0:00:02 > 0:00:03My name's Steve Backshall.
0:00:05 > 0:00:09And this is Deadly 60 On A Mission.
0:00:10 > 0:00:13My team and I are travelling the world
0:00:13 > 0:00:16in search of the planet's deadliest animals.
0:00:16 > 0:00:17Ho ho!
0:00:17 > 0:00:20I want to find out what makes them so deadly.
0:00:20 > 0:00:22That means getting close to them in the wild.
0:00:22 > 0:00:23Wow!
0:00:23 > 0:00:27Only the most lethal will make my list and in this series,
0:00:27 > 0:00:30we're going to show you my most extreme animal encounters.
0:00:30 > 0:00:33And you're coming with me every step of the way.
0:00:40 > 0:00:44This time on Deadly 60, we're in Costa Rica in Central America.
0:00:47 > 0:00:50This is one of the most biodiverse places on the planet.
0:00:50 > 0:00:53That means there's more species of plants and animals
0:00:53 > 0:00:55living here than anywhere else.
0:00:55 > 0:00:58We're going to be on the Pacific Coast.
0:00:58 > 0:01:01Where we're going is so remote, there's no roads at all.
0:01:01 > 0:01:03I think it's going to get a little bit bumpy.
0:01:05 > 0:01:08Getting there is half the fun, of course.
0:01:08 > 0:01:14But personally, I can't wait to get unloaded, into the forest and on the hunt for the Deadly 60.
0:01:16 > 0:01:20Located in the heart of Central America, Costa Rica has more
0:01:20 > 0:01:23than a third of its land covered in forest.
0:01:24 > 0:01:28It's home to hundreds of thousands of different species of plants
0:01:28 > 0:01:33and animals so my hopes of finding something really exciting are seriously high.
0:01:35 > 0:01:39But of course, it's the deadly ones that I'm after.
0:01:42 > 0:01:43If you've seen Deadly 60 before,
0:01:43 > 0:01:46you'll know I've got a thing for snakes
0:01:46 > 0:01:50so I've assembled a hit-list of Costa Rica's most incredible snakes.
0:01:50 > 0:01:53They're complex, they're fascinating and very, very different.
0:01:53 > 0:01:58All we need is to figure out which ones make it onto the Deadly 60.
0:01:59 > 0:02:02The first contender in our Costa Rican snake contest
0:02:02 > 0:02:04is the mighty boa constrictor.
0:02:05 > 0:02:08The largest snake in Central America,
0:02:08 > 0:02:10they can grow up to four metres in length.
0:02:10 > 0:02:13They kill their prey using constriction,
0:02:13 > 0:02:16crushing the life out of their victims.
0:02:16 > 0:02:18I'm hoping to show you just how that works.
0:02:23 > 0:02:28This three-metre snake had slithered into a local farmer's backyard.
0:02:28 > 0:02:31And unsurprisingly, he wanted it back in the wild.
0:02:31 > 0:02:35But before I release it, I want to experience first-hand
0:02:35 > 0:02:38the formidable power of this deadly predator.
0:02:39 > 0:02:41Snakes have to eat their prey whole,
0:02:41 > 0:02:44so a boa the size of this one couldn't eat me
0:02:44 > 0:02:47but it could still choke the life out of me.
0:02:48 > 0:02:50This magnificent creature...
0:02:50 > 0:02:53- SNAKE HISSES - 0oh!
0:02:53 > 0:02:55..is a boa constrictor.
0:02:55 > 0:02:59"Boa" refers to the group of snakes this belongs to.
0:02:59 > 0:03:02They're thick, heavy-bodied snakes.
0:03:02 > 0:03:05What I'd really like to do is to show you how it hunts.
0:03:05 > 0:03:10That's the constrictor bit. To do that, I'm going to need to get control of it.
0:03:10 > 0:03:12SNAKE HISSES
0:03:12 > 0:03:13Wow, listen to that hiss.
0:03:16 > 0:03:18You can see that it's not actually trying to bite me.
