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00:30Whatever your feelings about snakes, you can't deny that they have an extraordinary beauty.
00:46Their lack of limbs compels them to deal with life's problems in ways that are utterly different from ours.
01:00But nonetheless, the techniques they've developed are spectacularly successful.
01:07Snakes have one of the simplest of body shapes, essentially just a long, thin tube.
01:28But they have some remarkably effective ways of getting around.
01:31They can climb a tree simply by embracing its trunk.
01:43Some can flatten their bodies so that they catch the air beneath them and glide.
01:49By hitching up their undersides, they can inch themselves forward in a straight line.
02:02A sinuous wriggle enables them to skate across loose sand.
02:06And the same action works equally well in water.
02:17There, some swim close to the surface.
02:22Others explore the depths and can stay underwater for hours on end.
02:27One, believe it or not, can jump.
02:33So, leglessness hardly seems such a handicap.
02:56But how did snakes get that way?
03:00Well, their remote ancestors 100 million years ago, at the time of the dinosaurs, did have legs, rather like today's lizards.
03:15Doubtless, they were very effective runners.
03:18But some also started to burrow in search of prey.
03:26Below ground, legs are a hindrance, and over generations, they became smaller.
03:32Today, burrowing lizards, such as skinks, seem to be going through the same process.
03:37Many have tiny, but recognisable legs.
03:41In others, the limbs have become nothing more than functionless flaps.
03:48In this burrowing lizard, the process has gone even further.
03:54The animal still has the face of a lizard, but its legs have disappeared totally.
04:03It seems that the ancestral snakes went through just such a process,
04:08way back in geological history, some 95 million years ago.
04:14So, what did these very first snakes look like?
04:17Well, the answer can be found in Asian jungles, in American woodlands and gardens,
04:23and even in flowerpots, like this.
04:30It may look like an earthworm, but actually, it's a flowerpot snake.
04:37It's a flowerpot snake, and it's completely blind.
04:41It doesn't need to see, because it spends all its life underground.
04:47I'll put it back in its flowerpot, and put a flower on top,
04:52and it will live perfectly happily there in this flowerpot,
04:56all by itself, providing it has enough food.
04:58And there's a surprising amount for a small snake to eat underground.
05:04Ant larvae, for example.
05:07These early, legless reptiles flourished and remained underground for a long time.
05:25Then, around 50 million years ago, some of them returned to the surface.
05:31Why?
05:36Well, by this time, the dinosaurs have disappeared,
05:39and the early mammals had arrived.
05:41They were more nutritious than beetles and worms,
05:44so the snakes began to catch them instead,
05:47and became so good at doing so,
05:49that today they are among the most skilful hunters on earth.
05:53Here, in North America,
05:57there's a snake that combines its great speed and extraordinary senses
06:02in a remarkable hunting strategy we are only just beginning to understand.
06:10A timber rattlesnake.
06:14The morning sun has warmed its body, giving it energy,
06:18and it starts to move.
06:20It's searching for a place where it can conceal itself
06:33and wait for prey to come within striking distance.
06:41A little chipmunk.
06:42It's in no danger yet.
06:44The rattlesnake can't move fast enough to chase and catch it.
06:47But small mammals tend to use the same paths
06:53as they run over the forest floor,
06:55and they leave behind a faint trail of scent.
06:59The rattlesnake can detect that scent with its tongue.
07:03It can also locate the warm-blooded chipmunk,
07:14if it's nearby,
07:15with heat detectors in a pair of pits beneath its eyes.
07:22As it moves,
07:23it carefully holds its rattle above the ground,
07:25so it makes no noise.
07:27It's chosen the place to wait at the bottom of this tree stump.
07:38Its coloration matches the ground so closely
07:41it needs no further concealment.
07:45Now it's just a matter of time.
07:47Seeing a rattlesnake actually catching its prey
07:53is a very, very difficult thing to observe.
07:56In fact, some scientists have watched rattlesnakes for years
07:59without seeing that particular crucial moment.
08:03But we have a chance,
08:05partly because rattlesnakes are ambush hunters,
08:08so we know exactly where to put up our gear,
08:11and partly because in that gear
08:13we've got the very latest in surveillance equipment.
08:19There are remotely controlled cameras
08:21and infrared lights on stands.
08:28And there are motion detectors
08:30that will switch on the cameras if anything moves,
08:33so I needn't wait alongside.
08:35If anything happens,
08:36the cameras will switch on automatically.
08:38Later, I check the replay.
08:51There's a mast
08:52just along that log.
08:54That obviously came to nothing,
09:08but the cameras have started recording again
09:10and the snake is moving.
09:12He's checking out the trail with his tongue.
09:18See, that's exactly where that mast was running.
09:20It's pitch dark,
09:29and the mouse clearly has no idea
09:31that the snake is there.
09:33But the snake is well aware of the mouse,
09:36thanks, no doubt, to those heat-detecting pits.
09:43A snake strikes
09:44by suddenly straightening the curve in its neck,
09:47but at the moment,
09:48the mouse is not within range.
