Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news about fascinating discoveries, scientific breakthroughs and more.
CNN
—
A pair of orcas working in concert has been killing a great white off the coast of South Africa since at least 2017, robbing the shark of its nutrient-rich liver and discarding the rest.
Scientists have tried to understand the predator's attitude is operated Sharks away From parts of the coast around Cape Town, research has now revealed a startling new twist that could provide clues to what it means for the wider marine ecosystem.
Scientists found one of the predatorsA male orca, known as Starboard, killed a 2.5-meter (8.2-foot) young great white shark last year in the space of two minutes.
“During two decades of annual visits to South Africa, I have observed the profound impact these killer whales have on the local white shark population. Seeing a white shark liver pass our ship to starboard was unforgettable,” said Dr. Primo Miccarelli, a marine biologist at Italy's Shark Research Center and the University of Siena.
“Despite my awe of these predators, I am deeply concerned about the balance of coastal marine ecology,” Miccarelli said in a statement.
Hunting large animals individually is not unprecedented for orcas, highly intelligent and social animals. However, this is the first such case involving the great white shark, one of the world's largest predators, researchers said in a study published Friday in the African Journal of Marine Science.
Lead author Alison Downer said Starboard's kill contrasts with cooperative hunting behavior widely observed among orcas, which can surround and attack large prey such as sea lions, seals and sharks using their combined intelligence and strength. Rhodes University.
Attacks on great whites between two and six orcas have previously been observed and took up to two hours, according to the study.
“The sighting revealed evidence of solitary hunting by at least one killer whale, challenging the typical cooperative hunting behaviors known in the region,” said Downer, who has studied great white sharks for 17 years and learned about their movement patterns through tagging data. Report.
“These are amazing insights into the predatory behavior of this species,” he said. “The existence of these shark-hunting killer whales may be linked to broader ecosystem dynamics. The rapid developments in this phenomenon make it challenging for science to keep pace.
Port and Starboard
The event described in the study took place on June 18, 2023, in 800 meters (875 yards) of sea near Seal Island near Mosel Bay, about 400 kilometers (250 miles) east of Cape Town – where people on two boats were watching for orcas. .
Within an hour of arrival, a shark appeared close to the surface, and researchers, tourists and others on board saw the starboard starboard one grab the shark's left pectoral fin and “push forward with the shark several times”. minutes, the study said.
Then starboard is photographed from a vessel with a bloody piece of peach-colored liver in its mouth. Starboard's male mate, the port, was 100 meters (328 ft) away when the killing occurred and was not involved.
Christian Stopforth/Drone Fanatics SA
A second great white shark carcass washed ashore near Hortonbos, South Africa in June.
Twins are Well known He is among the authors of the study and has been involved in hunting and killing great white sharks for many years. Orcas' dorsal fins curve in opposite directions—the inspiration for their names.
Both travel long distances up the east coast of South Africa to Namibia. Researchers suspect they first started with a larger target White people in 2015. It wasn't until 2022 that aerial footage showed orcas killing a great white shark for the first time, Downer said.
“While we don't have concrete evidence of specific drivers, the arrival of a pair of killer whales may be linked to broader changes in the ecosystem,” Downer said. “It is clear that human activities such as climate change and industrial fishing are stressing our oceans. More research and funding is necessary to fully understand these dynamics.
“There are still a lot of unanswered questions about these shark-hunting killer whales and where they came from.”
Killer orcas terrorize great white shark populations, but researchers don't know where the sharks migrate. “When they migrate, they end up overlapping with heavy commercial fisheries,” Downer added.
The air smells distinctly of shark liver and gulls thinly dive to the surface of the water, as does a second shark carcass. The 3.55 meters (11.6 feet) found nearby led observers to believe another great white may have died before boats arrived that day, researchers said.
According to the study, a kill by a single orca was made possible by the small size of the prey, the young great white. Adult great whites reach a maximum length of 6.5 meters (21.3 ft) and weigh 2.5 tonnes.
The speed of the attack may reflect the starboard's efficiency and effectiveness as a predator, the study suggests, possibly in response to the stress of spending time hunting near shorelines in human-dense areas.
“We cannot speculate that this killer whale was very sophisticated, but the rapid time it took to kill the shark shows incredible skill and dexterity,” Downer said by email.
The liver is the largest organ in great whites, accounting for one-third of their body mass. and rich in lipids, and orcas discard the remaining carcass — a selective feeding behavior known among other carnivores such as harbor seals, brown bears and wolves, according to the study.
“The observations reported here add further layers to the fascinating story of these two killer whales and their capabilities,” said Dr Simon Elwen, Founding Director and Principal Scientist at the Marine Search Research and Conservation Organization and a researcher at the University of Stellenbosch in South Africa. A statement.
“As intelligent, efficient hunters, killer whales can quickly learn new hunting techniques on their own or from others, so observing and understanding the behaviors used by other killer whales here in South Africa is an important part of helping us understand more about these animals,” added Elwen, who was not involved in the research.
