Armoured Animals David Attenborough's Natural Curiosities

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 most fascinating of all.

Some animals appear to protect themselves

with formidable suits of armour.

The rhino carries plates of thick hide on its flanks.

While the hedgehog is covered in prickly spines.

Both, in previous centuries,

inspired far-fetched and outlandish ideas,

but what is the true nature of their strange coats?

Rhinoceroses are strange-looking creatures.

There are five kinds.

The Indian, this one, has a single horn, squat legs, tiny eyes...

Whoa!

..and thick folded skin.

For many centuries, before any had reached Europe,

they were surrounded by myth as much as the unicorn.

Few people had ever seen a live rhino, but, in 1741,

a young Indian rhinoceros called Clara came to Europe

and she transformed our image and understanding of the rhinoceros.

Thank you.

Before Clara arrived,

little was known in Europe about the rhinoceros.

A few animals arrived here in Roman times, but they didn't last long,

many being slaughtered during the brutal Roman Games.

It wasn't until the 16th century

that they first made a real mark on western society.

In 1515, a woodcut of a rhino was created by an artist called Durer.

It was a beautiful image of an elaborately armoured creature,

but it was inaccurate.

It's doubtful whether Durer ever saw a live rhinoceros.

It's little wonder that the rhinoceros was thought of

as a magical mythical creature

if Durer's woodcut of 1515 was to be believed.

He shows an armour-plated beast with a large horn

and a strange little spike on its back.

But in the 18th century, the perception of the rhinoceros was

to change when Clara came to Europe on an extraordinary 17-year tour.

Clara was captured in Assam at just a few months of age

when hunters killed her mother.

A director of the Dutch East India Company

raised her in his household as a pet.

She wandered indoors amongst the elegant furniture,

ate from a plate and was a popular attraction at his dinner parties.

But, inevitably, Clara got too big

and a little-known Dutch sea captain called Van der Meer

seized the chance to own possibly the only tame rhino in the world.

He saw the opportunity of making a lifetime's income

with an ambitious rhinoceros tour.

Clara became an orphan while she was still dependent on her mother.

Rhino calves usually stay with their mothers for up to two years,

sustained by the milk.

Only after that are they able to feed independently

on soft green grass.

Keeping a young rhino healthy was certainly a challenge,

but Van der Meer was smart and took good care of his new charge.

He travelled with her all the way from India

around the Cape of Good Hope, up the coast of Africa to the Netherlands

and his home town of Leiden.

He discovered very soon that Clara had a huge appetite

and he made sure that she always had plenty to eat.

Rhinoceros spend a great deal of time feeding.

They eat plant matter, but they don't have multiple stomachs

to digest and absorb nutrients,

so they need to eat large quantities of food to survive,

up to 100 kilos a day.

It takes a lot to fuel such an enormous body.

An adult rhino weighs over a tonne.

And the Indian rhino has a special mobile lip

to help it grasp and rip up the vegetation.

After reaching Europe, Clara lived quietly in Leiden for two years,

feeding and growing,

while Van der Meer made plans for his European tour.

At the time, a live rhino was a wondrous thing,

as Van der Meer well appreciated.

He was a clever businessman and he knew that publicity was needed

if his grand tour was to be a success.

Van der Meer made an unusual alliance with an ambitious

Dutch anatomist, BS Albinus,

who was hoping to produce a definitive medical textbook.

Both men were looking for publicity

and together they commissioned Jan Wandelaar,

an accomplished artist,

to make prints that would serve to advertise both the book and Clara.

They were strange but compelling pictures that combined

precisely drawn human skeletons and detailed images of Clara.

They were the most accurate drawings yet of the rhinoceros.

Wandelaar sketched Clara from life.

He was fascinated by the texture of her skin

and he depicted a rhino more realistically than Durer did,

so, at last,

the myths surrounding the animal's appearance came to an end.

As the news of Clara's tour spread,

everyone was eager to see this wonderful new creature

and Clara's first trip to Vienna was for a royal appointment.

The Empress Maria-Theresa was so eager to see Clara

and so impressed by her appearance and good temperament,

that she brought her children back for another private showing.