10:02He's worked out
10:03that that is the path
10:05along which the mice run.
10:09He's getting himself properly adjusted
10:12so he can strike
10:14when he next gets a chance.
10:17Now, once again,
10:32waiting.
10:34That's what the snakes are so good at.
10:36Oh, my goodness.
11:01Oh, my goodness.
11:01That's a dead mouse, all right.
11:11Slow down that shot
11:13and you can see
11:14that the snake stabs the mouse just once.
11:19After three convulsive kicks,
11:21the mouse is dead.
11:22The snake is moving again.
11:33He's going back now
11:34to look for the one
11:37that he knows is dead
11:40back there.
11:42Where is it?
11:43Ah, now it looks as though
11:49he's really got it.
11:55That's his dinner.
11:56And that can last him
11:58for three weeks,
12:02four weeks if necessary.
12:04Rattlesnakes are among the least
12:15obtrusive inhabitants
12:16of the forests of North America
12:18and they're probably far more numerous
12:20than many people realise.
12:25Like many other animals,
12:27snakes use their nostrils
12:28to detect smells.
12:29But the most sensitive
12:31and accurate information
12:32about the world around them
12:33comes from that
12:35constantly flickering tongue.
12:47With this,
12:48a snake gathers molecules
12:50from the air
12:50and carries them back
12:52for evaluation
12:52to a pair of extremely sensitive organs
12:55in the roof of its mouth.
12:57To see just how important
13:00scent can be to a snake,
13:03I've come here
13:03to Karnak Island
13:05just off the coast
13:06of Western Australia.
13:08It's home
13:08to a large population
13:10of highly venomous
13:12tiger snakes.
13:16Snakes have been established
13:17here for many years
13:19but there's something odd
13:20about this particular population.
13:23Many of them
13:25have damaged heads
13:26and some of them
13:28are actually blind,
13:30like this one.
13:31And yet,
13:32puzzlingly,
13:33in spite of the fact
13:35that they're blind,
13:36they all appear
13:37to be very well fed.
13:39So,
13:40how do their heads
13:41get damaged
13:41and how,
13:43in that condition,
13:44when they can't see anything,
13:45can they catch
13:46all the prey
13:47they need?
13:48The snakes,
13:53of course,
13:54are not the only
13:55inhabitants of the island.
13:56It's also home
13:57for a large colony
13:59of silver gulls.
14:02The gulls breed
14:03throughout the year
14:05so their chicks
14:06are a source of food
14:07for the snakes
14:08that never ends.
14:09In fact,
14:15the snakes
14:15eat pretty well
14:16nothing else.
14:22But the snakes
14:23don't get it
14:24all their own way.
14:25The gulls
14:26are valiant defenders
14:27of their nests
14:28and their chicks.
14:28their stabbing beaks
14:36are powerful,
14:37sharp and strong
14:38and the gulls
14:39always go
14:40for the snake's head.
14:58One in ten
15:07of the snakes
15:07are totally blinded.
15:11Piker snakes
15:11don't have
15:12those heat-sensitive pits
15:13that rattlesnakes have
15:15so these blinded hunters
15:16must be guided
15:17entirely
15:18by their forked tongue.
15:20It's a superb
15:22direction-finding device.
15:25The snake
15:25can measure
15:26the strength
15:27of the smell
15:27separately
15:28on each
15:28of the two forks
15:30of its tongue.
15:31And if it wishes
15:32to follow up
15:33a smell
15:34then it simply
15:35detects the one
15:36which has
15:37the stronger smell
15:37and goes in that direction.
15:44Gull chicks
15:45are an ideal prey
15:46for a blinded snake
15:47because they're
15:48programmed
15:49to stay
15:50on their nests.
15:58once a snake
16:09has located it
16:10a chick
16:11is doomed.
16:18Snakes, it must be admitted
16:19have had a bad reputation
16:21ever since one appeared
16:23in the Garden of Eden.
16:24but in reality
16:25even the most
16:27aggressive venomous snake
16:28will avoid
16:29biting a human being
16:30if it can.
16:32Why waste venom
16:33and risk
16:34violent retribution
16:35by biting something
16:37you're not going to eat?
16:40To prevent
16:41misunderstanding
16:42most venomous snakes
16:43warn other animals
16:45including human beings
16:46to keep out of their way.
16:47Some snakes
16:52do that
16:52with sound.
17:05Others
17:05such as cobras
17:06give a visual signal
17:08by expanding
17:09the skin
17:10around their heads
17:11to form
17:11a conspicuous hood.
17:15The threat
17:16of a bite
17:17is far better
17:18defence for a snake
17:19than the bite itself.
17:23However
17:24there are some snakes
17:26that not only use
17:28their venom
17:28to kill their prey
17:30but have also
17:31found a way
17:32of using it
17:34to deter
17:35their enemies
17:36without even
17:38biting them.
17:41This
17:41Mozambique cobra
17:42has a very special
17:44way of doing that.
