Inside Nature's Giants (2009) s01e02 Episode Script
The Whale
You can see the fin whale behind me out on a sand bar.
It's huge now, cos it's blown up with gas.
It died two days ago, came in from the ocean, and we don't know why, and we don't know what killed it.
But you can see people are now making their way over there.
We have a window of opportunity of literally a few hours to be able to get out there and start the postmortem to try and unlock all those clues that are not only gonna tell us why that whale died but also help us understand the whales that are still living out there.
And let me tell you, the weather is absolutely abysmal! On the 15th January 2009, a fin whale swam into a bay off the south coast of Ireland in County Cork.
Fishermen from Courtmacsherry made valiant attempts to save it, but once the tide started to go out, this 65 foot whale was doomed.
EXCITED CHATTER (BOY) I've never seen a whale in my life.
Here was a unique chance to explore the anatomy of a whale and discover its evolutionary story.
Why did these mammals live in the sea, and how did they become so large? This adult female was far too big to be transported to the Royal Veterinary College, like the other animals in our Animal Autopsy series.
She weighs about 50 tons, as the local digger operators were about to find out.
The whale was decomposing fast with a growing risk of explosion.
The Irish authorities feared this could degenerate into a public health nightmare.
The vet in charge, Dan Crowley, accepted our offer of help to fly in the queen of whale anatomy from New York, Joy Reidenberg.
'In the camper van HQ, she quickly takes charge of the operation.
' As soon as the first cut is made here, that is gonna cause a lot of hissing.
We make one cut and everybody backs up.
If you make the cut too deep and it goes through the muscle layer and into the peritoneum, which is where the guts are, then you're gonna have an eruption like a volcano, all the guts are gonna come out of that hole, and you're gonna see spouting through that little hole.
In Denmark, they learnt this lesson the hard way.
Aargh! WAVES CRASH, WIND WHISTLES The tide's now dropped, and we have just four hours before nightfall.
WIND HOWLS This is obviously the head of the whale, it's on its side and slightly on its back.
You can see one eye just down here.
This is its upper jaw, this is the baleen plates, and these are made of keratin like your fingernails, and they're used for filtering out all the food this animal eats when it dives and feeds.
This is its tongue, believe it or not, which has blown up because of the gas inside, it's absolutely massive, and you can even see these tiny little papilli on it, it's just slightly rough to the touch.
It is extraordinary being this close, it's so sad it's dead, butextraordinary.
OK, you guyswe need everybody here to be on the other side of that water, because we're gonna cut this end and it's all gonna pop out.
Everybody move, please.
Get out of the way, you're gonna be caught in whale goo.
OK, here we go.
WIND WHISTLES GAS WHISTLES FROM WHALE That gas is all from fermentation from bacteria decomposing the organs inside.
Even though it's cold outside, we're all bundled up with a lot of layers, that whale's bundled up with its own layers of blubber.
I'm trying to let gas out from as many small ports as I can rather than one large one, cos if there's one large one, all the internal organs will get pushed out through that hole.
GAS CONTINUES TO WHISTLE So now the inflation has come down quite a bit, so the big explosion isn't gonna happen anymore.
We've taken away most of the pressure, that part's done.
OK, this is freed up? Under the skin lies not only the clues to this animal's death but also the secrets of how the biggest mammals on earth evolved.
Whales remain hidden from view, apart from tantalising glimpses when they come to the surface for air.
How they survive so long at such depths is one of the great wonders of the natural world.
And the story of their evolution defies belief, as Richard Dawkins explains.
All our ancestors came from the sea and obviously went to great trouble to leave the sea and become radically changed to live on land.
And then some of them - whales, sea lions, penguins, turtles - went back into the sea, which would seem to sort of undo a lot of hard research and development, so to speak, and need to reverse it.
They didn't quite reverse it, I mean they rediscovered many things.
The shape of a whale or a dolphin is pretty much like a big fish, but amazingly if you look inside, deep inside a whale, you will find vestiges, vestiges of hind limbs, little tiny remnants of bones which show that the ancestors had real hind limbs that they actually used for walking.
Later we hope to find this vestigial hind leg, but first we need to strip off the blubber.
OK, you and you, come on up.
I want you on this side, OK? You can use one of the long knives and start to cut this blubber.
Be real careful of its head.
If you need him to move, let him know.
The wind is gonna pull on that when you lift it up.
You can start with the hand knife here.
This line right here.
When you get to here, you're gonna switch to the other tool.
If the wind is too strong and it's pulling it, stop, cos it'll fly out of your hand and impale someone.
All right, I'm gonna go up there in the meantime.
No, not that, not that.
Oh, just a hook? Just a hook, have you got a hook? If the wind isn't too bad, I'm gonna get up and do the cut.
I just need to see how bad the wind is.
If I feel like I'm gonna get blown off, I'm not gonna do it.
Are you OK with that? Yeah, I think I'm all right.
I wanna get to that depression, where I can sit better.
OK.
Hang on, there you go.
OK! I need a knife.
Beautiful.
Got it.
Joy's got the most dodgy job at the moment.
She's trying to balance on a very slippery whale.
She's cutting through the blubber from back to front, all the way round, so we end up with one big sheet of blubber that hopefully we can peel off like a banana skin, andthat'll give us access here to the thorax with the heart and the lungs in it, and further back into the abdominal organs like the digestive system, the kidneys, the genitals and so on.
The smell is absolutely unbelievable! So, I'm cutting along this area here, of the whale's belly.
We're heading towards the genitalia, which are right down there.
As the team continues to unzip the blubber on the fin whale, more and more people catch wind of the activity on the beach, and venture across for a rare glimpse of this giant from the deep.
Local businesses are quick to take advantage of the new tourist attraction .
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while the authorities fight a losing battle holding back the inquisitive crowds.
You know all those pieces hanging off there? Is that plastic, or is it skin? Hang on a minute.
That, what does it feel like? Plastic.
Plastic.
Skin.
So, who thinks plastic? Who thinks skin? Skin.
Skin.
Plastic.
It's skin.
It's the same stuff that's on your hands.
The outer layer of your skin is growing all the time and every day, when you wash and when your clothes rub on your skin, it comes off.
That's why you get flakes.
You know when you get dandruff? That's flakes of skin.
Or when you get sunburn.
When your skin peels off, that's exactly the same.
That's the outer layers peeling off the whale.
Once upon a time, all mammals' skins were covered in fur to keep them warm.
But in deep water, fur is a poor insulator, so the whales' ancestors swapped it for blubber.
But the really big question is why they left the land in the first place.
It's just that animals are going to pick up opportunities wherever they arise.
If they discover an opportunity, like seals, to spend a bit of time in the water, otters spending time in the water, there is a living to be made.
They make it.
