The Whale Heart That Beats Twice a Minute

0:00 Next time you're at the sink, I want you to fill your hands with cold water. Hold your breath and press your face into it. Within seconds, your heart starts to slow down. and your body switched to a reflex you share with every whale in the ocean. In a whale, that reflex is pushed so far that a single scare can turn it against them. Hey, everybody, welcome back to another exciting episode of the How to Protect the Ocean podcast. I'm your host, Andrew Lewin. We're going to be talking about the dive mechanisms and the heart rate of whales in this episode. Last episode, we watched a blue whale take the biggest mouthful on earth. And today we're going to follow it down and listen to his heart as it's searching for this like huge swarm of krill and try and feeding itself and do that lunge feeding. Now, if you've ever been on the water near whales, you've Heard like the rules, like stay back, don't chase, you know, cut your engine, don't want to make any kind of noise.

0:47 and part of you probably wonders like, does a 25-meter animal really care about a little boat? and I think that's the one that like everybody's like, I wonder like what it matters. And the answer lives inside a whale's chest, it's one of the coolest things in ocean science. I remember looking at this in comparative physiology in my undergrad. And I was lucky enough to be able to watch these whales from large boats in my career. and I'll be honest, I thought the distance worlds like for me was more about the noise and like interrupting their society, right? Interrupting their communications and their listening and all that. And it is, it it definitely is a lot about that. But this story kind of is changing my mind in terms of what it looks like. To dive and what it feels like to dive as a marine mammal. Every mammal, including you, we have a dive reflex.

1:30 So in adults, it kicks in fully when you hold your breath and your face hits the water, especially cold water. your heart slows down, your blood shifts away from your arms and legs towards your heart and brain. And your body is quietly rationing oxygen. to be honest, I've never felt this so much when until I did. my Hewitt helicopter training. It's like offshore training. You get into a helicopter, you sit in this helicopter. ~ it's like a model helicopter over a pool. It drops down about 10 to 20 feet. it hits the water, and then it's designed to flip over in the water. And this is to mimic what happens if you have a problem out on when you're offshore and you actually have to go in the water. a lot of times you're in a pool. So the whole point is to be safe and to understand the process.

2:12 So you have to punch out the window take off your seatbelt, hold onto the chair so you don't go floating away, grab the window or the opening in the window and then go out up to the surface so that you can get into the rescue boat, which is like a scary process when you first do it. We have to do this multiple times. And that was in a warm pool. Now think about it in a cold pool. They actually give you a bit of like a straw to breathe into, like a bag, I guess. because what happens when you hit that water right away, you wanna hold your breath. And by holding your breath, you kind of panic a little bit. And so it becomes a little difficult, especially with that cold water. So cold water, like I said, like the blood shifts away from your arms and legs, towards your heart and brain, your heart rate slows down, your body starts to ration oxygen.

2:54 And so it's stressful idea, just to think about it. So in people, like the drop it's modest, it's usually about 10% or a bit more, And you've never noticed it unless someone, had you hooked up to a monitor. You would never understand. the rate, your heart rate, how much it slows down or you actually measure it. But in some marine mammals, the same reflex slows their heart by ninety percent. That's crazy. Ninety percent. Now take that same reflex and turn the dial way, way up. A few years ago, a team of biologists led by Jeremy Goldbogen at Stanford University set out to do something nobody had done before. he wants to record the heartbeat of a wild blue whale. Think about that. The largest animal in the world trying to record that heartbeat. Now a blue whale heart weighs hundreds of kilograms.

3:35 you can't exactly get one to sit still for a checkup. So the team built a sensor package with suction cups and electrodes and placed it on a blue whale feeding in Monterey Bay, California, just behind its left flipper. The tag stayed on and recorded for hours, you which is an unbelievable thing to do. When the scientists pulled the data, they found something that seemed pretty impossible. During the dives, the whale's heart slowed down to as few as two beats a minute. Most of the time, it sat somewhere between four to eight beats a minute. If we did that as humans, we'd probably die. When the whale came back to the surface, To breathe, the heart rate shot up to about 25 to 37 beats a minute. with its body racing to reload the blood with oxygen as fast as it could.

4:17 and when a whale lunged into a swarm of krill on a dive. Its heart rate briefly climbed to about two and a half times its lowest rate, then fell again. the researchers think part of the secret is the whale's aorta, the main artery leaving the heart. it's stretchy, so it keeps squeezing blood to the body in the long gaps between beats. Goldbogan said Animals that are operating at physiological extremes can help us understand biological limits to size. The team suspects the blue whale heart is working to close to its maximum, which may be one reason nothing bigger has ever evolved. Now the heart is tuned perfectly to a calm dive. it slows beats underwater to save oxygen. Now fast beats at the surface help to reload it.

