Orcas are hunting whale sharks. Is there anything they can't take down?
Killer whales are known for their intelligence and power, even an inclination to sink yachts. Now, research is showing how they take down prey that few other animals can.
Orcas in Mexico's Gulf of California are hunting whale sharks using a highly specialized set of strategies to attack them. Generally, whale sharks have few predators to worry about, being the largest fish species on the planet. The gentle giants, which eat tiny plankton, can grow as long as a school bus. Still, killer whales have developed a way to take them down, which researchers documented in video footage.
"They are super smart," says Erick Higuera, one of the authors of the study. "They organize the hunt, the ambush. They're like snipers. They're specialists in their hunting tactics."
The findings add to a growing body of evidence showing that killer whales take the title for the ocean's top predator, using cunning and coordination in their close-knit family groups to hunt everything from blue whales to great white sharks.
"They're capable of predating on the ocean's largest creatures so I think there's no doubt about their apex predator status at this point," says Salvador Jorgensen, marine ecologist at California State University Monterey Bay, who was not involved in the research.
A coordinated attack
As a marine biologist and cinematographer, Higuera has followed one pod of killer whales for years off the coast of Mexico's Baja California Sur. He's observed them eating other species of sharks and rays. One day, he received a tourist video documenting something he'd never seen.
In it, a male killer whale is swimming around the body of a bleeding whale shark. Later, three more videos showed similar scenes, where a group of killer whales worked together to attack other whale sharks. All the whale sharks were juveniles, though still 15 to 20 feet long.
"My surprise and my amazement is that they are definitely specialist hunters," Higuera says. "When we saw the video, we got excited."
Here's how the killer whales do it, which Higuera and his colleagues published in the journal Frontiers. First, the killer whales work together to ram the whale shark, stunning it and preventing it from diving deep, one of the whale shark's only defenses.
"It's a huge animal that has very tiny teeth," says Francesca Pancaldi, a marine biologist at Centro Interdisciplinario de Ciencias Marinas and a co-author on the study. "It's relatively slow compared to other sharks and it cannot defend itself, other than dive down. The whale shark is a great diver."
At the same time, the killer whales flip the whale shark onto its back. When sharks are upside down, they can go into a trance-like state known as "tonic immobility." Then, the killer whales begin biting the soft underbelly of the whale shark, causing it to bleed profusely.
That could also give the killer whales access to eating one of the most nutritious parts of a shark – its liver, something that killer whales have been documented eating in other types of sharks.
"Sharks in general, they don't have a lot of fat," Pancaldi says. "The only fatty part in the body of a shark is the liver."
Killer whales are known for these highly coordinated attacks, where techniques are taught in multi-generational families, led by the matriarch.
"They have a tradition," Higuera says. "They have a culture that's unique to this family. There is definitely a cultural learning that has gone through generations."
Even great white sharks should worry
Orcas around the world specialize in different types of prey, each with their own unique hunting strategies. Some killer whales only eat fish, while others prey on marine mammals.
Some orcas have been documented hunting seals by using waves to break the ice the seals are resting on, washing them into their waiting jaws. Off Australia, they've been seen using coordinated attacks to hunt the largest animal on the planet, a blue whale.
Off California's coast, even great white sharks avoid orcas. One study found that white sharks fled when killer whales appeared, leaving their seasonal feeding grounds for as long as a year. Killer whales have been documented hunting white sharks off South Africa, going after their livers as well.
"When orcas come around, it creates this landscape of fear that white sharks, for example, are able to detect and respond to," Jorgensen says. "We've been seeing killer whales going after sharks and particularly larger sharks, which is the more surprising part of this, around the world."
As the ocean's top predators, killer whale families have developed the skills to take their pick. "They eat all the best stuff in the ocean," Jorgensen.
