Rattlesnakes feel the final bite

Science News, March 14, 1998 by Susan Milius

Movies of rattlesnake strikes don't leave much time for popcorn. The snake can zap a lethal dose of venom into its scurrying victim, then jerk its head away in about half a second.

Yet in these shortest of movie shorts, the snakes display impressive accuracy, says Kenneth V. Kardong of Washington State University in Pullman. He and Vincent L. Bels of the Agronomic Center of Applied Research in Hainaut, Belgium, analyzed the strike motion in movies of northern Pacific rattlesnakes biting mice. The results appear in the Feb. 18 Journal of Experimental Biology.

In 20 out of 21 bites, the snakes landed a lethal strike on the first try "They're really very good," Kardong says.

The snakes' sense of touch may play a role in that accuracy by guiding final adjustments, he suggests. Kardong did not see any midair, midstrike swerves that might have corrected the rattlers' course, although some other snakes do alter the trajectory of their heads as they strike. What he saw instead were shifts in fang position for optimal venom injection after the snake touched its victim.

The use of touch intrigued another maker of bite movies, William K. Hayes of Loma Linda (Calif.) University. "I don't think, we've appreciated the importance of tactile stimuli," he says.