Swarms: Why Thousands of Sharks Suddenly Gather

Subscribe and brace yourself—because this week, the swarm has teeth. 🦈

In this second episode of our Swarms Minisode Series, Laura and Katy dive into a lesser-known swarm behavior: shark aggregations. From 1,400 basking sharks off New England to over 15,000 spinning sharks off the Florida coast, this episode explores the science (and chaos) behind why some of the ocean’s most feared predators travel in giant, synchronized groups.

🦈 Why do basking sharks—normally loners—form feeding spirals?
 🌊 What caused 15,000 blacktip and spinner sharks to swarm near Florida in 2013?
 🧲 Could Earth’s magnetic fields (or sonar) influence shark migration patterns?
 🎯 And do predators swarm for the same reasons as prey?

This minisode is a fast, fascinating look at how even apex predators can get caught up in the group dynamic—and what it means for scientists, beachgoers, and Shark Week fans alike.

👉 This is episode 2 of 6 in our Swarms series—short, science-packed episodes exploring how and why animals move as one.

Transcript

Katy: We're talking about swarms again. So last week or two weeks ago, sorry. Last week we talked about things that smell. The week before that we kicked off the mini. So just like we've done in previous seasons, we have a long episode. Short, long, short, long short.

And we alternate 'em. So for this season, we are talking about swarms. The first episode we talked about, I talked about starlings and the mur, the mur, mur, mur, murmuration of them. And, and then today Laura is going to talk 

about, 

Laura: sharks because it's almost Shark Week. Everybody

also shout 

Katy: anticipation. We're gonna talk

Laura: Yeah, we're in Rush. Real quick though, shout out. One of our listeners reached out to me, , because of the smell of this episode we just did. And he said to, if we wanna check out a very, very bad movie, which made it hilarious and actually got 7.0 stars.

It's called Polyester from 1981, and it might be the first. [00:01:00] It was recorded in like it came with a scratch and sniff card. It was like one of the first 40 movies. 

Yeah, it looks disgust. I don't wanna, I don't know because it's mostly bad smells apparently. But if you're, if you wanna experience some smells and watch a really old, terrible movie, that's it.

Anyway, sharks, 'cause I was like, the sharks are cool. We talk about sharks a lot and it's almost shark week. So I wanted to talk about how sharks swarm and there are several species that do this, I just wanted to highlight too, 'cause they kind of do it for different reasons. One is basking sharks, which I like to picture 'cause they're huge.

So 32 feet long. Typically they're alone or in groups of fewer than seven. But since 1980, scientists have documented several instances of bask basking sharks squirming. For example, in 2013, a group of 1400 basking 

sharks. Yeah, we're spotted off the coast of New England. So just, they're just mouths open.

'cause these guys are the ones that [00:02:00] just roam around kinda like a whale. They're only like, I think they're like the second largest compared to a 

whale shark. So they're just roaming around with mouth is open. 1400 of 

them. 

Katy: Geez. 

Laura: Scientists aren't quite sure why, but there's a couple of theories floated. ,

The particular group from 2013, that group consisted of both adult and young sharks. So it probably didn't have anything to do with mating because of that like mixed age group. So they thought, maybe it could be that there is a ton of zoo planked in there making it like the perfect feeding spot.

Or, and I should say, and or, with so many of those sharks swimming around, like in a feeding loop, they're all reducing each other's drag during feedings. 

Katy: they're all just like, we're stuck here. Yeah, we're 

Laura: Yeah. I just like, yeah, just like how geese like reduced drag by flying in a v. These sharks were like, let's just keep it going.

'cause they don't have to do any work then. Like it's.

Katy: Like, this is great guys. Let's just, can we just keep this up for another, you know, two, 200 miles or so? That'd be fantastic.

Laura: Yeah, [00:03:00] but I don't know what happened in 2013. Something with the ocean. Because if you thought 1400 basking sharks was a lot in 2013, that is nothing compared to 2013 off the coast of Florida. 15,000 sharks swarmed off the coast of Florida. They were black tip and spinner sharks. So much smaller, only about five feet, but still 15,000 sharks.

The, I was reading an article and the person was like, they were just jumping up onto the beach, like they, Yeah. I believe was moving 'cause they were in such like a, so normally these guys are found in groups, and. Be black tip and spinner sharks. Spinner sharks are called this because they're known for jumping out of the water to feed, so they just jump out and spin.

So just 15,000 spinning sharks, I feel would be like, you'd be like, this is the apocalypse or shark, nato. This is where 

Katy: That's all I was gonna say. Yeah. shark NATO I feel like you missed, they missed the opportunity there

to tell The real shark nato. Yeah. The real spinning shark story there.

Laura: [00:04:00] And so these guys, they migrate south along Florida's coast every single year in late winter to their winter feeding grounds. So they're not going far, they're just going up and down like the coast. Yeah. 

But they're thinking that it could have been delayed due to warmer weather.

And normally there is a thousand sharks per almost half square mile in the ocean, like around there, which is still a lot of sharks. 

Katy: yeah. That is, 

Laura: two sharks a mile is a lot.

Katy: Our new measurement

here, two, about two sharks a mile. 

Laura: yeah, but this is excessive, they think it's just had, because of the delay of migration, it just fumbled them all into one spot and then they were hungry because there were so many of them, and they just went crazy.

Some scientists also just other types of sharks like hammerheads are known for also like swarming. But in general, scientists wonder if magnetic forces in certain areas might cause this behavior. Because they hunt using electromagnetic impulses and the Galapagos Cocos CAC house, whatever, however you say [00:05:00] that.

Katy: Is this like the devil's the triangle? Devil's triangle. 

Laura: Yeah. From a magnetic field that is triangle shaped, they think created by ancient lava flows. Which also just sounds really but there is something weird magnetic there. And of course they also s swm for mating purposes and likely for protection.

Katy: Huh. Oh, I mean, again, the protection thing makes sense 'cause that's like the starlings, you know

against the big, the birds to prey and stuff like that. But I mean too, this goes back to everybody saying with, ocean animals and whales and stuff, how sonars and everything like that.

'cause the ocean isn't as quiet as what people think it is. It's actually gotten really noisy. And so could all of that stuff also be affecting

Laura: funneling them into one spot or, well, and I think that you think about schooling fish because they're prey, but you don't usually think about that as sharks 'cause they're predators. But predators do the same stuff for different purposes.

Katy: Yeah. Yep.

Laura: But boy, 15,000 sharks in one spot is no joke.

Katy: No, that would be that's so

Laura: It'd be really cool to see, 

Katy: It would be, it [00:06:00] would be really cool. That's something that I would fly to go see if I heard it, you

Laura: Yeah, there were like just sharks jumping out of the water, eating 

Katy: That'd be crazy. Crazy. All right guys, , that was the end of our second swarms episode is to make sure you guys follow us on social media, wildly Curious podcast.

If you just search us for us on every platform, we're pretty much there. And subscribe to us on YouTube and make sure you go support us on Patreon so we can keep bringing you the guys this great content. Next week we have another regular long

episode, and then we will pick up the week after that with swarms.

See you guys next time. 

Laura: soon. Bye.