17:47to demonstrate
17:49this with some
17:50degree of safety
17:50I'm going to wear
17:52this visor
17:52which has been
17:53coated with a
17:54substance
17:54that turns pink
17:55in contact
17:56with venom.
17:58Let's see what
17:59happens.
18:03It's watching me
18:05waiting to see
18:06if I get too close
18:07for its liking
18:07and venom spurts
18:19from its fangs
18:19as it spits
18:22it turns its head
18:23from side to side
18:24so that the jets
18:25have the best chance
18:26of hitting my eyes.
18:27Well
18:34I was well
18:36and truly sprayed
18:36every one of those
18:38pink dots
18:39is a bead
18:40of venom
18:41and if any one
18:42of them had gone
18:42in my eye
18:43I would be now
18:44blind and in
18:46extreme pain
18:46so it's a fair
18:48warning from that
18:49snake to me
18:49not to get any
18:50closer
18:51and I dare say
18:52if I did
18:53I would deserve
18:55what I would get
18:56which would be
18:56a bite
18:57I have no intention
18:59of doing that.
19:02On the other hand
19:03some snakes
19:04which may appear
19:05to be venomous
19:06are in reality
19:07quite harmless.
19:11These two snakes
19:12look very
19:13very similar
19:14and they both
19:16occur here
19:17in the southern
19:18United States
19:18so you're quite likely
19:19to meet
19:20one or the other
19:21here.
19:23One of them
19:23however
19:24is harmless
19:25it's called
19:25a kingsnake
19:26the other one
19:27is a coral snake
19:29and highly venomous
19:30one bite
19:31certain death.
19:33The question is
19:34which is which?
19:37Well
19:37the key lies
19:39in the order
19:39of the colour rings.
19:41People here
19:42have a local saying
19:44red and black
19:46venom lack
19:47red and yellow
19:49can kill
19:50a fellow
19:51and this one
19:53has red
19:56and black
19:57so I guess
19:59that's a kingsnake.
20:03We'll see.
20:10So far so good.
20:13Yeah this is a kingsnake
20:14snake and what
20:15a beautiful snake
20:17it is.
20:21A really
20:22lovely reptile.
20:30The kingsnake
20:31pretends to be venomous
20:32when it's not
20:33and there's another snake
20:35that pretends to be dead
20:37when it isn't.
20:38snakes
20:40being cold-blooded
20:45seem to relish
20:46the warmth
20:47of sunbaked roads
20:48and often bask on them
20:50and as a result
20:51of course
20:51many get run over.
20:58But things
20:59aren't always exactly
21:00what they seem.
21:01he looks
21:07kind of dead.
21:12But in fact
21:13this hognose snake
21:15is perfectly
21:16all right.
21:20He was just
21:21feigning
21:23death
21:24so that
21:25things that might
21:26have been
21:27interested in a
21:28living snake
21:28are not
21:30and what's more
21:31he's
21:32produced
21:33a rather
21:34remarkable smell
21:35in fact
21:37the smell
21:37as it were
21:38of rotting flesh
21:41so
21:41maybe he was
21:43pretending too
21:43that he was
21:44not only dead
21:45but decomposing.
21:47Very convincing.
21:50Off you go.
21:57The lack of limbs
21:58that might seem
21:59to us
21:59seem to us
21:59to be such
22:00a huge handicap
22:01has not
22:02stopped snakes
22:02from getting
22:03around in all
22:04kinds of ways
22:04and neither
22:05does it prevent
22:06them from
22:06tackling all
22:07kinds of meals.
22:10This South African
22:12snake has become
22:13a specialist
22:13in swallowing
22:14a particularly
22:15awkward mouthful.
22:21It's as
22:22accomplished
22:22a tree climber
22:23as you'll find
22:24among snakes.
22:25The trees
22:38it frequents
22:39also hold
22:40colonies
22:41of masked
22:42weaver birds
22:43that suspend
22:43their nests
22:44from the very
22:45tip of the branches
22:46but the snake
22:48is a skilled
22:48enough climber
22:49to reach them.
22:51The weaver birds
22:52know it well
22:53and recognise
22:54it as a threat.
23:05It's well
23:06accustomed to
23:07these attacks.
23:30These defenders
23:31however
23:32are just
23:32too determined
23:33and it retreats.
23:35but it doesn't
23:41give up
23:42altogether.
23:58This nest
23:58is unguarded.
24:00and this
24:06is what
24:07the snake
24:07is after
24:07the eggs.
24:09Each
24:09is several
24:10times bigger
24:11than the snake's
24:12head
24:12but its jaws
24:13are linked
24:14by ligaments
24:14that are
24:15amazingly
24:16elastic.
24:23Once the egg
24:24is engulfed
24:25by the snake's
24:26jaws
24:26powerful throat
24:27muscles push
24:28it down
24:28its gullet.
24:29moving x-rays
24:37enable us
24:38to see
24:38exactly
24:39what's
24:39happening.
24:43Soon
24:44the egg
24:45reaches a part
24:46of the backbone
24:47that has
24:47downward
24:48pointing spines
24:49on it.