Once they have gone that far, then there's a living to be made going a bit further, there's a living to be made finally not coming back onto the land at all.
I'm going to make this last cut, it's going to spring down.
She's going to make the last cut and it is going to move down.
I'm holding on, hopefully I won't Are you all right? Drop the knife if you're going to fall! I need you to take the knife.
Are you OK? Yes.
I've got my nice hook, I'm all set.
Now, I can be Jonah in the mouth of the whale.
So, Joy, this here is all baleen, isn't it? The filtering system.
That is all baleen.
It's a sieve.
Like having a big moustache.
The whale is going to take all the food in, squeeze the water out, and the fish get trapped on the moustache.
Then it licks its moustache, like having a nice beer with a head on top, and you lick it off.
Does it regrow if it gets damaged? It does grow, just like your fingernails.
It keeps going.
If it has a damaged one it will grow it back out.
When baleen whales go in search of food, they prefer to shop in bulk.
They eat shoals of fish and krill that can be so densely populated, they stain the sea red.
To trap this much seafood in one go requires opening the mouth as wide as possible.
Unlike other mammals, the two halves of the baleen whale's lower jaw are not fused together.
Each side disarticulates, allowing its huge expandable throat to fill with water.
As it squeezes the water out, fish are trapped in the moustache-like baleen plates, ready to be licked away by the tongue.
Take a look up here.
This material here is the tongue.
This is it.
This stretchy stuff that you're looking at, here, is the floor of the mouth.
That is actually the tip of the tongue.
There we go.
That's all there is.
This is it.
That is the tongue? The tip of the tongue.
So most of this that was blown out of the front that I thought was the tongue, is actually just the floor of the mouth? And some of the tongue.
This was up there.
Now, it has all retracted because it is very elastic tissue.
Once the tension was off, it all pulled back this way.
It's very floppy.
There's not a lot of muscle there, but there is enough to cause it to curl, kind of like this.
When it makes that curl, as a baby, these little fringes, which are actually a little bigger on the babies, help, like fingers, to grab around the mother's teat, to form a tube so, when it's nursing, the water is channelled through that tube, so the milk is not lost to the ocean.
So far, have you found anything in terms of any possible reasons for death? Not yet.
I can't believe you are inside the mouth of a whale.
There you go.
I don't want to lose you inside yet.
The digger is just being manoeuvred into the right position so we can have the right angle of pull on this blubber.
Ideally, what we want to happen is, rather than try to pull it out at right angles to the body, they want to pull it longitudinally, like peeling back a banana-skin.
If the rope pulls through, the only alternative is to hand cut it off, which will take probably an hour and a half.
The tide will be on the turn and coming in any moment, so that would be a serious disaster.
This is going to be dramatic.
Go for it.
Here comes the rain, right on schedule.
Perfect.
OK.
With the blubber coat peeled off, we can finally investigate the internal anatomy, and we'll begin with the guts.
Their contents may yield vital clues about what led to this animal's death.
We're about two hours into the dissection at the moment and we're trying to work out how to get the small intestine out of the abdominal cavity to be able to drag it away, but the difficulty is, not only is it heavy, but, I mean, typical of intestine, it just wraps in amongst itself.
What's amazing is it's still so warm! You need one of these to get it out.
This could be very messy.
We need to get it away from here, because the tide will sling it all around.
We're organising to take that and all internal organs, right? Store them off up at the shore line.
OK, look how much we got done so far! It's not sunset yet.
Joy is on her own race against the tide.
For her, the holy grail of whale anatomy is understanding how whales talk to each other.
And there is a vital bone called the hyoid that she's determined to reach by diving down the whale's throat.
It looks just like a wishbone in a chicken, but pulling this wishbone out of a whale is a much greater challenge.
The hyoid bone is a free-floating bone in the neck.
It is not really attached to anything else in humans.
In whales, the hyoid bone IS attached to the skull, so this is going to be a hard bone to get out.
Can you pull it down now? This is the epiglottis, it's the beginning part of the larynx.
The larynx is the voice box itself - that's where the sounds are produced.
This bone is still attached to the larynx, so when it moves back and forth, it moves the larynx as well.
The songs of whales are so deep they are beyond the range of human hearing.
It was only during the Cold War, when the US Navy took microphones into the ocean to listen for Soviet submarines, that they inadvertently became the first humans to hear them.
WHALE SONG But what are they saying? They might say, "I found a really cool patch of krill, "come on over here, it's a food fest!" Or they might be saying, "Mum, where are you?" OR they might be saying, "I'm sexy, come mate with me.
" The puzzle for Joy is how a mammal's voice box modified to work under water.
She has her own theory, but she needs to dig out the larynx first.
As the sun sets and the weather turns bad again, the odds are not looking good.
Mother Nature is definitely taking hold of our dissection now - this is an incredible hailstorm, it really hurts on your face, and the team are trying to tidy up and move as many of the samples they've taken out of the carcass into safe ground, because obviously the tide's now coming in.
Poor old Joy, she's still battling away to try and get that hyoid bone and the larynx out and just where the digger bucket is now, they're just trying to excavate out the liver, because they've had enormous problems trying to get that out to get access to the diaphragm that separates the abdominal cavity and the thorax, or the chest, because if we can open that big curtain of muscle, we'll get to the heart, which is hopefully what we'll do tomorrow.
We've gotta be leaving soon because otherwise we won't get off this beach.
At last, Joy wins her tug-of-war with the monstrous wishbone.
But the hyoid snaps off the larynx.
One last shove and the larynx will be hers.
Easy way down! All right, that's it.
Despite driving rain and fading light, Joy cannot resist an impromptu tour of her favourite organ.
That's the voice box, called the larynx.
This is the front end.
That down here is the epiglottis, the front part of the larynx, it's a little bit shredded right here.
That's the opening in that air will take to get into the larynx.
These are the corniculate cartilages and they have these interesting flaps on them and it's not clear whether these animals pulse these flaps to make pulse sounds, so these might be part of the sound-producing apparatus.
If we follow the air through and go round to the back again, where it's coming out in the back right here, you'll notice that as you look through that hollow space, if you can see the light coming through where I'm putting my hand, it goes into a cleft and so as it goes through this gap .
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this sac is probably responsible for bringing those sounds out to the outside world.
So this sac can really balloon out and take a lot of volume in it.
It's this bag that pushes on those throat plates which are like an accordion, they can expand and contract, and that in turn would send a pulse into the water directly, and these animals are making low frequency sounds, so the bigger this is the lower the sound.
SLOP! I knew that was going to happen.
There it goes.
Tell you what, what a difference 12 hours makes in the weather though! Unbelievable.
It should be a very good day today I hope.
It'll be great to try and find the vestigial hind leg, which would be good.
It's female, there's even a possibility it might have been pregnant.
