And the secret to this cooperation...
0:19:31 > 0:19:34..lies in the detail of the cetacean brain.
0:19:34 > 0:19:38Spindle cells are thought to fast-track nerve impulses
0:19:38 > 0:19:43and crucially in dolphins they're found in areas associated with
0:19:43 > 0:19:45intuition and emotion.
0:19:48 > 0:19:52Whilst there's still much debate as to what this achieves,
0:19:52 > 0:19:55some scientists think that they help dolphins empathise,
0:19:55 > 0:19:59to understand another's emotions.
0:20:01 > 0:20:05And once you can empathise, you can live and hunt cooperatively.
0:20:11 > 0:20:16Dolphins are fast, acrobatic
0:20:16 > 0:20:18and social hunters...
0:20:21 > 0:20:24..but their brain is the real secret
0:20:24 > 0:20:27to their success
0:20:27 > 0:20:30and some are more successful than others.
0:20:35 > 0:20:39In terms of its size, social complexity,
0:20:39 > 0:20:43and ability to strategise, one species stands out from the crowd.
0:20:46 > 0:20:48The ten metre long orca
0:20:48 > 0:20:53is the largest dolphin of all and a supreme hunter.
0:20:58 > 0:21:02Their immense strength makes short work of sea lions.
0:21:05 > 0:21:09And pods can even take on 40 tonne grey whales...
0:21:12 > 0:21:14..to get at their calves.
0:21:24 > 0:21:28Orcas can thrive in the freezing polar waters.
0:21:34 > 0:21:38Here sub-zero water temperatures are too low for smaller dolphins
0:21:38 > 0:21:40to survive year round.
0:21:49 > 0:21:53Ten centimetres of fat insulates the orca's body.
0:21:54 > 0:21:58And a network of blood vessels in their fins can constrict...
0:22:00 > 0:22:02..reducing blood flow to the extremities...
0:22:07 > 0:22:09..to keep heat loss to a bare minimum.
0:22:15 > 0:22:17This super-dolphin is the
0:22:17 > 0:22:20most widespread marine mammal on the planet.
0:22:30 > 0:22:34Today, roughly half of the world's 50,000 orcas are believed to
0:22:34 > 0:22:35live in the Antarctic.
0:22:40 > 0:22:44Recently, scientists have discovered that within these waters
0:22:44 > 0:22:47there are at least three distinct types.
0:22:50 > 0:22:56On close inspection, their size, colour, fin-shape,
0:22:56 > 0:23:02saddle pattern and eyespot are all different.
0:23:08 > 0:23:13But the differences between them are much more than just skin deep.
0:23:15 > 0:23:19To communicate, each orca type has a distinct vocal dialect...
0:23:21 > 0:23:23..much like our accents.
0:23:26 > 0:23:30And what's really fascinating is that three different hunting
0:23:30 > 0:23:32strategies have emerged.
0:23:34 > 0:23:38To reduce competition for food, orcas have become specialists.
0:23:40 > 0:23:44Type A orcas, the largest, prey on minke whales.
0:23:48 > 0:23:51Whilst type C orcas feed on fish.
0:23:56 > 0:23:59But the most ingenious hunting tactic
0:23:59 > 0:24:02of any dolphin is seen by type B.
0:24:05 > 0:24:09Of the five seal species in the Antarctic, these orcas target
0:24:09 > 0:24:11Weddell seals almost exclusively.
0:24:16 > 0:24:21Orcas have good eyesight both below and above the water...
0:24:22 > 0:24:26..and by spy-hopping they can check out the species of seal.
0:24:31 > 0:24:34Whilst the seal remains on the ice floe, it's safe.
0:24:39 > 0:24:43So a thorough survey from up to ten different angles helps them
0:24:43 > 0:24:45form a plan of attack.
0:24:55 > 0:24:58Then it's time to put that plan in to action.
0:25:04 > 0:25:08Using their huge eyespots to align themselves,
0:25:08 > 0:25:11the team start the first phase of this coordinated attack.
0:25:16 > 0:25:20Four tail flukes beat in unison, creating a wave designed to
0:25:20 > 0:25:23act as an icebreaker.
0:25:32 > 0:25:35Assaults like this can last half an hour or more.
0:25:38 > 0:25:42And when the ice floe is small enough, the team change tactics.
0:25:50 > 0:25:52As they reach the ice edge,
0:25:52 > 0:25:57a carefully calculated power stroke creates a metre high giant wave.
0:26:00 > 0:26:04It gives the seal no chance.
0:26:13 > 0:26:15Once the seal is washed off the ice,
0:26:15 > 0:26:20the orcas work as a group to keep it from hauling out again.
0:26:23 > 0:26:28The same power that drives an orca at 30 miles an hour now turns
0:26:28 > 0:26:30the seal's world upside down.
0:26:34 > 0:26:39And huge lungs use explosive ventilation to confuse it further.
0:26:44 > 0:26:47Gradually they wear down their victim.
0:26:55 > 0:26:57Before a final nudge
0:26:57 > 0:26:59tips the balance firmly in the orcas' favour.
0:27:12 > 0:27:16More than 50% of these hunts end in success.
0:27:21 > 0:27:24And by passing on their chosen hunting strategy
0:27:24 > 0:27:27from generation to generation,
0:27:27 > 0:27:32each population of orcas creates its own culture.
0:27:44 > 0:27:49There's little doubt that dolphins are one of the most versatile
0:27:49 > 0:27:52predators on Earth.
0:27:52 > 0:27:56Their highly adapted anatomy has evolved over millions of years,
0:27:56 > 0:28:01and their complex communication skills allow them to develop
0:28:01 > 0:28:04ever more innovative ways of overcoming their prey.
0:28:12 > 0:28:18This combination of brains and brawn make for a master hunter
0:28:18 > 0:28:22and one of the most successful animals on the planet.
0:28:24 > 0:28:26That is the wonder of dolphins.