0:00:03 > 0:00:06My name's Steve Backshall.
0:00:06 > 0:00:09And this is Deadly Pole To Pole.
0:00:09 > 0:00:11Ohhh!
0:00:11 > 0:00:13From the top of the world to the bottom.
0:00:13 > 0:00:15Whoa!
0:00:15 > 0:00:17Deadly places...
0:00:17 > 0:00:18deadly adventures...
0:00:18 > 0:00:20and deadly animals.
0:00:21 > 0:00:24And you're coming with me, every step of the way!
0:00:26 > 0:00:27Arghhhh!
0:00:30 > 0:00:33My crew and I have been to some pretty extreme places
0:00:33 > 0:00:34on our travels.
0:00:37 > 0:00:39I think we've got a bit too many sharks!
0:00:41 > 0:00:42That is phenomenal!
0:00:43 > 0:00:48But there's one environment that's deadlier than all the rest.
0:00:48 > 0:00:51It is Extreme cold.
0:00:51 > 0:00:53I'm not talking about your average winter day,
0:00:53 > 0:00:58but full-on, bone chilling, lethal cold...
0:00:58 > 0:01:00with the power to shut down our bodies...
0:01:01 > 0:01:04I'm not putting this on, I swear.
0:01:04 > 0:01:07..and even stop our very cells from functioning.
0:01:09 > 0:01:12It has more killer potential than any predator.
0:01:13 > 0:01:15Argh, let me out.
0:01:18 > 0:01:21To find out more, I've come to the Extreme Environments Laboratory
0:01:21 > 0:01:23at the University of Portsmouth.
0:01:23 > 0:01:26Here, I'm going to be shut in a room that's colder than your freezer
0:01:26 > 0:01:30and put in chilly water until my body starts to shut down,
0:01:30 > 0:01:34which is just the most ridiculous way to spend a morning.
0:01:34 > 0:01:38Whether in the frozen north or the barren ice fields of Antarctica,
0:01:38 > 0:01:40life in the world's freezers
0:01:40 > 0:01:44has found some ingenious ways of fighting off the cold.
0:01:44 > 0:01:46I want to explore the challenges they face,
0:01:46 > 0:01:48to learn what it takes to stay alive.
0:01:56 > 0:01:59First up, it's time for a dip.
0:01:59 > 0:02:02Inside this tank is water that's been chilled
0:02:02 > 0:02:06to 12 degrees centigrade and that is very cold.
0:02:06 > 0:02:08If I was on an expedition
0:02:08 > 0:02:10and I fell into water like this it would instantly become
0:02:10 > 0:02:15a survival situation and to find out how and why, I'm going to be
0:02:15 > 0:02:16dumped in here until it brings me
0:02:16 > 0:02:18right down to hypothermic.
0:02:21 > 0:02:23While I get my trunks on, my crew prepare me
0:02:23 > 0:02:25a nice cold bath.
0:02:31 > 0:02:34I've never been, kind of surrounded by quite
0:02:34 > 0:02:38so many different machines that go ping.
0:02:38 > 0:02:40Which is all a little bit nerve-racking.
0:02:42 > 0:02:45Taking a plunge in chilly water can be risky business.
0:02:46 > 0:02:50It has to be done under strictly supervised conditions.
0:02:53 > 0:02:56This is something you definitely shouldn't try at home.
0:02:58 > 0:03:02Cold water can suck life-giving heat away from our bodies much quicker
0:03:02 > 0:03:04than air.
0:03:04 > 0:03:08Chuck in icebergs and crashing waves, and a quick swim
0:03:08 > 0:03:11soon becomes a deadly dip.
0:03:11 > 0:03:15But there's actually one group of mammals that spend their whole lives
0:03:15 > 0:03:19in these conditions. I want to see how I shape up to them.
0:03:19 > 0:03:23So there are a number of things here that are monitoring my progress.
0:03:23 > 0:03:26I've got these pads which are monitoring my heart activity.