While we're waiting for the tide to go out the job we can do now is all the bits we harvested yesterday - the digestive tract, the intestine - we can have a detailed look at that.
A bit of tape round the top, please.
Lovely mess! Do you get used to this smell? Oh, yeah.
This doesn't smell as nearly as bad to me as simple things like changing a baby's diaper.
Before we can find clues about its last meal, we need to lay out the tangled mass of guts.
Somewhere underneath is the stomach - the beginning of the tract, so we need to flap some of this over to get down to the stomach.
The intestines are over 80 metres long - four times the length of the whale.
The food is coming in through the stomach, which is all the stuff on this side of me, and then it's gonna run through the small intestine which is this stuff that's moved back and forth all the way down.
And then as it comes around the corner down to the end, that is the large intestine, ending up at the anus.
And this is a meal from before the animal became stranded, and we see what's coming out on the other end of the animal, this is poop for a whale.
But it's pretty wet stuff, so it's a lot wetter than what you expect on a land animal.
A whale needs to have something it could excrete while it's still swimming.
Joy now wants to check what it ate just before it died.
This is stomach.
This is, this is a really large See if you can pull it.
We need a bit of help here.
Here you go, hold on.
Let's make another hole, here, this one right here, pull.
If we can pull it this way it might go better.
Perfect.
We're looking at the beginning of the stomach, one of the chambers of the stomach here.
If the animal had eaten, this is where we would first find food, but we're not seeing anything in here except fluid, so this indicates to me that the animal was probably sick cos it wasn't feeding.
This would be the next chamber, you wanna get a sample of that? Even though they are fish eaters, bizarrely, whales have a multi-chambered stomach, more suited to a cow.
Amazingly, whales actually belong in the group called even-toed ungulates - that's the cloven-hoofed animals.
One always knew that there was some connection between them, but what was astonishing was that molecular biologists showed, looking at DNA, that whales are actually closest to hippos.
Hippos are even closer to whales than hippos are to pigs or cows or any of the other cloven-hoofed animals.
Now, that's an astonishing thing.
65 million years ago, the sudden extinction of the dinosaurs opened the door for mammals to become the new giants of the planet.
One species that survived spawned the evolutionary pathways that led to over 200 modern plant-eating animals.
But one of them came across a new opportunity at the water's edge.
This was pakicetus, the first whale.
It had sharp teeth that allowed it to hunt, and then gradually its legs shrank.
Over 50 million years, it went from the size of a dog to the largest animal that ever lived.
It's interesting - you tend to think about the fact that with the whale, everything is perfectly adapted for its environment, but actually, it's got all kinds of handicaps associated with the fact that its ancestry was on land - it's still not perfect by any means.
If evolution were intelligent, we wouldn't have these handicaps.
It's not, it's a mish mash, it's a patchwork.
Every time you wanna make a better mouse trap you put another patch on.
You have to work with what you've got - there's evolutionary baggage.
Makes you think though, in the very long-term future, would you end up with this evolving into an animal that then moves more to having gills or being able to extract oxygen out of the water rather than having to breathe like a land mammal? You can't make those predictions cos evolution isn't directed.
You never know what the environment's gonna do because it has to respond to how the environment changes.
Maybe global warming will cause whales to evolve into something else.
When whales took to the water, their swimming style was set some 50 million years ago.
Their ancestors used to gallop over the countryside.
Now they live in the sea.
In a sense you could say they gallop through the sea, because the spinal movement of a whale as it swims through the sea is up and down, which is similar to what mammals do when galloping over the land.
Unlike fish, from which they're all descended, where the spinal movement is side to side.
At some point in the history of mammals, they must have switched from a side-to-side spinal movement to an up-down spinal movement.
And the whales, even when they went back to the water, retained the up-down spinal movement.
Galloping in the sea didn't just mean swapping legs for a tail.
Joy thinks the hyoid bone she extracted yesterday from the whale's throat may hold the key to how whales swim.
Just like a human swimmer might do a dolphin kick, a dolphin kick isn't just kicking your feet, you have a whole body wave that begins with your head and moves up and down.
So the initiation, the beginning of that swimming motion, must start with the head pulling down, and then up.
The only thing that can really pull a head down is the muscle attached to this bone.
Because the attachments that go from the chin to this bone in turn then go to the sternum, that's the beginning of the ribcage.
And when you contract all of those muscles in a row that means the hyoid, being caught in the middle between those muscles, is gonna be responsible for bringing the whole head down.
So if the animal keeps its jaw closed and then contracts those muscles, instead of opening the jaw it's going to depress the head, and that's the beginning of the body wave that these animals use to swim.
So that makes this bone a bone that's involved in swimming.
And that's unusual, because here's an animal that's locomoting with its throat! Joy's research is turning the science of how whales swim on its head.
By studying a bone crucial to communication, she unwittingly stumbled across an explanation of how they learned to swim.
The fin whale is the greyhound of the sea.
Its streamlined body crosses oceans to reach its feeding grounds.
But in the case of our whale, something went wrong when it came to feed off the coast of Ireland.
Now the tide has receded, we have just four more hours to try to solve the mystery.
The preliminary evidence suggests the whale was sick, but Joy wants to rule out another possibility That it was hit by a ship.
Boat strikes tend to be marks that go this way, so we're looking for a big area that looks like it's been hit this way.
This is a possibility right here.
Unless they did it with that scraper, I'll have to ask, cos this looks new.
This is an old injury that's healed up - you can see that the skin is absolutely smooth here, but you see colour differences, they don't match up, so this animal had a gash here, it could have been a shark bite, could have been maybe a boat propeller.
That's not the cause of this problem but it's an old injury.
Thank you! There's a scrape on the side in the blubber there that's in a vertical line, that we think might have been caused by the excavator Yeah, it was, yeah.
OK, that's good, cos that rules out one of the possible causes.
Yeah, because we were turning it over OK.
So that made that stripe? So that takes care of us figuring out what that line's from, thank you.
Having inspected the entire whale, Joy is now confident she can rule out a ship strike as the cause of death.
There are no other wounds you've seen on this side now? Just parasite wounds, small things.
As this whale is a mature female, Joy wants to check whether she's carrying a calf.
But somewhere in this big hunk of tissue, we think we're gonna be seeing the ovaries.
It would be an oval-shaped structure, probably about that big.
I was hoping it would be in here.
This just seems to be fat as far as I can tell.
We're gonna keep looking.
The anatomy of whale sex is extraordinary.
Males can have penises up to three metres long and, hidden under their blubber, their testicles can weigh a ton.
Joy could find no evidence that this whale was pregnant, but back in her lab in New York, she showed us a fin whale foetus from another post mortem.