0:03:18 > 0:03:21Those strikes are just to try to frighten me away,
0:03:21 > 0:03:23as is the hissing sound.
0:03:23 > 0:03:26'Believe me, with all that solid muscle,
0:03:26 > 0:03:29'this isn't going to hurt the snake at all.'
0:03:29 > 0:03:31Right.
0:03:31 > 0:03:36So, if you look into the mouth, at those thin, needle-shaped,
0:03:36 > 0:03:40backward-pointing teeth, they're really vicious,
0:03:40 > 0:03:43designed for hooking into their prey.
0:03:47 > 0:03:48Right.
0:03:48 > 0:03:53Let's see if I can show you a little bit more about how this snake hunts.
0:03:53 > 0:03:57So now you can see quite a lot of the snake's bulk
0:03:57 > 0:04:00has gone straight around my neck.
0:04:00 > 0:04:03Around here is where my windpipe is,
0:04:03 > 0:04:06where air comes in and out of my lungs
0:04:06 > 0:04:11and also where the arteries are that carry blood to my brain.
0:04:11 > 0:04:13Now, as I breathe out...
0:04:19 > 0:04:22..the snake is very subtly
0:04:22 > 0:04:28increasing the pressure around my throat, as you can see.
0:04:29 > 0:04:33That's making it more and more difficult for me to breathe.
0:04:33 > 0:04:38And every time I breathe out, it just tightens a little bit more.
0:04:38 > 0:04:41Until eventually, I can't get any air
0:04:41 > 0:04:46in or out of my lungs and already at this stage,
0:04:46 > 0:04:51if I wasn't just to ease the pressure,
0:04:51 > 0:04:54I would be finding breathing very difficult indeed.
0:04:54 > 0:04:57This is what constricting means.
0:04:57 > 0:05:01If you see me starting to go blue or purple in the face,
0:05:01 > 0:05:03then I might need a little bit of help.
0:05:03 > 0:05:08Constructing basically means to strangle,
0:05:08 > 0:05:10to suffocate the life out of prey.
0:05:10 > 0:05:14And that's how this magnificent animal...
0:05:14 > 0:05:16HISSING
0:05:16 > 0:05:20..manages to kill the mammals it's feeding on.
0:05:20 > 0:05:25Its tail's going round the back of my neck now, it's just finding
0:05:25 > 0:05:29places and ways of getting purchase
0:05:29 > 0:05:33to use its really strong muscles in choking me.
0:05:33 > 0:05:38Now, we've only got quite a short time that I can show you this
0:05:38 > 0:05:41before I'll have to release myself.
0:05:41 > 0:05:46The amazing thing that happens next is that the boa constrictor
0:05:46 > 0:05:49will actually start to swallow its prey whole
0:05:49 > 0:05:55and to do that, it can open this mouth incredibly wide.
0:05:56 > 0:05:58GROANING Are you all right, Steve?
0:06:00 > 0:06:01Actually...
0:06:01 > 0:06:03Yeah...
0:06:03 > 0:06:05It's amazing how strong it is.
0:06:07 > 0:06:12I mean, this snake is only actually feeding on mammals
0:06:12 > 0:06:14about that sort of size, maximum,
0:06:14 > 0:06:18and it has the strength to choke the life out of me.
0:06:18 > 0:06:23I mean, I must be 10 times, 20 times the size of its normal prey
0:06:23 > 0:06:27and he easily has enough strength to choke me.
0:06:30 > 0:06:35There's no doubting this is an incredibly strong predator.
0:06:37 > 0:06:41I don't know, I think it's going to be very hard to beat.
0:06:41 > 0:06:43Can I take this off now, please?
0:06:43 > 0:06:46If I can get her off my neck.
0:06:53 > 0:06:54Wow.
0:06:58 > 0:07:01So, the boa constrictor is the muscle man
0:07:01 > 0:07:05of the snake world here in Costa Rica.
0:07:05 > 0:07:09Our next contender could not be more different.
0:07:09 > 0:07:13This is the wonderful eyelash pit viper.
