The sequence was filmed off the Philippines and analysed frame by frame. The shark approaches a school, pitches its body down, and throws the tail over the head in an overhead strike lasting a fraction of a second, with tail-tip speeds estimated near 80 kilometres per hour. Stunned or killed sardines then drift while the shark turns to collect them.
The strike does more than hit. The acceleration can drive dissolved gas out of solution, producing visible cavitation bubbles, and a single successful strike frequently disables more than one fish, which is why the tactic pays.
The filmed work was on the pelagic thresher, Alopias pelagicus, and the behaviour is inferred rather than filmed in equal detail for the common thresher, though tail-hooking in longline fisheries has long implied it. Threshers are Vulnerable globally, hurt by finning and by high post-release mortality after tail-hooking.