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Orcas are some of the most effective predators in the ocean, and each population of them has entirely different prey preferences and hunting techniques, more than earning their nickname “killer whale!”

Hosted by: Michael Aranda

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Sources:
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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4997274/
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Images:
https://en.wikipedia.org/wiki/File:Orca_internal_anatomy.svg
[♪ INTRO].

Orcas are some of the most effective predators in the ocean. And while there are a lot of ways to talk about animal intelligence, it seems clear that orcas are really good at figuring out ways to find their next meal.

They have an unusually large brain-to-body size ratio, right up there with humans. And it shows in their cognitive abilities, as they are really good at figuring out and mastering new skills. Not only that, but orcas pass down their hunting techniques to the next generation.

As a result, they have evolved to be potent hunting machines, more than worthy of the nickname “killer whale.” While all orcas may look similar to the untrained eye, there are actually many different populations, or ecotypes, across the globe. There can even be several ecotypes inhabiting the same waters. And just like human cultures around the world have different traditions, each ecotype has widely different prey preferences and hunting techniques.

So here are some of the many diverse ways these talented hunters score a meal. A nice fat seal is a tasty treat to certain orcas, but they have the annoying habit of parking themselves out of the water to avoid water-dwelling predators. In Antarctica, seals often haul themselves out onto large pieces of sea ice known as ice floes.

This doesn’t deter one of the five orca ecotypes found there, known to researchers as Type B1, because they have figured out a nifty technique to get those seals off the ice and into their bellies. They work together as a group, swimming in a straight line directly at an ice floe that has a big ol’, delicious-looking seal perched on top of it. And at the last minute, before hitting the floe, the pod of orcas will dive underneath and push at the water with their tails.

If they’ve timed it right, this creates a large wave that washes the seal right off the side of the floe, into the water where the rest of the group are waiting on the other side. In at least one case that researchers have observed, the floe was large enough that the wave didn’t knock the seal off. Instead, it only broke the ice up into chunks, trapping the seal on a smaller piece.

The seal fled to another ice floe, and the orcas kept at it. The orcas may also work together to break up a smaller ice floe, by using their heads or making more waves. They don’t give up until they dump the seal into the water.

These orcas have even been observed putting the seal back onto the ice floe, at the risk of losing it in the process. It’s been hypothesized that this gives the juveniles in the pod a chance to knock the seal off the ice too, so they can learn the behavior for themselves. Researchers have only observed Type B1 Antarctic orcas performing this technique, so they think it may be a behavior that is specific to this part of the world, but more observations of other orca ecotypes are needed to know for certain.

But what about places that don’t have sea ice? Well, orcas have found other ways to get their prey into the water, too. See, most cetaceans, the group that includes whales and dolphins, find themselves in trouble when they end up on land.

That’s because for cetaceans, beaching can mean certain death if they get stuck. But orcas are the largest cetacean species known to beach themselves intentionally to get at their prey. They often deploy this strategy to get at a tasty meal on the shore, like a young elephant seal splashing around in the surf, practicing its swimming skills, without a care in the world.

Upon spying a seal, the orcas will swim at the shore as fast as they can, depositing themselves on the beach just beyond the surf line. If they don’t quite make it onto the sand, another orca in the group may give them a boost and push them onto the beach. This often occurs when mothers are teaching their young how to perform this feat.

Once they grab their prize, the orcas then hustle back into the water by awkwardly wiggling their bodies back to the water line and riding the next wave out to sea. Orcas tend to be more successful catching juvenile seals than adults using this technique, simply because juveniles don’t know well enough to pay attention. This behavior is typically observed on South American beaches, but there is also some documentation of it happening in the Indian Ocean.

This suggests this may be an example of a more generalized behavior that occurs among several orca ecotypes. Seals are practically snack-sized compared to some of orcas’ other options. These predators also think nothing of taking down an animal much larger than themselves, like a grey whale or a humpback whale.

Their preferred killing method for a large animal like a whale is suffocation. They will work together to submerge it under the water, holding them under or even laying on top of them to block their blowholes so they can’t breathe. This move speaks to their impressive brain power.

It’s a major cognitive leap to understand that whales also breathe out of a blowhole, and that by blocking it, the orca is able to stop the whale from breathing. While one or two orcas are blocking the blowhole, the other orcas in the pod will swim at the whale, ramming into its sides and biting the tail and flippers, to injure it so it can’t fight back. They don’t give up until the whale suffocates or drowns.

If they can, the orcas will then work together to move the whale into shallower water so they can feed on as much of the carcass as possible. If the kill happened too far from shore, they work as a group to hold the body at the surface, so they can take turns feeding on it before letting the rest sink to deeper waters. This behavior has been observed in more than one population of orcas, so it’s another example of a more generalized strategy.

Anywhere orcas are actively hunting large whales, they may be using this technique. Not all orcas eat marine mammals; there are some populations who have a preference for smaller prey like fish. But when you’re a cunning killing machine, you don’t just swim up and snag a fish out of the water.

No, that’s amateur hour. Instead, some orcas prefer to trap as many fish as they can in a giant whirlpool, and then stun them to snack on at their leisure. This behavior is technically known as carousel feeding.

And it has only been documented in a specific ecotype:. Type 1 orcas living in the North Atlantic. This may be due to the type of fish they prefer to eat, which is typically herring or mackerel; smaller, schooling fish that can be easy to find in large groups.

Working together, the pod of orcas hunt down a school of fish and surround them. Then, using a combination of vocalizations, bubble blowing, and flashing their bellies at the fish, they herd the school into a tight ball. Then, they swim around the ball in circles, keeping the fish packed in together.

Once they’ve spun them up, they slap at the water with their tails, which generates a kind of shock wave and stuns the fish. This makes them easy to then grab out of the water for a tasty snack! But some orcas have bigger fish to fry.

Or stun. This is because orcas have figured out that sharks are delicious. Some orca populations may even risk wearing their teeth down to nubs on rough shark skin in order to chow down as often as possible.

Some orcas consume as much of the shark as they can. Other populations appear to know a little something about shark anatomy and only go after their nutrient-packed liver, leaving liverless carcasses scattered on the seafloor like a scene out of a shark-directed horror film. The way one New Zealand population of orcas hunts down sharks might make you think they’ve brushed up on shark physiology, in the process of figuring out how to catch them.

When they find a shark to eat, they first use their tails to generate an underwater vortex, which helps push the shark up to the surface. Once at the surface, the orcas whack the shark on the head with their tails. This karate chop move stuns the creature.

There are shark eating orcas all around the world, but this unique karate chop style of killing has only been documented in orcas living in the waters around New Zealand, a population we know very little about. So there’s definitely more to learn. It seems like the moniker of “killer whale” is well earned after all!

There are many groups of these incredible hunters all around the world, but there is still so much left to learn about them. We don’t even know how many different populations of orcas there are in the world. And in the populations we do know about, there is still much left to learn about all of their unique solutions to the same problem: finding their next meal!

Who knows what they’ll come up with next? Thanks for watching this episode of SciShow. If you want even more SciShow every week, check out our podcast, SciShow Tangents!

We refer to Tangents as a “lightly competitive knowledge showcase.” What that means is that, even though the primary goal is to present mind-blowing science facts, they’re also keeping score, and every season has a winner. Season 2 ends the last week of December, and it’s still basically anyone’s game! So be sure and catch up on Season 2 before we announce this year’s champion.

You can find SciShow Tangents anywhere you get your podcasts! [♪ OUTRO].