0:03:26 > 0:03:29I'm also wearing an internal thermometer so you'll be able
0:03:29 > 0:03:32to actually see what my core temperature is.
0:03:32 > 0:03:35If that starts to drop then I'm in real trouble,
0:03:35 > 0:03:38even a drop of one or two degrees could be very dangerous.
0:03:39 > 0:03:44- OK.- Three, two, one. Here we go.
0:03:45 > 0:03:47Oooh.
0:03:47 > 0:03:49Oh, wow.
0:03:52 > 0:03:55It's colder than I was expecting actually.
0:03:57 > 0:04:01In a real immersion situation this would be the most dangerous bit,
0:04:01 > 0:04:06because your body is instantly, has a shock response to the water.
0:04:06 > 0:04:10So the first thing that you want to do is to breathe in
0:04:10 > 0:04:11very, very deeply.
0:04:12 > 0:04:15You can imagine if you were going into the sea,
0:04:15 > 0:04:19and there were waves and ripples, it would be very, very easy
0:04:19 > 0:04:23to swallow a lot of water in one go.
0:04:25 > 0:04:28And if that happened, that would probably be the end of you.
0:04:30 > 0:04:34Oh, oh, that's actually that is colder than
0:04:34 > 0:04:37I expected, I'm already getting brain freeze and I can feel
0:04:37 > 0:04:41my fingertips starting to go a little bit numb already.
0:04:41 > 0:04:44Less than a minute! That's not a good sign.
0:04:46 > 0:04:50My body's already starting to shake and shiver
0:04:50 > 0:04:53and generating a bit of extra warmth, just try and warm me up
0:04:53 > 0:04:54from the inside out.
0:04:56 > 0:04:59I really don't want to be in here for 40 minutes,
0:04:59 > 0:05:01it's just horrible already.
0:05:05 > 0:05:08Something that's happened straightaway is that all
0:05:08 > 0:05:14of my hairs on my arms and body have stood up, erect and they're trapping
0:05:14 > 0:05:18a layer of bubbles. Those bubbles
0:05:18 > 0:05:22contain air and they can be heated up by the temperature of the body
0:05:22 > 0:05:25to provide an extra layer of warmth.
0:05:25 > 0:05:27In a human being, because we're not very hairy it doesn't work
0:05:27 > 0:05:31very well, but in a lot of marine mammals, animals that spend
0:05:31 > 0:05:35a lot of time in the water, they have incredibly dense hairs.
0:05:35 > 0:05:40And the densest of all furs belongs to the silky sea otter.
0:05:41 > 0:05:44These bundles of fluff may look cute...
0:05:44 > 0:05:46but don't be fooled.
0:05:46 > 0:05:48Their pristine pelts are perfect
0:05:48 > 0:05:50at repelling the perils of chilly water.
0:05:52 > 0:05:55Essential if you want to hunt in icy seas.
0:06:00 > 0:06:02To find out why they need this hardcore insulation,
0:06:02 > 0:06:05I've headed to Alaska. Wow.
0:06:05 > 0:06:08There's a pretty good raft just over there.
0:06:08 > 0:06:10Oh my goodness that's unreal, wow.
0:06:10 > 0:06:13This is one of the best places on the planet to get up close
0:06:13 > 0:06:16with these mighty mustelids.
0:06:18 > 0:06:20They're just wonderful animals aren't they,
0:06:20 > 0:06:22like little floating bears.
0:06:22 > 0:06:25But there's only one way to really understand
0:06:25 > 0:06:27the struggles they face.
0:06:27 > 0:06:28I can't quite believe I'm saying this,
0:06:28 > 0:06:32but I'm going to need to get in and it looks really, really cold.
0:06:34 > 0:06:38The water is around a teeth-chattering 10 degrees C.
0:06:38 > 0:06:42That's even colder than the lab.
0:06:42 > 0:06:43Oh.
0:06:43 > 0:06:51Crumbs. It really quite takes the breath away. It's very, very cold.
