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Whatever your feelings about snakes,

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you can't deny that they have an extraordinary beauty.

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Their lack of limbs compels them to deal with life's problems in ways that are utterly different from ours.

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But nonetheless, the techniques they've developed

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are spectacularly successful.

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Snakes have one of the simplest of body shapes,

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essentially just a long, thin tube,

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but they have some remarkably effective ways of getting around.

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They can climb a tree simply by embracing its trunk.

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Some can flatten their bodies

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so that they catch the air beneath them and glide.

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By hitching up their undersides,

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they can inch themselves forward in a straight line.

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A sinuous wriggle enables them to skate across loose sand.

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And the same action works equally well in water.

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There, some swim close to the surface.

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Others explore the depths and can stay underwater for hours on end.

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One, believe it or not, can jump.

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So, leglessness hardly seems such a handicap,

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but how did snakes get that way?

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Well, their remote ancestors 100 million years ago,

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at the time of the dinosaurs, did have legs,

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rather like today's lizards.

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Doubtless they were very effective runners,

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but some also started to burrow in search of prey.

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Below ground, legs are a hindrance,

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and over generations, they became smaller.

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Today, burrowing lizards such as skinks

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seem to be going through the same process.

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Many have tiny but recognisable legs.

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In others, the limbs have become nothing more than functionless flaps.

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In this burrowing lizard, the process has gone even further.

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The animal still has the face of a lizard...

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but its legs have disappeared totally.

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It seems that the ancestral snakes went through just such a process

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way back in geological history, some 95 million years ago.

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So, what did these very first snakes look like?

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Well, the answer can be found in Asian jungles,

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in American woodlands and gardens,

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and even in flowerpots like this.

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It may look like an earthworm, but actually it's a flowerpot snake,

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and it's completely blind.

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It doesn't need to see because it spends all its life underground.

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I'll put it back in its flowerpot,

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put a flower on top and it will live perfectly happily there

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in this flowerpot, all by itself, providing it has enough food.

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And there's a surprising amount for a small snake to eat underground.

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Ant larvae, for example.

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These early legless reptiles

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flourished and remained underground for a long time.

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Then, around 50 million years ago, some of them returned to the surface.

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Why? Well, by this time the dinosaurs had disappeared

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and the early mammals had arrived.

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They were more nutritious than beetles and worms,

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so the snakes began to catch them instead,

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and became so good at doing so that today,

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they are among the most skilful hunters on earth.

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Here in North America, there's a snake

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that combines its great speed and extraordinary senses

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in a remarkable hunting strategy

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we are only just beginning to understand.

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A timber rattlesnake.

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The morning sun has warmed its body,

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giving it energy, and it starts to move.

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It's searching for a place where it can conceal itself,

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and wait for prey to come within striking distance.

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A little chipmunk. It's in no danger yet.

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The rattlesnake can't move fast enough to chase and catch it.

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But small mammals tend to use the same paths

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as they run over the forest floor,

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and they leave behind a faint trail of scent.

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The rattlesnake can detect that scent with its tongue.

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It can also locate the warm-blooded chipmunk if it's nearby,

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with heat detectors in a pair of pits beneath its eyes.

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As it moves, it carefully holds its rattle above the ground

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so it makes no noise.

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It's chosen the place to wait at the bottom of this tree stump.

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Its colouration matches the ground so closely

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it needs no further concealment.

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Now, it's just a matter of time.

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Seeing a rattlesnake actually catching its prey

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is a very, very difficult thing to observe.

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In fact, some scientists have watched rattlesnakes for years

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without seeing that particular crucial moment.

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But we have a chance, partly because rattlesnakes are ambush hunters

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so we know exactly where to put up our gear,

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and partly because in that gear,

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we've got the very latest in surveillance equipment.

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There are remotely controlled cameras,

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and infra-red lights on stands.

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And there are motion detectors

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that will switch on the cameras if anything moves.

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So I needn't wait alongside.

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If anything happens, the cameras will switch on automatically.

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Later, I check the replay.

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There's a mouse,

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just along that log.

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That obviously came to nothing,

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but the cameras have started recording again

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and the snake is moving.

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He's checking out the trail with his tongue.

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See, that's exactly where that mouse was running.

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It's pitch dark and the mouse clearly has no idea that the snake is there.

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But the snake is well aware of the mouse,

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thanks, no doubt, to those heat-detecting pits.

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The snake strikes by suddenly straightening the curve in its neck,

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but at the moment, the mouse is not within range.

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He's worked out that that is the path

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along which the mice run.

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And he's getting himself properly adjusted

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so he can strike when he next gets a chance.

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Now once again, waiting.

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That's what snakes are so good at.

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Oh, my goodness!

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That's a dead mouse, all right.

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Slow down that shot,

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and you can see that the snake stabs the mouse just once.

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After three convulsive kicks, the mouse is dead.

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Snake is moving again.

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He's going back now

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to look for the one that he knows is dead back there.

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Where is it?

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Ah, now it looks as though he's really got it.

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That's his dinner,

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and that can last him

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for...three weeks,

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four weeks if necessary.

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Rattlesnakes are among the least obtrusive inhabitants

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of the forests of North America,

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and they're probably far more numerous than many people realise.

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Like many other animals, snakes use their nostrils to detect smells,

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but the most sensitive and accurate information

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about the world around them

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comes from that constantly flickering tongue.

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With this, a snake gathers molecules from the air

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and carries them back for evaluation

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to a pair of extremely sensitive organs in the roof of its mouth.

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To see just how important scent can be to a snake,

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I've come here to Carnac Island, just off the coast of Western Australia.

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It's home to a large population of highly venomous tiger snakes.

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Snakes have been established here for many years,

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but there's something odd about this particular population.

