Orcas that attack and eat great white sharks: the bloody battle between the largest marine predators that has scientists perplexed

Image source, Getty ImagesPhoto caption, Scientists discovered that the sharks had been attacked by a pair of sister orcas. (Not the ones in the photo)By, Isabelle GerretsenAuthor's title, BBC EarthPublication date 17 minutesReading time: 11 minWhen scientists first found dead great white sharks on the coasts of South Africa, they could not believe their eyes. All of them bore the same mutilation marks — their bodies were torn open and their livers had been extracted — pointing to the same culprit. These deadly tactics are now being observed around the world. On 3 May 2017, the remains of an enormous great white shark washed up on the coast of Gansbaai, a fishing village near Cape Town, South Africa. The female shark weighed 1,100 kg and had an open wound in her belly through which her 90 kg liver had been extracted."We wondered: 'What the hell did this?'" recalls Alison Towner, who led the necropsy of the dead shark. Five more dead great white sharks would appear in the months that followed. All with the same characteristic wounds; they had been torn open and their livers removed. According to Towner, a shark biologist at Rhodes University in Grahamstown, South Africa, "it was extraordinary." "By that point I had seen hundreds of great white sharks... but I had never seen them wash ashore one after another, over and over again," she recalls.Skip Most read and continue readingMost readEnd of Most readIt was the first sign that an underwater battle was being waged. One, as she would later learn, that would have repercussions in oceans around the world. Image source, Chris Brunskill / GettyPhoto caption, The great white shark is being displaced by orca attacks. The suspectsTowner performed the necropsies on all the sharks and, upon observing the same mutilation pattern, immediately suspected two culprits: a pair of orcas named Port and Starboard. These two male orcas, believed to be brothers, first appeared in the waters near Cape Town in 2015. They were named Port and Starboard because of their distinctive dorsal fins, collapsed to the left and right respectively. Shortly after the pair of orcas was sighted, divers came upon a group of dead broadnose sevengill sharks. The stocky bodies of these prehistoric-looking sharks bore tears and were missing their livers. "Port and Starboard arrived just as the divers were pulling the carcasses out of the water," Towner recounts. "We had the victims and the culprits at the scene, but at that moment we couldn't grasp what had happened." Marine biologists and the public kept sighting the two orcas along the Cape Town coast, including around Dyer Island, once known as "the McDonald's self-service for great white sharks" because of the sharks that patrolled the area during the winter months in search of seals, Towner explains."No one doubted that Dyer Island was one of the best places on the planet to see a great white shark," she notes. Yet they suddenly disappeared. "They vanished overnight," Towner says. Like other experts, she had suspicions, but they had to wait until 2022 to officially link the orcas to the shark deaths. "It seemed like a criminal investigation... we were piecing together clues, but the definitive proof was missing. Then we got it." Image source, GettyPhoto caption, Orcas and great white sharks occupy the top of their respective food chains. A duel between apex predatorsOn 16 May 2022, an amateur drone operator filmed three orcas attacking a 3-meter-long great white shark off the coast of Mossel Bay, 400 km east of Cape Town. During the encounter, one of the three orcas used its snout to push the shark toward the surface and flip it onto its right side, before biting an area near the pectoral fins and releasing a pool of blood. One of the orcas then dove with the shark in its mouth, while another appeared to grab the shark's tail before disappearing from view. More recently, orcas have also been seen killing great white sharks off the coasts of California and Australia, demonstrating their remarkable hunting prowess, intelligence, and teamwork. Faced with climate change and environmental pressures that have brought these two species ever closer together, scientists warn that the ongoing battle between the ocean's top superpredators has drastic ramifications for life in the sea. Orcas and great white sharks occupy the top of their respective food chains and play a significant ecological role in the sea. Both species compete for similar prey such as seals and dolphins. Orcas are the only known predator of the great white shark. Towner points out that they are highly selective in seeking out the organs from which they derive nourishment, and the liver is the most nutritious part of a shark. Great white sharks use their large livers as enormous energy reserves for the long migrations they often must undertake and to stay buoyant. The liver of an adult specimen accounts for up to 28% of its body weight, while 90% of its volume consists of highly energetic lipids. Australian scientists have also documented cases of orcas extracting sharks' livers, as well as the pectoral muscle of penguins, according to Isabella Reeves, a marine biologist specializing in orcas at the University of Western Australia. Deborah Giles, an orca scientist at the University of California, Davis, notes that it is complex to determine whether this hunting strategy constitutes new behavior or is simply being recorded more frequently due to the proliferation of underwater cameras and drones over the sea. Either way, the tactic evidences the "extreme intelligence" of orcas and their ability to exploit the resources available in their home territories. Reeves agrees that orcas have the advantage due to their culture and the fact that they live in societies structured by families with clear rules and foundations. Orcas live and hunt in social groups called pods, and use unique vocal "dialects" to communicate with one another. They show great coordination in their hunting tactics, according to Towner. Great white sharks, by contrast, are essentially solitary animals. Image source, Getty ImagesPhoto caption, Orcas live and hunt in family groups, which gives them an advantage over the solitary sharks. Only on rare occasions have orcas been seen hunting alone. On 18 June 2023, Starboard was filmed attacking a great white shark on its own. It killed a 2.5-meter juvenile shark and extracted its liver in less than two minutes. Tourists aboard a boat filmed the orca with the shark's liver in its mouth, while gulls scavenged the remains of hepatic oil left on the sea's surface. The next day, the carcass of a second mutilated 3.5-meter shark washed up on the nearby coast, suggesting that Starboard had killed two great white sharks around those dates. "This showed us that Starboard is a very sophisticated predator... that doesn't need accomplices," Towner says. Paralyzed sharksErick Higuera, a marine biologist and wildlife filmmaker in Baja California, Mexico, could not believe his eyes when reviewing a fragment of