0:07:15 > 0:07:18Even if you're someone who absolutely hates snakes,
0:07:18 > 0:07:23you'd have to admit that that is a really beautiful animal.
0:07:23 > 0:07:26But they're also very highly adapted hunters,
0:07:26 > 0:07:30and the clue to that is in their name - pit vipers.
0:07:30 > 0:07:34That doesn't mean, as I thought when I was a kid, that they live in pits.
0:07:34 > 0:07:37Actually what it's talking about is a tiny pit
0:07:37 > 0:07:39that they have between their nostril and their eye
0:07:39 > 0:07:42which is incredibly sensitive at picking up heat.
0:07:42 > 0:07:49I've got a special camera here, a nice little toy,
0:07:49 > 0:07:54which, hopefully, I can get close enough to show you that pit.
0:07:56 > 0:07:58Move carefully here.
0:07:58 > 0:08:04I don't want to have it strike at me.
0:08:04 > 0:08:07That's looking right down the heat-sensitive pit
0:08:07 > 0:08:10of the eyelash pit viper.
0:08:10 > 0:08:16Now, that pit works like a kind of sixth sense.
0:08:16 > 0:08:18It can actually pick up heat,
0:08:18 > 0:08:21and how that helps it hunting is that
0:08:21 > 0:08:25most of the animals it will feed on actually generate warmth
0:08:25 > 0:08:28in their muscles as they move, so even if it's completely dark
0:08:28 > 0:08:31it can build up a three-dimensional picture
0:08:31 > 0:08:33of anything it wants to hunt,
0:08:33 > 0:08:38just using those incredible heat-sensitive pits.
0:08:38 > 0:08:42Now, I've got a little Deadly 60 experiment,
0:08:42 > 0:08:46that I'm hoping will show you how those pits work.
0:08:46 > 0:08:48I've been dying to give this a go.
0:08:50 > 0:08:52Typical food for the eyelash pit viper
0:08:52 > 0:08:55would be something like a small mouse, perhaps a bat,
0:08:55 > 0:08:58they'll even catch hummingbirds on the wing.
0:08:58 > 0:09:01The core body temperature of a bird or a small mammal
0:09:01 > 0:09:05is around about 38 degrees, so what I have here is a balloon
0:09:05 > 0:09:08filled with hot water that's almost exactly that temperature.
0:09:08 > 0:09:11I'm going to move it in close to the viper,
0:09:11 > 0:09:15and, hopefully, I'll get it to strike towards the balloon.
0:09:15 > 0:09:18Here we've got our mini-cam set up and ready to record at high speed.
0:09:18 > 0:09:22That means that we should see the strike slowed right down
0:09:22 > 0:09:26and be able to really appreciate quite how awesome it is.
0:09:26 > 0:09:28Let's see what happens.
0:09:36 > 0:09:38That was amazing!
0:09:38 > 0:09:41What do you reckon, Nick, do you think you got it?
0:09:41 > 0:09:43Let's see.
0:09:50 > 0:09:51Incredible.
0:09:51 > 0:09:53Absolutely incredible.
0:09:53 > 0:09:57Saw the mouth open almost so it was fully wide like that,
0:09:57 > 0:10:00almost as if it was creating a stabbing kind of shape
0:10:00 > 0:10:03rather than a downward strike,
0:10:03 > 0:10:06and the fangs are almost used like daggers
0:10:06 > 0:10:08to pierce into the balloon.
0:10:08 > 0:10:10That was amazing.
0:10:11 > 0:10:15Can I have another go? Is that all right? I could do this all day long.
0:10:16 > 0:10:19The eyelash pit viper's venom is hemotoxic
0:10:19 > 0:10:23which means that it affects the blood and circulatory system
0:10:23 > 0:10:26causing almost instant death to small prey
0:10:26 > 0:10:30and severe pain, swelling and tissue damage in humans.
0:10:30 > 0:10:33Worryingly, these snakes occasionally end up
0:10:33 > 0:10:36in shipments of bananas to the UK.