0:06:51 > 0:06:55Of course the sea otter has such thick, dense fur,
0:06:55 > 0:06:59the densest fur of any animal that it can actually live in these
0:06:59 > 0:07:01waters with no problems whatsoever.
0:07:01 > 0:07:05Even with my wet suit though, this is a bit unpleasant.
0:07:05 > 0:07:07OK, I'm going to dive down, have a look.
0:07:13 > 0:07:16Within seconds I'm overcome by the cold.
0:07:17 > 0:07:21I can't believe they manage to live in this, day in day out,
0:07:21 > 0:07:24let alone scour the sea bed for tasty clams.
0:07:25 > 0:07:29It's an utterly alien world, and after just minutes,
0:07:29 > 0:07:30I'm ready to come out.
0:07:32 > 0:07:34Argh, my head.
0:07:34 > 0:07:38Oh, I've got the worst ice cream headache I've ever had.
0:07:38 > 0:07:42Phwoar, it's so cold. Oh.
0:07:42 > 0:07:48The sea otter, a hardy hunter, with a world-beating wet suit.
0:07:48 > 0:07:51Back in the lab, without the benefit of insulation,
0:07:51 > 0:07:56my core body temperature is starting to plummet.
0:07:56 > 0:07:58We're beginning to see this on our thermal imaging camera,
0:07:58 > 0:08:00which shows the heat of my body.
0:08:00 > 0:08:05Yellow and white areas are warm, while cold looks dark blue
0:08:05 > 0:08:09We human beings just are not built for this.
0:08:09 > 0:08:13Perhaps the reason that this is such a challenging environment is
0:08:13 > 0:08:17that water conducts heat away from the body more than 20 times
0:08:17 > 0:08:21more efficiently than air does, so you cool down
0:08:21 > 0:08:25faster than you would do in air, being in water like this.
0:08:25 > 0:08:29It becomes very uncomfortable, very quickly indeed.
0:08:29 > 0:08:33I've been in for seven minutes now and already I'm shivering
0:08:33 > 0:08:36quite a lot. The thermal imaging camera though shows that
0:08:36 > 0:08:40my head and face is still exactly the same as when I got in here
0:08:40 > 0:08:45but my hand, if I put that onto my face,
0:08:45 > 0:08:49you can see how that cooling works. Look at that.
0:08:49 > 0:08:54I look a bit like a clown it's kind of a bit strange.
0:08:54 > 0:08:57But you can see where the surface of the skin has cooled.
0:08:57 > 0:09:00In that case, not very much, so instead of being white or yellow,
0:09:00 > 0:09:02it's gone orange or red.
0:09:02 > 0:09:06But in my hand, completely black.
0:09:06 > 0:09:08Now this is one of the most important...
0:09:08 > 0:09:11I've just rubbed the end of my nose, it's gone blue!
0:09:11 > 0:09:13That is brilliant.
0:09:13 > 0:09:15That looks very, very strange indeed.
0:09:16 > 0:09:20We human beings, as mammals are, as you can see already,
0:09:20 > 0:09:24very, very poorly adapted to life in these kind of conditions.
0:09:24 > 0:09:26But we have some quite close relatives
0:09:26 > 0:09:29that under the skin are not too dissimilar to us,
0:09:29 > 0:09:32that deal incredibly well with temperatures like this.
0:09:32 > 0:09:35They have to deal with cold water every single day of their lives.
0:09:39 > 0:09:42And where better to find them than in the icy waters
0:09:42 > 0:09:43of the high arctic?
0:09:47 > 0:09:48Yes!
0:09:48 > 0:09:52There are splashes, waves,
0:09:52 > 0:09:55eruptions of white water,
0:09:55 > 0:09:58no more than about 30 metres off in front of us.
0:09:58 > 0:10:02Every once in the while, a white head breaks the surface.
0:10:05 > 0:10:07Every summer these waters are inundated
0:10:07 > 0:10:09with hundreds of curious creatures.
