Despite being an apex predator, great white sharks are far from the biggest creatures in the ocean, which is why they often have to make do with carrion scavenged from carcasses rather than risk picking a fight with a marine giant. However, for the first time ever, two white sharks have been spotted attacking and killing a humpback whale off the coast of South Africa.

The attack, which is described in the journal Marine and Freshwater Research, was witnessed by the crew of the Oceans Research Institute’s research vessel, who were called out to investigate reports of a whale that had become caught in fishing gear in Mossel Bay in February 2017.

Upon arrival, they found a poorly 7-meter (23-foot) humpback that displayed signs of emaciation, while the abundance of barnacles and whale lice on its skin indicated that it hadn’t been able to dive for some time. Things then got dramatically worse for the stricken whale, as a great white shark measuring 3.5 meters (11.5 feet) in length turned up about half an hour after the crew.

After circling the whale for a few minutes, the shark bit it just behind its left pectoral, causing a considerable loss of blood. However, while white sharks normally hold on to their prey and violently shake their heads in order to rip off chunks of flesh, this shark immediately let go of the whale and displayed no head-shaking.

The study authors say the shark was deliberately employing a “bit and spit” tactic, choosing to let the whale bleed to death rather than risk injury by engaging in a tussle. After circling the humpback for the next half-hour, the shark then bit it on the tail stock (the muscular bit between the main body and the flukes), again letting go immediately after biting.

By this point, a trail of blood more than 50 meters (164 feet) long was seen pouring out from the whale’s wounds, attracting the attention of a second, larger shark. Measuring 4 meters (13 feet) in length, the new arrival continued to attack the whale in the exact same manner as the first shark, which left the scene after realizing that it had company.

Shark number two began by biting the whale’s tail and immediately letting go, before later bumping the head of the humpback and then applying yet another bite to the tail. Three minutes after the final bite, the whale sank.

The fact that both sharks employed the same tactics despite acting separately is what the study authors find truly fascinating about this unprecedented sighting. They describe the bite and spit tactic as “precise, deliberate and effective,” explaining how the sharks “worked to ensure a severe loss of blood, targeting important areas such as the tail stock and the axilla, to debilitate the whale, preventing it from escaping.”

Despite the fact that the researchers did not see the sharks actually eat the whale after killing it, they certainly saw enough to re-shape their understanding of the predatory behaviors of great whites. After all, these immense predators have long been known to feast on the carcasses of dead whales, yet this is the first time anyone has ever seen a white shark actually hunting one of this size.