Clara became the talk of the town

and European heads of state were eager to meet her.

She travelled through Europe like a celebrity

and met both royalty and crowds of curious onlookers.

Her horn in particular attracted much attention.

In Paris she started a rhino-mania

with fashionable women styling their hair 'a la rhinoceros!'

Some regarded rhinos as living unicorns.

The scientific name for the Indian rhino is, in fact,

Rhinoceros Unicornis,

and, at the time, it was believed that the horn was made of bone.

But this in fact is not the case.

Rhinoceros horn grows from a spongy base positioned here on the skull.

The horn has no bony core.

It's made of keratin, the same substance as fingernails

and can grow again if it's lost.

Well, in June 1750, Clara's horn fell off,

probably due to her rubbing it on the travel crate.

To Van der Meer, this seemed to be a disaster

since he had no idea that it would regrow.

But, ingenuously, he used the event as a publicity stunt and the crowds

flocked all the more to see Clara fearing that she might be dying.

Even without a horn, Clara was still a fascinating creature

and her strange armoured skin was another talking point.

Why would such a gentle creature have such thick and elaborate folds?

The rhinoceros's skin in some parts is almost five centimetres thick,

nearly three times thicker than you would expect

for an animal that size.

We now know that, in the wild,

rhinoceros are not always as gentle as Clara.

They can be very aggressive,

particularly during the mating season,

and the tough skin provides them with some protection.

But it also has other benefits.

Thick skin is a good barrier against sun, flies and other parasites,

but why the skin of an Indian rhino grows in plate-like structures

with deep grooves has only recently been explained.

We know that the thicker skin areas are good physical protection,

but something deeper is going on.

It seems that the large folds increase the surface area

of the skin and help the rhino regulate its body temperature.

The tissues around the grooves are particularly rich in blood vessels

and transmit heat to the enlarged skin plates

which act like cooling radiators.

Indian rhinoceros bathe regularly and the folds in their skin

not only trap water but hold it even after they come back onto land.

So it turns out that the Indian rhinoceros's skin

is a far more specialised structure than anyone could have imagined.

For 17 years, Clara travelled across Europe,

stopping off in all the main towns and cities.

Everywhere she went, the crowds queued up to see her.

She visited England three times,

but her third visit proved to be her last.

In 1758, at the age of little more than 20,

Clara unexpectedly died in London.

Van der Meer was deeply shocked as he thought she might live to be 100.

Life on the road was over, but Clara's 17-year tour

had changed the image of the rhinoceros forever.

Durer's classic engraving of the fierce armoured beast was now

a part of history and new accurate images were produced.

The true Indian rhinoceros, like Clara,

looked just like this wonderful animal

painted by the great 18th-century artist George Stubbs.

Van der Meer made his fortune with her on the grand tour,

but Clara, more importantly, also enabled people

to get a first realistic view of what a rhinoceros looks like

and put to rest the idea of a heavily armoured mythical creature.

There is a more familiar animal whose body armour

also perplexed us for a surprisingly long time.

The hedgehog.

This delightful little creature is one of our most familiar

garden animals and yet it's got a surprisingly unusual appearance.

Instead of fur, like most mammals, it's got a thick coat of spines.

The only part of its body not covered by them

are its face and its underside.

The hedgehog's coat may appear to be painfully prickly,

but when the hedgehog is relaxed, it can lay its spines down flat.

When it senses danger, of course, it rolls itself up into a ball

and is completely hidden and protected.

It's a formidable suit of armour, these spines.

Nothing much can get past them.

It seems obvious that spines must serve as a protection

but their function was, in fact, misunderstood for a long time.

Early books claimed the spines were used for collecting food.

The hedgehogs were said to climb apple trees,

knock down the fruit and roll on it, impaling the apples on their spines

and carrying them off to their burrows.

Today we know that hedgehogs are better at climbing

than you might think, but they still haven't been seen to climb trees.

And there were other myths.

In medieval times, farmers believed that hedgehogs would steal milk

from their cows at night.

So the Elizabethan Parliament put a three-pence bounty on the head

of every hedgehog and thousands were slaughtered as a result.

Our attitude to the hedgehog is now very different.