4:58 Everything works when the whale controls this pace. So what happens when something takes the control away? in East Greenland, narwhal sometimes get caught in nets set by indigenous hunters. Researchers working with those hunters had a rare chance to study what happens next. So before releasing nine narwhals, they fitted them with suction cup tags that recorded heart rate and movement. on a normal dive, a narwhal's heart drops to about 10 to 20 beats a minute, depending on how hard it's swimming. that's the dive reflex doing its job. It does it automatically. and the release narwhals did something else. They bolted for the deep, swimming as hard as they could. and their hearts dropped to three to four beats per minute. The fastest swimming, The slowest heart rate. Our bodies could never do that.

5:38 When you sprint, your heart speeds up to push oxygen to your muscles. These narwhals are sprinting with their oxygen supply almost shut off. the escape dives use 97% of their stored energy. Normal dives to similar depths use about 52%. The lead scientist Terry Williams of UC Santa Cruz described it in this way. escaping marine mammals are trying to integrate a dive response on top of an exercise response on top of a fear response. Three systems that are pulling in different directions at once, and that's the hidden cause of being scared when doing this die. Now the researchers flagged a bit of a bigger worry. As Arctic ice melts, more ships and more noise are moving into narwhal waters. similar responses could help explain why deep diving whales strand after loud responses.

6:21 A whale's heart is the most efficient engine in the ocean when it sets its own rhythm. A sudden case of a boat cutting it off Or a loud engine overheard or even seismic guns that are going off looking for oil deposits. all of that could change the rhythm. But here's the good news. Giving Wales room is one of the simplest protections we have, and countries around the world have written it into their rules. if you go whale watching almost anywhere in the world, someone will tell you how close you're allowed to get. Like the numbers are pretty similar. In the United States, Noah asks people to stay at least 100 yards away from whales, about the length of a football field. For some whales, the rules are stricter and carry a force of law. Endangered North Atlantic right whales gets about 500 yards. In Australia, boats must not deliberately approach a whale close than 100 meters.

7:03 And within 300 meters, they have to slow down and take care. in the New Zealand, it's at least 50 meters away from any whale And 200 meters from a baleen or sperm whale mother with her calf. In Canada, it's 100 meters for all whales, dolphins, and porpoises by law. and when a population is in real trouble, the buffer grows. Off the Pacific coast of Canada, an endangered population of salmon-eating orcas called the Southern Residents down to about 70 animals. In 2026, Canada raised the distance boats must keep from these animals From 400 meters to a thousand meters. The idea behind every one of these rules is pretty much the same. A whale doesn't have to dodge boats, can spend its energy and its oxygen on whatever it came to do. So eat, rest, raise its young, whatever it decides.

7:44 different countries, different numbers, one shared idea, The space is the protection. We don't have Like long-term proof that bigger buffers alone recover a population. What we do know though is that from the physiology is that disturbance costs whales oxygen and energy that they can't easily spare. Space is a cheap way to give them that back. so when you're out on the boat, make sure that the boat that you're on, if it's by yourself or with a whale watching boat, make sure you give it at least 100 meters or about 100 yards every single time. That's the minimum or the guidelines in many places. And it's more cautious than some. wherever you are, check your local rules because endangered whales and mothers with calves often get much more rules in their regulations.

8:25 If a whale surfaces closer than that, put your engine in neutral and let them move on their own terms. Don't try and disturb them, just let them go on their own. You can take a video, you can do all that, but just leave them alone. Now that distance is what keeps a whale's dive a calm dive. Two beats a minute only works when nothing is chasing you. think about like a blue whale surfacing. it's blowing out its blowhole. The heart is racing to reload, the sliding back under, heart dropping to a few slow beats as it heads down to the next swarm. Nobody chasing it, nobody cutting it off. the most remarkable heart on the planet just needs us to keep our distance. And that's really what we can do is just keep our distance. in tomorrow's episode, we're gonna be talking about what happens when the swarms themselves move and the whales have to follow them into danger.

9:07 That's gonna be an interesting episode, so you don't want to miss out. Hit that follow button. And I want to thank you. If you have a question or a comment about this episode, I'd love to hear if you're watching listening on Spotify. Leave a comment. And if you're listening to this on your favorite podcast app, my social media links are in the show notes. You can check it out. If you're listening to this on YouTube, if hopefully I put post this here, you can hit me up in the comments below. Don't forget to subscribe, follow, whatever you'd like to do. I want to thank you so much for joining me on today's episode of the How to Protect the Ocean Podcast. I'm your host, Andrew Lewin. Have a great day. We'll talk to you next time and happy conservation.