Two scientists from the federal research center in La Jolla have documented killer whale behaviors such as cooperative hunting and prey-handling that rarely have been seen before. Their work in the Antarctic is being featured in National Geographic and a new BBC special called "Frozen Planet."
A newly released scientific journal paper by Robert Pitman and John Durban for the first time publishes the results of a directed study on the feeding habits of pack ice killer whales near the South Pole. They work at the Southwest Fisheries Science Center, an outpost of the National Marine Fisheries Service. The agency's science programs are designed to improve understanding and management of the world's oceans.
Pitman and Durban tracked the enigmatic black-and-white creatures in the Antarctic during January 2009, and their recent paper in the journal Marine Mammal Science describes new or refined insights into killer whale behavior. It was the first focused study of orca feeding in the Antarctic.
It says whales hunt in packs and routinely use their huge bodies to create waves that wash seals off floating patches of ice or break the ice into smaller pieces so the prey is more vulnerable to another attack.
Once seals were forced into the icy water, the whales worked as a team to keep it from escaping. For instance, they seemed to try to confuse the seal by creating water turbulence with their flukes and blowing water through their blow holes.
Orcas also seem to discriminate between types of prey. “These killer whales would identify and then attack Weddell seals almost exclusively, even though they made up only about 15 percent of the available seal population,” Pitman said.
The killer whale -- known as Orcinus orca by scientists -- occurs in all the world's oceans and may be the most widespread vertebrate on earth. It's considered to be a single species worldwide but research by the fisheries service in Antarctic waters shows there are at least three different-looking forms or "ecotypes" of killer whales that appear to target Minke whales, ice seals and fish, respectively. Recent genetic work suggests that these represent at least three different species.
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