Off the coast of South Africa, killer whales are serial killers: since 2017, they have killed at least eight great white sharks and only one did not eat its liver. But others, found by biologists on the shore torn to pieces, also did not have a heart.

Orcas, also known as killer whales, are known for their ferocious behavior, killing everything from small fish to sharks, sea lions and even blue whales.

But the violence demonstrated by the two specimens has had a profound effect on the habitat, say the authors of a new study published in the African Journal of Maritime Science.

Sightings of great white sharks in the Hansbay area, where they have historically dominated, have plummeted after two serial killer whales were released, researchers said.

Observations and transmitter tags have shown that sharks clearly avoid the region when killer whales are nearby. Sometimes they disappear for months at a time, exhibiting behavior like the wild dogs of Tanzania’s Serengeti in response to the presence of lions.

Gansbaai is 120 km east of Cape Town and due to the year-round presence of great whites, it has been a popular sightseeing spot for tourists. The main predators among fish, they were hunted when two adult killer whales appeared in their waters.

Killer whales are easy to recognize by their individual markings: one had its dorsal fin bent to the right, the other to the left. It was easy for local residents to call them Port and Starboard.

A matted great white shark was found washed ashore shortly after whale watchers spotted it in the area.

Over the next six months, five more specimens were found, four with open bodies and no liver. Unlike bony fish, sharks have very large and fatty livers, a source of food and energy for their attackers.

Each case was associated with the presence in the area of ​​the starboard and port side. The number has risen to eight, but researchers say many bodies have sunk at sea.

The mass migration of great whites had a cascading effect on the local ecosystem. Another shark, a mid-level predator and usually the prey of great whites, emerged to fill the niche they had left empty. According to the researchers, this change could disrupt the entire food chain, putting pressure on the ecosystem.

What caused the behavior of the orcs? Although killer whales are top predators, they don’t usually prey on great white sharks, the researchers said, but they also spotted a rare subspecies of “flat-toothed” killer whales in South Africa that appear to specialize in hunting sharks.

It is quite possible that the left and right sides belong to this group. And their sudden appearance on Hansbaai may be related to the decrease in their usual prey, including fish and sharks, which disturbed the usual environment.

But the carnage in the ranks of those popularized as the ocean’s most fearsome predators shows us that it’s time to get to know orcas better.

They are magnificent creatures, measuring from 7 to 9 meters and weighing up to 4 tons, with amazing intelligence and fully deserving of their nickname “orcas”.

They are by no means the innocent, playful creatures we admire at Sea World or empathize with in the movie Free Willy…

Sources: Live Science, Whiskey Riff

• Read also: Orcs are dangerous! Boaters are advised not to leave the port at night