24:52The snake
24:53arches its
24:54backbone
24:54and then
24:55squeezes.
24:56the shell
25:01cracks
25:01and the
25:02spines
25:02on the
25:03backbone
25:03slit
25:04the membrane.
25:08The shell
25:09is crushed
25:10and rich
25:11nutritious
25:11yolk
25:12flows
25:13into
25:13the snake's
25:13gut.
25:14then what's
25:29left of the
25:30shell
25:30is regurgitated.
25:34But that of course
25:36was a small meal.
25:38Some snakes
25:38can tackle much
25:39bigger meals
25:40than that.
25:45An African
25:45rock python.
25:46One of the biggest
25:47of all snakes
25:48that can grow over
25:49seven meters,
25:5020 feet long.
25:52And it is eating
25:53an antelope.
25:55It too
25:56has an elastic
25:57ligament
25:58connecting its jaws.
26:02It killed the antelope
26:04not with venom
26:05but by squeezing
26:06it so tightly
26:07that it was
26:08unable to breathe.
26:13A python's teeth
26:15can't cut
26:16or rip.
26:17It has to swallow
26:18its prey whole
26:19or not at all.
26:20And that may take
26:21a day
26:22or more.
26:24Without limbs
26:25the python
26:26can't push
26:27the antelope
26:27down its throat.
26:29Instead
26:29it hitches
26:30its jaws
26:31diagonally
26:31back and forth
26:32so that they
26:33as it were
26:34walk along
26:35and over
26:36the prey.
26:39Its tube-like
26:39body
26:40has to stretch
26:41so extremely
26:42to accommodate
26:43such a gigantic meal
26:44that its flanks
26:45are torn.
26:47But such injuries
26:48heal very quickly.
26:54The last
26:55of the antelope
26:56its hooves
26:57are about to
26:57disappear.
27:02gone.
27:14The python
27:15will now
27:16hide itself
27:17away
27:17and begin
27:18the long
27:19process of
27:19digestion.
27:21Everything
27:21will be
27:22dissolved.
27:23Skin,
27:23hair,
27:24hooves,
27:25even
27:26horns.
27:26This python
27:35will not
27:36need to
27:36eat again
27:37for a
27:37year
27:38or more.
27:44Whenever
27:45it's warm
27:46and there
27:46are animals
27:47of some
27:47kind
27:48there will
27:49be snakes
27:49to hunt
27:49them
27:50no matter
27:51how difficult
27:51the conditions
27:52and how
27:53awkward
27:53the mouthful.
27:54crabs are
27:57in plentiful
27:57supply
27:58in this
27:59mangrove
27:59swamp.
27:59There must
28:00be 50
28:01on any
28:01one of
28:01these
28:02trees
28:02around
28:03them.
28:03They're
28:03all up
28:03there
28:04waiting
28:05for the
28:05tide
28:05to go
28:06out
28:06so
28:06they
28:06can
28:06feed
28:07in
28:07the
28:07mud
28:08below.
28:09So
28:09there
28:10is
28:10a
28:11meal
28:11for
28:11a
28:11snake
28:11here
28:12but
28:13crabs
28:13are
28:14not
28:14easy
28:14to
28:14tackle.
28:16They're
28:16strong
28:16armour
28:17plated
28:18and
28:18covered
28:18in
28:19spines.
28:19For
28:20a
28:20snake
28:21to
28:21tackle
28:21one
28:22of
28:22these
28:22would
28:23be
28:23like
28:23me
28:24trying
28:24to
28:25eat
28:25a
28:25lobster
28:25twice
28:26the
28:26size
28:26of
28:26my
28:26head
28:27with
28:27my
28:27hands
28:28tied
28:28behind
28:28my
28:29back.
28:30But
28:30there
28:30is
28:31a
28:31snake
28:31that
28:32knows
28:32how
28:32to
28:32do
28:33so.
28:34The
28:35crabs
28:35cling
28:36to
28:36the
28:36arching
28:37struts
28:37of
28:37the
28:37mangroves
28:38to
28:38keep
28:38out
28:38of
28:39the
28:39way
28:39of
28:39predatory
28:39fish
28:40but
28:41as
28:41the
28:41tide
28:41retreats
28:42it
28:42becomes
28:43safe
28:43for
28:43them
28:43to
28:43climb
28:44down
28:44and
28:45start
28:45looking
28:45for
28:45such
28:46edible
28:46bits
28:46as
28:47the
28:47tide
28:47has
28:47left
28:48behind
28:48on
28:48the
28:48mud.