0:10:10 > 0:10:14Meet the beluga, the hardy white whale of the frozen north.
0:10:19 > 0:10:22There are very few marine mammals that could survive
0:10:22 > 0:10:24an entire lifetime in the Arctic Ocean.
0:10:24 > 0:10:27The way they manage this is through a thick layer of fat
0:10:27 > 0:10:29underneath their skin called blubber.
0:10:30 > 0:10:33This blubber allows the belugas to survive in waters
0:10:33 > 0:10:36that can drop to nearly minus two degrees C.
0:10:38 > 0:10:40It's a special kind of fat that can grow as much
0:10:40 > 0:10:43as ten-centimetres thick and make up half of their body weight.
0:10:45 > 0:10:47It's an incredibly efficient insulator,
0:10:47 > 0:10:50especially when the beluga is diving deep in arctic waters.
0:10:56 > 0:10:58Many marine mammals rely on blubber to keep them warm
0:10:58 > 0:11:00both topside and under the waves.
0:11:02 > 0:11:05Some of the blubberiest blubber is worn by the elephant seal
0:11:05 > 0:11:07of the southern ocean.
0:11:08 > 0:11:11Which can weigh more than a family car,
0:11:11 > 0:11:13keeping it warm in the worst weather.
0:11:17 > 0:11:20'Never mind a whole lifetime spent in winter water
0:11:20 > 0:11:23'my body's shutting down and I'm shaking like a leaf.'
0:11:24 > 0:11:26I'm not putting this on, I swear.
0:11:26 > 0:11:29This is really my shivering is going.
0:11:32 > 0:11:35Um, I don't feel as cold as I did before, though.
0:11:35 > 0:11:40But already, when I think about it,
0:11:40 > 0:11:43my brain's not working as well.
0:11:43 > 0:11:44Already now just...
0:11:44 > 0:11:48just speaking and trying to think about simple things is quite hard.
0:11:49 > 0:11:51'I may be losing my marbles
0:11:51 > 0:11:54'but things are about to get a whole lot worse.'
0:11:54 > 0:11:59At the moment there is still one part of my body that is warm -
0:11:59 > 0:12:03my face and my head because it hasn't gone under.
0:12:03 > 0:12:05Really, I suppose, I ought to go the whole hog.
0:12:05 > 0:12:08So let's just see what happens if I put my face in.
0:12:17 > 0:12:20OK, so now on the thermal imaging camera you can see already
0:12:20 > 0:12:23that my eye sockets are still very warm,
0:12:23 > 0:12:25I guess, because I had my eyes tight closed,
0:12:25 > 0:12:29but you can see all of the heat already leaching away
0:12:29 > 0:12:31from the skin on my face.
0:12:40 > 0:12:43The only way us humans really stand a chance of surviving cold water
0:12:43 > 0:12:46is to learn from the adaptations of marine mammals.
0:12:49 > 0:12:52Kitting ourselves up head-to-toe in hi tech insulation.
0:12:53 > 0:12:56But even then we can't match our aquatic cousins
0:12:56 > 0:13:00and are only able to stay in the coldest waters for mere minutes,
0:13:00 > 0:13:03before we have to come back to our own world.
0:13:08 > 0:13:11Without any of this protection, my time's nearly up.
0:13:14 > 0:13:18My body core temperature hasn't quite dropped by one degree C,
0:13:18 > 0:13:20but I think we're going to call it a day there
0:13:20 > 0:13:25and lift me out and see quite how extreme the effects have been.
0:13:25 > 0:13:27OK, Mike, take it away.
0:13:36 > 0:13:40You can see that...my...skin
0:13:40 > 0:13:44that was out in the air is still...yellow,
0:13:44 > 0:13:47which means it's not far off its normal temperature.
0:13:47 > 0:13:51But the rest of me is pretty much the same temperature as the water.