And you can see the front of the animal's head right here, if we open the mouth, and we can because it's so flexible, because the bone is still cartilage, it hasn't turned to bone yet, this is all cartilage in here.
We're bending open the mouth and we see this, this is the tongue.
And these ridges are where the baleen would develop, And the animal is folded quite compactly inside the womb like this, in a very compact, streamlined form, just like that, all folded together.
And when the mother delivers the baby they usually deliver them tail first, so that the animal doesn't take a breath until it's actually outside the mother.
After it's born they will swim to the surface and take its first breath through the nostrils, which are on the top of its head.
After taking a breath, some whales can stay under water for half an hour or more before returning to the surface again.
Their lungs have adapted to refresh 90% of their air with one exhalation.
Now we want to reach the lungs and heart in the remaining hours before the tide comes in.
How confident are you that we can get in to the chest cavity? I keep my spirits up, I think we can do it.
The heart and lungs are encased inside the whale's vast ribcage.
But because a local village wants to preserve the skeleton, Joy can't saw through the ribs as she originally planned.
So she has to dive under the ribcage to try to release the organs.
You can see here Joy's just pulling out, or some lung has prolapsed out from the chest, which is the light-coloured pinky tissue she's working on now.
She's trying to cut the rest of the diaphragm away cos we wanna be able to particularly look at the heart that's inside.
Hopefully in a few minutes we might actually find it.
This is the aorta, and this is the major blood vessel that's carrying blood from the heart down through the rest of the body.
Where have your legs gone? (CHUCKLES) Don't even ask! I'm so messy now it doesn't matter any more.
The heart is right in here where my hand is reaching, that's the heart.
I can feel it, but it's so large I can't pull it out until I can free the top, and I don't know if I'm gonna be able to get in there deep enough to do that.
But I'm still trying.
The heart is held in place by massive blood vessels that are just too deep inside for Joy to reach.
Right, I won't be able to get to the top of the heart, it's too far up to cut those.
The only way we're gonna get that is if we cut the ribs, so it's too much.
But I can tell you how big it is.
The heart is The bottom is here and the top of it is about here somewhere.
So it's about that wide, about that tall, and about from here to about here in width.
So we're talking about something that's about this big.
When the whale is under water, the gigantic heart pumps as slowly as three beats a minute.
The lungs can inhale 2,000 litres of fresh air in a single breath.
That's how whales can spend so much time at great depths.
No! Stand back.
Nice and slow.
Hold it there.
It's getting quite frantic now cos we're losing the light and they're trying desperately to be able to take the bones, the skeleton out of this to be able to save them.
And they've currently got the lower jaw, they've taken it off at the hinges back here where the other digger bucket is just about a foot the other side, and they're gonna pull the whole thing out forwards.
It's a huge, huge bone, it's this bit here under us.
But they're gonna lose the light.
They are gonna lose the light.
Right the way up.
While there's still light, Joy wants to examine the anatomy of this whale's senses to see how they work in deep water.
OK, this is the eye of the whale.
I'm gonna cut the lids.
This is the lower lid, cos the animal's lying on its back, and this is the upper lid.
So we're gonna cut through this, widen that passage, and then cut the eye out.
We have to cut it from its muscle connections, and then we'll see how interesting the whale eye is, cos it's adapted for seeing in water and dealing with high pressures of diving.
We're almost there.
It's about to come out.
Here we go.
Now it's hanging on just by the nerve in the back that transmits the image back to the brain.
We'll cut it right down the middle to show you the anatomy on the inside.
This is very thick and very hard to cut.
It's really solid with connective tissue, so if I try to really lean on it, I'm gonna lean on this and push on it, I've got all my weight pushing down on it right now, and all I'm doing is squeezing the blood out of that muscle, but I'm not able to deform that eye.
It stays in that shape.
It's a very, very sturdy construction.
The lens is really interesting.
OK, we're gonna put it on the I for Irish.
See how much bigger the I looks now, that letter I? Because the lens is actually magnified.
Tiny lens, isn't it? It's, yeah, it's actually, it's really not a lot bigger than what you see in a cow.
It's bigger, but not by a lot.
Even though whales' vision is very limited underwater, when they surface, being able to see has definite advantages .
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especially for killer whales hunting their prey.
But when whales dive into deep water they have to rely on other ways of "seeing" in the dark.
They use sound waves instead.
Listening for echoes bouncing back from sounds produced in their voice box, high frequency pulses can pinpoint the precise location of a fish, which is particularly useful for killer whales and dolphins.
But for fin whales, it's the low frequency sounds that are important.
They pass straight through small fish and travel much greater distances to reflect off shoals.
This allows them to detect a school of fish a mile away in only two seconds.
Joy has been working on the head and has managed to dig out the ears that hear these low frequency sounds.
So here we can see the ear attached into the skull.
It has this soft finger here which is called the glove finger.
It looks remarkably like my glove finger, doesn't it? It's even soft, you can push on it.
And this part here is probably the remnant of the ear drum.
The rest of this is bone, and inside here there's more to this ear, but it broke off and that's still in the skull, and inside here is the hearing apparatus.
Whales' ears also use echolocation to map out coastlines.
So did this one know where it was going when it came into shore? An animal will seek a shallow place to rest because it has no energy if it's sick, but when the tide goes out, gravity becomes a factor and now the weight of the animal crushes its internal organs.
It probably died from suffocation from its own weight crushing.
It probably was sick, which is why it came in on the sand bar.
Just as we're about to finish, one of the team makes a discovery.
OK, let's see what you got.
You got it, yes! CHEERING That's definitely it.
It's the vestigial hind leg.
The missing link to a life on land.
So this is an indication that these animals evolved from four-legged terrestrial animals, but they've made their hind legs so small that they're embedded into the body wall now.
They don't stick out as hind legs.
So what we see is just a little remnant of the thigh bone.
That leaves one last question Why did whales grow so much larger than their hippo cousins? I think it's something to do with being freed up from the constraints of gravity.
A land animal has an immense weight to carry about and big animals like elephants, for example, have great tree trunks of limbs.
Whales freed themselves up from that.
It's almost like going into space or becoming a balloon floating through the air.
They are no longer constrained by gravity, they're supported by the water.
It then becomes possible to become more or less indefinitely large.
It's been an incredible two days, battling the elements in Ireland, trying to learn as much as possible about this poor dead whale behind us.
In terms of why it died, we've got lots of clues.
We think it had an acute illness and for some reason ended up in this bay and got stranded, and it's one of the Achilles heels of whales that when they do end up stranded, they suffocate because they simply cannot breathe when their body's not supported by water.
The most incredible thing for me though is the fact that seeing a whale from the inside proves to you it's a mammal just like us.
It breathes air, it's got the same kind of body systems and organs, yet it's adapted to live right out there in the ocean rather than here on land.
An amazing thing.