28:57For
28:58the
28:58moment
28:58they're
28:59safe
28:59but
29:00soon
29:00the
29:01sun
29:01will
29:01set
29:02then
29:03the
29:03snakes
29:04will
29:04come
29:04out
29:04of
29:04their
29:05burrows
29:05they
29:06hunt
29:06in
29:07the
29:07darkness
29:08but
29:09we'll
29:09be
29:09able
29:09to
29:09follow
29:10them
29:10with
29:10our
29:10infrared
29:11cameras
29:13it's
29:20now
29:21very
29:21dark
29:22indeed
29:22and
29:23the
29:23snake
29:24has
29:24to
29:24find
29:24its
29:25way
29:25around
29:25entirely
29:26by
29:26touch
29:27and
29:27smell
29:28finding
29:38crabs
29:39is
29:39not
29:40difficult
29:40they
29:41swarm
29:41all
29:41over
29:42the
29:42mud
29:42and
29:42the
29:43snake
29:43is
29:43almost
29:43bound
29:44to
29:44encounter
29:44one
29:45sooner
29:45rather
29:46than
29:46later
29:46the
29:55snake
29:55is
29:55armed
29:56with
29:56venom
29:56and
29:57has
29:57short
29:58strong
29:58fangs
29:59which
29:59can
29:59pierce
30:00a
30:00crab
30:00shell
30:00and
30:01stun
30:01it
30:01but
30:02that's
30:02only
30:03half
30:03the
30:03problem
30:03it's
30:04what
30:04it
30:04does
30:05after
30:05it's
30:06caught
30:06its
30:06crab
30:06that
30:07sets
30:07it
30:07apart
30:08from
30:08all
30:08other
30:09snakes
30:09it has it
30:37now
30:38now
30:38what
30:38the crab
30:40is so
30:40large
30:41that the
30:41snake
30:41can't
30:42swallow
30:42it
30:42whole
30:42slowly
30:44and
30:45deliberately
30:45the snake
30:46dismembers
30:47the crab
30:48each leg
30:54contains
30:54nutritious muscle
30:55but
31:05the
31:05crab's
31:06armoured
31:06body
31:07is
31:07simply
31:08discarded
31:08too
31:10difficult
31:10there
31:15are
31:15hard
31:15shelled
31:16creatures
31:16in
31:16fresh
31:17waters
31:17as
31:18well
31:18as
31:18in
31:18salt
31:18not
31:19nearly
31:19as
31:19many
31:20but
31:20sufficient
31:21number
31:21for
31:21some
31:22snakes
31:22to
31:22specialise
31:23in
31:23eating
31:23them
31:24and
31:27in
31:27the
31:27eastern
31:27united
31:28states
31:28many
31:29rivers
31:30contain
31:30crayfish
31:31like
31:36crabs
31:36they
31:37have
31:37a
31:37hard
31:38protective
31:38shell
31:39and
31:39they
31:39have
31:40particularly
31:40powerful
31:41pincers
31:41as
31:42well
31:42the
31:50queen
31:51snake
31:51however
31:51eats
31:52crayfish
31:53and
31:54nothing
31:54else
31:55but
32:15not
32:15just
32:15any
32:16crayfish
32:17it's
32:22very
32:23selective
32:23crayfish
32:26as
32:27they
32:27grow
32:27shed
32:28their
32:28armor
32:29every
32:33three
32:33to
32:33four
32:34weeks
32:34a
32:34split
32:35appears
32:35across
32:36the
32:36back
32:36of
32:36its
32:36shell
32:37the
32:41old
32:41shell
32:41hinges
32:42away
32:42and
32:42the
32:43crayfish
32:43hauls
32:44itself
32:44out
32:44and
32:45expands
32:45its
32:46body
32:46which
32:46is
32:46soft
32:47it's
32:50now
32:50that
32:51the
32:51snake
32:51has
32:51its
32:51chance
32:52a
33:04newly
33:04moulted
33:05crayfish
33:05looks
33:06much
33:06the
33:06same
33:07but
33:07it
33:07gives
33:08off
33:08different
33:08chemicals
33:09that
33:09the
33:10snake
33:10can
33:10detect
33:11in
33:11the
33:11water
33:11with
33:11its
33:11tongue
33:12and
33:13from
33:13some
33:13distance
33:14away
33:14it
33:33can
33:33swallow
33:34this
33:34crayfish
33:35because
33:35since
33:36it's
33:36newly
33:36mouted
33:37it's
33:38as
33:38soft
33:39as
33:39a
33:39boiled
33:39egg
33:40on
34:05occasion
34:06snakes
34:07have
34:07to
34:07grapple
34:07not
34:08only
34:08with
34:08their
34:09prey
34:09but
34:09with
34:10one
34:10another
34:10in
34:11disputes
34:11over
34:12mates
34:12and
34:12territory
34:13this
34:16is
34:16one
34:16of
34:16the
34:16most
34:17formidable
34:17the
34:17king
34:18cobra
34:18highly
34:19venomous
34:20and
34:20about
34:204
34:20meters
34:2114
34:21feet
34:22long
34:23disputes
34:26between
34:26rival
34:27male
34:27king
34:28cobras
34:28are
34:29potentially
34:29very
34:29dangerous
34:30indeed
34:31for
34:31this
34:31species
34:32specializes
34:33in
34:33eating
34:34other
34:34kinds
34:35of
34:35snakes
34:35so
34:38they
34:39observe
34:39strict
34:39rules
34:40in
34:40their
34:40fights
34:41which
34:41prohibit
34:42the
34:42use
34:42of
34:43their
34:43lethal
34:43bite
34:44slow
34:49down
34:49it's
34:50a
34:50performance
34:50full
34:51of
34:51grace
34:51as
34:52each
34:52contestant
34:53strives
34:54not
34:54to
34:54kill
34:55his
34:55opponent
34:55but
34:56simply
34:56to
34:57slam
34:57him
34:57to
34:57the
34:58ground
34:58who
34:59are
35:00men
35:01to
35:01to
35:02the
35:03to
35:03a
35:04to
35:05to
35:06the
35:06who
35:07will
35:07help
35:07you
35:08to
35:08the
35:09and
35:10to
35:11the
35:12who
35:12can
35:13come to
35:13the
35:13one
35:14and
35:15who
35:16can
35:16you
35:16see
35:17the
35:17one
35:17and
35:18have
35:18to
35:19the
35:19grace
35:20as
35:20the
35:20one
35:21and
35:21can
35:22have
35:22to
35:23the
35:24and
35:24the
35:55The defeated male leaves the arena and no harm has been done.
