In 1987, an orca in the Puget Sound was  seen sporting an unusual new accessory: a dead salmon, worn on her head like a hat.

The behavior started out with just one  orca balancing a fish corpse on her head, and it spread to others,  even into other orca pods. Over time, the behavior died out,  so you probably won’t spot any fish-wearing orcas out on  a whale watch anytime soon.

But the whole thing was a charming, if smelly, case study in how seemingly random  behaviors can become trendy in orca pods. But decades later, orca trends  started getting dangerous. [♪ INTRO] It’s the early 2020s, and along with  everything else going on in the world, orcas in the Strait of Gibraltar  have been sinking boats. They’re targeting specific  kinds of boats, like sailboats, and they seem to know how to do the  most damage; by attacking the rudder.

Now, an orca whacking into a  boat occasionally is nothing new, but the number of these  interactions seems to be increasing. In 2020, there were only 52 recorded  incidents of orcas purportedly attacking boats in and near the Strait of Gibraltar. But by 2023, there were as many  as 207 recorded interactions, which sank at least three yachts.

In 2023, an orca rammed a yacht  in the North Sea, near Scotland, which is far enough from Spain and Portugal for people to worry that  the behavior is spreading. But research shows that orcas  might not be attacking at all. A recent study found that when wild  orcas were presented with fake rudders, their behavior was a lot  more playful than aggressive.

It looked more like they were just  pushing the rudders with their noses until they broke, rather than  launching an all-out attack. That might be cold comfort to  anyone sitting on the deck of a boat that’s getting rammed by orcas, but  it does provide some insight into why the orcas might be fiddling  with these rudders at all. Because they see their  friends doing it and it’s fun.

To the orcas, pushing rudders until they  break is possibly just a cool new game. Unfortunately for us, though, orcas weigh between three to seven metric tonnes, the  game is a little less funny to us. There are some theories about  how this game got started.

The first is that this behavior  started as a trauma response. It’s been suggested that an individual  called White Gladis might have been the first orca to start breaking rudders, possibly due to a traumatic  experience with fishing lines. Other orcas in her pod started mimicking her, and the behavior may have become a kind of game, even among orcas that might not have the  same negative experiences with boats.

And the second theory is that it was  all fun and games from the beginning. Young orcas are naturally curious, and  they might just be interested in ships enough to make up a game that became trendy. And while we don’t know which theory  is true, researchers expect that this trend will go the way of human  trends like pet rocks or silly bands.

But while it sticks around,  it gives us an opportunity to learn about orca intelligence and culture. Yes, culture. Because even though we  tend to think of culture as something that only belongs to humans, it turns out  orcas have a lot of cultural traits, too.

See, orcas are capable of what’s  known as action imitation, which is the ability to copy behaviors. That might not sound like much,  but in the animal kingdom, action imitation is a strong sign of intelligence. It means that orcas can learn how to do  something just by watching others do it, rather than figuring it out for themselves.

Action imitation is considered one of  the most important adaptive benefits of sociality, and has been  observed in some birds, apes, dogs, and marine mammals like dolphins and orcas. Not only can orcas imitate  actions, they have large brains, advanced social systems, and high  trainability, which lets them participate in some pretty complex coordinated  behaviors, like hunting in a group. But action imitation isn’t  just a sign of intelligence.

It’s even been thought that  the ability to imitate actions is one of the most important drivers of culture. See, cultures can be defined  in three different ways. The first is that information or behavior  is acquired through social learning, something that action imitation  definitely helps with.

Lots of animals can do this,  so it isn’t necessarily earth-shattering that orcas can do it, too. The second definition of culture  has to do with traditions. Basically, you need to have one or more  socially-learned behaviors that are shared by members of a group,  but not shared by other groups in the same species, and we’ve  seen this in orcas for decades.

In British Columbia, one resident  orca pod likes rubbing themselves on pebbly beaches to scratch their skin, a behavior that isn’t shared by  any other resident orca pods there. And in the Salish Sea, orcas tend to,  for lack of a better word, frolic. They slap their fins and jump up into  the air way more than any other pods do.

And orca pods eat different types of food. This has nothing to do with  what’s available, because different pods living in the same area  will have different preferred foods. Some orca pods have complex greeting  ceremonies, and depending on where the orcas are from, their vocalizations  have distinct “accents”, just like humans.

Even mating can be defined by pod culture. Orcas tend to prefer other orcas with  different sounding calls to themselves, most likely to avoid inbreeding. Which brings us to the  third definition of culture, which has to do with passing down  behaviors to the next generation, leading to the accumulation and  improvement of cultural traits over time.

And while the amount of knowledge  orcas pass down might be up for debate, orcas are matrilineal, which means  they travel with their mother’s pod. The oldest female in a pod is the matriarch,  and since orcas can live for more than 60 years, she acquires and passes down a lot of knowledge to the group over generations. During the Gibraltar  incidents, both groups of orcas that were spotted ramming  boats had matriarchs present.

In White Gladis’s pod, her mom came  along to observe the other orcas, although she didn’t interact  with the boats themselves. White Gladis, her younger siblings, and her calves were the ones  taking part in the interaction. In fact, aside from the pod in  Scotland, which seems to have picked this behavior up, most of the recent  interactions with boats were caused by the same few individual orcas, who probably  learned the behavior from each other.

And since behavioral observations suggest  the orcas are just playing around, it’s starting to seem more like this trend  is only taking off in certain orca cliques, and it’s not some kind of  “orca-strated” revolution. It wouldn’t even be the first time  orcas have invented new games. Young orcas have been observed  grabbing on to the ends of older animals and letting themselves  be dragged along for the ride.

And like we said before,  they’ve even worn fish corpses on their heads as accessories. But those trends come and go. So rather than bracing for an oceanic uprising,  it’s more likely that we’ll just need to wait for the orcas to get bored  and move on to the next big thing.

Maybe mood rings. And hey, if all this talk of fashion trends  is making you rethink your own closet, we’ve got just the thing to  help you zhuzh up your wardrobe. Our brand new bucket hats feature an  adorable orca wearing a slightly-less adorable dead salmon as its  own hat, which is pretty meta.

And if you wanna join the club (and all  the cool kids are doing it) you can head on over to the DFTBA.com/scishow to  pre-order one, while they’re still trendy. [♪ OUTRO]