They are filled with sensitive nerve endings, which help them detect distances and changes in their surroundings. When tigers hunt, they go for the kill shot: the carotid artery located in the neck. After the tiger’s canines have pierced the artery, the whiskers move forward, encircling the prey’s neck, and determine if the prey’s pulse is gone.
Correction: Contrary to what the Sierra article says, the nerve endings aren't in the whiskers but rather the hair follicles.
David Pescovitz is Boing Boing's co-editor/managing partner. He's also a research director at Institute for the Future. On Instagram, he's @pesco.