0:13:51 > 0:13:57So it's blue, my skin's dark blue, except under here in my armpits,
0:13:57 > 0:14:00where my skin's been clasped together and it's kind of
0:14:00 > 0:14:02insulated itself.
0:14:02 > 0:14:06But I'm just so glad to be out of there!
0:14:08 > 0:14:12'It's phenomenal how debilitating the cold can be for us humans.'
0:14:15 > 0:14:17Right, so if you could just hold that.
0:14:17 > 0:14:19No spinning, just twist that as fast as you can.
0:14:19 > 0:14:21'Unlike our marine mammal cousins,
0:14:21 > 0:14:26'even just a short dip can make the simplest tasks nearly impossible.
0:14:28 > 0:14:31'I can't feel a thing.'
0:14:33 > 0:14:37OK, fingers if you can, rather than twisting.
0:14:37 > 0:14:40'This is a real challenge.
0:14:49 > 0:14:54'Right, test done and it's time to warm up. I can't wait!'
0:14:58 > 0:15:00- Agh, argh!- Careful.
0:15:04 > 0:15:07Ahh, that's so nice!
0:15:10 > 0:15:14- Oh!- So you can bend your knees, keep your feet under, there you go.
0:15:14 > 0:15:15Ah!
0:15:15 > 0:15:18- It's good, isn't it? - It's just amazing!
0:15:21 > 0:15:26That's probably the best bath I've ever had.
0:15:26 > 0:15:28'But I'm not done yet.'
0:15:30 > 0:15:32BATH TOY SQUEAKS
0:15:36 > 0:15:39Marine mammals certainly seem to have the ice cracked,
0:15:39 > 0:15:42but they're not the only subzero survivors on the block.
0:15:43 > 0:15:46Life on the land is just as tough.
0:15:46 > 0:15:51At the poles, temperatures can plummet to minus 93 degrees C.
0:15:54 > 0:15:57With some of the worst weather on the planet,
0:15:57 > 0:16:01you have a supremely savage scenario.
0:16:01 > 0:16:05Animals that live here use awesome adaptations to stay alive.
0:16:08 > 0:16:11To learn more about how they live life in the freezer,
0:16:11 > 0:16:15there's only one thing for it - I'm going to have to get in one.
0:16:20 > 0:16:23Right, we're now in a sealed room
0:16:23 > 0:16:25at about minus 18 degrees centigrade, which is
0:16:25 > 0:16:28about the same as the inside of your freezer at home.
0:16:28 > 0:16:33It's also the kind of entry level for extreme Arctic temperatures.
0:16:34 > 0:16:36At this temperature,
0:16:36 > 0:16:39most Arctic animals wouldn't even start shivering.
0:16:40 > 0:16:43And, for me, in all these clothes, it's actually pretty bearable.
0:16:43 > 0:16:46I could manage to survive here for quite a while.
0:16:46 > 0:16:49The big game changer, though, is if you get wind,
0:16:49 > 0:16:51and we can recreate that with this fan.
0:16:51 > 0:16:53Johnny, do you want to switch it on?
0:16:53 > 0:16:55FAN BLASTS
0:16:55 > 0:16:58So, this is now getting going,
0:16:58 > 0:17:01and it's blowing wind at about 10mph.
0:17:01 > 0:17:07At 10mph, minus 17 or minus 18 degrees C
0:17:07 > 0:17:09feels like minus 30 degrees C.
0:17:12 > 0:17:14For us human beings, at minus 30,
0:17:14 > 0:17:18exposed flesh will start to freeze almost immediately,
0:17:18 > 0:17:20so we have to protect ourselves.
0:17:21 > 0:17:24And we do it with an external hard-shell jacket
0:17:24 > 0:17:26made of special man-made fibres.
0:17:29 > 0:17:31Animals do it in a totally different way
0:17:31 > 0:17:35by having very thick, dense, external guard hairs -
0:17:35 > 0:17:38animals like the musk oxen.
