All language subtitles for David.Attenboroughs.Natural.Curiosities.Series.3.4of6.Curious.Feeders.720p.HDTV.x264.AAC.MVGroup.org

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The natural world is
full of extraordinary

animals, with amazing
life histories.

Yet, certain stories are
more intriguing than most.

The mysteries of a
butterfly's life cycle,

or the strange biology
of the Emperor penguin.

Some of these creatures
were surrounded by myth

and misunderstandings,
for a very long time.

And some, have only recently
revealed their secrets.

These are the animals, that
stand out from the crowd,

The curiosities, I find
particularly fascinating.

In this program, we
meet two animals,

who's extraordinary body shapes
are determined by their diet.

The blue whale grows enormous by

feeding on tiny
shrimp-like creatures,

while flamingos
spend their lives,

eating with their
heads upside down.

And yet, both ways are
curiously similar.

The blue whale weighs
almost 200 tons.

It's the largest
animal on earth,

and it's rarely seen.

I didn't glimpse one,
until I had been

filming animals, for
almost 50 years,

and when I did, it was one of the
greatest thrills of my life.

I can see its tail, just
under my boat here.

And it's coming up, coming up !

There!

The blue whale,

is 100 feet long, 30 meters.

Nothing like that
can grow on land,

because no bone is strong
enough, to support such bulk.

Only in the sea, can
you get such huge size

as that magnificent creature.

The blue whale was a mystery
to science, for a long time.

Living out in the deep oceans,
people rarely caught sight of

more than the spout
of this giant.

The first published description,
comes from a physician,

Robert Sibbald, who
found a whale,

stranded off the coast
of Scotland, in 1692.

It was first named
after Sibbald,

but later given the
scientific name

Balaenoptera musculus.

The Latin "musculus",
means both,

"muscle" and "little mouth".

An ironic double meaning, for
the largest animal on earth.

When the first blue
whale specimens,

were washed up on our shores,

they must have caused quite
a stir and excitement.

Here was a colossal animal,
weighing over 150 tonnes.

Nothing as big, had
ever been seen before.

A giant of this scale,
must be a predator

at the top of the food chain.

But what kind of
creature was it?

And what was it feeding
on, to make it so big?

The first blue whale specimens,

were found at a time,

when scientists were just
starting to classify animals,

not only by their
external appearance,

but by their
internal structures.

And few animals proved as
problematic as the whales.

From the outside, they looked
and behaved like fish.

But the internal organs, were
like those of a large mammal.

The bones of the
whale's front fins,

are very similar, to
those in our own arms.

The five digits on the
hand, are clearly visible.

But they've been modified
into paddles, for swimming.

What kind of creatures were these,
truly extraordinary animals?

The controversy, as to whether
whales were fish or mammals,

came to a head, in a New
York courtroom in 1818.

A jury was asked, to pass
judgment on the question,

for the purpose of the
New York State law.

The issue had come up,
because a shrewd merchant,

who owned three
barrels of whale oil,

had refused to pay tax,
levied on fish oil.

He pointed out, that
according to the latest

scientific opinion, whales
weren't in fact fish.

The inspector, collecting the
tax, had scorned the idea.

"What, whale is not fish?" he said,

and slapped handcuffs
on the merchant.

The lead witness, was a
respected scientist,

called Samuel Mitchell.

Mitchell entered the courtroom,
expecting to explain to everybody,

why whales were
mammals, not fish.

But instead, found
himself being attacked

by the most gifted
lawyer in the country,

William Sampson

Sampson argued, that scientists
didn't have the right,

to rename God's creatures and
force them into absurd groupings.

The idea, that humans and
whales, should be in

the same category,
seemed to him grotesque.

Mitchell and science,
never stood a chance.

After deliberating
for 15 minutes,

the jury announced the
verdict, in favor

of Sampson and the
fish-oil inspector.

According to New York State law,

whales were deemed to
be fish, not mammals.

Although the general public still
considered whales, to be fish,

scientists were by now, largely agreed,
that they were indeed mammals,

that had taken to living in the sea.

But what was the blue
whale feeding on,

to allow it, to grow to
such an extraordinary size?

The answer could be found,
by looking inside the mouth,

which contains some very
bizarre looking structures.

This is the skeleton
of a right whale

and its mouth parts are very
similar, to those of a blue whale.

Instead of teeth it
has these strange,

plate-like structures,
hanging from the upper jaw.

The plates are aligned
alongside each other

and the inner edges fray,
because the large tongue

continually rubs
up against them.

And then, the frayed
edges entangle,

to form a thick mat, that
acts like a gigantic sieve.