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Many of them have damaged heads, and some of them are actually blind,

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like this one.

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And yet, puzzlingly, in spite of the fact that they're blind,

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they all appear to be very well fed.

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So how do their heads get damaged,

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and how, in that condition when they can't see anything,

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can they catch all the prey they need?

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The snakes, of course, are not the only inhabitants of the island.

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It's also home for a large colony of silver gulls.

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The gulls breed throughout the year,

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so their chicks are a source of food for the snakes that never ends.

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In fact, the snakes eat pretty well nothing else.

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But the snakes don't get it all their own way.

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The gulls are valiant defenders of their nests and their chicks.

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Their stabbing beaks are powerful,

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sharp and strong, and the gulls always go for the snake's head.

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One in ten of the snakes are totally blinded.

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Tiger snakes don't have those heat-sensitive pits

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that rattlesnakes have,

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so these blinded hunters are guided entirely by their forked tongue.

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It's a superb direction-finding device.

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The snake can measure the strength of the smell separately

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on each of the two forks of its tongue.

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And if it wishes to follow up a smell, then it simply detects the one

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which has the stronger smell, and goes in that direction.

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Gull chicks are an ideal prey for a blinded snake,

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because they are programmed to stay on their nests.

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Once a snake has located it, a chick is doomed.

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Snakes, it must be admitted, have had a bad reputation

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ever since one appeared in the Garden of Eden.

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But in reality, even the most aggressive venomous snake

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will avoid biting a human being if it can.

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Why waste venom and risk a violent retribution

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by biting something you're not going to eat?

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To prevent misunderstanding,

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most venomous snakes warn other animals, including human beings,

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to keep out of their way.

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RATTLING

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Some snakes do that with sound.

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HISS!

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Others, such as cobras, give a visual signal,

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by expanding the skin around their heads to form a conspicuous hood.

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The threat of a bite

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is far better defence for a snake than the bite itself.

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However, there are some snakes

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that not only use their venom to kill their prey,

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but have also found a way of using it

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to deter their enemies without even biting them.

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This Mozambique cobra has a very special way of doing that.

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To demonstrate this with some degree of safety,

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I'm going to wear this visor which has been coated with a substance

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that turns pink in contact with venom.

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See what happens.

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It's watching me, waiting to see if I get too close for its liking.

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Venom spurts from its fangs.

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As it spits, it turns its head from side to side

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so that the jets have the best chance of hitting my eyes.

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Well, I was well and truly sprayed.

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Every one of those pink dots is a bead of venom,

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and if any one of them had gone in my eye,

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I would be now blind and in extreme pain.

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So it's a fair warning from that snake to me not to get any closer,

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and I daresay if I did

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I would deserve what I would get, which would be a bite.

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I have no intention of doing that.

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On the other hand, some snakes which may appear to be venomous

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are in reality quite harmless.

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These two snakes look very, very similar, and they both occur here

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in the southern United States,

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so you are quite likely to meet one or the other here.

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One of them, however, is harmless. It's called a king snake.

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The other one is a coral snake and highly venomous.

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One bite, certain death.

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The question is, which is which?

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Well, the key lies in the order of the colour rings.

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People here have a local saying - "Red and black, venom lack.

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"Red and yellow can kill a fellow."

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This one has red and black,

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so I guess that's a king snake.

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We'll see.

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So far, so good.

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Yeah, this is a king snake.

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And what a beautiful snake it is.

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A really lovely reptile.

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The king snake pretends to be venomous when it's not,

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and there's another snake that pretends to be dead when it isn't.

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Snakes, being cold-blooded, seem to relish the warmth of sun-baked roads

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and often bask on them, and as a result, of course, many get run over.

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But things aren't always exactly what they seem.

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He looks fairly dead.

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But in fact, this hog-nosed snake is perfectly all right.

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He was just feigning death

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so that things that might have been

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interested in a living snake

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are not, and what's more,

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he's produced rather a remarkable smell.

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In fact the smell, as it were,

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of rotting flesh.

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Maybe he was pretending, too, that he was not only dead but decomposing.

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Very convincing. Off you go.

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The lack of limbs that might seem to us to be such a huge handicap

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has not stopped snakes from getting around in all kinds of ways,

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and neither does it prevent them from tackling all kinds of meals.

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This South African snake

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has become a specialist in swallowing a particularly awkward mouthful.

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It's as accomplished a tree-climber as you'll find among snakes.

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The trees it frequents

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also hold colonies of masked weaver birds,

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that suspend their nests from the very tip of the branches.

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But the snake is a skilled enough climber to reach them.

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The weaver birds know it well and recognise it as a threat.

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BIRDS TWITTER

255
00:23:05,240 --> 00:23:07,360
It's well accustomed to these attacks.

256
00:23:28,920 --> 00:23:35,480
These defenders, however, are just too determined, and it retreats.

257
00:23:38,920 --> 00:23:42,120
But it doesn't give up altogether.

258
00:23:56,600 --> 00:24:00,720
This nest is unguarded.

259
00:24:04,000 --> 00:24:08,360
And this is what the snake is after, the eggs.

260
00:24:08,360 --> 00:24:11,840
Each is several times bigger than the snake's head

261
00:24:11,840 --> 00:24:16,280
but its jaws are linked by ligaments that are amazingly elastic.

262
00:24:22,160 --> 00:24:25,280
Once the egg is engulfed by the snake's jaws,

263
00:24:25,280 --> 00:24:28,720
powerful throat muscles push it down its gullet.

264
00:24:35,160 --> 00:24:40,080
Moving X-rays enable us to see exactly what's happening.