0:17:40 > 0:17:42Weighing over 300 kilos,
0:17:42 > 0:17:45these musk oxen are built like fluffy tanks,
0:17:45 > 0:17:49with huge shoulders, strong, muscular legs,
0:17:49 > 0:17:53and a thick coat that can protect them from the worst Arctic storms.
0:17:53 > 0:17:57It contains some of the longest hairs in the animal kingdom.
0:17:57 > 0:17:59They are true cold weather champions.
0:18:01 > 0:18:04In Somerset Island, I managed to get my hands
0:18:04 > 0:18:06on the secret of their success.
0:18:09 > 0:18:11So, as human beings, if we want to survive
0:18:11 > 0:18:14in an Arctic winter, then we need to use layers.
0:18:14 > 0:18:17On the bottom, we'll go for a nice, warm fleece, and on top of that,
0:18:17 > 0:18:20something like a Gore-Tex jacket, which cuts out the wind.
0:18:20 > 0:18:24The musk oxen has something which is far more efficient.
0:18:26 > 0:18:28This is one of their pelts.
0:18:28 > 0:18:34So, on the outside, you have these thick, dense hairs,
0:18:34 > 0:18:36which cut out the wind.
0:18:36 > 0:18:41Underneath it all, you have this wonderful, soft underfur.
0:18:41 > 0:18:45It's almost like cotton wool, and that'll trap air close to the skin.
0:18:45 > 0:18:48This is far more efficient than anything that modern technology's
0:18:48 > 0:18:51managed to come up with. In fact, if I was to try and keep this on
0:18:51 > 0:18:53for just a couple of minutes, I would overheat.
0:18:53 > 0:18:57This is the secret to surviving in extreme cold.
0:19:01 > 0:19:04To show how vital all of these layers are,
0:19:04 > 0:19:06we have a thermal imaging camera over here.
0:19:06 > 0:19:10Once I start to take all this stuff off, you'll see a real change.
0:19:10 > 0:19:14So let's get rid of my windproof layer.
0:19:16 > 0:19:19It's already getting quite icy, look. Look at that! Hmm.
0:19:20 > 0:19:23Oh, crunchy.
0:19:23 > 0:19:27OK. Now we're getting down to proper insulation layers.
0:19:27 > 0:19:30What I've got here is a down jacket.
0:19:30 > 0:19:35The inside of this is filled with feathers, with down, like this.
0:19:36 > 0:19:40So, even today, in our hi tech era,
0:19:40 > 0:19:46we still use proper, real goose or duck down feathers
0:19:46 > 0:19:47as insulation inside this.
0:19:47 > 0:19:50There is nothing that human beings have managed to create
0:19:50 > 0:19:54that can have the same insulating properties as these feathers.
0:19:57 > 0:20:00Ducks and geese may use these insulating waterproof feathers
0:20:00 > 0:20:04to soar high above frozen landscapes
0:20:04 > 0:20:07and dive deep in icy Arctic waters...
0:20:09 > 0:20:12..but this is Deadly, and we're on the prowl for predators.
0:20:15 > 0:20:19The elegant great grey owl is one of the most well-insulated birds
0:20:19 > 0:20:20on the planet.
0:20:22 > 0:20:26It uses a down jacket to help it hunt in frozen forests,
0:20:26 > 0:20:29watching and listening for voles under the snow.
0:20:31 > 0:20:34Its feathers also allow it to pounce in stealth mode,
0:20:34 > 0:20:37helping it fly quietly into the kill.
0:20:39 > 0:20:42Unfortunately, for the purpose of this experiment,
0:20:42 > 0:20:45I'm not allowed the luxury of thermal feathers.
0:20:45 > 0:20:48OK, so, now, I'm going to lose my main insulating layer
0:20:48 > 0:20:51and this is when the thermal imaging camera
0:20:51 > 0:20:54is really going to start to see the difference.
0:20:54 > 0:20:57Ohhh, look at that! Already, yeah, I can see
0:20:57 > 0:21:02bright, bright orange, and as my hat comes off, look at that -
0:21:02 > 0:21:04it's almost white, my head!
