Top Story: August 5, 2013

Thresher Shark Tail-Slap

thresher shark, shark week, divers, tail, hunt, behavior, thresher shark research and conservation project, activity, research, sardines, tail-slap

By Alyssa Keimach

Is it just Shark Week, or did thresher sharks get smarter?

Divers off the coast of Cebu, an island in the Philippines, called Simon Oliver when they noticed sharks exhibiting some strange behavior.

Oliver, an expert on these sharks since he began studying them in 2005, dropped everything to see what all the fuss was about. Apparently they were using their tails to hunt—strange behavior because it was thought that only smart mammals like dolphins and whales practiced tactical use of the tail fin.

Equipped with underwater camera equipment, the Thresher Shark Research and Conservation Project set out to film the new shark activity. They captured footage of 25 hunting events, then went back to the lab to analyze the videos.

The researchers found that the sharks hunt schooling sardines using a four-step procedure. This way, instead of collecting just one fish in their mouth per hunting event, they first stun the fish to eat an average of 3.5 sardines.

Thresher sharks’ tails comprise about 50% of their total length, which is particularly impressive for the 20-foot, 1,000-pound individuals. A sardine lucky enough to survive its initial fear would witness an incredible “tail-slap,” only to die or become stunned shortly after.

First the shark prepares. This preparatory lunge lasts longer than the other three phases, allowing the shark to perform some advanced physics calculations in order to determine tail velocity needed based on mass… Just kidding, they aren’t that smart! The shark then strikes, recovers briefly, and collects its prey.

“This extraordinary story highlights the diversity of shark hunting strategies in an ocean where top predators are forced to adapt to the complex evasion behaviors of their ever declining prey,” said Oliver.

These sharks had been studied previously, but Oliver thinks that lack of food has caused the sharks to hunt near the surface, finally giving humans a glimpse of their unique hunting techniques.

The footage is pretty incredible, and you can check it out here!

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

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