0:10:36 > 0:10:41That's so perfect. You can see it resetting itself at the end.
0:10:41 > 0:10:45Letting the fang come back into position.
0:10:45 > 0:10:46Absolutely incredible.
0:10:46 > 0:10:51So two sublime undoubtedly deadly snakes so far.
0:10:51 > 0:10:55But Costa Rica is snake central so before I make my final decision,
0:10:55 > 0:10:58I have one more contender I have to include.
0:10:58 > 0:11:01The most feared snake in Central America.
0:11:02 > 0:11:05It's called the bushmaster
0:11:05 > 0:11:08and because of the sheer quantity of toxin it injects,
0:11:08 > 0:11:12it's considered to be the most venomous snake in the New World.
0:11:14 > 0:11:17The venom works so fast, it can stop a rat in seconds
0:11:17 > 0:11:19and could kill a man in minutes.
0:11:19 > 0:11:22But what makes the snake so intimidating is its camouflage.
0:11:22 > 0:11:28It's so good, you just wouldn't see it until it was too late.
0:11:28 > 0:11:32To prove it, a local snake expert is going to hide one
0:11:32 > 0:11:36and I'm going to try and find it before it finds me.
0:11:39 > 0:11:42I'm going to start looking around about here.
0:11:42 > 0:11:45The snake expert said that he's not going to put it
0:11:45 > 0:11:48too far off the side of the trail, it's going to be very close.
0:11:48 > 0:11:49So...
0:11:50 > 0:11:53Big heavy-bodied snake, they don't climb
0:11:53 > 0:11:54like the eyelash pit viper,
0:11:54 > 0:11:57they're always down on the ground.
0:12:03 > 0:12:05OK.
0:12:12 > 0:12:15Ah! I have it.
0:12:15 > 0:12:16OK.
0:12:16 > 0:12:20Oh, that is just amazing!
0:12:20 > 0:12:21OK.
0:12:21 > 0:12:25Now, I'm going to go in quietly and carefully so it doesn't move.
0:12:25 > 0:12:30And I think you'll have a lot of trouble spotting it.
0:12:33 > 0:12:35Right.
0:12:35 > 0:12:36OK.
0:12:36 > 0:12:39So, follow the end of my stick.
0:12:42 > 0:12:44That is its head.
0:12:45 > 0:12:47- Can you see that?- Yeah.
0:12:47 > 0:12:48Yeah?
0:12:51 > 0:12:54Just remarkable, the way that all those diamond patterns
0:12:54 > 0:12:56down the back and the stripe down the neck
0:12:56 > 0:13:00completely break up its outline and make it almost invisible.
0:13:00 > 0:13:02And this is exactly the kind of position
0:13:02 > 0:13:04the snake would just hang in,
0:13:04 > 0:13:08perhaps for days on end, waiting for a meal to come past.
0:13:09 > 0:13:13Right, let's get him out so I can show you him properly.
0:13:21 > 0:13:25Such a heavy-bodied, thick snake.
0:13:25 > 0:13:29And all of that weight is used to anchor it down as it strikes.
0:13:31 > 0:13:35Really heavily, what's called, keeled scales.
0:13:36 > 0:13:38Very dinosaur-like.
0:13:38 > 0:13:40And absolutely magnificent.
0:13:42 > 0:13:46Well, I have to say, I'm a little bit undecided.
0:13:46 > 0:13:49I think all three have been utterly magnificent.
0:13:50 > 0:13:51This is really tough.
0:13:51 > 0:13:55There's no doubt all three snakes deserve a place in the Deadly 60.
0:13:55 > 0:13:58The boa is by far the most powerful.
0:13:58 > 0:14:01The eyelash viper is accurate enough to catch hummingbirds on the wing.
0:14:01 > 0:14:05And the bushmaster has enough venom to bring down a buffalo.
0:14:05 > 0:14:06Three wondrous snakes.
0:14:06 > 0:14:09But on the day, it's the eyelash pit viper
0:14:09 > 0:14:13with the speed of its strike which has impressed me most.
