thresher2

Video screen grab showing hunting thresher shark

It has for years been suspected that thresher sharks use their long, scythe-like tails to slap and stun small fish before feeding. But the pelagic sharks are elusive and extremely difficult to study.

However, this week a study published by PLOS ONE revealed rare and vivid footage of thresher sharks hunting sardines in the Philippines. (The video has been shortened to begin at 50 seconds. Viewers can click here to view full version.)

http://www.youtube.com/watch?feature=player_profilepage&v=QhG84R3zBio#t=50s

The study footage is said to be the first showing the hunting methods of pelagic thresher sharks. The footage was captured in 2010, but held until publication of the paper “Thresher Sharks Use Tail-Slaps as a Hunting Strategy.”

The collaborative study involved Simon P. Oliver, John R. Turner, Klemens Gann, Medel Silvosa, and Tim D’Urban Jackson.

The footage was captured off Pescadore Island, which is rich in marine life and a known hunting ground for thresher sharks, which boast tail fins that are often as long as their bodies, and small mouths designed for eating small fish such as sardines and anchovies.

thresher3

Video screen grab

The maximum reported length of a thresher shark is nearly 25 feet, but that includes the tail fin.

Though elusive in terms of scientific study, the sharks are targeted by recreational and commercial fishermen, and are widely caught by longline gear.

The video shows threshers participating in each of the various stages of hunting: preparation, winding up, striking, recovering their position, and collecting fish or fish scraps.

Scientists used 61 observations, captured via handheld video cameras, between June and October in 2010, in their study.

A snippet from the paper’s abstract:

“Tail-slaps occurred with such force that they may have caused dissolved gas to diffuse out of the water column forming bubbles.

 

“Thresher sharks were able to consume more than one sardine at a time, suggesting that tail-slapping is an effective foraging strategy for hunting schooling prey.

 

“Pelagic thresher sharks appear to pursue sardines opportunistically by day and night, which may make them vulnerable to fisheries.”

Even if scientists, fishermen, and divers have strongly suspected that these unique predators hunt with their tails--this event, most likely, has never been witnessed. Now there’s empirical video proof.

And that, shark fans will agree, is pretty cool.