When capturing prey, killer whales use a number of chilling tactics. Some of these, like repeatedly ramming into a pod of sperm whales, are seldom seen.
Others, like stunning and flipping a creature out of the water and then eating it, are more frequently reported, but seldom captured in eerie detail.
“Dolphins and porpoises are very fast and very maneuverable,” said Robin Baird, a biologist at the Cascadia Research Collective. “They use their speed and agility to get away.”
But killer whales hunt in packs, coordinating attacks from multiple directions, and making it difficult for a fleeing dolphin to know which way to turn.
Eventually, a large killer whale known as CA138 came up from below and flung the dolphin into the air with her head. “I could see what looked like a bowling pin flying through the air,” Frediani said. “According to the time stamp on my images, the toss took one second.”
And then it was over — a super-fast, lethal acrobatic attack caught on camera. CA138 shared the dolphin with two of her juvenile offspring; Fatfin, an orphaned male she adopted 15 years ago, was nearby.
Since killer whales often hunt at very high speeds, especially when pursuing a dolphin, the orcas will sometimes subdue prey by bodily impact, stunning it before biting into it.
“Imagine being a whale chasing a dolphin at 20 knots. It really can’t open its mouth because the drag on its lower jaw would be pretty horrific,” said John Ford, a whale biologist at Fisheries and Oceans Canada. “So they tend to just ram them, and in doing so, the prey often do go flying in the air.”
Marine ecologist Robert Pitman, from NOAA’s Southwest Fisheries Science Center, says the head-butt-and-punt behavior is more likely to occur when the orcas are pursuing fast-moving prey.
“I have seen this with several different species of dolphins from various places around the world, so I think that killer whales probably do this regularly but not commonly,” he said. “With slower swimming species, like seals and sea lions, killer whales prefer to use their tails to swat them out of the water.”
Killer whales, collectively known as Orcinus orca, form matrilineal family groups, with adult male sons sticking by their mothers for life, Baird said. They’re the largest member of the dolphin family, and can be found in oceans all over the world. Though the world’s orcas have historically been classified as a single species, there are several different distinct types.
“They’re still officially one species, but there are many of us who feel that they will eventually be determined to be different species,” Ford said.
One type, called “resident” killer whales, has rounder, more curved dorsal fins and feeds primarily on fish. In the chilly waters off British Columbia, this means salmon. The second type is known as “transient.”
“Transients are marine mammal specialists: seals, porpoises, dolphins, other species of whale,” Baird said. “When they’re feeding on marine mammals, they often will throw them up in the air.”
This is the type of killer whale Frediani observed in Monterey Bay, a type with pointier dorsal fins and different black-and-white coloring than residents. Now, transient pods are lurking in the Bay, hoping to capture migrating gray whale calves.
“These appear to be cultural traditions,” Ford said. “They’re behavior specializations that are passed on across generations by mimicry and learning, by young whales.”
A third type of killer whale, called “offshore,” targets sharks. “We don’t know very much about these,” Ford said.
None of these groups hunt humans in the wild. There has only been one (moderately reliable) account of a wild killer whale attacking a person, Ford said, an accidental encounter involving a surfer in the 1970s. Since then, people have described orcas zooming in for close inspections, but veering away at the last minute. Why they ignore humans is a mystery. It could be that orcas haven’t recognized that humans are edible, or it could be that neoprene wet suits typically render divers opaque to orca sonar. The nitrogen bubbles embedded in the rubber not only thermally insulate a swimmer, but in a stealthy coincidence, are acoustically reflective.
That’s something an orca should appreciate. “They tend to be silent all the time,” Baird said. “They hunt through stealth.”
All Images: Jodi Frediani. Photos taken from the Sea Wolf II with Nancy Black, Monterey Bay Whale Watch..
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