Dolphins The Wonder of Animals

Planet Earth...

millions of different species...

..but a few are special...

..thriving, dominating.

The key to their success lies in their opportunism.

For others, it's down to their ability to collaborate.

And for some, it's all about surviving where others can't.

So, what is their secret?

By delving deep beneath the skin, we'll reveal the unique

features that set some species apart.

In this series, new behaviour and the very latest scientific

research will throw fresh insight into The Wonder Of Animals.

Tropical waters, murky lagoons...

..the frigid polar seas.

32 species of dolphin thrive in

a vast array of underwater worlds.

These highly social animals spend their lives roaming

the oceanic highways.

They're the most widespread of all marine mammals.

So, what exactly is the secret to their success?

Despite their cheerful and charismatic appearance,

every member of the dolphin family

is, in fact, a ruthless predator.

From the 50 kilogram Hector's dolphin to the ten tonne orca.

They all share a highly adapted anatomy...

..complex communication...

..and a big brain.

And it's these three characteristics

which have enabled them to become

the ocean's most versatile predators.

First up is that incredible anatomy.

In their constant search for food,

dolphins spend their lives racing through the world's oceans.

Some can reach 30 miles an hour,

that's six times faster than an Olympic swimmer.

And in a medium that's 800 times denser than air,

efficiency rules.

Tail muscles are surrounded by blocks of fibrous fat,

that compress and store energy at the end of each stroke.

And then release it like a spring as the tail changes direction.

A torpedo-like body reduces drag.

While pectoral fins act like wings to give lift.

Allowing these hydrodynamic bullets to effectively fly through

the water with the minimum of effort.

Thanks to their super streamlined bodies, a pod of dolphins can travel

up to 120 kilometres in a single day.

So, saving energy is crucial.

At top speeds, leaping out of the water burns 50 percent fewer

calories than swimming beneath it.

And explosive ventilation through the blowhole can fill ten litre

lungs in just a third of a second.

But it's what's underneath this modified set of nostrils that

makes a dolphin such a proficient hunter.

Two pairs of phonic lips, one set for each nostril,

serve a similar function to our vocal cords.

By passing air over these lips independently,

a dolphin can produce both clicks and whistles simultaneously.

Whilst both are used in communication, the clicks

produced by the first set of phonic lips are also used to find food.

Due to their ultrasonic frequency, these clicks are normally

inaudible to us but to a dolphin they're as loud as a jet engine.

By changing the shape of a fat-filled

structure, called the melon,

they can focus this sound in to a narrow beam.

Up to 500 clicks a second hit the prey,

and echo back towards the dolphin.

Fat pads in their lower jaw act as a receiver,

and the echoes are transmitted along the bone and into the inner ear.

Echolocation is an anatomical marvel that helps a dolphin detect

and even stun its prey beneath the sand.

A single dolphin is a highly efficient predator,

but what makes these incredible animals so effective is their

ability to work together.

And to do that, they need to be able to communicate.

All dolphins use non-vocal communication as part

of their repertoire.

Somersaults, breaches...

..and lob-tailing

all indicate levels of excitement.

But they also convey information about the direction of travel

and location of potential food.

A spinner dolphin's three metre leaps

are generated by muscles ten times more powerful than our own.

And on exit, torque created by a single tail fluke gives the twist.

The sounds of the slap rip through the water

at over 3,000 miles an hour

and can be heard by other dolphin pods eight kilometres away.

Attracted by this sound,

spinner dolphins join forces to hunt

in super-pods over 1,000 strong.

The combination of leaps and splashes

not only serves to corral the bait fish beneath them

but it also allows other dolphins in the pod to build up a mental picture

of what's happening well beyond their line of sight.

Of course, non-vocal communication

can convey much more complex information.

Body rubbing,

blowing bubbles

and touching of fins

all help to maintain the close

relationships that bond the pod together.

Dolphins also communicate with each other using their second

set of phonic lips.

Unlike echolocation clicks,

this rich repertoire of low-frequency whistles

is audible to humans.

HIGH PITCHED CLICKING

The meaning of each of these whistles can be

altered by the accompanying body position which further

enhances the complexity of their communication.

But to coordinate a hunt effectively,

dolphins need to know not just what is being said

but who is saying it.

They do this by using what is known as a signature whistle.

This short sound of between four and 20 kilohertz,

is unique to each individual, much like our names.

All dolphins live in a fission,

fusion society, where members of a pod will come and go constantly.

So, when one dolphin meets another, it whistles its own name.

Scientists have found that individuals can

remember their pod mate's whistle for over 20 years.

This long-term memory allows each dolphin to adapt its behaviour

to suit any situation, and that includes hunting.

By knowing who they're hunting with,

and by communicating constantly, a pod can work as a team.

Together, they herd the bait fish, forcing them to the

surface to cut off their escape route.

Burst pulses and click trains allow each dolphin to communicate

and echolocate simultaneously.

This way, a group of intelligent

individuals can coordinate their behaviour perfectly.

Working together like one giant super-organism.

It's no coincidence that species that live in large social groups

are amongst the most intelligent animals on the planet.

Complex communication

and sophisticated social interaction require a well-developed brain.

When you're smart and you know what your neighbour's thinking,

you can develop ever more effective strategies to outwit your prey.

Key to a dolphin's ability to strategise is this incredible

brain...and scientists are now beginning to work out

where its processing power is focused.

The cerebellum is highly developed.

