The Biggest Mouthful: How Blue Whales Eat and Why Krill Matters
Release Date: 10/06/2026
How To Protect The Ocean
In 2014, a patch of unusually warm water nicknamed "the blob" settled off the west coast of North America. The cold, food-rich water that normally stretches far offshore shrank into a narrow strip along the coast, and hungry humpback whales followed their food straight into the waters where Dungeness crabbers had set thousands of traps, each tied to a vertical rope. Entanglements jumped from about 10 a year to 53 in 2015 and 55 in 2016. In this episode, Andrew traces the line from warmer water to a specific whale in a specific rope. You'll learn why lunge-feeding whales depend on dense patches...
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Fill your hands with cold water, hold your breath, and press your face in. Your heart slows within seconds. That reflex lives in every whale in the ocean too, and in a blue whale it is pushed so far that the largest heart on Earth can drop to two beats a minute on a deep dive. In this episode, Andrew walks through the first heart rate recording from a wild blue whale, led by Jeremy Goldbogen's team at Stanford, and a study by Terrie Williams of UC Santa Cruz that tracked narwhals fleeing after release from nets in East Greenland. The narwhals swam as hard as they could while their hearts fell...
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A blue whale can swallow a volume of water bigger than its own body in a single gulp. That move, called lunge feeding, is one of the most extreme feats in the animal kingdom, and it only pays off when krill is packed into thick, dense swarms. In a thin patch, a blue whale gets back about six times the energy it spent. In a dense swarm, it gets back more than 200 times. In this first episode of the Age of Giants series, Andrew breaks down how rorqual whales feed, then follows the krill. In 2025, the Antarctic krill fishery hit its 620,000 tonne precautionary limit for the first time and closed...
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What happens to the heart of the largest animal on Earth when it charges into a swarm of krill? Dr. Ashley Blawas, a postdoctoral scholar in Jeremy Goldbogen's lab at Stanford's Hopkins Marine Station, joins Andrew to unpack new research published in PNAS that measured the heart rates of lunge-feeding blue whales and humpback whales using suction-cup ECG tags. Ashley explains the three phases of lunge feeding (accelerate, engulf, filter) and why these giants behave a lot like human sprinters. Their heart rates stay high after each lunge, then gradually recover while they glide and filter,...
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In 1988, someone found a striped mussel the size of a fingernail in Lake St. Clair. Within a few years, zebra mussels coated pipes, boats, and the bottom of the Great Lakes, and they became the poster child for "it's too late." Andrew closes Marine Pollution week with the pollutant that breaks every rule: a living one that reproduces instead of diluting. He follows two invaders. Zebra mussels rode in on ship ballast water, clogged power plant intakes, and stripped plankton from the base of the food web. Lionfish, likely released from home aquariums, spread from Florida across the Caribbean and...
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You rinse the yogurt tub, check the number on the bottom, and drop it in the blue bin. In Canada, only about 9% of plastic waste actually gets recycled, and the global rate is the same. Andrew breaks down why plastic is so hard to recycle, why microplastics are so hard to study, and what the controversy over plastic-in-the-brain headlines does and doesn't tell us. Then the story moves to a beach in Stanley Park in 1994, where Vancouver Aquarium staff and volunteers started picking up trash and writing down what they found. That cleanup grew into a national program, and its data fed into the...
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In 2001, government scientists started adding a tiny amount of the synthetic estrogen found in birth control pills to a remote lake in northwestern Ontario, at levels already measured in city wastewater. Within seven weeks, male fish were making egg-yolk protein. After two summers, some had eggs growing in their testes, and the fathead minnow population collapsed to about 1% of normal. Andrew explains how the same chemistry leaves our bodies every day, passes through treatment plants built for sewage and bacteria, and flows into rivers, lakes, and the coast. Hormones are only part of it. In...
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This summer, people are boarding whale watching boats and seeing humpbacks feeding in sight of the Manhattan skyline. Fifty years ago, that same water was an open sewer, and every toilet on Manhattan's West Side flushed straight into the Hudson River, untreated. Andrew tells the story of how the whales got here, and why it took most of a century. He starts with the cause: sewers built to empty into the rivers, roughly 590 million gallons of raw sewage a day by the early 1900s, and floating screens at Coney Island to keep it away from swimmers. Then the turn. The city began testing the harbor...
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Plastic keeps getting made, it never goes away, and almost none of it gets recycled. Dr. Judith Weis, Professor Emerita at Rutgers University Newark and Andrew's very first guest on this podcast more than 2,000 episodes ago, returns for her fourth appearance to talk about the second edition of her book, Marine Pollution: What Everyone Needs to Know. Judith walks through every major category of marine pollution: nutrients, metals, oil, pesticides, marine debris, pharmaceuticals, ocean acidification, and one category that surprises most people, biological pollution. She explains why...
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All week, Andrew has asked listeners to comment on and show up for California's marine protected area review. Today he answers the question that comes after: once the meeting ends and the news coverage stops, how do you find out if anything actually changed? He works through four practical questions every ocean advocate should know how to answer. First, where to find the current rules for any of the 124 MPAs in California's network (the California Department of Fish and Wildlife's own MPA pages). Second, why a Fish and Game Commission vote isn't the finish line, since approved changes still go...
info_outlineA blue whale can swallow a volume of water bigger than its own body in a single gulp. That move, called lunge feeding, is one of the most extreme feats in the animal kingdom, and it only pays off when krill is packed into thick, dense swarms. In a thin patch, a blue whale gets back about six times the energy it spent. In a dense swarm, it gets back more than 200 times.
In this first episode of the Age of Giants series, Andrew breaks down how rorqual whales feed, then follows the krill. In 2025, the Antarctic krill fishery hit its 620,000 tonne precautionary limit for the first time and closed months early, with catches concentrated in the same Antarctic Peninsula waters where whales feed. Andrew also explains the "krill paradox": scientists now know whales eat about three times more than older estimates, and their iron-rich poop fertilizes the plankton that krill depend on. Whales help grow the very swarms they eat.
The episode closes on South Georgia, where whalers killed 42,698 blue whales and surveys recorded one sighting in twenty years. In 2020, researchers counted 58 blue whale sightings in three weeks. Andrew shares one simple action you can take today to keep more krill in the ocean for whales.
Takeaways
- Rorqual whales (blue, fin, humpback) feed by lunging, expanding pleated throats to engulf huge volumes of water and prey.
- A single blue whale lunge costs roughly 3,000 to 8,000 kilojoules, so lunge feeding only works on dense krill swarms.
- A feeding blue whale in the eastern North Pacific can eat about 16 tonnes of krill a day.
- The Antarctic krill fishery reached its 620,000 tonne trigger level for the first time in 2025 and closed early.
- Whales recycle iron that fuels plankton growth; Southern Ocean whales recycle about one tenth of the iron they did before whaling.
- Blue whales are returning to South Georgia after being hunted out locally, about 50 years after whaling ended there.
- Action: skip krill oil and choose an algae-based omega-3 supplement.
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