36:07Snakes must also find a way of preventing their courtship from becoming lethal.
36:13This is a Californian kingsnake, a male.
36:17He has detected the scent of a female ready to mate.
36:29Like all snakes, his eyesight is not good.
36:32But he can tell from the taste of the air that she's close by.
36:42In fact, she is within inches.
36:45For some time, the two follow one another nose to tail.
37:02The male begins to caress her,
37:05sensually jerking and rocking his body as he holds her close.
37:09He has a pair of sexual organs,
37:10one of which can project to the left and the other to the right.
37:12So, no matter which side of him, she happens to lie.
37:15The male begins to caress her,
37:17sensually jerking and rocking his body as he holds her close.
37:22He has a pair of sexual organs, one of which can project to the left and the other to the right.
37:37So, no matter which side of him, she happens to lie, he can reach her.
37:46At last, union is achieved.
37:48They may remain together for several hours.
38:09In a few weeks' time, the female will lay a clutch of eggs.
38:31It may take six or seven weeks for them to hatch,
38:34but the regions where most snakes live are warm enough for them to develop
38:38without any help from the parents.
38:45Cobras lay them on the ground in the leaf litter.
38:57Their soft, parchment-like shell is easily split when pushed from within.
39:08The front end of a cobra hatchling is quite capable of giving a bite,
39:15even while the back end is still within the shell.
39:18They're fangs may be small, but since it only takes a tiny drop of cobra venom to kill an animal,
39:27these youngsters can be as lethal as their parents.
39:32They're fangs may be small, but since it only takes a tiny drop of cobra venom to kill an animal,
39:41these youngsters can be as lethal as their parents.
39:44They already have that characteristic warning signal, the hood.
39:59They already have that characteristic warning signal, the hood.
40:16Not all snakes lay their eggs.
40:20In some species, the female retains them within her body until they're ready to hatch,
40:25so she gives birth to live young.
40:31The marshes of northern Argentina,
40:33home to one of the largest of live-bearing snakes, the anaconda.
40:38This is a female, and she's heavily pregnant.
40:57It's morning, and she's chilly,
40:59so she moves out of the water and onto the swamp to warm herself in the sun.
41:08Slowly, the day begins to warm up.
41:22Now it's getting a little too hot for her, so she moves back to the water to cool off.
41:44In this way, she manages to keep her body close to 29 degrees centigrade,
41:49perfect for the babies developing within her.
42:00But she won't give birth here and now.
42:03There are caiman around.
42:05At last, she finds the quiet pool that she needs.
42:18And her contractions start.
42:35The first of her babies has arrived.
42:55Up it goes to the surface to take its first breath of air.
42:58But there are more babies to come.
43:07Eventually, she produces 15.
43:08In fact, that's quite modest for an anaconda.
43:09They can produce up to 40.
43:10Right from the beginning of their lives,
43:12they're totally fine.
43:13They're totally fine.
43:14They can produce up to 40.
43:15Eventually, she produces 15.
43:16In fact, that's quite modest for an anaconda.
43:20They can produce up to 40.
43:22Right from the beginning of their lives, they're totally independent,
43:26and get no care or protection from their mother.
43:31The anaconda spends so much of its time in water and is such a powerful swimmer
43:36that it can be able to survive.
43:37They can produce up to 40.
43:38They can produce up to 40.
43:39Right from the beginning of their lives, they're totally independent
43:41and get no care or protection from their mother.
43:45The anaconda spends so much of its time in water
43:49and is such a powerful swimmer that it can be properly considered aquatic.
43:59Snakes have become adapted to almost every environment,
44:03including even the sea, as this one has.
44:08It doesn't often bite, but it does have an extremely powerful venom,
44:12so I'm not going to handle it, but I will help it a little with this stick.
44:17As you can see, it has a very flattened paddle at the end of its tail.
44:24But on land, it's pretty helpless.
