They say to kill a rattlesnake, just shoot in its general direction and it'll intercept the bullet, inadvertently killing itself.
The lunging movements of rattlesnakes and other vipers have been described as "lightning fast" and the "fastest strike on the planet." The G forces they employ to capture their food would be enough to cause even experienced jet pilots to black out.
But some of the conventional wisdom about the speed of viper strikes may not be entirely correct, new research reveals. It turns out that vipers aren't necessarily the fastest in the world. Nonvenomous snakes can move just as fast.
Snakes rely on their ultra-quick ability to strike in order to eat and to defend themselves. When necessary, they can hit a target in as little as 50 to 90 milliseconds. For the sake of comparison, a blink of an eye takes 202 milliseconds.
"It's such a cheesy sentence but it's literally true: They strike within a blink of an eye," said David Penning, who studies functional morphology at the University of Louisiana at Lafayette.
Penning, a graduate student, was trying to see how a snake's size affected its ability to strike. One day, undergraduate researcher Baxter Sawvel clocked a harmless Texas rat snake striking with similar speed to what they'd expect of a viper. Surprised, they ran the test again and again and soon a new question emerged: Are vipers really the fastest snakes?
To find out, Penning and his colleagues tested the reflexes of 14 Texas rat snakes and snakes from two venomous species: 6 western cottonmouth vipers and 12 western diamond-backed rattlesnakes.
The snakes were filmed with a high-speed video camera as they lashed out at a waving glove stuffed with paper towels or foam, meant to elicit a defensive response. (The lab's venomous snakes still have all their fangs and venom glands, so Penning had to build a special case to make sure they couldn't escape.)
It turns out that the harmless rat snakes struck just as fast as – if not faster than – the vipers across short distances.
On average, the rat snakes accelerated toward their target at a rate of 190 meters per second squared, or 19 Gs. (A snake at rest experiences a force of just 1 G.) The cottonmouths and rattlesnakes were slightly slower, with average accelerations of 173 m/s2 and 169 m/s2, respectively.
The single fastest snake in the experiment was a rattlesnake, but it didn't win by much. Its strike hit 28 Gs, but a rat snake followed closely with 27 Gs.
These are G-forces that would make lesser animals – including humans – pass out. Fighter jet pilots experience a mere 2 to 5 Gs when taking off from an aircraft carrier. At about 8 Gs, pilots wearing protective suits lose the ability to move their limbs; at 10 to 15 Gs, even the best pilots start to lose vision.
The snakes not only maintain consciousness, they also show some degree of control as they ready an attack. And while more tests are needed to find out how exactly they do this, it's possible the short duration of the strike prevents injury to the critter.
People seem to have a built-in assumption that vipers are especially quick, but there's no reason for this, Penning said.
Rat snakes and rattlesnakes alike want to catch the same types of food, so they use similar means to close the distance between predator and prey.
And rat snakes don't seem to be special among nonvenomous snakes, Penning said. Preliminary evidence suggests that several other species are capable of moving as fast as vipers, too.
"Prey aren't just passively waiting to be eaten," Penning said. "They have their own defenses and lives. They don't care what kind of snake you are. They just don't want to get caught."
The strike is over before most mammals can muster a startle response or jump out of the way.
That goes for humans as well.
"Our startle response time is pathetically slow compared to a snake's ability to strike," Penning said. "You should just never mess with a venomous snake in the wild.
"You won't be able to grab it before it's able to do something back and that 'something back' is a hospital visit, or worse."
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