When summer descends on the Antarctic, the sea ice breaks into chunks called pack ice. Seals often haul themselves up onto them, but they’re not a safe place to rest—not if a pack of killer whales finds you.
Killer whales are top predators with complex social relationships, so they hunt in groups, and they hunt well. In 2009, Dr Robert Pitman and Dr John Durban, marine scientists at NOAA, studied the whales’ extraordinary hunting tactic called “wave-washing” with a crew filming the documentary Frozen Planet, off the western Antarctic Peninsula.
Here’s how it went down: The whales line up, sometimes seven abreast, and charge towards the ice floe where the poor seal is stranded. Then, as they dive under it, they work together to kick up their tails and create a wave that rushes over the ice. The whales repeats this an average of four times before the terrified seal is eventually knocked off, then they work to corner it, blowing bubbles and creating turbulence to create confusion, before finally drowning it.
The researchers also found that the killer whales actually skin and dissect their prey underwater before dividing it up between the group.
Previous research has shown that there are at least four distinctive types of killer whale living in the Antarctic, all with different colourings and behaviours, and this particular population is referred to as “pack ice killer whales.” These different groups don’t seem to mix even though their territories overlap, so more research needs to be done to see if they’re separate species of just different subspecies.