That animal is more closely related to a mouse than it is to a fish.
Red Bee Media Ltd
It's huge now, cos it's blown up with gas.
It died two days ago, came in from the ocean, and we don't know why, and we don't know what killed it.
But you can see people are now making their way over there.
We have a window of opportunity of literally a few hours to be able to get out there and start the postmortem to try and unlock all those clues that are not only gonna tell us why that whale died but also help us understand the whales that are still living out there.
And let me tell you, the weather is absolutely abysmal! On the 15th January 2009, a fin whale swam into a bay off the south coast of Ireland in County Cork.
Fishermen from Courtmacsherry made valiant attempts to save it, but once the tide started to go out, this 65 foot whale was doomed.
EXCITED CHATTER (BOY) I've never seen a whale in my life.
Here was a unique chance to explore the anatomy of a whale and discover its evolutionary story.
Why did these mammals live in the sea, and how did they become so large? This adult female was far too big to be transported to the Royal Veterinary College, like the other animals in our Animal Autopsy series.
She weighs about 50 tons, as the local digger operators were about to find out.
The whale was decomposing fast with a growing risk of explosion.
The Irish authorities feared this could degenerate into a public health nightmare.
The vet in charge, Dan Crowley, accepted our offer of help to fly in the queen of whale anatomy from New York, Joy Reidenberg.
'In the camper van HQ, she quickly takes charge of the operation.
' As soon as the first cut is made here, that is gonna cause a lot of hissing.
We make one cut and everybody backs up.
If you make the cut too deep and it goes through the muscle layer and into the peritoneum, which is where the guts are, then you're gonna have an eruption like a volcano, all the guts are gonna come out of that hole, and you're gonna see spouting through that little hole.
In Denmark, they learnt this lesson the hard way.
Aargh! WAVES CRASH, WIND WHISTLES The tide's now dropped, and we have just four hours before nightfall.
WIND HOWLS This is obviously the head of the whale, it's on its side and slightly on its back.
You can see one eye just down here.
This is its upper jaw, this is the baleen plates, and these are made of keratin like your fingernails, and they're used for filtering out all the food this animal eats when it dives and feeds.
This is its tongue, believe it or not, which has blown up because of the gas inside, it's absolutely massive, and you can even see these tiny little papilli on it, it's just slightly rough to the touch.
It is extraordinary being this close, it's so sad it's dead, butextraordinary.
OK, you guyswe need everybody here to be on the other side of that water, because we're gonna cut this end and it's all gonna pop out.
Everybody move, please.
Get out of the way, you're gonna be caught in whale goo.
OK, here we go.
WIND WHISTLES GAS WHISTLES FROM WHALE That gas is all from fermentation from bacteria decomposing the organs inside.
Even though it's cold outside, we're all bundled up with a lot of layers, that whale's bundled up with its own layers of blubber.
I'm trying to let gas out from as many small ports as I can rather than one large one, cos if there's one large one, all the internal organs will get pushed out through that hole.
GAS CONTINUES TO WHISTLE So now the inflation has come down quite a bit, so the big explosion isn't gonna happen anymore.
We've taken away most of the pressure, that part's done.
OK, this is freed up? Under the skin lies not only the clues to this animal's death but also the secrets of how the biggest mammals on earth evolved.
Whales remain hidden from view, apart from tantalising glimpses when they come to the surface for air.
How they survive so long at such depths is one of the great wonders of the natural world.
And the story of their evolution defies belief, as Richard Dawkins explains.
All our ancestors came from the sea and obviously went to great trouble to leave the sea and become radically changed to live on land.
And then some of them - whales, sea lions, penguins, turtles - went back into the sea, which would seem to sort of undo a lot of hard research and development, so to speak, and need to reverse it.
They didn't quite reverse it, I mean they rediscovered many things.
The shape of a whale or a dolphin is pretty much like a big fish, but amazingly if you look inside, deep inside a whale, you will find vestiges, vestiges of hind limbs, little tiny remnants of bones which show that the ancestors had real hind limbs that they actually used for walking.
Later we hope to find this vestigial hind leg, but first we need to strip off the blubber.
OK, you and you, come on up.
I want you on this side, OK? You can use one of the long knives and start to cut this blubber.
Be real careful of its head.
If you need him to move, let him know.
The wind is gonna pull on that when you lift it up.
You can start with the hand knife here.
This line right here.
When you get to here, you're gonna switch to the other tool.
If the wind is too strong and it's pulling it, stop, cos it'll fly out of your hand and impale someone.
All right, I'm gonna go up there in the meantime.
No, not that, not that.
Oh, just a hook? Just a hook, have you got a hook? If the wind isn't too bad, I'm gonna get up and do the cut.
I just need to see how bad the wind is.
If I feel like I'm gonna get blown off, I'm not gonna do it.
Are you OK with that? Yeah, I think I'm all right.
I wanna get to that depression, where I can sit better.
OK.
Hang on, there you go.
OK! I need a knife.
Beautiful.
Got it.
Joy's got the most dodgy job at the moment.
She's trying to balance on a very slippery whale.
She's cutting through the blubber from back to front, all the way round, so we end up with one big sheet of blubber that hopefully we can peel off like a banana skin, andthat'll give us access here to the thorax with the heart and the lungs in it, and further back into the abdominal organs like the digestive system, the kidneys, the genitals and so on.
The smell is absolutely unbelievable! So, I'm cutting along this area here, of the whale's belly.
We're heading towards the genitalia, which are right down there.
As the team continues to unzip the blubber on the fin whale, more and more people catch wind of the activity on the beach, and venture across for a rare glimpse of this giant from the deep.
Local businesses are quick to take advantage of the new tourist attraction .
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while the authorities fight a losing battle holding back the inquisitive crowds.
You know all those pieces hanging off there? Is that plastic, or is it skin? Hang on a minute.
That, what does it feel like? Plastic.
Plastic.
Skin.
So, who thinks plastic? Who thinks skin? Skin.
Skin.
Plastic.
It's skin.
It's the same stuff that's on your hands.
The outer layer of your skin is growing all the time and every day, when you wash and when your clothes rub on your skin, it comes off.
That's why you get flakes.
You know when you get dandruff? That's flakes of skin.
Or when you get sunburn.
When your skin peels off, that's exactly the same.
That's the outer layers peeling off the whale.
Once upon a time, all mammals' skins were covered in fur to keep them warm.
But in deep water, fur is a poor insulator, so the whales' ancestors swapped it for blubber.
But the really big question is why they left the land in the first place.
It's just that animals are going to pick up opportunities wherever they arise.
If they discover an opportunity, like seals, to spend a bit of time in the water, otters spending time in the water, there is a living to be made.
They make it.
Once they have gone that far, then there's a living to be made going a bit further, there's a living to be made finally not coming back onto the land at all.
