Puff adder ambush
With fangs that pack around twice as much venom as most rattlers, puff adders probably kill more people than any other African snake. Rodents are its favourite food, so villages can be the perfect hunting ground. Flicking its tongue to taste the air, the snake uses its fabulous sense of smell to follow the scent trail used by people and animals. They are most active at nightfall when they can go incognito. They seldom wriggle, preferring to crawl in a straight line. Inside, muscles anchored to the ribs pull the loose belly skin back and forth in waves across the ground. The overlapping scales slide smoothly forwards and then grip when pulled back like the tracks on a tank. The puff adder has excellent night vision, but its the sense of smell that allows it to home in on its victim. Rats leave a trail that the adders can follow and set up an ambush to wait. It can afford to be patient - a single rat dinner will last for a month. It seems odd for such a professional to lack a sense of hearing, but the snake has another way to detect vibration. With its head flat on the ground it can feel the patter of the rat's feet through its jaw bones. As the victim draws near, rapid tongue flicks confirm its identity. The viper's hinged fangs flip open at the last minute like tiny switch blades. Sharp as hyperdermic needles they squirt venom deep into the rat's body. Loaded with venom, the rat won't get far. The snake follows the victim's scent trai, but there's a new problem when it catches up to the dead rat. How can it swallow a meal that's twice the size of its head, without any cutting teeth or limbs to hold it steady? Snakes have four jaws, two above and two below, all with their own muscles so they move independently. Loosely connected with ligaments, they stretch apart to create a gape four times the normal size. Each fang works like a hook, spiking the rat's body and pulling it deep into the mouth. Once the jaws have done their work, the throat muscles take over.