his drone footage in 2020. Higuera, who directs the orca program of the non-profit organizations Conexiones Terramar and Pelagic Life, had filmed a group of five orcas hunting a shark in the Gulf of California. In the footage, the orcas push the great white toward the surface before flipping it over together. They then drag the shark underwater and emerge with the liver already in their mouths. "The orcas rammed the shark and struck it. Then they extracted its liver and ate it," Higuera says. "They showed no signs of consuming the carcass, only the liver." Image source, GettyPhoto caption, Orca attacks have caused drastic changes in great white shark behavior. The orcas belong to the Moctezuma pod, named after a prominent adult male who bore the name of the Aztec emperor. The group had already been seen hunting Mobula rays in 2018. Two years later they moved on to larger prey: great whites and whale sharks. In 2022, Higuera filmed five orcas from the Moctezuma pod hunting another juvenile great white shark. The orcas pushed the shark onto its back and lifted it to the surface. Flipping the shark over induces a state of paralysis called tonic immobility, according to Higuera: "It is a natural and temporary paralysis that occurs when the shark is inverted, leaving it completely inert and preventing it from reacting for at least a minute," enough time for the orcas' deadly skill."Once the shark has been safely neutralized, the orcas can easily section its abdomen to extract and consume the energy-rich liver without risking injury from a counterattack." This hunting strategy constitutes learned behavior, Higuera explains: "It corresponds to cultural learning within this family; they transmit across generations information that comes from the matriarch." The warming of the waters has increased the presence of juvenile great white sharks in the waters of the Gulf of California, placing them in the habitat and range of the Moctezuma pod, Higuera explains."Climate change brings these superpredators closer together, although it does not directly change the way they hunt; it creates opportunities for the orcas to apply their already sophisticated hunting strategies to a new target." This shift is also happening elsewhere. The predation of great whites by orcas has also been documented in Australia. In October 2023, the carcass of a 4.7-meter-long great white shark washed up in southeastern Australia. It was missing its liver and its digestive and reproductive organs."We did the forensic work, as would be done anywhere at a crime scene, and confirmed the presence of orca DNA in the wounds. It was the first confirmed predation in Australian waters," says Reeves, who led the investigation. The predation of great whites by orcas has been witnessed at other points along the Australian coast, though it remains infrequent because there are few areas where both superpredators coincide, Reeves notes. The flight of the great white sharksThe orcas' attacks have caused drastic changes in the behavior of great white sharks in South Africa. According to Towner, they have abruptly abandoned their previous habitat in the Western Cape, heading out to sea or moving east along the coast. The marine biologist draws a comparison with the behavior of predators in the Serengeti (Tanzania)."Suppose lions are introduced into an area where leopards are the main predator; the leopards begin to forage at night to avoid crossing paths with the lions during the day. However, African wild dogs act completely differently: they leave entirely. We assume that great white sharks closely resemble the dogs in their reaction to another superpredator new to their territory." Image source, Dave Fleetham / GettyPhoto caption, Scientists believe great white sharks move away from areas where orcas have appeared. The great white shark population in South Africa was already on the brink before the orca attacks were discovered. A study conducted in 2016 concluded that these sharks faced extinction due to poaching driven by demand for their jaws and fins, pollution, the depletion of their food sources, and the use of nets and baited hooks. A 2015 study revealed extremely low genetic diversity. Since then, the population has suffered a further decline, as Sara Andreotti, a marine biologist at Stellenbosch University, warns. Although many specimens die accidentally when caught in fishing for other species, the nets installed along the coast to keep them away from the busiest beaches constitute the leading legal cause of mortality, followed by longline fishing, which eliminates the young and small sharks that form the base of their diet. The orcas' hunting exacerbates this decline and triggers significant repercussions for the global marine ecosystem. In False Bay (Cape Town), where a stable population had been documented until 2015, the great white sharks had disappeared completely by 2018. One study indicated that the orcas likely played a role in the population decline. A similar pattern of flight has been recorded off the coasts of California. Brief visits by orcas displaced the great white sharks from the Southeast Farallon Islands, an islet located about 43 km west of San Francisco. Electronic tracking data showed that the sharks abandoned the area within minutes of the orcas' arrival and did not return until the following season, which reduced attacks on elephant seals four- to sevenfold during their absence. Image source, Getty ImagesPhoto caption, The pressure of orcas on great white sharks has consequences for other species, such as African penguins, exposed to greater predation by the sharks. By contributing to the displacement of great white sharks from their traditional aggregation sites — the specific geographic areas where animals of the same species naturally congregate — in the Western Cape, the orcas are already having an impact on other species, including the critically endangered African penguins, which face increased predation by the sharks, Towner notes. On the other hand, another kind of shark, the copper shark, now occupies the territory where the great whites are absent, Towner indicates. These animals have become the main attraction in cage dives due to the absence of white sharks in the Western Cape. According to a recent study, the disappearance of the great whites in False Bay (Cape Town) has a domino effect on the food chain that leads to an increase in their prey, especially South African fur seals and broadnose sevengill sharks. In turn, this phenomenon causes a decline in smaller fish and sharks. When orcas displace or kill great white sharks from part of a coastline, the ecological consequences are remarkable, Towner says: "We are already seeing those effects in real time." Download the new BBC World Service app. Choose BBC News Mundo and receive news alerts, documentaries, and analysis, all in one place. Important: the new app is not available in the UK or the United States. You can also follow us on YouTube, Instagram, TikTok, Facebook, X, and our WhatsApp channel. And don't forget to subscribe here to our newsletter to receive a special selection of our best content every Friday.