0:14:14 > 0:14:18So fast they can catch a humming bird on the wing.
0:14:18 > 0:14:21With fierce hemotoxic venom
0:14:21 > 0:14:26and heat sensitive pits to enable it to hunt in pitch darkness.
0:14:26 > 0:14:29Eyelash pit viper could be the most striking snake
0:14:29 > 0:14:31on the Deadly 60.
0:14:31 > 0:14:34It's the perfect start. Now in our search
0:14:34 > 0:14:36for Costa Rica's deadliest,
0:14:36 > 0:14:38we're going to take a break from the jungle
0:14:38 > 0:14:41and head to an area used by cattle farmers.
0:14:43 > 0:14:46Locals report their livestock are under nightly attack.
0:14:48 > 0:14:50This is one of the cows
0:14:50 > 0:14:54that's been being preyed on by our deadly predator.
0:14:54 > 0:14:58You can just see here the evidence of the presence
0:14:58 > 0:15:01of our next deadly animal.
0:15:01 > 0:15:03This is all dried blood.
0:15:03 > 0:15:07It's been lapped up and then spilled down on to the fur.
0:15:11 > 0:15:15So, to find to the bloodthirsty creature responsible,
0:15:15 > 0:15:17we're going to enter a twilight world
0:15:17 > 0:15:18where few would choose to tread.
0:15:20 > 0:15:24So, just there ahead of us,
0:15:24 > 0:15:26that dark hole is a cave.
0:15:26 > 0:15:28And that's where we're heading.
0:15:28 > 0:15:30Watch your step, it's slippery.
0:15:31 > 0:15:34We're going underground to find a creature
0:15:34 > 0:15:39whose feeding habits strike fear deep in the human psyche.
0:15:40 > 0:15:42The cave is the perfect hiding hole
0:15:42 > 0:15:45for a particularly intimidating species of bat
0:15:45 > 0:15:48and is knee deep with the hundreds of years of their droppings.
0:15:55 > 0:16:00In the darkest corners of the cave, fluttering shapes catch my eye.
0:16:00 > 0:16:02Oh, lord, look at that!
0:16:04 > 0:16:06BATS SQUEAK
0:16:09 > 0:16:11Got one then?
0:16:11 > 0:16:12Yep, got one.
0:16:15 > 0:16:20So, what I have in this bag is an animal that's probably
0:16:20 > 0:16:25inspired more myth and legend than any other animal in the world.
0:16:25 > 0:16:27It's a vampire bat.
0:16:27 > 0:16:31They have also, possibly the sharpest teeth of any animal.
0:16:31 > 0:16:34Which explains why I'm wearing these thick gardening gloves
0:16:34 > 0:16:36before I think about trying to get it out.
0:16:36 > 0:16:40Last time I tried to do this it bit clean through the glove
0:16:40 > 0:16:42and into my finger.
0:16:44 > 0:16:46BAT SQUEAKS
0:16:46 > 0:16:48Oh!
0:16:51 > 0:16:54Right.
0:16:54 > 0:16:56OK, let's get you into a good position.
0:16:56 > 0:16:59BAT SQUEALS
0:16:59 > 0:17:00Whoa! Look at him whirling around
0:17:00 > 0:17:04to try and get his huge canine teeth into my fingers.
0:17:07 > 0:17:09OK.
0:17:09 > 0:17:14So, that is the face that all the fuss is about.
0:17:14 > 0:17:16The vampire bat.
0:17:17 > 0:17:22So, up above me now is a roost of about 30 or 40 vampire bats.
0:17:22 > 0:17:26And at night, they'll take wing
0:17:28 > 0:17:33using that remarkable wing membrane
0:17:33 > 0:17:37and fly out in search of a warm blood meal.
0:17:44 > 0:17:47They use the ridiculously sharp teeth
0:17:47 > 0:17:49at the front of the mouth here.
0:17:49 > 0:17:51I don't my finger too close
0:17:51 > 0:17:53cos I know I'm going to get bitten on camera!
