They can live out here in the open ocean and 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. Most sea snakes like this bar-bellied species hunt fish. They have one of the most lethal venoms known which kills almost instantaneously. And that is a very important quality if you hunt fast-swimming ocean-going prey. But paradoxically the most highly specialized sea snake of all has abandoned venom altogether. It has a beak like a turtle and a wholly different way of feeding. Reef fish don't like to have it around. They mob it. It doesn't even retaliate. It's not interested in them. It's after their eggs. These the fish have stuck to the stony branches of the coral. The snake's hardened turtle-like top lip enables it to scrape them off. It's a slow-moving browser that algae and other small organisms grow on its skin as they do on the bottom of a boat. The loss of limbs could seem to be a handicap and certainly makes the snakes seem alien creatures to us. But 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. And it is that absence of limbs too which has enabled them to do it with such elegance and grace. Filming venomous snakes presented a lot of special problems to the Life in Cold Blood team but the toughest was trying to film rattlesnake hunting in the wild. A rattlesnake making a kill has rarely even been seen and never before filmed and for several reasons. For one thing rattlesnakes are so well camouflaged they're very difficult to find. We enlisted the help of snake expert Harry Greene and his team. They'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. Most of us will never find them and they're superbly camouflaged. Exactly but that's been one of the wonderful things about radio telemetry is we can have an animal that we can dial up.
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To have any chance of success the crew had to be able to find the rattlesnakes on their own. So producer James Brickell had to take a course in telemetry techniques himself. Hmm point it a little bit more this way. Each snake has been implanted with a tiny transmitter. If you dial its frequency you can pick up a beeping sound. And that gets louder the nearer you get to the snake. And so its just like if you were trying to find your favourite rock-and-roll station or something but now were gonna find our favourite rattlesnake. So you just punch in its number and it's on the air. It sounds simple in theory but there's a snag. Its here somewhere. Just are really careful guys. In a forest the signal can bounce off trees and give you a false reading so that it can seem that the snake is everywhere. And you don't want to think a reading is false and then tread on your snake by mistake. He's that way there? You'll find has up there somewhere. Let's find him. James it's starting to get dark. Yeah I know. He's in there. I reckon has hunting. James is careful where you're going. And it isn't just the one snake you're tracking. There are dozens of others in the area that aren't tagged. Follow my hand. There he is. Its about 20 feet. All right good. Six metres. And so at last the crew meets a very special snake called Hank. Hank is in a perfect position for his ambush. To film the action without disturbing him or his prey cameraman Mark MacEwen has fitted his camera with motion detectors from a burglar alarm. They will turn on the camera without anyone having to be here. So for the first time they set up their gear in front of a live snake . They could now leave Hank and track another of Harris snakes. So that means you know individual snakes over a long period of time. Do they differ very much? Absolutely. Now there are species differences so certain rattlesnake species are more sort of nasty-tempered than others. But 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.
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