I'm going to make this last cut, it's going to spring down.
She's going to make the last cut and it is going to move down.
I'm holding on, hopefully I won't Are you all right? Drop the knife if you're going to fall! I need you to take the knife.
Are you OK? Yes.
I've got my nice hook, I'm all set.
Now, I can be Jonah in the mouth of the whale.
So, Joy, this here is all baleen, isn't it? The filtering system.
That is all baleen.
It's a sieve.
Like having a big moustache.
The whale is going to take all the food in, squeeze the water out, and the fish get trapped on the moustache.
Then it licks its moustache, like having a nice beer with a head on top, and you lick it off.
Does it regrow if it gets damaged? It does grow, just like your fingernails.
It keeps going.
If it has a damaged one it will grow it back out.
When baleen whales go in search of food, they prefer to shop in bulk.
They eat shoals of fish and krill that can be so densely populated, they stain the sea red.
To trap this much seafood in one go requires opening the mouth as wide as possible.
Unlike other mammals, the two halves of the baleen whale's lower jaw are not fused together.
Each side disarticulates, allowing its huge expandable throat to fill with water.
As it squeezes the water out, fish are trapped in the moustache-like baleen plates, ready to be licked away by the tongue.
Take a look up here.
This material here is the tongue.
This is it.
This stretchy stuff that you're looking at, here, is the floor of the mouth.
That is actually the tip of the tongue.
There we go.
That's all there is.
This is it.
That is the tongue? The tip of the tongue.
So most of this that was blown out of the front that I thought was the tongue, is actually just the floor of the mouth? And some of the tongue.
This was up there.
Now, it has all retracted because it is very elastic tissue.
Once the tension was off, it all pulled back this way.
It's very floppy.
There's not a lot of muscle there, but there is enough to cause it to curl, kind of like this.
When it makes that curl, as a baby, these little fringes, which are actually a little bigger on the babies, help, like fingers, to grab around the mother's teat, to form a tube so, when it's nursing, the water is channelled through that tube, so the milk is not lost to the ocean.
So far, have you found anything in terms of any possible reasons for death? Not yet.
I can't believe you are inside the mouth of a whale.
There you go.
I don't want to lose you inside yet.
The digger is just being manoeuvred into the right position so we can have the right angle of pull on this blubber.
Ideally, what we want to happen is, rather than try to pull it out at right angles to the body, they want to pull it longitudinally, like peeling back a banana-skin.
If the rope pulls through, the only alternative is to hand cut it off, which will take probably an hour and a half.
The tide will be on the turn and coming in any moment, so that would be a serious disaster.
This is going to be dramatic.
Go for it.
Here comes the rain, right on schedule.
Perfect.
OK.
With the blubber coat peeled off, we can finally investigate the internal anatomy, and we'll begin with the guts.
Their contents may yield vital clues about what led to this animal's death.
We're about two hours into the dissection at the moment and we're trying to work out how to get the small intestine out of the abdominal cavity to be able to drag it away, but the difficulty is, not only is it heavy, but, I mean, typical of intestine, it just wraps in amongst itself.
What's amazing is it's still so warm! You need one of these to get it out.
This could be very messy.
We need to get it away from here, because the tide will sling it all around.
We're organising to take that and all internal organs, right? Store them off up at the shore line.
OK, look how much we got done so far! It's not sunset yet.
Joy is on her own race against the tide.
For her, the holy grail of whale anatomy is understanding how whales talk to each other.
And there is a vital bone called the hyoid that she's determined to reach by diving down the whale's throat.
It looks just like a wishbone in a chicken, but pulling this wishbone out of a whale is a much greater challenge.
The hyoid bone is a free-floating bone in the neck.
It is not really attached to anything else in humans.
In whales, the hyoid bone IS attached to the skull, so this is going to be a hard bone to get out.
Can you pull it down now? This is the epiglottis, it's the beginning part of the larynx.
The larynx is the voice box itself - that's where the sounds are produced.
This bone is still attached to the larynx, so when it moves back and forth, it moves the larynx as well.
The songs of whales are so deep they are beyond the range of human hearing.
It was only during the Cold War, when the US Navy took microphones into the ocean to listen for Soviet submarines, that they inadvertently became the first humans to hear them.
WHALE SONG But what are they saying? They might say, "I found a really cool patch of krill, "come on over here, it's a food fest!" Or they might be saying, "Mum, where are you?" OR they might be saying, "I'm sexy, come mate with me.
" The puzzle for Joy is how a mammal's voice box modified to work under water.
She has her own theory, but she needs to dig out the larynx first.
As the sun sets and the weather turns bad again, the odds are not looking good.
Mother Nature is definitely taking hold of our dissection now - this is an incredible hailstorm, it really hurts on your face, and the team are trying to tidy up and move as many of the samples they've taken out of the carcass into safe ground, because obviously the tide's now coming in.
Poor old Joy, she's still battling away to try and get that hyoid bone and the larynx out and just where the digger bucket is now, they're just trying to excavate out the liver, because they've had enormous problems trying to get that out to get access to the diaphragm that separates the abdominal cavity and the thorax, or the chest, because if we can open that big curtain of muscle, we'll get to the heart, which is hopefully what we'll do tomorrow.
We've gotta be leaving soon because otherwise we won't get off this beach.
At last, Joy wins her tug-of-war with the monstrous wishbone.
But the hyoid snaps off the larynx.
One last shove and the larynx will be hers.
Easy way down! All right, that's it.
Despite driving rain and fading light, Joy cannot resist an impromptu tour of her favourite organ.
That's the voice box, called the larynx.
This is the front end.
That down here is the epiglottis, the front part of the larynx, it's a little bit shredded right here.
That's the opening in that air will take to get into the larynx.
These are the corniculate cartilages and they have these interesting flaps on them and it's not clear whether these animals pulse these flaps to make pulse sounds, so these might be part of the sound-producing apparatus.
If we follow the air through and go round to the back again, where it's coming out in the back right here, you'll notice that as you look through that hollow space, if you can see the light coming through where I'm putting my hand, it goes into a cleft and so as it goes through this gap .
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this sac is probably responsible for bringing those sounds out to the outside world.
So this sac can really balloon out and take a lot of volume in it.
It's this bag that pushes on those throat plates which are like an accordion, they can expand and contract, and that in turn would send a pulse into the water directly, and these animals are making low frequency sounds, so the bigger this is the lower the sound.
SLOP! I knew that was going to happen.
There it goes.
Tell you what, what a difference 12 hours makes in the weather though! Unbelievable.
It should be a very good day today I hope.
It'll be great to try and find the vestigial hind leg, which would be good.
It's female, there's even a possibility it might have been pregnant.