265
00:24:43,280 --> 00:24:46,320
Soon, the egg reaches a part of the backbone

266
00:24:46,320 --> 00:24:49,280
that has downward-pointing spines on it.

267
00:24:51,200 --> 00:24:55,760
The snake arches its backbone and then squeezes.

268
00:24:59,000 --> 00:25:04,080
The shell cracks and the spines on the backbone slit the membrane.

269
00:25:08,120 --> 00:25:09,640
The shell is crushed

270
00:25:09,640 --> 00:25:13,600
and rich, nutritious yolk flows into the snake's gut.

271
00:25:27,000 --> 00:25:31,400
Then, what's left of the shell is regurgitated.

272
00:25:33,800 --> 00:25:36,920
But that, of course, was a small meal.

273
00:25:36,920 --> 00:25:40,360
Some snakes can tackle much bigger meals than that.

274
00:25:42,800 --> 00:25:47,240
An African rock python - one of the biggest of all snakes,

275
00:25:47,240 --> 00:25:50,880
that can grow over seven metres, 20 feet long.

276
00:25:50,880 --> 00:25:54,280
And it is eating an antelope.

277
00:25:54,280 --> 00:25:58,800
It too has an elastic ligament connecting its jaws.

278
00:26:01,560 --> 00:26:04,320
It killed the antelope not with venom,

279
00:26:04,320 --> 00:26:08,600
but by squeezing it so tightly that it was unable to breathe.

280
00:26:12,440 --> 00:26:15,880
A python's teeth can't cut or rip.

281
00:26:15,880 --> 00:26:19,480
It has to swallow its prey whole, or not at all.

282
00:26:19,480 --> 00:26:23,320
And that may take a day or more.

283
00:26:23,320 --> 00:26:28,000
Without limbs, the python can't push the antelope down its throat.

284
00:26:28,000 --> 00:26:33,040
Instead, it hitches its jaws diagonally back and forth

285
00:26:33,040 --> 00:26:37,040
so that they, as it were, walk over the prey.

286
00:26:37,040 --> 00:26:41,600
Its tube-like body has to stretch so extremely

287
00:26:41,600 --> 00:26:44,040
to accommodate such a gigantic meal

288
00:26:44,040 --> 00:26:48,320
that its flanks have torn, but such injuries heal very quickly.

289
00:26:53,240 --> 00:26:57,760
The last of the antelope, its hooves, are about to disappear.

290
00:27:06,760 --> 00:27:08,000
Gone.

291
00:27:13,840 --> 00:27:16,520
The python will now hide itself away

292
00:27:16,520 --> 00:27:19,720
and begin the long process of digestion.

293
00:27:19,720 --> 00:27:25,720
Everything will be dissolved - skin, hair, hooves, even horns.

294
00:27:33,240 --> 00:27:38,160
This python will not need to eat again for a year or more.

295
00:27:43,840 --> 00:27:46,680
Wherever it's warm and there are animals of some kind,

296
00:27:46,680 --> 00:27:48,520
there will be snakes to hunt them,

297
00:27:48,520 --> 00:27:51,120
no matter how difficult the conditions

298
00:27:51,120 --> 00:27:52,880
and how awkward the mouthful.

299
00:27:55,120 --> 00:27:58,760
Crabs are in plentiful supply in this mangrove swamp.

300
00:27:58,760 --> 00:28:02,440
There must be 50 on any one of these trees around me.

301
00:28:02,440 --> 00:28:06,360
They're all up there waiting for the tide to go out

302
00:28:06,360 --> 00:28:08,160
so that they can feed in the mud below.

303
00:28:08,160 --> 00:28:14,160
So, there is a meal for a snake here, but crabs are not easy to tackle.

304
00:28:14,160 --> 00:28:19,120
They're strong, armour-plated and covered in spines.

305
00:28:19,120 --> 00:28:21,360
For a snake to tackle one of these

306
00:28:21,360 --> 00:28:26,280
would be like me trying to eat a lobster twice the size of my head

307
00:28:26,280 --> 00:28:29,120
with my hands tied behind my back.

308
00:28:29,120 --> 00:28:32,160
But there is a snake that knows how to do so.

309
00:28:33,680 --> 00:28:37,040
The crabs cling to the arching struts of the mangroves

310
00:28:37,040 --> 00:28:39,680
to keep out of the way of predatory fish,

311
00:28:39,680 --> 00:28:43,240
but as the tide retreats, it becomes safe for them to climb down

312
00:28:43,240 --> 00:28:46,320
and start looking for such edible bits

313
00:28:46,320 --> 00:28:48,840
as the tide has left behind on the mud.

314
00:28:56,640 --> 00:29:01,360
For the moment they're safe, but soon the sun will set.

315
00:29:01,360 --> 00:29:04,840
Then the snakes will come out of their burrows.

316
00:29:04,840 --> 00:29:06,560
They hunt in the darkness,

317
00:29:06,560 --> 00:29:10,600
but we'll be able to follow them with our infra-red cameras.

318
00:29:19,200 --> 00:29:21,400
It's now very dark indeed

319
00:29:21,400 --> 00:29:27,360
and the snake has to find its way around entirely by touch and smell.

320
00:29:36,840 --> 00:29:38,960
Finding crabs is not difficult.

321
00:29:38,960 --> 00:29:41,640
They swarm all over the mud

322
00:29:41,640 --> 00:29:44,600
and the snake is almost bound to encounter one

323
00:29:44,600 --> 00:29:46,240
sooner rather than later.

324
00:29:54,360 --> 00:29:56,280
The snake is armed with venom,

325
00:29:56,280 --> 00:30:00,960
and has short, strong fangs which can pierce a crab's shell and stun it.

326
00:30:00,960 --> 00:30:03,360
But that's only half the problem.

