Moments ago, a seal was resting on a piece of floating ice deep in an Antarctic channel. Then three hungry killer whales appeared. When the seal noticed them, it was already surrounded.
On this sheet of sea ice, the nearly thousand-pound sea l would be unreachable for most of his enemies in nature. But these killer whales had mastered a hunting technique called wave washing: working together to turn water into a weapon.
Having identified their target, the killer whales formed a battle line and started rushing toward the ice. Just before reaching it, they rolled to their sides in a single, synchronized(同步的)motion. The wave they created was so powerful that it flooded the ice sheet and washed the frightened seal close to the edge of the ice sheet. Slowly and methodically, they repeated the attack. At the third time, the wave sent the helpless seal flying into the sea. It struggled to climb onto a piece of ice, but then disappeared from view...
"The level of intelligence that went into making each wave was staggering. They solved the problem with very complex teamwork. They used water as a tool," said wildlife filmmaker Bertie Gregory, who had spent a decade tracking those killer whales, known as Bls. "I rarely saw failed hunts. This behavior was not what they were born with. It was learned and mastered over decades. Every time they made waves, it almost felt like more of a teaching experience than hunting. It was terrifying to watch."
But as Antarctica warms and sea ice disappears, seals are increasingly staying on land, out of killer whales' reach.
"I've found Bls are losing about 5 percent of their population every year. Whether this subgroup will go extinct or just adapt their behavior, I don't know," said Gregory. "But with fewer opportunities for the killer whales to wave wash, I'm seeing an extinction of a culture."
