Slideshow: Killer Whales Devise Lethal Splash to Catch Seals

Killer whales living off Antarctica have come up with an ingenious and deadly seal-hunting maneuver. After locating a seal loafing on an ice floe, groups of whales rush the floe, their tails pumping in sync to generate a wave that washes the seal into the water. If at first they don't succeed, the whales return relentlessly to deliver a barrage of waves—and they'll even reposition the ice floe or break it up to improve their odds of success. Once the hapless seal is in the water, the whales gang up to hunt it down, confusing it by blowing swarms of bubbles at it and dragging it below by its hind flippers until it's exhausted and drowns. Then, off they carry their catch to dismember it with remarkable precision and share it.

Researchers from the National Oceanic and Atmospheric Administration's Southwest Fisheries Science Center in San Diego, California, describe 22 wave-washing attacks in Marine Mammal Science. Only five instances of wave-washing had previously been documented, and researchers had presumed it uncommon. But the new paper reports that wave-washing appears to be the main hunting tactic of a group of whales the authors call "pack ice killer whales"—and is probably unique to them. In fact, it may be a defining feature of this group. In a 2010 paper, the authors and colleaguesdescribed genetic evidence suggesting that there are at least three distinct species of killer whales rather than just one, as had been supposed. Pack ice killer whales belong to one of the proposed new species.

These photographs show the pack ice killer whales' distinctive hunting behavior: how they spot a seal, how they wash it into the sea, and evidence of their extraordinary butchery. (Warning: Some images are graphic.)

  • sneaky peak
    Credit: Robert Pitman

    Sneaky peek. A pack ice killer whale "spy-hops"—raises it head to see what's going on above water—to scan the ice for seals.

  • predatory showdown
    Credit: Robert Pitman

    Predatory showdown. A pack ice killer whale spies a Weddell seal. Two other seal species living in the area are abundant and frequently preyed upon by different kinds of killer whales, but the researchers discovered that pack ice killer whales have a strong taste for Weddell seal.

  • Reading the menu
    Credit: Robert Pitman

    Reading the menu. Other members of the group come over to investigate.

  • Cooperative kill
    Credit: Robert Pitman

    Cooperative kill. The killer whale group gathers and swims in formation away from the seal.

  • Making waves
    Credit: John Durban

    Making waves. A group of killer whales charges a Weddell seal on an ice floe, their tails beating in unison to begin to form a wave. Blood on the ice suggests that this is not their first attack.

  • The deadliest splash
    Credit: Robert Pitman

    The deadliest splash. A wave crashes over the seal, washing it into the water, where the killer whales are waiting.

  • Closing the loop
    Credit: Robert Pitman

    Closing the loop. The killer whales move in immediately on the swamped seal as it tries to regain safety on the ice floe.

  • Last legs
    Credit: Robert Pitman

    Last legs. A killer whale takes the seal by the hind flippers, pulls it under, and drowns it.

  • Butcher shop
    Credit: Kathryn Jeffs

    Butcher shop. The authors were surprised by how precisely the whales had dismembered a kill they retrieved. The whales cut the skin and blubber around the waist, disarticulated the front flippers, and slit the skin behind the neck, drawing it over the head to reveal the skull (near the gas can).

  • Sealskin jacket
    Credit: Kathryn Jeffs

    Sealskin jacket. The whales went on to snip the seal's spine at the base of the skull and neatly slip the entire carcass out. "I couldn't have done better with [a] butcher knife," Robert Pitman, one of the authors, writes in an e-mail.

  • Death mask
    Credit: Kathryn Jeffs

    Death mask. The seal's head, after the authors pulled the skin back over it.

  • Chicken of the sea
    Credit: Elizabeth White

    Chicken of the sea. Killer whales appear to be picky eaters. In a 2010 paper, the authors described how a group they now believe is distinct from the pack ice killer whales often eats just the breast meat of penguins, discarding the leftovers, as they did with this chinstrap penguin.

  • Unhappy feet
    Credit: Robert Pitman

    Unhappy feet. A killer whale chases a live penguin, whose chest feathers it has stripped off in preparation for eating the breast muscles. Writes Pitman: "Killer whales must have prehensile tongues!"