327
00:30:03,360 --> 00:30:06,000
It's what it does after it's caught its crab

328
00:30:06,000 --> 00:30:08,920
that sets it apart from all other snakes.

329
00:30:34,720 --> 00:30:36,840
It has it.

330
00:30:36,840 --> 00:30:38,880
Now what?

331
00:30:38,880 --> 00:30:43,240
The crab is so large that the snake can't swallow it whole.

332
00:30:43,240 --> 00:30:47,600
Slowly and deliberately, the snake dismembers the crab.

333
00:30:51,760 --> 00:30:55,320
Each leg contains nutritious muscle.

334
00:31:03,960 --> 00:31:08,720
But the crab's armoured body is simply discarded.

335
00:31:08,720 --> 00:31:10,240
Too difficult.

336
00:31:13,280 --> 00:31:18,080
There are hard-shelled creatures in fresh waters, as well as in salt.

337
00:31:18,080 --> 00:31:19,600
Not nearly as many,

338
00:31:19,600 --> 00:31:23,280
but sufficient number for some snakes to specialise in eating them.

339
00:31:25,440 --> 00:31:30,440
And in the eastern United States, many rivers contain crayfish.

340
00:31:34,560 --> 00:31:38,240
Like crabs, they have a hard protective shell,

341
00:31:38,240 --> 00:31:41,760
and they have particularly powerful pincers as well.

342
00:31:48,480 --> 00:31:54,840
The queen snake, however, eats crayfish and nothing else.

343
00:32:13,640 --> 00:32:16,240
But not just any crayfish.

344
00:32:20,640 --> 00:32:24,440
It's very selective.

345
00:32:24,440 --> 00:32:28,480
Crayfish, as they grow, shed their armour.

346
00:32:31,840 --> 00:32:36,440
Every three to four weeks, a split appears across the back of its shell.

347
00:32:39,520 --> 00:32:41,400
The old shell hinges away

348
00:32:41,400 --> 00:32:46,680
and the crayfish hauls itself out and expands its body, which is soft.

349
00:32:48,480 --> 00:32:51,840
It's now that the snake has its chance.

350
00:33:02,800 --> 00:33:06,080
A newly moulted crayfish looks much the same,

351
00:33:06,080 --> 00:33:08,240
but it gives off different chemicals

352
00:33:08,240 --> 00:33:12,120
that the snake can detect in the water with its tongue,

353
00:33:12,120 --> 00:33:14,960
and from some distance away.

354
00:33:31,680 --> 00:33:37,160
It can swallow this crayfish because, since it's newly moulted,

355
00:33:37,160 --> 00:33:39,680
it's as soft as a boiled egg.

356
00:34:03,400 --> 00:34:08,320
On occasion, snakes have to grapple not only with their prey

357
00:34:08,320 --> 00:34:12,480
but with one another, in disputes over mates and territory.

358
00:34:14,920 --> 00:34:17,960
This is one of the most formidable, the king cobra.

359
00:34:17,960 --> 00:34:23,280
Highly venomous and about four metres, 14 feet long.

360
00:34:24,360 --> 00:34:28,040
Disputes between rival male king cobras

361
00:34:28,040 --> 00:34:33,320
are potentially very dangerous indeed, for this species specialises

362
00:34:33,320 --> 00:34:35,360
in eating other kinds of snakes.

363
00:34:37,400 --> 00:34:40,720
So they observe strict rules in their fights,

364
00:34:40,720 --> 00:34:44,040
which prohibit the use of their lethal bite.

365
00:34:47,640 --> 00:34:53,320
Slowed down, it's a performance full of grace, as each contestant strives

366
00:34:53,320 --> 00:34:57,320
not to kill his opponent but simply to slam him to the ground.

367
00:35:54,880 --> 00:35:59,840
The defeated male leaves the arena and no harm has been done.

368
00:36:07,720 --> 00:36:09,520
Snakes must also find a way

369
00:36:09,520 --> 00:36:13,120
of preventing their courtship from becoming lethal.

370
00:36:13,120 --> 00:36:17,840
This is a Californian king snake, a male.

371
00:36:21,400 --> 00:36:24,720
He has detected the scent of a female ready to mate.

372
00:36:28,880 --> 00:36:32,360
Like all snakes, his eyesight is not good

373
00:36:32,360 --> 00:36:37,360
but he can tell from the taste of the air that she's close by.

374
00:36:41,480 --> 00:36:45,520
In fact, she is within inches.

375
00:37:08,680 --> 00:37:14,120
For some time, the two follow one another, nose to tail.

376
00:37:19,240 --> 00:37:21,840
The male begins to caress her,

377
00:37:21,840 --> 00:37:26,720
sensually jerking and rocking his body as he holds her close.

378
00:37:31,120 --> 00:37:33,720
He has a pair of sexual organs,

379
00:37:33,720 --> 00:37:38,160
one of which can project to the left and the other to the right.

380
00:37:38,160 --> 00:37:42,960
So, no matter which side of him she happens to lie, he can reach her.

381
00:37:45,600 --> 00:37:48,480
At last, union is achieved.

382
00:38:06,680 --> 00:38:09,880
They may remain together for several hours.

383
00:38:26,920 --> 00:38:31,400
In a few weeks' time, the female will lay a clutch of eggs.

384
00:38:31,400 --> 00:38:34,120
It may take six or seven weeks for them to hatch,

385
00:38:34,120 --> 00:38:37,240
but the regions where most snakes live are warm enough

386
00:38:37,240 --> 00:38:40,280
for them to develop without any help from the parents.

387
00:38:43,920 --> 00:38:48,760
Cobras lay them on the ground in the leaf litter.

388
00:38:55,920 --> 00:39:02,360
Their soft, parchment-like shell is easily split when pushed from within.

