Reporting from Orlando, Fla. — Neuroscientist Lori Marino and a team of researchers explored the brain of a dead killer whale with an MRI and found an astounding potential for intelligence.
Killer whales, or orcas, have the second-biggest brains among ocean mammals, weighing as much as 15 pounds. It's not clear whether orcas are as well-endowed with memory cells as humans, but scientists have found they are amazingly well-wired for sensing and analyzing their watery environment.
Scientists are trying to better understand how killer whales learn local dialects, teach one another specialized methods of hunting and pass on behaviors that can persist for generations -- longer, possibly, than in any other species except humans.
Researchers have yet to find evidence that an orca in the wild has killed a person. But they aren't surprised that the world's biggest, most powerful and possibly smartest predator, captured and kept for years in a tank and cut off from the influences of an extended family, could have an encounter fatal for a human.
Human interaction with captive killer whales has come under increased scrutiny since Feb. 24, when a large male orca with a checkered past killed a trainer at SeaWorld Orlando by dragging her into a tank.
"I'm not trying to second-guess what was in this particular whale's mind," said Marino, part of the Neuroscience and Behavioral Biology Program at Emory University in Atlanta. "But, certainly, if we are talking about whether killer whales have the wherewithal and the cognitive capacity to intentionally strike out at someone, or to be angry, or to really know what they are doing, I would have to say the answer is yes."
At least three distinct orca populations swim the world's oceans, and they are more widely distributed than any whale, dolphin or porpoise. Fish-eating orcas stay in one area, flesh-eaters wander more widely along coasts, and a third group roams the deep-blue waters.
The three groups have starkly different diets, languages, hunting techniques and manners of behaving around other marine life, and they don't seem to interact much with one another.
"If they didn't have the same paint jobs, you'd call them different species," said Brad Hanson, a National Oceanic and Atmospheric Administration wildlife biologist in Seattle.
