NARRATOR: What's more thrilling than a shark?
A mob of them.
Sharks might have invented crowdsourcing.
Every year between May and July, billions of migrating sardines
come to spawn off the coast of South Africa,
catering one of the largest feeding frenzies in the world.
Sharks make the guest list.
Hundreds of copper sharks swooping through
a dense oily cloud of fish.
[music playing]
The sardines try to thwart the attack
by banding together into a tight shimmering disco ball.
When a shark strikes, the sardines scatter and escape,
or at least that's the plan.
But the battle's not over.
While the sharks harass the sardines from below,
cape gannets mount an aerial attack.
Sharks and birds corner the little fishes,
benefiting them both.
[birds chirping]
Air trapped in their feathers hampers
the gannets' ability to dive deep,
so they have to strike hard.
They hit the water head first with arrow-like posture,
folding their wings behind them to minimize
the force of impact.
Besieged on all sides, the sardine defense starts to fail.
[music playing]
To make things worse, a Bryde's whale crashes the party.
Rising from the depths, this 15 ton giant devours
sardines by the thousands.
Even the copper sharks give this 50 foot behemoth a wide berth.
And then it's over as suddenly as it began.