44:28However, if I assist it in getting into the sea...
44:39...and now it's in its element.
44:42Sea snakes have had to modify many of the features that enabled their far-distant ancestors to colonize the land.
44:53They still have a lung with which to breathe air, like other snakes,
44:57but they can also absorb oxygen from the seawater through their skin.
45:00Salt inevitably gets into a sea snake's body, but the snake manages to get rid of that by excreting it from a gland under its tongue.
45:18It also needs to drink fresh water.
45:21So, in calm seas, it waits at the surface for rain.
45:27Sea snakes really are truly marine creatures.
45:31They can live out here in the open ocean.
45:34And the only clue you have to their link with the land is that they have to come up every quarter of an hour or so for a gulp of air.
45:43Most sea snakes, like this barbellied species, hunt fish.
45:59They have one of the most lethal venoms known, which kills almost instantaneously.
46:05And that is a very important quality if you hunt fast-swimming, ocean-going prey.
46:10But paradoxically, the most highly specialized sea snake of all has abandoned venom altogether.
46:21It has a beak like a turtle, and a wholly different way of feeding.
46:40Reef fish don't like to have it around.
46:43They mob it.
46:55It doesn't even retaliate.
46:57It's not interested in them.
46:59It's after their eggs.
47:08These, the fish, have stuck to the stony branches of the coral.
47:18The snake's hardened, turtle-like top lip enables it to scrape them off.
47:23It's such a slow-moving browser that algae and other small organisms grow on its skin as they do on the bottom of a boat.
47:40The loss of limbs could seem to be a handicap, and certainly makes the snakes seem alien creatures to us.
47:54But it is that very loss that has enabled the snakes to colonize every environment, from below the ground to above the ground, from bushes to trees to the air and even to the sea.
48:07And it is that absence of limbs, too, which has enabled them to do it with such elegance and grace.
48:26Filming venomous snakes presented a lot of special problems to the Life in Cold Blood team.
48:31But the toughest was trying to film a rattlesnake hunting in the wild.
48:37A rattlesnake making a kill has rarely even been seen and never before filmed, and for several reasons.
48:44For one thing, rattlesnakes are so well camouflaged they're very difficult to find.
48:50We enlisted the help of snake expert Harry Green and his team.
48:54They've been studying a group of timber rattlesnakes using radio telemetry, which enables them to find their rattlesnakes at any time of day or night.
49:03Most of us will never find them, and they're superbly camouflaged.
49:07Exactly.
49:09But that's been one of the wonderful things about radio telemetry, is we can have an animal that we can dial up.
49:14To have any chance of success, the crew had to be able to find the rattlesnakes on their own.
49:20So producer James Brickle had to take a course in telemetry techniques himself.
49:25Point a little bit more on this one.
49:28Each snake has been implanted with a tiny transmitter.
49:31If you dial its frequency, you can pick up a beeping sound.
49:35And that gets louder the nearer you get to the snake.
49:37And so it's just like if you were trying to find your favourite rock and roll station or something, but now we're going to find our favourite rattlesnake.
49:50So you just punch in its number, and it's on the air.
49:54It sounds simple in theory, but there's a snag.
50:00It's here somewhere.
50:02Just be really careful, guys.
50:04In a forest, the signal can bounce off trees and give you a false reading, so that it can seem that the snake is everywhere.
50:12And you don't want to think a reading is false, and then tread on your snake by mistake.
50:17Is that one there?
50:18You're fine. He's up there somewhere.
50:20Let's find him.
50:22James, it's starting to get dark.
50:24He's in there. I reckon he's hunting.
50:26James, be careful where you're going.
50:27And it isn't just the one snake you're tracking.
50:29There are dozens of others in the area that aren't tagged.
50:34I'll follow my hand.
50:35There he is.
50:37It's about 20 feet.
50:39That's six metres.
50:41And so, at last, the crew meet a very special snake called Hank.
50:52Hank is in a perfect position for his ambush.
50:54To film the action without disturbing him or his prey, cameraman Mark McEwan has fitted his camera with motion detectors from a burglar alarm.
51:04They will turn on the camera without anyone having to be there.
51:07So, for the first time, they set up their gear in front of a live snake.
51:15They could now leave Hank and track another of Harry's snakes.
51:20So, that means you know individual snakes over a long period of time.
51:24Do they differ very much?
51:25Absolutely.
51:26Absolutely.
51:27Absolutely.
51:28Now, there are species differences.
51:29So, certain rattlesnake species are more sort of nasty-tempered than others.
51:33Yes.
51:34But, even within a population, you'll have one that just never gets riled up and one that you know you just can't get too close to without it getting upset.
51:42With one camera set up on Hank, James decides to track another snake and to do so in the dark, which is when most rattlesnakes hunt.
51:51But, in the pitch blackness, there was a distinct possibility that James would accidentally get so close to the snake he was looking for, he would step within striking distance.
52:01Quite unnerving, if you haven't done it before.
52:03It's actually pretty dangerous walking around in the middle of the night trying to find the rattlesnake in these conditions.
