By Terry Rodgers

UNION-TRIBUNE STAFF WRITER

November 30, 2005

Marine biologist Robert Pitman spends summers in Antarctica shooting darts at killer whales. Fortunately for him, the black-and-white behemoths don't seem to mind. When Pitman isn't pricking his subjects to obtain tissue samples the size of a pencil eraser, he's photographing the whales as they swim up cracks and channels in the Antarctic ice.

The La Jolla-based researcher is chasing down a scientific mystery: Is there more than one species of killer whale? Pitman suspects there may be two unrecognized species of killer whale that inhabit the frigid but fertile waters of the Antarctic Ocean. Russian scientists were the first to notice the differences in killer whales, but no one has completed detailed studies to confirm those findings.

The National Geographic Society's Committee for Research and Exploration has given $30,000 to Pitman and two of his colleagues to pursue their goal of documenting the potentially new whale species.

The grant will pay for about a dozen satellite tracking devices that will tell scientists where the killer whales go during the dark Antarctic winter.

(When it's summer in Southern California, it's winter in Antarctica.)

Pitman, who will return to Antarctica in January with fellow researchers Wayne Perryman and Rick LeDuc, will try to attach the tracking "tags" to the whales' dorsal fins using a special pole.

The two possibly new species of killer whale are smaller than the recognized species, which roams the sea worldwide and migrates to Antarctica to feed on minke whales. One of the prospective new species feeds mainly on seals, Pitman said. A second type feeds primarily on Antarctic toothfish.

The seal-eating variety has developed sophisticated techniques for knocking its prey off the ice. These killer whales swim under small ice floes and tip the surface, causing the seal to spill into the water. They also gather in small groups, then swim fast and turn to create waves that knock seals off the ice.

"By and large, they prey on intelligent mammals, so they have to be smarter than their prey," said Pitman, who works for the National Oceanic and Atmospheric Administration. "They are so interesting to study."

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Terry Rodgers: (619) 542-4566; terry.rodgers@uniontrib.com