Sardines are helpless in the wake of a shark's paralyzing whip. Previous research has suggested that pelagic thresher sharks (Alopias pelagicus), 3-meter-long sharks found in the Indian and Pacific Oceans, slap their long, scythelike tails with enough force to stun and kill multiple fish at a time. But until now, the actual motion of this hunting strategy was not well understood. In a study published online today in PLOS ONE, scientists used underwater video cameras to record 25 hunting events in the waters near Pescador Island in the Philippines. The team analyzed the videos in the lab and characterized the sharks' overhead tail slaps into four phases: preparation, strike, wind-down recovery, and prey item collection. The tail strikes began with the shark lunging forward near its prey and then slinging its back fin up over its body toward the snout, producing a slap (seen in the video above). The team also found that the preparatory lunge was much longer than the other phases, allowing the sharks to build up the momentum to catapult their tails up over their backs. For hunting schools of small prey, this tail-slapping strategy proved to be more efficient than chasing down the fish individually.