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Solo south African orcas learn how to hunt great white sharks
Killer whales in South Africa no longer need help to catch a great white shark.
The orcas have learnt to catch and eat young great white sharks in less than two minutes, slashing the time taken by group hunts to take down the apex predators.
Shark-eating orcas have strengthened their control of the waters off Africa’s southern coast.
A pair of killer whales, known as Port and Starboard, have been attacking great white sharks near the tourist hotspot of Gansbaai since 2017, targeting them for their nutrient-rich livers. This has lead to great white sharks abandoning the area, triggering changes to the entire region’s underwater ecosystem.
New recordings reveal that the skill of these orcas is even greater than first realised. While previous great white shark hunts in South Africa involved multiple orcas, footage has shown that Starboard is capable of attacking a great white shark and removing its liver in just two minutes, without any help.
While it’s not certain if Port is also able to carry about solo hunts, the findings have raised further concerns about the region’s marine ecosystems.
Dr Alison Towner, the lead author of the research, says, ‘The astonishing predation off the coast of Mossel Bay, South Africa, represents unprecedented behaviour underscoring the exceptional proficiency of the killer whale.’
‘This sighting revealed evidence of solitary hunting by at least one killer whale, challenging conventional cooperative hunting behaviours known in the region.’
‘These are groundbreaking insights into the predatory behaviour of this species, and our findings significantly contribute to the global understanding of killer whale predation dynamics, enhancing knowledge of marine ecosystems and predator-prey relationships.’
The findings of the research were published in the African Journal of Marine Science.
Tourist trips from South Africa's southern coast recorded the first footage of the behaviour. Image © Anya Newrcha/Shutterstock.
How do orcas hunt great white sharks?
While orcas are able to eat a wide range of different prey, the specialisation seen in the South African killer whales reflects the complex social lives of whales and dolphins, as well as their ability to learn.
Prey specialisation can be specific to certain whale pods and lifestyles, even when different groups inhabit the same area. For instance, in the north Pacific, resident killer whales focus on salmon, while those living further out tend to hunt sharks. Orcas moving through the region, meanwhile, specialise in eating seals, porpoises and whales.
These preferences might be learnt from other members of a pod, or developed independently. At the moment, it’s unclear which category Port and Starboard fall into, as the southern hemisphere’s shark-eating orcas were only discovered within the past decade.
Previous sightings of their hunts suggested that taking down a great white was at least a two-orca job. While one orca would hunt the shark, as many as five others would lie in wait to block off its possible escape routes.
Young great white sharks are small enough that orcas can hunt them without assistance. Image © Jsegalexplore/Shutterstock.
From start to finish, this could take as long as two hours. The individual hunting style, however, takes a matter of minutes, but there is a catch – the orca is only going after sharks which aren’t fully grown.
Being able to tackle a 3.5-metre-long shark is still quite the achievement though. The new footage shows Starboard grabbing hold of the great white’s left pectoral fin, and thrusting forward with the limb still in its mouth.
Two minutes later, it’s all over. While it’s not exactly sure how orcas extract organs from sharks, Starboard was spotted with the liver in its mouth.
Another great white that washed up on a nearby beach, however, might give some clues. Its corpse had large stretch marks along the side of its body, suggesting that the killer whales might be pulling or twisting the body of the sharks too.
More detailed examinations of the hunts and resulting dead sharks will be needed to confirm whether or not this is the case.