While we're waiting for the tide to go out the job we can do now is all the bits we harvested yesterday - the digestive tract, the intestine - we can have a detailed look at that.
A bit of tape round the top, please.
Lovely mess! Do you get used to this smell? Oh, yeah.
This doesn't smell as nearly as bad to me as simple things like changing a baby's diaper.
Before we can find clues about its last meal, we need to lay out the tangled mass of guts.
Somewhere underneath is the stomach - the beginning of the tract, so we need to flap some of this over to get down to the stomach.
The intestines are over 80 metres long - four times the length of the whale.
The food is coming in through the stomach, which is all the stuff on this side of me, and then it's gonna run through the small intestine which is this stuff that's moved back and forth all the way down.
And then as it comes around the corner down to the end, that is the large intestine, ending up at the anus.
And this is a meal from before the animal became stranded, and we see what's coming out on the other end of the animal, this is poop for a whale.
But it's pretty wet stuff, so it's a lot wetter than what you expect on a land animal.
A whale needs to have something it could excrete while it's still swimming.
Joy now wants to check what it ate just before it died.
This is stomach.
This is, this is a really large See if you can pull it.
We need a bit of help here.
Here you go, hold on.
Let's make another hole, here, this one right here, pull.
If we can pull it this way it might go better.
Perfect.
We're looking at the beginning of the stomach, one of the chambers of the stomach here.
If the animal had eaten, this is where we would first find food, but we're not seeing anything in here except fluid, so this indicates to me that the animal was probably sick cos it wasn't feeding.
This would be the next chamber, you wanna get a sample of that? Even though they are fish eaters, bizarrely, whales have a multi-chambered stomach, more suited to a cow.
Amazingly, whales actually belong in the group called even-toed ungulates - that's the cloven-hoofed animals.
One always knew that there was some connection between them, but what was astonishing was that molecular biologists showed, looking at DNA, that whales are actually closest to hippos.
Hippos are even closer to whales than hippos are to pigs or cows or any of the other cloven-hoofed animals.
Now, that's an astonishing thing.
65 million years ago, the sudden extinction of the dinosaurs opened the door for mammals to become the new giants of the planet.
One species that survived spawned the evolutionary pathways that led to over 200 modern plant-eating animals.
But one of them came across a new opportunity at the water's edge.
This was pakicetus, the first whale.
It had sharp teeth that allowed it to hunt, and then gradually its legs shrank.
Over 50 million years, it went from the size of a dog to the largest animal that ever lived.
It's interesting - you tend to think about the fact that with the whale, everything is perfectly adapted for its environment, but actually, it's got all kinds of handicaps associated with the fact that its ancestry was on land - it's still not perfect by any means.
If evolution were intelligent, we wouldn't have these handicaps.
It's not, it's a mish mash, it's a patchwork.
Every time you wanna make a better mouse trap you put another patch on.
You have to work with what you've got - there's evolutionary baggage.
Makes you think though, in the very long-term future, would you end up with this evolving into an animal that then moves more to having gills or being able to extract oxygen out of the water rather than having to breathe like a land mammal? You can't make those predictions cos evolution isn't directed.
You never know what the environment's gonna do because it has to respond to how the environment changes.
Maybe global warming will cause whales to evolve into something else.
When whales took to the water, their swimming style was set some 50 million years ago.
Their ancestors used to gallop over the countryside.
Now they live in the sea.
In a sense you could say they gallop through the sea, because the spinal movement of a whale as it swims through the sea is up and down, which is similar to what mammals do when galloping over the land.
Unlike fish, from which they're all descended, where the spinal movement is side to side.
At some point in the history of mammals, they must have switched from a side-to-side spinal movement to an up-down spinal movement.
And the whales, even when they went back to the water, retained the up-down spinal movement.
Galloping in the sea didn't just mean swapping legs for a tail.
Joy thinks the hyoid bone she extracted yesterday from the whale's throat may hold the key to how whales swim.
Just like a human swimmer might do a dolphin kick, a dolphin kick isn't just kicking your feet, you have a whole body wave that begins with your head and moves up and down.
So the initiation, the beginning of that swimming motion, must start with the head pulling down, and then up.
The only thing that can really pull a head down is the muscle attached to this bone.
Because the attachments that go from the chin to this bone in turn then go to the sternum, that's the beginning of the ribcage.
And when you contract all of those muscles in a row that means the hyoid, being caught in the middle between those muscles, is gonna be responsible for bringing the whole head down.
So if the animal keeps its jaw closed and then contracts those muscles, instead of opening the jaw it's going to depress the head, and that's the beginning of the body wave that these animals use to swim.
So that makes this bone a bone that's involved in swimming.
And that's unusual, because here's an animal that's locomoting with its throat! Joy's research is turning the science of how whales swim on its head.
By studying a bone crucial to communication, she unwittingly stumbled across an explanation of how they learned to swim.
The fin whale is the greyhound of the sea.
Its streamlined body crosses oceans to reach its feeding grounds.
But in the case of our whale, something went wrong when it came to feed off the coast of Ireland.
Now the tide has receded, we have just four more hours to try to solve the mystery.
The preliminary evidence suggests the whale was sick, but Joy wants to rule out another possibility That it was hit by a ship.
Boat strikes tend to be marks that go this way, so we're looking for a big area that looks like it's been hit this way.
This is a possibility right here.
Unless they did it with that scraper, I'll have to ask, cos this looks new.
This is an old injury that's healed up - you can see that the skin is absolutely smooth here, but you see colour differences, they don't match up, so this animal had a gash here, it could have been a shark bite, could have been maybe a boat propeller.
That's not the cause of this problem but it's an old injury.
Thank you! There's a scrape on the side in the blubber there that's in a vertical line, that we think might have been caused by the excavator Yeah, it was, yeah.
OK, that's good, cos that rules out one of the possible causes.
Yeah, because we were turning it over OK.
So that made that stripe? So that takes care of us figuring out what that line's from, thank you.
Having inspected the entire whale, Joy is now confident she can rule out a ship strike as the cause of death.
There are no other wounds you've seen on this side now? Just parasite wounds, small things.
As this whale is a mature female, Joy wants to check whether she's carrying a calf.
But somewhere in this big hunk of tissue, we think we're gonna be seeing the ovaries.
It would be an oval-shaped structure, probably about that big.
I was hoping it would be in here.
This just seems to be fat as far as I can tell.
We're gonna keep looking.
The anatomy of whale sex is extraordinary.
Males can have penises up to three metres long and, hidden under their blubber, their testicles can weigh a ton.
Joy could find no evidence that this whale was pregnant, but back in her lab in New York, she showed us a fin whale foetus from another post mortem.
And you can see the front of the animal's head right here, if we open the mouth, and we can because it's so flexible, because the bone is still cartilage, it hasn't turned to bone yet, this is all cartilage in here.
