Non-lethal snakes just as swift Study finds ven­omous ser­pents no faster than oth­ers

Winnipeg Free Press - SundayXtra - - LIFE / SCIENCE - By Sean Greene

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 vipers aren’t nec­es­sar­ily the fastest snakes in the world. Non-ven­omous 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. By 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: six 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 the harm­less rat snakes struck just as fast as — if not faster than — the vipers across short dis­tances.

On av­er­age, the rat snakes ac­cel­er­ated to­wards their tar­get at a rate of 190 me­tres per se­cond squared, or 19 Gs. (A snake at rest ex­pe­ri­ences a force of just one 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 two to five Gs when tak­ing off from an air­craft car­rier. At about eight 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 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 non-ven­omous snakes, Pen­ning said. Pre­lim­i­nary ev­i­dence sug­gests 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 de­fences 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.”


A re­cent study found non-ven­omous snakes strike just as quickly as vipers or western di­a­mond-backed rat­tlesnakes (above).

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