And when early naturalists, opened
up the gigantic gut of these whales,

they found not fish,
or other large prey,

but tiny, shrimp-like
creatures, called krill.

To everyone's astonishment,
it turned out,

that these whales feed, on some
of the smallest prey in the sea.

And these strange plates, serve to
filter the krill, out of the water.

The rows of plates
are called baleen.

And we now know, that they form

a highly specialized
filter feeding system.

The giant animal dives
deep, beneath the surface,

in search of swarms of krill.

The pleated skin, on the
throat and belly expand,

and the mouth balloons outward,
to four times the size,

taking in an enormous
mouthful of water.

The tongue, then
forces the water out

through the baleen, and thousands
of tiny krill are left behind.

Today, we know a lot more about
this unusual feeding structure.

This is baleen.

It's often referred
to as "whale bone",

but it's not bone at
all, it's keratin.

The same substance, as our
hair and finger nails.

And it's both strong,
and slightly elastic.

The plates emerge from the
whale's jaws, instead of teeth,

and continue to grow throughout
the whale's life time.

These bands in it, are much
like the rings of a tree.

Several may be laid down,
in the course of a year,

so the baleen can give us an
indication, of the age of a whale.

We also know from
other evidence, that

blue whales can live, to
be over 100 years old.

Recently discovered
fossil whales,

had both teeth, and
simple filters.

Which suggests, that early
filter feeding whales

may have sucked small
animals from the seafloor.

There is a whale alive today,
that feeds in just that way.

The Grey whale.

It stirs up the sediment, and
scoops it into its mouth,

and then filters out, small food
particles, with its baleen.

Krill is abundant in the oceans.

And blue whales,
can eat enormous

quantities of it,
with each mouthful.

Soon swallowing 90 times more,

than they immediately need.

The surplus is then stored,
in the form of blubber.

And this helps them cope with
periods, when food is scarce.

The blue whale was a mystery
to us, for a long time.

But we now know, that its
enormous body is fueled

with vast quantities,
of the tiniest of prey.

Over the course of its lifetime,
a blue whale will consume

around 50 thousand
tonnes of krill.

And, unlike teeth, which
fall out with old age,

the baleen never stops growing,

and is constantly replaced.

Maybe, this unusual body design,

not only helps the blue whale
grow to this enormous size,

but also to such a
formidable old age.

In part two, we meet
another filter feeder,

and discover how
its unique diet,

has affected both its body
design, and lifestyle.

The blue whale, has
become a giant

by filtering tiny creatures
out of the ocean.

Our second curiosity,
the flamingo, also has

an unusual body, that has
been shaped, by its diet.

For a long time, the flamingos

were birds of myth and mystery.

Travelers in Africa, saw them,
shrouded by the hazy mists,

rising from volcanic soda lakes,

and believed that
they were fire birds.

In Egyptian mythology, the
fire bird or Phoenix,

was a sacred creature, with
beautiful red plumage,

which was consumed
by magical fire,

and then rose again,
from its own ashes.

The flamingo's scientific
name Phoenicopterus,

reflects some of its
legendary past.

It means "Phoenix wing".

These beautiful and
elegant creatures

are some of the most
curious looking of birds.

No other bird, has a beak
shaped quite like this.

Or indeed, such
glorious pink colours.

And yet, we're so
familiar with them,

that we rarely think about
their strange appearance.

Why is it, that the flamingo is so
different, from all other birds?

In that classic children's
book, Alice in Wonderland,

Lewis Carroll has fun, with
the flamingo's oddity.

Alice plays croquet, with the Red
Queen, using them as mallets,

holding their heads and
necks upside down,

in much the same posture, as
the birds take, when feeding.

When you look at the
skeleton of a flamingo,

the thing that strikes
you most, is the

extraordinary length of
the legs and the neck.

The neck has 17 bones in it.

Which is no more
than in other birds,

but each is greatly elongated,

giving the flamingo its extra
long neck, and flexibility.

But the flamingo's most curious
feature, is surely, its beak.

And the reason, it
looks so strange,

is, that it is the only beak,
adapted for use upside down.

In most birds, the upper part of the bill

is larger than the lower one.

But in flamingos, it's
the other way around.

The lower bill is much bigger
and has a deep, central

groove in it, that holds
the flamingo's tongue.

The upper jaw is
thin, and movable.

So, when the bird's
head is upside down,

the flamingo's jaws work
as it were, normally.

When feeding, the flamingo gently
sweeps its bill back and forth,

sucking water in at the front, and
squirting it out from the sides.

The water that
goes in, is murky,

while that, which flows out, is clear.