0:17:53 > 0:17:57But they shave away a portion of hair from the animal
0:17:57 > 0:17:59that they're going to be feeding on
0:17:59 > 0:18:01and then bite a tiny hole
0:18:01 > 0:18:03and lap away at the blood that leaks out.
0:18:03 > 0:18:06Their saliva keeps the blood flowing,
0:18:06 > 0:18:08it's what is called an anti-coagulant.
0:18:09 > 0:18:13They know exactly where to bite, using their sensitive noses
0:18:13 > 0:18:18to pinpoint where the blood flows closest to the surface of the skin.
0:18:18 > 0:18:20They take in about a soup spoon of blood,
0:18:20 > 0:18:22which doesn't sound like much
0:18:22 > 0:18:25but when you look at the size of this tiny bat,
0:18:25 > 0:18:29actually, for its body weight, that's an enormous meal.
0:18:31 > 0:18:34While it might seem everything about vampire bats
0:18:34 > 0:18:36is just a bit grim and grotesque,
0:18:36 > 0:18:39amongst themselves, they're really quite thoughtful creatures.
0:18:39 > 0:18:42In fact, if they come back from having got a really good meal
0:18:42 > 0:18:45and there's another bat that hasn't managed to feed,
0:18:45 > 0:18:49one of these guys will actually regurgitate their blood meal
0:18:49 > 0:18:52and give some to the other bat.
0:18:52 > 0:18:53They look after each other.
0:18:55 > 0:18:59So, vampire bats they may be the creature of nightmares
0:18:59 > 0:19:02but with possibly the sharpest teeth in the whole animal kingdom,
0:19:02 > 0:19:06I reckon they're worth a place on the Deadly 60.
0:19:09 > 0:19:11He's not on my back, is he?
0:19:13 > 0:19:16With the sharpest teeth in the world,
0:19:16 > 0:19:19centres in their nose help them pick the best place to bite,
0:19:19 > 0:19:25they consume a third of their body weight in blood at every meal.
0:19:25 > 0:19:29Vampire bats are on my deadly list.
0:19:32 > 0:19:36We're heading back into the jungle for my next deadly creature.
0:19:36 > 0:19:38In some parts of Costa Rica
0:19:38 > 0:19:40they get four metres of rain a year.
0:19:40 > 0:19:43Which creates the perfect conditions for something tiny
0:19:43 > 0:19:46but utterly and completely lethal.
0:19:46 > 0:19:50In fact, just one could kill the entire crew.
0:19:50 > 0:19:52But its identity might surprise you.
0:19:54 > 0:19:58The most poisonous creature in the world by some distance
0:19:58 > 0:20:01is a tiny frog no bigger than the end of my thumb.
0:20:01 > 0:20:03They're called poison dart frogs
0:20:03 > 0:20:06and a particularly beautiful variety is found right here.
0:20:07 > 0:20:10Poison dart frogs secrete poison onto their skins.
0:20:10 > 0:20:12When Colombian Indians are hunting,
0:20:12 > 0:20:16they wipe their blowpipe darts on the back of the frog.
0:20:16 > 0:20:19Any animal they hit with their dart will be dead within minutes.
0:20:19 > 0:20:22These technicoloured amphibians
0:20:22 > 0:20:26come in an array of different bright colours, warning how dangerous they are.
0:20:30 > 0:20:33No, there's three - there's three in there.
0:20:36 > 0:20:38Now, I've made sure that I've washed my hands,
0:20:38 > 0:20:43because these frogs are very, very sensitive in the skin...
0:20:46 > 0:20:51..and you don't want any insect repellent or anything hurting them.
0:20:52 > 0:20:58Most people are absolutely blown away, the first time they see a dart frog, about how small they are.
0:20:58 > 0:21:05It's incredible to think that an animal this size can be the most poisonous on the planet.
0:21:05 > 0:21:08Those bright, bright colours are part of the reason that this frog
0:21:08 > 0:21:10is actually found active during the day.
0:21:10 > 0:21:13Every other frog around here comes out at night.
