Gov­ern­ment researchers have tagged 338 sharks with acoustic trans­mit­ters that mon­i­tor where the ani­mals are. When a tagged shark is about half a mile away from a beach, it trig­gers a com­put­er alert, which tweets out a mes­sage on the Surf Life Sav­ing West­ern Aus­tralia Twit­ter feed. The tweet notes the shark’s size, breed and approx­i­mate location.