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PHL shark uses built-in 'whip' to stun its prey

July 17, 2013 11:22am
Thresher shark in action
Thresher shark in action. A thresher shark (Alopias pelagicus) is filmed off the coast of Cebu, Philippines, using its distinctive long tail to "stun" its prey. Klemens Gann, via YouTube
These Pinoy sharks are in a league of their own.
 
Most sharks kill prey with powerful bites, but these sharks from the Philippines get the job done differently: by using their tails like powerful whips.
 
Researchers from the Philippines and United Kingdom observed these pelagic thresher sharks (Alopias pelagicus) at work  at Pescador Island.

"Thresher sharks employed tail-slaps to debilitate sardines at all times of day. Hunting events comprised preparation, strike, wind-down recovery and prey item collection phases, which occurred sequentially," they said in their paper on PLOS One.
 
Pescador is a small coral island in the Tañon Strait, about 5 km west from Moalboal, Cebu.

During their study, the researchers recorded 61 observations of 25 hunting events with a handheld underwater video camera between June and October 2010.


 
According to the researchers, the sharks performed tail-slaps "with such force that they may have caused dissolved gas to diffuse out of the water column forming bubbles."
 
They added the alopiids possess specialist pectoral and caudal fins that are "likely to have evolved, at least in part, for tail-slapping."
 
A separate article on Discovery News said the sharks ate an average of 3.5 sardines after each successful hunting event.
 
"Clearly this method works, and it’s more efficient than hunting fish one by one. Sardines are on the small side, so a predator could quickly run out of steam trying to chase a single fish, and then another and another," it said.
 
Scientific American added the thresher sharks managed to use the schooling defense against the fish – the tighter those sardines are packed in, the more casualties there are likely to be.
 
The researchers said their study was undertaken with the permission of the Governor of Cebu and adhered to the Philippine Wildlife Resources Conservation and Protection Act.
 
Tail-slaps for communicating too
 
Discovery News also said the tail slaps may also help sharks to communicate with each other, although that has yet to be proven.
 
It noted humpback and sperm whales slap their tails a lot, turning them into "a sort of oceanic Morse code to communicate over long distances." — TJD, GMA News
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