David Attenborough's Natural Curiosities (2013) s03e04 Episode Script
Curious Feeders
1 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 flamingoâs 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.
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 flamingoâs 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.