We're bending open the mouth and we see this, this is the tongue.
And these ridges are where the baleen would develop, And the animal is folded quite compactly inside the womb like this, in a very compact, streamlined form, just like that, all folded together.
And when the mother delivers the baby they usually deliver them tail first, so that the animal doesn't take a breath until it's actually outside the mother.
After it's born they will swim to the surface and take its first breath through the nostrils, which are on the top of its head.
After taking a breath, some whales can stay under water for half an hour or more before returning to the surface again.
Their lungs have adapted to refresh 90% of their air with one exhalation.
Now we want to reach the lungs and heart in the remaining hours before the tide comes in.
How confident are you that we can get in to the chest cavity? I keep my spirits up, I think we can do it.
The heart and lungs are encased inside the whale's vast ribcage.
But because a local village wants to preserve the skeleton, Joy can't saw through the ribs as she originally planned.
So she has to dive under the ribcage to try to release the organs.
You can see here Joy's just pulling out, or some lung has prolapsed out from the chest, which is the light-coloured pinky tissue she's working on now.
She's trying to cut the rest of the diaphragm away cos we wanna be able to particularly look at the heart that's inside.
Hopefully in a few minutes we might actually find it.
This is the aorta, and this is the major blood vessel that's carrying blood from the heart down through the rest of the body.
Where have your legs gone? (CHUCKLES) Don't even ask! I'm so messy now it doesn't matter any more.
The heart is right in here where my hand is reaching, that's the heart.
I can feel it, but it's so large I can't pull it out until I can free the top, and I don't know if I'm gonna be able to get in there deep enough to do that.
But I'm still trying.
The heart is held in place by massive blood vessels that are just too deep inside for Joy to reach.
Right, I won't be able to get to the top of the heart, it's too far up to cut those.
The only way we're gonna get that is if we cut the ribs, so it's too much.
But I can tell you how big it is.
The heart is The bottom is here and the top of it is about here somewhere.
So it's about that wide, about that tall, and about from here to about here in width.
So we're talking about something that's about this big.
When the whale is under water, the gigantic heart pumps as slowly as three beats a minute.
The lungs can inhale 2,000 litres of fresh air in a single breath.
That's how whales can spend so much time at great depths.
No! Stand back.
Nice and slow.
Hold it there.
It's getting quite frantic now cos we're losing the light and they're trying desperately to be able to take the bones, the skeleton out of this to be able to save them.
And they've currently got the lower jaw, they've taken it off at the hinges back here where the other digger bucket is just about a foot the other side, and they're gonna pull the whole thing out forwards.
It's a huge, huge bone, it's this bit here under us.
But they're gonna lose the light.
They are gonna lose the light.
Right the way up.
While there's still light, Joy wants to examine the anatomy of this whale's senses to see how they work in deep water.
OK, this is the eye of the whale.
I'm gonna cut the lids.
This is the lower lid, cos the animal's lying on its back, and this is the upper lid.
So we're gonna cut through this, widen that passage, and then cut the eye out.
We have to cut it from its muscle connections, and then we'll see how interesting the whale eye is, cos it's adapted for seeing in water and dealing with high pressures of diving.
We're almost there.
It's about to come out.
Here we go.
Now it's hanging on just by the nerve in the back that transmits the image back to the brain.
We'll cut it right down the middle to show you the anatomy on the inside.
This is very thick and very hard to cut.
It's really solid with connective tissue, so if I try to really lean on it, I'm gonna lean on this and push on it, I've got all my weight pushing down on it right now, and all I'm doing is squeezing the blood out of that muscle, but I'm not able to deform that eye.
It stays in that shape.
It's a very, very sturdy construction.
The lens is really interesting.
OK, we're gonna put it on the I for Irish.
See how much bigger the I looks now, that letter I? Because the lens is actually magnified.
Tiny lens, isn't it? It's, yeah, it's actually, it's really not a lot bigger than what you see in a cow.
It's bigger, but not by a lot.
Even though whales' vision is very limited underwater, when they surface, being able to see has definite advantages .
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especially for killer whales hunting their prey.
But when whales dive into deep water they have to rely on other ways of "seeing" in the dark.
They use sound waves instead.
Listening for echoes bouncing back from sounds produced in their voice box, high frequency pulses can pinpoint the precise location of a fish, which is particularly useful for killer whales and dolphins.
But for fin whales, it's the low frequency sounds that are important.
They pass straight through small fish and travel much greater distances to reflect off shoals.
This allows them to detect a school of fish a mile away in only two seconds.
Joy has been working on the head and has managed to dig out the ears that hear these low frequency sounds.
So here we can see the ear attached into the skull.
It has this soft finger here which is called the glove finger.
It looks remarkably like my glove finger, doesn't it? It's even soft, you can push on it.
And this part here is probably the remnant of the ear drum.
The rest of this is bone, and inside here there's more to this ear, but it broke off and that's still in the skull, and inside here is the hearing apparatus.
Whales' ears also use echolocation to map out coastlines.
So did this one know where it was going when it came into shore? An animal will seek a shallow place to rest because it has no energy if it's sick, but when the tide goes out, gravity becomes a factor and now the weight of the animal crushes its internal organs.
It probably died from suffocation from its own weight crushing.
It probably was sick, which is why it came in on the sand bar.
Just as we're about to finish, one of the team makes a discovery.
OK, let's see what you got.
You got it, yes! CHEERING That's definitely it.
It's the vestigial hind leg.
The missing link to a life on land.
So this is an indication that these animals evolved from four-legged terrestrial animals, but they've made their hind legs so small that they're embedded into the body wall now.
They don't stick out as hind legs.
So what we see is just a little remnant of the thigh bone.
That leaves one last question Why did whales grow so much larger than their hippo cousins? I think it's something to do with being freed up from the constraints of gravity.
A land animal has an immense weight to carry about and big animals like elephants, for example, have great tree trunks of limbs.
Whales freed themselves up from that.
It's almost like going into space or becoming a balloon floating through the air.
They are no longer constrained by gravity, they're supported by the water.
It then becomes possible to become more or less indefinitely large.
It's been an incredible two days, battling the elements in Ireland, trying to learn as much as possible about this poor dead whale behind us.
In terms of why it died, we've got lots of clues.
We think it had an acute illness and for some reason ended up in this bay and got stranded, and it's one of the Achilles heels of whales that when they do end up stranded, they suffocate because they simply cannot breathe when their body's not supported by water.
The most incredible thing for me though is the fact that seeing a whale from the inside proves to you it's a mammal just like us.
It breathes air, it's got the same kind of body systems and organs, yet it's adapted to live right out there in the ocean rather than here on land.
An amazing thing.
That animal is more closely related to a mouse than it is to a fish.
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