52:21He's really close.
52:23Stomper here, over near these logs.
52:25I think the snake's about five, ten metres away.
52:28It'd be easier to find a needle in a haystack.
52:30And to find a reptile that looks like a load of dead leaves in a huge pile of dead leaves.
52:38Have you found it, fellas?
52:41A negative mark.
52:43We've got to a huge pile of logs and wood.
52:47The team decide to abandon tracking the second snake and instead check on the camera they'd left on Hank in the afternoon.
52:54I think it's too dangerous, actually, to go poking around in there and anywhere you wouldn't be able to get the lights and the camera in.
52:59So we're going to wrap on it and come back.
53:02We've seen things on your videos we've never seen before.
53:05Really?
53:06Which is kind of surprising.
53:07I mean, we've watched snakes a lot.
53:09We, I mean all the, all rattlesnake biologists.
53:12We've seen things on your videos we haven't seen before.
53:15So I think it's actually kind of exciting to think about how this kind of collaboration might really be a feedback between the media and the public and science and so forth.
53:24And something very surprising had happened.
53:27At our very first attempt and in broad daylight, a chipmunk had tripped the motion detectors and Hank makes a kill right in front of the cameras.
53:36We've got a strike already. We've got it.
53:47I thought you were winding up.
53:48I was like, James, there's, erm, something's happened here.
53:50I thought, well, that's just a classic wind up. First, first night to get that.
53:55We hadn't got the eating shot, but it's a start.
53:59And then the camera is set off again by a second chipmunk behaving very strangely.
54:03We showed the recording to Harry and he was fascinated.
54:07Now, now what was that chipmunk doing?
54:09Was it perceiving something that the other chipmunk left as some kind of alarm odor or something?
54:14Was it perceiving the odor of the rattlesnake or was it something I can't even imagine yet?
54:19But something was going on there that I didn't know to expect anyway. It's in your film.
54:23Hank could clearly be the star of the show, so the crew decide to concentrate all their efforts on him and to track him for two weeks around the clock.
54:34They quickly learn that despite his ability to hurt one of them very seriously, he seems pretty unconcerned.
54:40In fact, he never even rattles a warning at them.
54:45The more they get to know him, the more they think they've got a good chance of filming another hunt.
54:50But then there is a serious problem.
54:53It's just been raining here non-stop for the past three days.
54:56And they say that Tuesday afternoon's hard rainstorm was the straw that broke the camel's back.
55:01Just as things are looking so promising, New York State has its worst floods for a decade and all filming comes to a standstill.
55:10As you can see, the weather's awful.
55:13It won't affect the rattlesnake at all. He's perfectly happy.
55:15He'll be sat down in here somewhere just waiting, but it does affect the mammals.
55:19The chipmunks and the mice, they'll just be hunkered down somewhere, not doing anything very much.
55:24And it affects us, but he'll be fine.
55:27It's just we can't film anything, so it's just a matter of waiting now.
55:32After tracking him in the rain for ten days, there's a break in the weather and Hank starts hunting again.
55:38He chooses a position for an ambush in a very accessible spot.
55:43The team has another chance to use their remote cameras, this time operating in night vision.
55:49James, just be careful where you come in. Don't go that way.
55:53I think that's the direction he's headed in.
55:55You've got something, have you?
55:57Um, mate, we've got him hitting a mouse in the middle of frame and swallowing it.
56:02This time, they get more than the strike.
56:07This time, Hank decides to eat his dinner very obligingly right in front of the camera.
56:13Mate, that is the most incredible piece of behaviour you've ever seen.
56:17So, after two weeks and a lot of effort, they succeed in capturing a crucial and intimate moment in the life of this very special snake.
56:28People don't automatically love snakes. Most of them don't.
56:31And yet, if you can show them things about the lives of these animals that impress them with the fact these are animals with complex daily activities.
56:39These aren't things that are waiting around for an opportunity to kill people.
56:42You tell people things like that, then they get drawn in.
56:46And hopefully, when we show them your films, they'll be drawn in.
56:49Well, you've drawn me in.
56:51Thank you very much.
56:52Pleasure.
56:54And when I get to see the footage, it's fair to say that I'm just as knocked sideways as the crew had been.
57:02Ah, there's the mouse.
57:06Oh, my goodness.
57:10Yes.
57:12That's a dead mouse, all right.
57:42I've gone on, on her cradle.
57:44Oh, my God.
57:45Yes.
57:49And I'm concise.
57:51OK.
57:52And since it'sully-cooked this town, I mean you can look like, voiceings themselves together.
57:54You can see them all who are building with them.
57:58Oh, my goodness.
57:59Ah, I mean that's my good Brother.
58:00Oh, my goodness.
58:01Oh, my goodness.
58:02Oh, my God.
58:03Let's go.
58:04To each other父.
58:05Oh, my God.
58:06Oh, my goodness.
58:07Oh, that's my goodness
58:08I mean you can find out всех that you couldn't like me so many words or you couldn't Вид.