389
00:39:09,960 --> 00:39:14,200
The front end of a cobra hatchling is quite capable of giving a bite,

390
00:39:14,200 --> 00:39:17,760
even while the back end is still within the shell.

391
00:39:33,640 --> 00:39:35,600
Their fangs may be small,

392
00:39:35,600 --> 00:39:40,880
but since it only takes a tiny drop of cobra venom to kill an animal,

393
00:39:40,880 --> 00:39:44,600
these youngsters can be as lethal as their parents.

394
00:40:08,920 --> 00:40:13,640
They already have that characteristic warning signal, the hood.

395
00:40:16,200 --> 00:40:19,800
Not all snakes lay their eggs.

396
00:40:19,800 --> 00:40:23,520
In some species, the female retains them within her body

397
00:40:23,520 --> 00:40:28,240
until they're ready to hatch, so she gives birth to live young.

398
00:40:31,240 --> 00:40:33,720
The marshes of Northern Argentina...

399
00:40:33,720 --> 00:40:38,400
home to one of the largest of live-bearing snakes, the anaconda.

400
00:40:44,920 --> 00:40:49,720
This is a female and she's heavily pregnant.

401
00:40:56,880 --> 00:40:59,320
It's morning, and she's chilly,

402
00:40:59,320 --> 00:41:01,480
so she moves out of the water

403
00:41:01,480 --> 00:41:04,920
and on to the swamp to warm herself in the sun.

404
00:41:18,080 --> 00:41:22,120
Slowly, the day begins to warm up.

405
00:41:33,400 --> 00:41:39,040
Now it's getting a little too hot for her, so she moves back

406
00:41:39,040 --> 00:41:41,280
to the water to cool off.

407
00:41:44,200 --> 00:41:49,280
In this way, she manages to keep her body close to 29 degrees C,

408
00:41:49,280 --> 00:41:52,680
perfect for the babies developing within her.

409
00:41:59,280 --> 00:42:03,320
But she won't give birth here and now.

410
00:42:03,320 --> 00:42:04,960
There are caiman around.

411
00:42:11,360 --> 00:42:14,880
At last, she finds the quiet pool that she needs,

412
00:42:16,560 --> 00:42:19,560
and her contractions start.

413
00:42:46,600 --> 00:42:50,720
The first of her babies has arrived.

414
00:42:54,040 --> 00:42:57,320
Up it goes to the surface to take its first breath of air.

415
00:43:06,400 --> 00:43:08,560
But there are more babies to come.

416
00:43:26,240 --> 00:43:29,240
Eventually, she produces 15.

417
00:43:29,240 --> 00:43:32,760
In fact, that's quite modest for an anaconda.

418
00:43:32,760 --> 00:43:36,840
They can produce up to 40.

419
00:43:36,840 --> 00:43:40,880
Right from the beginning of their lives they're totally independent,

420
00:43:40,880 --> 00:43:43,760
and get no care or protection from their mother.

421
00:43:46,040 --> 00:43:49,920
The anaconda spends so much of its time in water, and is such

422
00:43:49,920 --> 00:43:53,880
a powerful swimmer, that it can be properly considered aquatic.

423
00:43:58,760 --> 00:44:03,960
Snakes have become adapted to almost every environment,

424
00:44:03,960 --> 00:44:07,480
including even the sea, as this one has.

425
00:44:07,480 --> 00:44:11,920
It doesn't often bite, but it does have an extremely powerful venom

426
00:44:11,920 --> 00:44:13,800
so I'm not going to handle it.

427
00:44:13,800 --> 00:44:17,240
But I will help it a little with this stick.

428
00:44:17,240 --> 00:44:20,440
As you can see, it has a very flattened...

429
00:44:20,440 --> 00:44:23,960
paddle at the end of its tail,

430
00:44:23,960 --> 00:44:26,840
but on land, it's pretty helpless.

431
00:44:28,440 --> 00:44:30,800
However, if I assist it...

432
00:44:30,800 --> 00:44:33,280
in getting into the sea...

433
00:44:38,680 --> 00:44:41,760
And now it's in its element.

434
00:44:44,280 --> 00:44:48,280
Sea snakes have had to modify many of the features

435
00:44:48,280 --> 00:44:52,360
that enabled their far distant ancestors to colonise the land.

436
00:44:52,360 --> 00:44:56,000
They still have a lung with which to breathe air like other snakes,

437
00:44:56,000 --> 00:45:01,400
but they can also absorb oxygen from sea water through their skin.

438
00:45:08,880 --> 00:45:13,880
Salt inevitably gets into a sea snake's body, but the snake manages

439
00:45:13,880 --> 00:45:18,440
to get rid of that by excreting it from a gland under its tongue.

440
00:45:18,440 --> 00:45:22,880
It also needs to drink fresh water, so in calm seas,

441
00:45:22,880 --> 00:45:25,800
it waits at the surface for rain.

442
00:45:25,800 --> 00:45:31,440
Sea snakes really are truly marine creatures.

443
00:45:31,440 --> 00:45:34,560
They can live out here in the open ocean,

444
00:45:34,560 --> 00:45:39,080
and the only clue you have to their link with the land is that

445
00:45:39,080 --> 00:45:43,920
they have to come up every quarter of an hour or so for a gulp of air.

446
00:45:54,120 --> 00:45:59,240
Most sea snakes, like this bar-bellied species, hunt fish.

447
00:45:59,240 --> 00:46:02,200
They have one of the most lethal venoms known,

448
00:46:02,200 --> 00:46:04,760
which kills almost instantaneously.

449
00:46:04,760 --> 00:46:07,800
And that is a very important quality

450
00:46:07,800 --> 00:46:11,880
if you hunt fast-swimming ocean-going prey.