0:21:04 > 0:21:07But the temperature we're at at the moment, minus 18,
0:21:07 > 0:21:10I really don't want to be like this for very long.
0:21:10 > 0:21:14Now I'm down to the base layer. This is incredibly important.
0:21:14 > 0:21:18It doesn't have to be very thick, but it's very tight to the skin,
0:21:18 > 0:21:22and it's incredibly important to insulating a thin layer of air
0:21:22 > 0:21:24very, very close to the skin.
0:21:24 > 0:21:27You'll find this in all Arctic animals,
0:21:27 > 0:21:30especially things like bears and foxes.
0:21:30 > 0:21:33To live in a place where seasons look like this,
0:21:33 > 0:21:35you need decent thermals.
0:21:35 > 0:21:37And a polar bear has some of the best
0:21:37 > 0:21:39thermal pants on the planet.
0:21:39 > 0:21:43Just like the musk ox, it uses guard hairs to keep out
0:21:43 > 0:21:45wind and snow.
0:21:45 > 0:21:48But its insulating underfur is so good,
0:21:48 > 0:21:52it allows it to stay warm on land and at sea.
0:21:52 > 0:21:55But it doesn't just survive here, it thrives,
0:21:55 > 0:21:58using its thermals to help it hunt on the ice.
0:22:00 > 0:22:04Its neighbour, the Arctic fox, has even denser fur.
0:22:04 > 0:22:07It can withstand the harshest winter storms
0:22:07 > 0:22:09without the need for shelter,
0:22:09 > 0:22:10even sleeping out on the ice,
0:22:10 > 0:22:14using the thick thermal fur of its tail like a sleeping bag.
0:22:19 > 0:22:24OK, and last of all, right down to bare skin.
0:22:24 > 0:22:28Now, obviously, there are no land-living,
0:22:28 > 0:22:30Arctic mammals that would do this.
0:22:30 > 0:22:35You can see, for me... I mean, I am white hot. All that energy
0:22:35 > 0:22:39is just instantly being lost through my skin. Perhaps as much as
0:22:39 > 0:22:4290% of my body heat is just going to go instantly, straightaway,
0:22:42 > 0:22:44from my skin. And if the wind was blowing,
0:22:44 > 0:22:48I would be in very, very big trouble within a matter of minutes.
0:22:48 > 0:22:50And I have to say, already,
0:22:50 > 0:22:52I'm desperate to get my clothing back on.
0:22:52 > 0:22:56There is, however, one last thing that Arctic animals can do
0:22:56 > 0:22:57to make sure they're insulated,
0:22:57 > 0:23:00and that is eating like you would not believe.
0:23:01 > 0:23:03Our old friend, the Arctic fox,
0:23:03 > 0:23:06takes advantage of warmer months to lay down
0:23:06 > 0:23:09as much as half its body weight as fat
0:23:09 > 0:23:11in preparation for the cold.
0:23:11 > 0:23:14When the winter comes, it's not only got good insulation,
0:23:14 > 0:23:15but calories to burn,
0:23:15 > 0:23:19to fuel the fire to keep warm and stay alive.
0:23:19 > 0:23:20ARCTIC FOX BARKS
0:23:20 > 0:23:24Unfortunately, I'm nowhere near as good at piling on the pounds.
0:23:24 > 0:23:26It's time for me to leave.
0:23:26 > 0:23:28Argh, let me out!
0:23:35 > 0:23:38It's pretty obvious that when it comes to surviving extreme cold,
0:23:38 > 0:23:41us humans are rubbish compared to the birds and mammals
0:23:41 > 0:23:43of colder climes.
0:23:45 > 0:23:48Without the insulation of blubber and fat,
0:23:48 > 0:23:52or the protection of feathers and fur,
0:23:52 > 0:23:56we just don't stand a chance.
