Thresher sharks hunt schooling fish by bull-whipping their tails hard enough to maim and kill several prey at once.
Research published in the open access journal PLOS ONE describes the first observations of thresher sharks hunting in the wild. Thresher sharks are oceanic and pelagic and much of the knowledge of them to date is based on fisheries bycatch.
The study shows that thresher sharks initiate explosive shockwaves in the water column, which are lethal to schooling prey fish, by whipping their tails in a trebuchet catapult-like motion. The results provide an insight into the behavioural ecology and biology of a shark species, which urgently requires protection.
Dr Simon Oliver, founder of the Thresher Shark Research and Conservation Project and now at Liverpool University, undertook the research while at the School of Ocean Sciences, Bangor funded by a NERC Studentship supervised by Dr John Turner.
He said "This extraordinary story highlights the diversity of shark hunting strategies in an ocean where top predators are forced to adapt to the complex evasion behaviours of their ever declining prey. The study profiles new knowledge on sharks interacting with and adapting to their natural environment, and provides an informed basis for conservation management to protect these sites, which form part of their habitat."
The researchers tracked shark activity with handheld video cameras and analysed 25 instances of tail-slapping to stun prey. Sharks appeared to initiate the behavior by drawing their pectoral fins inward to lift their posteriors rapidly, followed by tail-slapping forceful enough to stun or kill several prey, and cause dissolved gases to bubble out of the water. After a successful tail-slap, thresher sharks ate up to seven fish at a time.
For large marine predators, being able to stun more than one prey at a time is likely to be a more efficient means to hunt than chasing after many small fish in a school. Dolphins and killer whales are known to use tail-slaps to control or stun prey, while humpback and sperm whales use tail-slaps to communicate at the surface over long distances.
For ore information see the paper: Thresher Sharks Use Tail-Slaps as a Hunting Strategy by Simon P. Oliver, John R. Turner, Klemens Gann, Medel Silvosa and Tim D’Urban Jackson.