451
00:46:11,880 --> 00:46:16,280
But paradoxically, the most highly specialised sea snake of all

452
00:46:16,280 --> 00:46:18,600
has abandoned venom altogether.

453
00:46:20,800 --> 00:46:25,600
It has a beak like a turtle and a wholly different way of feeding.

454
00:46:40,520 --> 00:46:42,760
Reef fish don't like to have it around.

455
00:46:42,760 --> 00:46:44,600
They mob it.

456
00:46:55,600 --> 00:46:57,920
It doesn't even retaliate.

457
00:46:57,920 --> 00:46:59,680
It's not interested in them.

458
00:47:06,200 --> 00:47:08,280
It's after their eggs.

459
00:47:08,280 --> 00:47:12,160
These, the fish have stuck to the stony branches of the coral.

460
00:47:17,040 --> 00:47:23,560
The snake's hardened, turtle-like top lip enables it to scrape them off.

461
00:47:31,920 --> 00:47:33,920
It's such a slow-moving browser

462
00:47:33,920 --> 00:47:38,600
that algae and other small organisms grow on its skin,

463
00:47:38,600 --> 00:47:41,440
as they do on the bottom of a boat.

464
00:47:45,520 --> 00:47:49,520
The loss of limbs could seem to be a handicap,

465
00:47:49,520 --> 00:47:54,480
and certainly makes a snake seem alien creatures to us.

466
00:47:54,480 --> 00:47:56,280
But it is that very loss

467
00:47:56,280 --> 00:48:01,080
that has enabled the snakes to colonise every environment,

468
00:48:01,080 --> 00:48:04,160
from below to the ground to above the ground,

469
00:48:04,160 --> 00:48:07,640
from bushes to trees, to the air and even to the sea.

470
00:48:07,640 --> 00:48:10,880
And it is that absence of limbs, too,

471
00:48:10,880 --> 00:48:16,400
which has enabled them to do it with such elegance and grace.

472
00:48:25,560 --> 00:48:27,360
Filming venomous snakes

473
00:48:27,360 --> 00:48:32,160
presented a lot of special problems to the Life In Cold Blood team.

474
00:48:32,160 --> 00:48:37,120
But the toughest was trying to film the rattlesnake hunting in the wild.

475
00:48:37,120 --> 00:48:41,120
A rattlesnake making a kill has rarely even been seen,

476
00:48:41,120 --> 00:48:44,680
and never before filmed, and for several reasons.

477
00:48:44,680 --> 00:48:47,680
For one thing, rattlesnakes are so well camouflaged

478
00:48:47,680 --> 00:48:49,560
they're very difficult to find.

479
00:48:49,560 --> 00:48:53,280
We enlisted the help of snake expert Harry Greene and his team.

480
00:48:53,280 --> 00:48:56,680
They've been studying a group of timber rattlesnakes

481
00:48:56,680 --> 00:49:01,320
using radio telemetry, which enables them to find their rattlesnakes

482
00:49:01,320 --> 00:49:03,120
at any time of day or night.

483
00:49:03,120 --> 00:49:07,120
Most of us would never find them. And they're superbly camouflaged.

484
00:49:07,120 --> 00:49:08,720
Exactly,

485
00:49:08,720 --> 00:49:12,080
but that's one of the wonderful things about radio telemetry,

486
00:49:12,080 --> 00:49:14,240
we can have an animal that we can dial up.

487
00:49:14,240 --> 00:49:16,040
To have any chance of success,

488
00:49:16,040 --> 00:49:19,760
the crew had to be able to find the rattlesnakes on their own.

489
00:49:19,760 --> 00:49:22,840
So producer James Brickell had to take a course

490
00:49:22,840 --> 00:49:24,920
in telemetry techniques himself.

491
00:49:24,920 --> 00:49:27,600
Point it a little bit more over this way.

492
00:49:27,600 --> 00:49:31,120
Each snake has been implanted with a tiny transmitter.

493
00:49:31,120 --> 00:49:34,760
If you dial its frequency, you can pick up a beeping sound,

494
00:49:34,760 --> 00:49:37,640
and that gets louder the nearer you get to the snake.

495
00:49:38,920 --> 00:49:41,600
RHYTHMIC BEEPING

496
00:49:43,680 --> 00:49:47,360
It's just like trying to find your favourite rock'n'roll station,

497
00:49:47,360 --> 00:49:50,240
but now we're going to find our favourite rattlesnake.

498
00:49:50,240 --> 00:49:52,960
So you just punch in its number and it's on the air.

499
00:49:52,960 --> 00:49:56,360
It sounds simple in theory, but there's a snag.

500
00:49:59,480 --> 00:50:02,160
It's here somewhere.

501
00:50:02,160 --> 00:50:04,600
Just be really careful, guys.

502
00:50:04,600 --> 00:50:07,480
In a forest, the signal can bounce off trees

503
00:50:07,480 --> 00:50:09,120
and give you a false reading,

504
00:50:09,120 --> 00:50:12,080
so that it can seem that the snake is everywhere,

505
00:50:12,080 --> 00:50:14,600
and you don't want to think a reading is false

506
00:50:14,600 --> 00:50:16,840
and then tread on your snake by mistake.

507
00:50:16,840 --> 00:50:19,720
...And you'll find he's up there somewhere.

508
00:50:19,720 --> 00:50:21,280
Let's find him.

509
00:50:21,280 --> 00:50:23,080
James, it's starting to get dark.

510
00:50:23,080 --> 00:50:25,560
He's in there. I reckon he's hunting.

511
00:50:25,560 --> 00:50:26,920
James, be careful where you're going.

