Orcas VS Great White Sharks! When Predators Become Prey

What happens when an apex predator becomes the prey? With documented cases from around the world, great white sharks have become the preferred prey of certain types of killer whales. This was first recorded in 1997 when two members of a mysterious group of orcas named the LA pod were filmed killing and eating the liver of a great white shark.

Last year, a group of orcas known as Montezuma’s pod began hunting juvenile great whites off the Baja Peninsula. In 2023, the aptly named orcas Ripple, Bent Left, and Jagged Fin were seen hunting and tossing a large prey item in the Bridgewater Bay of Southeastern Australia. The next day, a large great white shark washed ashore with its liver removed.

Genomic analysis found killer whale DNA in the wound. But the most famous case of orcas hunting great white sharks involves two brothers named Port and Starboard, who first appeared in Cape Town, South Africa in 2015. Shortly after these two orcas showed up, great white sharks began washing ashore and their livers torn out through their pectoral girdle.

 You probably know what happened next. The white sharks vanished. This set off a massive chain reaction. The introduction of a novel and highly dominant apex predator into an ecosystem can have unpredictable consequences, not only on other predatory species, but on the structure and stability of the entire ecosystem. I’m KP, a marine biologist who specializes in marine mammals like seals and cetaceans, [music] and today we’re talking about what happens when two apex predators come face to face.

Let’s start by clarifying what biologists mean when we say apex predator, because there’s some confusion in my comment section. A lot of people seem to think that an apex predator is something from the movie Highlander. There can be only one. But that’s not at all what apex predator means. It’s not some hypothetical who would win cage match.

 It’s simply an ecological term for understanding food webs in different ecosystems. Apex predators occupy the uppermost links of the food chain and thus have few to no natural predators. It’s fairly common for a single ecosystem to have multiple apex predators that coexist. And we don’t have to look any further than False Bay for an example of this.

Before Port and Starboard showed up, False Bay was home to two apex predators, great white sharks and the broadnose sevengill [music] cow shark. Which is not a very good name for an apex predator. Both of these sharks preyed on Cape fur seals, but the white sharks are diurnal feeders, meaning that they mostly hunt during the day.

Sevengill sharks are nocturnal. During the day they would stick to the sheltered kelp forest in the western end of the bay called Miller’s Point. At night the sevengills would venture out into the bay to feed on the seals while the white sharks were less active. The kelp forests at Miller’s Point are a major tourist attraction.

 Scuba divers could regularly see over 70 sevengill sharks during a single hour-long dive. But in November of 2015, the sevengills completely abandoned the kelp forest overnight. No live sharks were seen in these kelp forests for over a month. The sevengills were simply gone. However, scuba divers discovered multiple shark carcasses that day.

In each case, the liver had been removed. Days after this event, two unique and easily identifiable orcas were first spotted near Miller’s Point. Specifically, two half brothers named Port and Starboard. Who I talked about in a video that you can find right up here. These brothers are easily identified by their collapsed dorsal fins.

 Port’s dorsal collapsed to the left and Starboard’s fin is collapsed to the right, which is how they got their names, obviously. One thing I didn’t talk about in that video was their collapsed dorsal fins, which I promise I’ll address in [music] just a little bit. A large number of sevengills returned in January of 2016, but in April of that year, it happened again.

The sharks vanished overnight, and the next day, five carcasses were discovered with their livers removed. Necropsies on the carcasses confirmed the wounds were caused by killer whales. Shortly after the second event, Port and Starboard were filmed killing and eating the livers of great white sharks. Like the sevengill sharks, the great whites also vanished.

Cage diving companies and shark tours went out of business because they could no longer find any sharks. The absence of the white sharks and sevengill sharks was felt throughout the ecosystem. This is something called a trophic cascade. That’s an ecological phenomenon where the addition or removal of top predators triggers changes in the populations of prey and their resources across multiple lower trophic levels.

These top-down effects can dramatically alter the structure of ecosystems. In False Bay, the sharks not only preyed on Cape fur seals, more importantly, they influenced the seals’ behavior. When the sharks vanished, the seals became bolder, more effective predators, and have increased pressure on sardines and anchovies, which African penguins rely on for food.

 As competition for the fish increased, the seals began feeding on the penguins. African penguins are critically endangered and are expected to go extinct this decade. To be very clear, the primary threats they face are man-made, though. Specifically, overfishing of sardines and anchovies directly led to the starvation of over 60,000 African penguins [music] between 2004 and 2012.

The absence of sharks in False Bay is making conservation efforts that much more important, but also that much more difficult. And while it might not look like it on the surface, the appearance of Port and Starboard might also be man-made. To understand why, let’s turn to two recent papers. The first is a 2010 publication titled confirmation of the occurrence of [music] second killer whale morphotype in South African waters.

 You can’t search that. I’m going to make a shirt. Bring putting the SEO in science. I’ve talked a lot about orca ecotypes on this channel, but for those of you who are new, there are at least 10 distinct types of orcas currently recognized by marine biologists. Each with unique genetics, appearance, vocalizations, and diet.