0:21:13 > 0:21:16It's deafening with the calls of frogs.
0:21:16 > 0:21:18But these dart frogs can be active during the day
0:21:18 > 0:21:22and they're brightly coloured because they know that predators
0:21:22 > 0:21:27are going to see these colours and know it means just one thing - this is highly poisonous
0:21:27 > 0:21:29and certainly not going to be good to eat.
0:21:29 > 0:21:34So the poisons that are created by this little frog
0:21:34 > 0:21:37are one of the absolute miracles of nature.
0:21:37 > 0:21:39They start off in the leaves of plants.
0:21:39 > 0:21:42Ants eat the leaves, frogs eat the ants,
0:21:42 > 0:21:46and then they almost sweat the poison out on their skin.
0:21:46 > 0:21:48There's one particular species of dart frog,
0:21:48 > 0:21:51about the same size as this. It's found in Colombia
0:21:51 > 0:21:55and it has enough poison in its body to kill ten people.
0:21:55 > 0:21:58That's pretty incredible.
0:21:59 > 0:22:03This tiny little animal is a living chemical weapons factory
0:22:03 > 0:22:07and for that reason alone, it's got to go on the Deadly 60.
0:22:07 > 0:22:12The dart frog produces the world's most powerful poison.
0:22:12 > 0:22:14It's vibrant colours warn off predators
0:22:14 > 0:22:18and just one frog could kill ten humans.
0:22:18 > 0:22:20Small but utterly deadly.
0:22:25 > 0:22:27Before I leave Costa Rica,
0:22:27 > 0:22:30there's one final creature I want to put on my list
0:22:30 > 0:22:33and...it's a bit of a monster.
0:22:35 > 0:22:40It can grow up to six metres long and weigh in at a staggering 1,000kg.
0:22:42 > 0:22:45This area is infested with them.
0:22:48 > 0:22:50They're most active at night
0:22:50 > 0:22:53and I'm starting my search on a beach near our camp.
0:23:02 > 0:23:05Wow!
0:23:05 > 0:23:07Look at that!
0:23:10 > 0:23:14Wow! What a magnificent creature.
0:23:14 > 0:23:17Right down at the surf.
0:23:17 > 0:23:20This is an American crocodile.
0:23:20 > 0:23:22Isn't it wonderful?
0:23:22 > 0:23:23Still comparatively young.
0:23:23 > 0:23:26It's probably only about... I guess, two years old.
0:23:26 > 0:23:33But still you can see the power that makes it such a formidable predator.
0:23:33 > 0:23:35Look at those teeth!
0:23:35 > 0:23:42They actually...overlap the jaw so that it can't actually completely shut its mouth and hide its teeth.
0:23:42 > 0:23:44You still see them bristling from the mouth.
0:23:44 > 0:23:48And those are used almost like a trap for catching fish.
0:23:48 > 0:23:51And when it gets bigger they'll also catch large mammals,
0:23:51 > 0:23:53even things as big as deer.
0:23:53 > 0:23:58And every once in a while, big American crocs have been known to take people.
0:23:58 > 0:24:03But at this size...well, I don't think he's any danger to me.
0:24:03 > 0:24:06But absolutely glorious.
0:24:07 > 0:24:11I would love to put American crocodiles onto the Deadly 60
0:24:11 > 0:24:14but to do that, I think I'm going to have to find something
0:24:14 > 0:24:16a little bit bigger.
0:24:16 > 0:24:18Come on, fella.
0:24:27 > 0:24:32There are definitely some bigger ones around, so the hunt is on.
0:24:32 > 0:24:35What makes these crocs so capable is that they're adaptable,
0:24:35 > 0:24:38at home exploiting both freshwater and sea.
0:24:42 > 0:24:45I have a plan to entice what I hope will be a large adult
0:24:45 > 0:24:50out of hiding and onto my Deadly 60 list.
0:24:52 > 0:24:56Did you see that lightning?
0:24:56 > 0:24:59Crocs have well-developed senses of hearing and smell
0:24:59 > 0:25:03and can also pick up vibrations of struggling prey in the water.