It's thought to be involved in the complex tasks of echolocation

and moving in a three dimensional world.

And the cerebral cortex, used for planning

and higher order thinking, is 40% more folded than our own.

It's thought that this complexity helps a dolphin hunt cooperatively.

But to power this big brain takes up to 20% of a dolphin's

metabolic energy.

So a reliable high calorie diet is important.

The shallow murky waters of Florida bay are a difficult place to live.

The fish that live here are fast and manoeuvrable

and there's no obvious way to corner them.

But these particular dolphins are not your average hunters.

Even in murky water their echolocation can detect

a target shoal from over 80 metres away.

As they close in on the fish, one key role emerges.

The chasers' job is to create an artificial barrier to stop

the fish dead in their tracks.

They conjure up a net made of mud.

And the other members drive the fish in to a dead end.

In panic, the fish take to the air...

..straight into a trap.

An innovative feeding strategy allows these particular dolphins

to thrive in an area of the bay that no other can.

But in some environments teamwork isn't enough to survive.

In Western Australia, the resident bottlenose dolphins employ

a truly ingenious strategy to find hidden food.

Here a covering of sea grass

scatters their echolocating clicks...

..making it difficult to find concealed prey.

But the key to this pod's hunting prowess

lies in their power of observation.

Over time, the dolphins have worked out that a stingray can detect

food in a way that they can't.

Electromagnetic sensors on the underside of a stingray allow

it to sense the tiniest muscle movements of hidden prey.

And by watching carefully, these wily predators know

when it's found something.

Calculating the exact moment to make its move isn't easy...

..but eventually the quick-witted dolphin gets a free meal.

Using another animal's senses to overcome

the limitations of your own is a truly advanced strategy.

But even greater rewards are to be had by actively cooperating

with another species.

In Brazil, around 25 dolphins have learned to do something

totally counterintuitive.

Working as a team they drive shoals of fish straight towards

a line of local fishermen.

By performing special dives they signal to the fishermen to

cast their nets.

But crucially there's something in it for them as well.

When the nets are cast,

ensuing panic amongst the shoals of fish make them much easier to catch.

So, by working hand in hand with humans,

these dolphins actively increase their food intake.

And the secret to this cooperation...

..lies in the detail of the cetacean brain.

Spindle cells are thought to fast-track nerve impulses

and crucially in dolphins they're found in areas associated with

intuition and emotion.

Whilst there's still much debate as to what this achieves,

some scientists think that they help dolphins empathise,

to understand another's emotions.

And once you can empathise, you can live and hunt cooperatively.

Dolphins are fast, acrobatic

and social hunters...

..but their brain is the real secret

to their success

and some are more successful than others.

In terms of its size, social complexity,

and ability to strategise, one species stands out from the crowd.

The ten metre long orca

is the largest dolphin of all and a supreme hunter.

Their immense strength makes short work of sea lions.

And pods can even take on 40 tonne grey whales...

..to get at their calves.

Orcas can thrive in the freezing polar waters.

Here sub-zero water temperatures are too low for smaller dolphins

to survive year round.

Ten centimetres of fat insulates the orca's body.

And a network of blood vessels in their fins can constrict...

..reducing blood flow to the extremities...

..to keep heat loss to a bare minimum.

This super-dolphin is the

most widespread marine mammal on the planet.

Today, roughly half of the world's 50,000 orcas are believed to

live in the Antarctic.

Recently, scientists have discovered that within these waters

there are at least three distinct types.

On close inspection, their size, colour, fin-shape,

saddle pattern and eyespot are all different.

But the differences between them are much more than just skin deep.

To communicate, each orca type has a distinct vocal dialect...

..much like our accents.

And what's really fascinating is that three different hunting

strategies have emerged.

To reduce competition for food, orcas have become specialists.

Type A orcas, the largest, prey on minke whales.

Whilst type C orcas feed on fish.

But the most ingenious hunting tactic

of any dolphin is seen by type B.

Of the five seal species in the Antarctic, these orcas target

Weddell seals almost exclusively.

Orcas have good eyesight both below and above the water...

..and by spy-hopping they can check out the species of seal.

Whilst the seal remains on the ice floe, it's safe.

So a thorough survey from up to ten different angles helps them

form a plan of attack.

Then it's time to put that plan in to action.

Using their huge eyespots to align themselves,

the team start the first phase of this coordinated attack.

Four tail flukes beat in unison, creating a wave designed to

act as an icebreaker.

Assaults like this can last half an hour or more.

And when the ice floe is small enough, the team change tactics.

As they reach the ice edge,

a carefully calculated power stroke creates a metre high giant wave.

It gives the seal no chance.

Once the seal is washed off the ice,

the orcas work as a group to keep it from hauling out again.

The same power that drives an orca at 30 miles an hour now turns

the seal's world upside down.

And huge lungs use explosive ventilation to confuse it further.

Gradually they wear down their victim.

Before a final nudge

tips the balance firmly in the orcas' favour.

More than 50% of these hunts end in success.

And by passing on their chosen hunting strategy

from generation to generation,

each population of orcas creates its own culture.

There's little doubt that dolphins are one of the most versatile

predators on Earth.

Their highly adapted anatomy has evolved over millions of years,

and their complex communication skills allow them to develop

ever more innovative ways of overcoming their prey.

This combination of brains and brawn make for a master hunter

and one of the most successful animals on the planet.

That is the wonder of dolphins.