And that gives us a clue,
to what it's feeding on.

The beak has tiny bristles,
all along its edges,

much like the whale's baleen.

And the tongue, has two rows of
horny spikes, along its length.

When feeding, the bristles
and spikes, form a sieve,

trapping any particles inside.

And the large tongue, acts as a
pump, pushing water in and out.

It's a unique design for a beak.

No other bird has one like it.

Although, at first sight,
they may look the same,

flamingo beaks, in fact, come
in two different shapes.

And this is, because they eat
slightly different food.

This is the beak of
a Greater flamingo.

which feeds on crustaceans,

which are usually found
near the bottom of a lake.

It's long and
shallow, so the birds

can feed in water, only
a few millimeters deep.

This beak, on the other hand,
is from a Lesser flamingo.

It's bill is shorter, but
more bulbous and deep-keeled.

The Lesser flamingo, feeds
on microscopic algae,

which usually float, just below
the surface of the water.

And the deep keel,
acts as a buoy,

bobbing along, just
at the right depth,

as the bird moves
through the water.

These different bills, allow
two species of flamingo,

to live side by side.

In Africa's Rift valley,
Greater and Lesser flamingos

are found on the soda lakes,

having specialized on food,
that others can't reach.

The waters are so hot and toxic,

that they would strip the
flesh off any other animal.

But flamingos thrive here.

Their long, spindly legs, have tough scales

and their webbed feet, prevent them
from sinking into the soft mud.

The birds can even
drink the water,

which is 2 or 3 times
saltier than the ocean.

But it's not just the mud and
water, which are poisonous.

The blue-green algae, which
many of them feed on,

actually contain nasty,
toxic chemicals.

If that were to accumulate,
in the internal

organs of the bird,
they could be lethal.

But the flamingo deals with that,
by directing these chemicals

into the feathers and the skin,
where they do no damage.

The feathers of the flamingo, contain
very high concentrations of toxins,

but they also contain
another chemical.

Carotene.

Carotene is the reddish pigment, that gives
flamingos their distinctive pink color.

And it also comes
from their diet.

But carotene is not harmful.
On the contrary.

It's a source of vitamin
A, and boosts the

immune system, protecting
against illness.

So, a pink bird is
also a healthy bird.

This glorious pink
color, was probably

an incidental bi-product
to their diet.

Nonetheless, over time,
it has evolved to play

an important role in the
flamingo’s social life.

The flashes of colour, are an integral
part of their courtship display.

And recent research has shown,
that the pinkest flamingos,

are the most popular, when
it comes to finding a mate.

When flamingos breed, much of
the carotene in their diet

gets channeled into
the developing young.

Even the eggs receive pigments.

So much in fact, that the yoke can
be virtually blood-red in colour.

These eggs are from captive
flamingos, and are infertile.

Let's have a look.

There.

Well, it's nothing
like the colour of any

other bird yoke, that
I've ever seen.

Flamingos are so efficient at
collecting their specialized food,

that the yoke is actually
packed full of protein and fat.

And this allows the chick to
grow particularly quickly

and gives it a good
start in life.

Despite the colour of the yoke,

the chicks hatch with
fluffy Grey feathers.

They're fed on special milk,
from their parent's crop.

This is not regurgitated
food, but a secretion,

produced by the lining
of the digestive tract.

And it's deep red in colour.

The flamingo chick
relies on this,

for the first few
weeks of its life.

And it will
eventually enable it,

to grow its glorious
pink plumes.

We now know, that much
of the flamingo's

bizarre appearance, has
been shaped by its diet.

The one question, that continues
to baffle scientists,

to which group of birds, do the
flamingos actually belong?

Some thought, that they must
be related to ducks and geese.

Because of their webbed feet,
and short, duck-like beaks.

But others were convinced,
that with their long legs,

they're more like
waders, such as storks.

Recent DNA studies, contradict
both these suggestions.

They reveal, that the
flamingo's closest relative

may in fact be a small diving bird,
that looks nothing like a flamingo.

The Grebe.

Further studies found other similarities
in the structure of the eye,

and the number of
feathers on the wing.

So it seems, that
flamingos and grebes are

indeed each other's
closest relatives.

But over time, diet
and lifestyle,

have shaped the flamingo into a
very different looking bird.

Far removed, from its
grebe-like ancestor.

It's fair to say, there's nothing
else quite like a flamingo.

The flamingo and the blue whale,
are two very different creatures.

One living on land, and
one in the deep oceans.

And yet, their bodies have been shaped
in a similar way, by their diet.

Making each of them a curiosity,
within its own group.

***