512
00:50:26,920 --> 00:50:28,640
And it isn't just the one snake you're tracking.

513
00:50:28,640 --> 00:50:31,840
There are dozens of others in the area that aren't tagged.

514
00:50:34,520 --> 00:50:37,040
Follow my hand, there he is.

515
00:50:37,040 --> 00:50:38,920
About 20 feet.

516
00:50:38,920 --> 00:50:41,520
Six metres.

517
00:50:41,520 --> 00:50:46,320
And so at last, the crew meet a very special snake called Hank.

518
00:50:50,840 --> 00:50:53,880
Hank is in a perfect position for his ambush.

519
00:50:53,880 --> 00:50:58,000
To film the action without disturbing him or his prey,

520
00:50:58,000 --> 00:51:02,560
cameraman Mark MacEwen has fitted his camera with motion detectors,

521
00:51:02,560 --> 00:51:04,080
from a burglar alarm.

522
00:51:04,080 --> 00:51:07,200
They will turn on the camera without anyone having to be there.

523
00:51:08,960 --> 00:51:14,960
So, for the first time, they set up their gear in front of a live snake.

524
00:51:14,960 --> 00:51:20,200
They can now leave Hank and track another of Harry's snakes.

525
00:51:20,200 --> 00:51:23,960
So that means you know individual snakes over a long period of time.

526
00:51:23,960 --> 00:51:25,560
Do they differ very much?

527
00:51:25,560 --> 00:51:27,480
Absolutely, absolutely.

528
00:51:27,480 --> 00:51:29,360
Now there are species differences,

529
00:51:29,360 --> 00:51:33,000
so certain rattlesnakes species are more nasty-tempered than others,

530
00:51:33,000 --> 00:51:36,360
but even among a...within a population you'll have one

531
00:51:36,360 --> 00:51:37,960
that just never gets riled up

532
00:51:37,960 --> 00:51:40,440
and one you know you just can't get too close to

533
00:51:40,440 --> 00:51:42,200
without it getting upset.

534
00:51:42,200 --> 00:51:46,160
With one camera set up on Hank, James decides to track another snake,

535
00:51:46,160 --> 00:51:50,920
and to do so in the dark, which is when most rattlesnakes hunt.

536
00:51:50,920 --> 00:51:54,240
But in the pitch blackness, there was a distinct possibility that

537
00:51:54,240 --> 00:51:57,960
James would accidentally get so close to the snake he was looking for,

538
00:51:57,960 --> 00:52:00,200
he would step within striking distance.

539
00:52:00,200 --> 00:52:04,240
Quite unnerving if you haven't done it before.

540
00:52:08,680 --> 00:52:10,160
It's actually pretty dangerous

541
00:52:10,160 --> 00:52:11,600
walking around in the middle of the night

542
00:52:11,600 --> 00:52:14,520
trying to find a rattlesnake in these conditions.

543
00:52:21,000 --> 00:52:24,600
It's really close. It's stronger here, over near these logs.

544
00:52:24,600 --> 00:52:28,000
I think the snake's about probably five, 10 metres away.

545
00:52:28,000 --> 00:52:30,840
It would be easier to find a needle in a haystack,

546
00:52:32,360 --> 00:52:34,440
than to find a reptile that looks

547
00:52:34,440 --> 00:52:38,040
like a load of dead leaves in a huge pile of dead leaves.

548
00:52:38,040 --> 00:52:41,160
Have you found him, fellas?

549
00:52:41,160 --> 00:52:46,360
Negative, Mark, we've got to a huge pile of logs and wood.

550
00:52:46,360 --> 00:52:49,440
The team decide to abandon tracking the second snake

551
00:52:49,440 --> 00:52:54,560
and instead check on the camera they'd left on Hank in the afternoon.

552
00:52:54,560 --> 00:52:57,560
I think it's too dangerous to go poking around in there,

553
00:52:57,560 --> 00:53:00,280
and you wouldn't get the lights and the camera in,

554
00:53:00,280 --> 00:53:01,920
so we're going to come back.

555
00:53:01,920 --> 00:53:04,920
We've seen things on your videos we've never seen before,

556
00:53:04,920 --> 00:53:06,480
which is kind of surprising.

557
00:53:06,480 --> 00:53:10,360
I mean, we've watched snakes a lot, all the rattlesnake biologists,

558
00:53:10,360 --> 00:53:14,760
and we've seen things on your videos we haven't seen before.

559
00:53:14,760 --> 00:53:18,440
So its actually kind of exciting to think about how this kind of

560
00:53:18,440 --> 00:53:20,680
collaboration might really be a feedback

561
00:53:20,680 --> 00:53:23,720
between the media and the public and science and so forth.

562
00:53:23,720 --> 00:53:26,920
And something very surprising had happened.

563
00:53:26,920 --> 00:53:29,880
At our very first attempt and in broad daylight,

564
00:53:29,880 --> 00:53:34,120
a chipmunk had tripped the motion detectors and Hank makes a kill

565
00:53:34,120 --> 00:53:36,240
right in front of the cameras.

566
00:53:43,240 --> 00:53:46,960
We've got a strike already, we've got it.

567
00:53:46,960 --> 00:53:50,680
- I thought you were winding me up.
- I said, "James, something's happened."

568
00:53:50,680 --> 00:53:55,640
I thought, "That's a classic wind-up." First night, to get that.

569
00:53:55,640 --> 00:53:58,560
We hadn't got the eating shot, but it's a start.

570
00:53:58,560 --> 00:54:00,600
And then the camera is set off again

571
00:54:00,600 --> 00:54:03,280
by a second chipmunk behaving very strangely.

572
00:54:03,280 --> 00:54:07,560
We showed the recording to Harry, and he was fascinated.

