Ken Catania and colleagues at Vanderbilt University in Nashville, Tennessee, used a hair to deflect the upper-lip tentacles of tentacled snakes (Erpeton tentaculatum), and recorded the resulting nerve activity. The tentacles proved to be exquisitely sensitive to even the tiniest deflection.
Mapping the path of the tentacle nerves showed that they feed into an area of the brain that processes sensory signals, close to where it responds strongly to visual signals. "This suggests that [the snakes] are putting the two parts of the information together," Catania says.
To test how well the snakes could hunt by either sense alone, the team put them in a tank with a clear bottom, through which they displayed a movie of cartoon fish swimming. The snakes struck at the fish accurately, suggesting they can capture prey using vision alone.
They were then put with live fish in a pitch-black tank, and filmed with an infrared camera. Although the snakes struck out less often, they could "strike at and capture fish swimming several centimetres from the head and tentacles", Catania says.
Catania suggests the tentacles may enable snakes to catch prey at night or in murky waters.
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