Today, many of us get great pleasure

from seeing this appealing little creature in our gardens.

We know that they are a gardener's friend,

feeding mostly on insects and slugs

and helping to rid our plants of pests.

Some of us even put out special food to attract them.

We now also understand more about the hedgehog's spines.

They are, in fact, modified hairs,

hollow inside but reinforced with keratin,

the same material that forms a rhinoceros's horn.

That makes them strong while keeping weight down to a minimum.

A hedgehog has over 5,000 spines

and their main purpose is indeed protection.

But hedgehogs don't start life with a coat of armour.

It would be painful for a hedgehog mother

to give birth to spiny babies.

But nature has dealt with that problem.

Tiny hoglets are born with their spines covered by a layer of skin.

Within a few hours, the thin quills break through.

A baby hedgehog's first spines are soft and white

but these soon fall out and are replaced by darker and harder ones.

Hedgehog spines are shed and regrown at various stages in their lives,

just like the hair of mammals.

Surprisingly, a spiny armour is not common in the animal kingdom.

In Europe, the hedgehog is the only one of its kind.

But in other parts of the world, there are creatures that have

evolved a similar spiky coat.

This is an African crested porcupine.

It's got a formidable coat of spines but it's no relative

of the hedgehog and the spines are in fact very different.

For one thing, they are very much longer.

Normally, they lie flat against the body but if the animal is irritated,

it directs them to give a very spectacular warning.

Even the most ferocious predator will take care

when approaching a porcupine.

The quills will break off easily and become lodged in the skin.

The lion's only chance is to attack from the front.

As they circle, the porcupine twists and turns

to keep its armoured back to them.

This time, the lion got too close.

It has no way of removing the spike and may be unable to feed.

It could prove fatal for the predator.

Although the porcupine's quills may appear thin, even flimsy,

once they get stuck in your flesh, they are remarkably difficult

and painful to remove.

Why this should be was not known until recently.

But when looked at under an electron microscope, you can see

that each quill is coated with tiny backwards facing barbs.

The barbs act like the teeth on a serrated knife,

making it easier to penetrate the skin,

but when it comes to removing the quills,

the barbs have the opposite effect and act as anchors,

preventing the spine from sliding out of the wound.

The porcupine's spiky coat seems more formidable than the hedgehog's.

But the hedgehog has a very effective way of protecting

its vulnerable underbelly.

It rolls itself into a ball, so that it is completely encased in spines.

Foxes do attack hedgehogs but a fox must wait until the animal

is on the move if it is to get at its unprotected underside.

If the hedgehog stays rolled in a defensive ball,

the fox can't harm it.

All the hedgehog has to do is to sit it out until the fox loses interest.

But if spines are such an effective defence,

why don't many other animals adopt them?

The answer seems to be connected with the difficulties

of life with spines.

Spines may be something of a hindrance when it comes to mating.

Indeed, early naturalists thought that the hedgehogs must mate

belly to belly to avoid being impaled on each other's spines.

We now know that that's not the case.

The spines seem to do nothing

to hinder the ardour of a male hedgehog.

If she is willing, he tries to oblige.

But it still looks like a tricky and uncomfortable operation.

Despite the limitations of a spiny coat,

hedgehogs have remained largely unchanged

for almost 15 million years.

New evidence suggests that the spines may play another

rather surprising role in their lives.

Hedgehogs, when encountering an unfamiliar or toxic object,

sometimes behave in a very strange way.

They will lick and bite it until they start to foam at the mouth.

The froth is then transferred to their spines.

We still don't fully understand this strange behaviour.

It may help to camouflage the hedgehog's smell,

or make the spiny coat more distasteful to predators.

Or maybe it helps hedgehogs communicate with each other.

Or make them more attractive to the opposite sex.

We might one day discover its true purpose but we haven't yet.

Our familiar British hedgehog has provoked some very strange

and far-fetched ideas, but, for many of us,

it remains one of the most engaging animals in the British countryside,

and its prickly coat makes it that much more attractive.

So, it turns out that some of the early ideas about the purpose

of the rhino's armour and the hedgehog's spines

were only partly correct.

Their true functions are far more complex than we yet realise.