573
00:54:07,560 --> 00:54:09,200
Now what was that chipmunk doing?

574
00:54:09,200 --> 00:54:11,720
Was it perceiving something that the other chipmunk left

575
00:54:11,720 --> 00:54:14,400
as some kind of alarm odour or something?

576
00:54:14,400 --> 00:54:16,960
Was it perceiving the odour of the rattlesnake,

577
00:54:16,960 --> 00:54:19,320
or was it something I can't even imagine yet?

578
00:54:19,320 --> 00:54:23,280
But something was going on there that I didn't know to expect anyway,

579
00:54:23,280 --> 00:54:24,520
and it's in your film.

580
00:54:24,520 --> 00:54:27,200
Hank could clearly be the star of the show,

581
00:54:27,200 --> 00:54:30,800
so the crew decide to concentrate all their efforts on him

582
00:54:30,800 --> 00:54:33,680
and to track him for two weeks around the clock.

583
00:54:33,680 --> 00:54:35,880
They quickly learn that

584
00:54:35,880 --> 00:54:38,720
despite his ability to hurt one of them very seriously,

585
00:54:38,720 --> 00:54:40,320
he seems pretty unconcerned.

586
00:54:40,320 --> 00:54:43,320
In fact, he never even rattles a warning at them.

587
00:54:43,320 --> 00:54:46,320
The more they get to know him,

588
00:54:46,320 --> 00:54:49,880
the more they think they've got a good chance of filming another hunt.

589
00:54:49,880 --> 00:54:52,600
But then there is a serious problem.

590
00:54:52,600 --> 00:54:55,800
It's just been raining here non-stop for the past three days,

591
00:54:55,800 --> 00:54:59,760
and they say that Tuesday afternoon's hard rain storm was...

592
00:54:59,760 --> 00:55:04,160
Just as things are looking so promising, New York State has its

593
00:55:04,160 --> 00:55:08,680
worst floods for a decade and all filming comes to a standstill.

594
00:55:10,080 --> 00:55:12,400
As you can see, the weather's awful.

595
00:55:12,400 --> 00:55:15,600
Won't affect the rattlesnake at all, he's perfectly happy.

596
00:55:15,600 --> 00:55:17,440
He'll be sat down in here just waiting.

597
00:55:17,440 --> 00:55:19,520
But it does affect the mammals.

598
00:55:19,520 --> 00:55:22,840
The chipmunks and the mice, they'll just be hunkered down somewhere,

599
00:55:22,840 --> 00:55:26,840
not doing anything very much, and it affects us, but he'll be fine.

600
00:55:26,840 --> 00:55:31,040
We can't film anything, so it's just a matter of waiting now.

601
00:55:31,040 --> 00:55:34,600
After tracking him in the rain for ten days,

602
00:55:34,600 --> 00:55:39,360
there's a break in the weather and Hank starts hunting again.

603
00:55:39,360 --> 00:55:43,520
He chooses a position for an ambush in a very accessible spot.

604
00:55:43,520 --> 00:55:46,680
The team has another chance to use their remote cameras,

605
00:55:46,680 --> 00:55:49,760
this time operating in night vision.

606
00:55:49,760 --> 00:55:52,840
James, just be careful where you come in. Don't go that way.

607
00:55:52,840 --> 00:55:54,880
I think that's the direction he's headed in.

608
00:55:54,880 --> 00:55:57,800
You've got something, have you?

609
00:55:57,800 --> 00:56:02,360
We've got him hitting a mouse in the middle of frame and swallowing it.

610
00:56:02,360 --> 00:56:05,640
This time they get more than the strike.

611
00:56:05,640 --> 00:56:10,160
This time, Hank decides to eat his dinner, very obligingly,

612
00:56:10,160 --> 00:56:12,120
right in front of the camera.

613
00:56:12,120 --> 00:56:15,400
Mate, that is the most incredible piece of behaviour

614
00:56:15,400 --> 00:56:16,960
you have ever seen.

615
00:56:16,960 --> 00:56:22,280
So, after two weeks and a lot of effort, they succeed in capturing

616
00:56:22,280 --> 00:56:27,400
a crucial and intimate moment in the life of this very special snake.

617
00:56:27,400 --> 00:56:31,200
People don't automatically love snakes, most of them don't.

618
00:56:31,200 --> 00:56:34,240
And yet, if you can show them things about the lives of these animals

619
00:56:34,240 --> 00:56:37,120
that impress them with the fact these are animals

620
00:56:37,120 --> 00:56:39,080
with complex daily activities.

621
00:56:39,080 --> 00:56:41,920
These aren't waiting around for an opportunity to kill people.

622
00:56:41,920 --> 00:56:46,120
When you tell people things like that, they get drawn in.

623
00:56:46,120 --> 00:56:49,440
And hopefully when we show them your films, they'll be drawn in.

624
00:56:49,440 --> 00:56:53,640
- Well, you've drawn me in. Thank you very much.
- Pleasure.

625
00:56:53,640 --> 00:56:57,200
And when I get to see the footage, it's fair to say

626
00:56:57,200 --> 00:57:01,760
that I'm just as knocked sideways as the crew had been.

627
00:57:01,760 --> 00:57:03,520
There's the mouse.

628
00:57:05,640 --> 00:57:08,360
Oh, my goodness!

629
00:57:09,880 --> 00:57:12,200
Yes.

630
00:57:12,200 --> 00:57:14,600
That's a dead mouse all right.

631
00:57:16,400 --> 00:57:20,840
Next week, join me for the story of the armoured giants -

632
00:57:20,840 --> 00:57:24,080
the tortoises, turtles and crocodiles.

633
00:57:29,040 --> 00:57:31,880
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