 Before Port and Starboard showed up, every orca found in South African waters was assumed to be type A. This is the largest ecotype in the world, measuring up to 10 m or 33 ft. And their diet consists solely of marine mammals like seals, >> [music] >> sea lions, and other cetaceans. Two unusual killer whales stranded in South Africa in 1969 and 77.

 Both were fully mature males, but just 6 m or a little over 20 ft in length. Now, that’s significantly smaller than the average type A male. Despite their small size, the orcas had really long and wide pectoral flippers and massive dorsal fins. But the most interesting thing was their teeth.

 They were worn down to the gum line. In 2010, a female orca was stranded. She was also very small, about 2 m or 6 ft shorter than an average type A female. And the tooth wear was excessive. Inside her stomach were the remains of at least 10 or 11 blue sharks. The balance of evidence confirms the existence of a second morphotype of killer whale in South African waters, differing in size, morphometrics, dental wear, diet, and possibly schooling behavior from the better known larger form or forms.

This morphotype was named the flat-toothed ecotype, and the paper notes that they resemble the North Pacific offshore orcas in several ways. As the name suggests, offshore orcas live offshore over the outer continental shelf. They are the smallest ecotype in the North Pacific, and their teeth are worn flat because of the abrasive sandpaper-like skin of their preferred prey, sharks.

Because of their similarities, the 2010 paper and this paper published in 2019 hypothesized that the flat-toothed ecotype, like the offshore killer whales, primarily live in deeper shelf waters, further offshore, where they feed on blue and mako sharks. And a decline in these species, thanks to man-made causes, resulted in a shift in the orcas’ habitat.

 Essentially, with fewer and fewer mako and blue sharks to feed on because of overfishing and bycatch, Port and Starboard and other flat-toothed killer whales left their offshore waters in search of food. And they found it in the sharks of False Bay. This is a possible explanation for the appearance of the orcas preying on sharks in Southern Australia, Ripple, Bent Left, and Jagged Fin.

Unfortunately, Australian orcas are some of the most understudied and poorly understood populations in the world. But there appears to be three distinct ecotypes, including the possibility of an offshore flat-toothed population that has moved closer to the coast because overfishing reduced their natural prey.

And like False Bay, the Australian great whites also disappear for a month at a time after a predation event. But the story is different in the North Pacific, off California and Mexico. The LA pod, who were the first to be recorded preying on white sharks, physically resembled the offshore ecotype with dorsal fins that had lots of nicks, scarring, and other abnormalities.

But they didn’t match any known offshore individuals, and they were never seen socializing with them, either. They were only seen with other members of the LA pod. The two orcas filmed attacking white sharks were CA2 and CA6. But in this case, it was actually the orcas who vanished afterwards. This attack was the last time CA6 was ever seen.

 CA2 was briefly spotted a month or two later with a few other members of the LA pod. But then after that, the entire pod disappeared and has never been seen again. We have no idea where they came from, where they went, or why they left. Some marine biologists think if the LA pod is still alive, that they are probably down south in Mexican waters.

Which is where we find a pod of killer whales identified by a male named Montezuma. The ecotype of Montezuma’s pod is currently unknown. Like the LA pod, they’ve never been seen with other orcas. They also don’t appear to eat marine mammals. In fact, sea lions apparently feel perfectly comfortable around them and have even been seen stealing their kills.

Which again, as the theme of this video, as their prey is primarily sharks. Specifically, whale sharks until recently. For the first time, marine scientists are seeing how orcas hunt whale sharks. However, rising ocean temperatures are pushing great white shark populations further north where they become prey to Montezuma’s pod.

Now, I’ve personally wondered if the orcas of Montezuma’s pod might be related to the LA pod or even their descendants. But right now, there is no hard evidence for that to be the case. And [music] what happened to the LA pod remains one of the most fascinating mysteries in marine biology. One thing you might have noticed is that a lot of these shark-eating orcas have abnormal dorsal fins.

 Bent left dorsal fin is bent left. Ripple’s fin is rippled and jagged fin You get the idea. It is unfortunately a myth that collapsed dorsal fins are related to physical or mental health in any way and that they only collapse in aquariums. An orca’s dorsal fin is made of fibrous connective tissue without any bones or structure to hold them up.

 We don’t 100% know why dorsal fins collapse, but one factor is simply gravity. Like I said, these are smaller orcas, but their dorsal fins are massive. There is also evidence that there is a genetic factor because dorsal abnormalities happen more often in family groups. Port and Starboard are brothers, after all.

 A study of killer whales in New Zealand who also prey on sharks found roughly 23% of adult male killer whales had collapsed, [music] bent, or wavy dorsal fins. Here’s a picture of a wild orca NZ15 Corkscrew, and you can see his dorsal fin is a disaster. So, he probably has a dietary has probably has something to do with diet, too.