Moments before that, the seal was resting on an ice floe deep in one of the Antarctic channels (Antarctica). Then the heads of three orcas – known as killer whales – emerged, bobbing up and down. She was hunting. On this sea ice sheet, these seals, which weigh about 500 kilograms, are usually out of reach of most marine predators. But the orcas – a mother leader with her daughter and granddaughter – are three of about 100 known to have mastered a hunting technique called wave washing. The secret to the success of this technology lies in working collectively to turn water into a weapon. After killer whales determine their target, they form a battle line and begin rushing towards the ice sheet. Before reaching it, it turns on its sides in one synchronized movement, then dives under the water. This driving force creates a very strong wave that submerges the ice sheet, causing its surface to crack and the seal to lose its balance. These predators resume their attacks in a slow and organized manner. The ice becomes more broken. In the third attack, the wave throws the seal into the sea. It strives to climb onto a piece of ice, then disappears from sight as one of the killer whales grabs it from below. “It’s a scene full of wit and malice,” says wildlife filmmaker Bertie Gregory, who has spent a decade tracking these orca whales, known as B1, a group of killer whales that live among ice floes. The level of intelligence that goes into shaping each wave is “amazing,” he says. “It’s not random. They solve problems using very complex teamwork. They use water as a tool.” Sometimes, it only takes one wave, about five minutes, to drop a seal into the sea. Other times, a pod of whales can re-form waves 30 times; That is, what requires working for a period of time ranging between two and three hours, before obtaining the prey. Scientists rarely see failed hunts. “This behavior is not innate to these whales, they learn and perfect it over decades,” says Gregory. “Every time they make waves, it feels more like a learning experience than a hunt.” But as Antarctica warms and sea ice disappears, Weddell seals are spending more time on land, out of reach of killer whales. To track how B1 killer whales deal with their warming habitat, scientists counted their total number, which is approximately 100 whales. They found that this subgroup loses about 5 percent of its population each year; It is not known whether “it will become extinct or just adapt its behavior,” says Gregory. But as killer whales have fewer opportunities to make waves, “we are witnessing the extinction of a culture.”