0:23:56 > 0:23:59But there's one last cold weather strategy
0:23:59 > 0:24:03that trumps all these tricks, and it has to be seen to be believed.
0:24:09 > 0:24:13This is a surprisingly wonderful find.
0:24:13 > 0:24:15It's a woolly bear caterpillar.
0:24:15 > 0:24:18This is one of nature's great survivors.
0:24:20 > 0:24:23These caterpillars live in the frozen north
0:24:23 > 0:24:26and have to make it through harsh Arctic winters.
0:24:26 > 0:24:30The way they do this is by completely
0:24:30 > 0:24:34shutting down their bodies and freezing themselves solid.
0:24:34 > 0:24:37But when the summer comes, these hungry caterpillars
0:24:37 > 0:24:40rise from the dead, and are able to munch on
0:24:40 > 0:24:41the freshest Arctic veg.
0:24:43 > 0:24:47A caterpillar that can become an ice pop may sound impressive,
0:24:47 > 0:24:48but it's a pretty simple animal.
0:24:48 > 0:24:52There's a far more complex critter that can pull off this trick,
0:24:52 > 0:24:55and it's my supreme ice-cold survivor.
0:25:00 > 0:25:02The wood frog lives in North America,
0:25:02 > 0:25:04where the winters are harsh.
0:25:04 > 0:25:08Its range may even stretch up into Alaska, further north
0:25:08 > 0:25:10than any other frog.
0:25:10 > 0:25:14Cold-blooded creatures struggle to survive in cold weather,
0:25:14 > 0:25:17so this frog takes extreme survival to another level.
0:25:20 > 0:25:23When the winter temperatures start to drop,
0:25:23 > 0:25:25the wood frog takes refuge underground.
0:25:28 > 0:25:33As it gets colder still, the icy frost penetrates the soil.
0:25:33 > 0:25:38Being cold-blooded, our freaky frog starts to freeze.
0:25:40 > 0:25:44All living things contain water in their cells.
0:25:44 > 0:25:45As this water freezes,
0:25:45 > 0:25:49it forms spiky ice which can rip these cells apart.
0:25:49 > 0:25:55But the frog uses clever chemistry to protect itself.
0:25:55 > 0:25:57It packs its cells with sugars,
0:25:57 > 0:26:01which force the ice to form in places where it can't do any harm.
0:26:09 > 0:26:13With no breathing, no movement, and even no heartbeat,
0:26:13 > 0:26:15the frog should be dead.
0:26:16 > 0:26:19But the sugars stored in its body provide just enough
0:26:19 > 0:26:23energy to keep the cells alive through the deepest parts of winter.
0:26:26 > 0:26:28Frozen in time,
0:26:28 > 0:26:31this incredible frog can survive for weeks on end.
0:26:31 > 0:26:35But even with all its vital functions on hold,
0:26:35 > 0:26:38it hasn't croaked it - there's life in the old frog yet.
0:26:41 > 0:26:45When spring arrives and the temperatures start to rise,
0:26:45 > 0:26:47the frog's body begins to thaw.
0:26:47 > 0:26:52The defrosted heart muscles kick-start it back into action
0:26:52 > 0:26:54and blood starts pumping around the body.
0:26:54 > 0:26:58The once-frozen frog is almost completely back to normal
0:26:58 > 0:27:00within just 24 hours.
0:27:00 > 0:27:06And it hops to it, taking advantage of being the only frog in town,
0:27:06 > 0:27:09free to gobble up insects ahead of the competition.
0:27:10 > 0:27:16This Frankenstein frog has to be the ultimate subzero survivor.
0:27:16 > 0:27:19Instead of fighting off the cold with blubber and fur,
0:27:19 > 0:27:23it embraces it, almost making itself dead in the process.
0:27:25 > 0:27:29Any environment that forces an animal to go to lengths like that
0:27:29 > 0:27:31has got to be deadly.
0:27:38 > 0:27:41Join me next time for more Deadly Pole to Pole.