0:25:03 > 0:25:05Let's see if they'll sense my fish bait.
0:25:05 > 0:25:08This is absolutely extraordinary.
0:25:08 > 0:25:12There's a massive American crocodile...
0:25:12 > 0:25:15just zeroing in on my bait.
0:25:18 > 0:25:20I should explain that there's no hook on this line.
0:25:20 > 0:25:23It's just a piece of fish tied onto a rope,
0:25:23 > 0:25:26so there's no way that it can hurt the croc if it decides to go for it.
0:25:26 > 0:25:31In actual fact, all he's going to get is a free meal.
0:25:31 > 0:25:33He's just there.
0:25:33 > 0:25:35He's got it! He's got the fish!
0:25:35 > 0:25:36He's got the fish.
0:25:36 > 0:25:38Come on then, big fella.
0:25:38 > 0:25:40Come on.
0:25:40 > 0:25:42Let's get a look at you.
0:25:46 > 0:25:49Whoa! That's some strength!
0:25:49 > 0:25:51Look at that.
0:25:51 > 0:25:54Ah-ha-ha-ha!
0:25:54 > 0:25:56Oh!
0:25:56 > 0:25:58Slipping around in the riverside mud,
0:25:58 > 0:26:00you can see why crocs are so deadly.
0:26:00 > 0:26:03Even when I'm out of the water on the riverbank,
0:26:03 > 0:26:06he still has the upper hand.
0:26:06 > 0:26:09Just when I think my job can't get any weirder,
0:26:09 > 0:26:12I end up fishing for crocs in an electrical storm.
0:26:12 > 0:26:14Madness.
0:26:18 > 0:26:21He is the master of these murky waters
0:26:21 > 0:26:25and I certainly wouldn't fancy swimming in there.
0:26:25 > 0:26:28Crocodiles probably have the most powerful bite in the world,
0:26:28 > 0:26:3112 times stronger than a great white shark.
0:26:33 > 0:26:38Oh, that's strong. That is so strong.
0:26:41 > 0:26:45Because the tail is paddle shaped,
0:26:45 > 0:26:49it gives them great power through the water when they need it.
0:26:50 > 0:26:57Which isn't often, because most of the time is spent almost motionless.
0:26:57 > 0:26:59Our last fish.
0:26:59 > 0:27:04This is our last chance for an encounter with this magnificent living dinosaur.
0:27:07 > 0:27:11There he is.
0:27:11 > 0:27:15Though the American crocodile is primarily a fish feeder,
0:27:15 > 0:27:21a big croc like this could easily take decent-sized mammal prey.
0:27:23 > 0:27:26Or chug back a huge fish in one gulp.
0:27:28 > 0:27:31Effortless. Just effortless.
0:27:33 > 0:27:37That's not just one of the most deadly predators in Costa Rica -
0:27:37 > 0:27:41that's one of the most deadly predators in the world.
0:27:43 > 0:27:46They've been around since before the dinosaurs,
0:27:46 > 0:27:51they grow and replace up to 3,000 teeth in their lifetime,
0:27:51 > 0:27:54reach an enormous six metres in length.
0:27:54 > 0:27:57American crocodiles are definitely...
0:27:57 > 0:27:58WHISPER: Deadly!
0:28:01 > 0:28:03So my trip has given us a huge haul
0:28:03 > 0:28:06of fascinating and formidable creatures,
0:28:06 > 0:28:09from but hugely powerful croc...
0:28:09 > 0:28:12to the lethally-fast eyelash pit viper.
0:28:12 > 0:28:15And from the phenomenally-toxic poison dart frog
0:28:15 > 0:28:18to the sharp-toothed vampire bat.
0:28:19 > 0:28:22Costa Rica has certainly lived up to expectations.
0:28:22 > 0:28:26So join me next time for some more of the planet's Deadly 60.
0:28:36 > 0:28:39Subtitles by Red Bee Media Ltd
0:28:39 > 0:28:42E-mail subtitling@bbc.co.uk