How Does a Blue Whale Feed?
How Does a Blue Whale Feed?
Giants of the Sea, Part 3
A baleen whale opens its mouth wide in a huge feeding lunge near the surface of the ocean. The Museum’s logo unfolds across the screen, reading “150 Years | American Museum of Natural History.” The whale closes its mouth on an enormous amount of water and dives back below.
JEREMY GOLDBOGEN (Assistant Professor of Biology, Hopkins Marine Station of Stanford University): The first time I saw a blue whale lunge feeding event, I almost couldn't believe it. It is absolutely a crazy feeding mechanism. The whale literally doubles in size as it's feeding, so it's inflating at this really capacious ventral feeding sac on the underside of the animal. So, it's literally inflating with water and food.
An animated title reads, “Giants of the Sea, Part 3: How does a blue whale feed?
Goldbogen speaks from his office. Text identifies him as Jeremy Goldbogen, Assistant Professor of Biology, Hopkins Marine Station of Stanford University.
GOLDBOGEN: These questions come to mind—how does that work? how does that evolve? and how does such a large whale feed on very, very small prey?—and these must be linked in some way.
Researcher David Cade speaks from his office, standing in front of two computer monitors. One shows aerial footage of a whale. Text identifies him as David Cade, Postdoctoral Researcher, Institute of Marine Sciences, UC Santa Cruz.
DAVID CADE (Postdoctoral Researcher, Institute of Marine Sciences, UC Santa Cruz): So, this is actually a fin whale which is very closely related to a blue whale.
Aerial footage of a fin whale, swimming close to the ocean’s surface. It has a long, relatively thin body shape—almost like a pencil with flippers.
CADE: A fin whale is the second largest animal, probably, to have ever lived by mass.
Cade speaks in front of the footage playing on his computer monitor.
CADE: So, it has that nice, streamlined shape and it's really easy for this whale to accelerate to high speed.
The fin whale swims through the water, rolling onto its side, and opening its mouth. The pouch below its lower jaw balloons to an enormous size, inflated by a large mass of water. It closes its mouth and turns to dive.
CADE: And as it does that, it rolls onto its side, it opens its mouth right at the krill patch, and then as it engulfs this water you can see its pouch totally engulf all that huge amount of water. And then it spends about 30 seconds to a minute or so actually filtering out all that water.
Cade speaks in front of the computer monitors.
CADE: So, every rorqual lunge has those three phases.
A diagram illustrates the three phases of rorqual whale feeding. An animated rorqual whale swims vertically toward the surface. Text reads, “Acceleration (7.4 ± 3.6 seconds).”
CADE: It has an acceleration phase where it goes up to about three or four meters per second.
The animated whale turns on its side and opens its mouth in front of a patch of krill. Its pouch inflates with water. Text reads, “Engulfment (5.1 ± 1.0 seconds).”
CADE: It has an engulfment phase which lasts about five seconds.
The animated whale closes its mount around the krill patch, its pouch still inflated. It rolls back upright. Text reads, “Filtering (79.4 ± 18.0 seconds).”
CADE: And then it has that filtering phase. It does this over and over and over and over again, sometimes a hundred times a day.
A split screen shows the front and rear cameras of a tag attached to a whale’s back as it swims, breaches the surface, then dives back below. The whale’s long body is visible in the lower half of each camera angle.
CADE: So, what's unique about our tags is that we were able to integrate not just the sensor data, but also video. So, now we can see what the whale is actually doing from its own perspective.
Cade reviews the split screen tag footage on a computer monitor.
CADE: Now this whale's out looking for food, so he's going to do one long breath and he's going to dive down. So, he's going to dive down to about 100 meters here.
In the original tag camera view, the footage has become grainy and dark as the whale dives deeper below the surface. The rear view captures the whale’s tail and some of the light from the surface.
CADE: So, he's diving down, it's getting darker. And he’s gonna come up from below this prey patch.
Cade speaks from his office, in front of the computer monitors.
CADE: He's gonna start maneuvering his body up towards this prey patch,
Split screen of the whale tag cameras. Now the rear angle (with the tail) is dark and the front camera heads towards the lighter surface waters. As the whale arcs upward, its head and front flukes come into view.
CADE: …accelerating up to about four meters a second. A couple of big fluke strokes, and then right when he gets up to that prey patch he's gonna open his mouth and engulf all that water and then, basically, start that filtering process. So, you can tell that the whale's opening its mouth because you can see its normal head motions…
Cade speaks from his office, in front of the computer monitors. He indicates the whale’s mouth in the tag footage.
CADE: and then you'll see the jaw actually separate.
The split screen view shows the moment where the whale opens its mouth. An arrow indicates a protrusion (the lower jaw) that can be seen momentarily as the whale lunges upwards.
CADE: You can actually see the whale's mouth the bottom of its jaw over there on the left-hand side.
Cade speaks in his office and uses his hands to imitate the shape of the whale’s mouth. His index fingers hook forward, facing one another, while the rest of his hand makes a loose fist.
CADE: The rotation of these jaws is amazing. These jaws are about- some of them on a big blue whale they can be up to 12 or 13 feet long and it'll be just the jaws there.
A diagram of a whale skeleton is superimposed on the footage of Cade speaking in his office. Arrows indicate the motion of the two lower jaw bones—a short of skinny U-shape, turning outwards as the mouth hinges open.
CADE: They sit in the whale's mouth, kind of arched up like this, and then as that whale feeds it opens it up, basically doubling the area that it can engulf. And so it's like- imagine, like, a whole wall of this room coming at you. It's engulfing all that water.
The diagram illustrates the jaw bones rotating back inwards, as the mouth closes.
CADE: And then as it starts to close its mouth, those jaws will rotate back up, so you have a minimal area around the edge for the water to actually come back out.
Goldbogen speaks from his office.
GOLDBOGEN: The interesting thing about blue whales is that they evolved from much smaller ancestors.
An illustration of a torpedo-shaped blue whale. The animal is long and slender, very streamlined. A much smaller whale—about 1/6th the size of the blue whale—is shown in comparison. Text identifies it as Maiabalaena nesbittae.
GOLDBOGEN: So, about three to five million years ago. whales were really dolphin sized.
Goldbogen speaks in his office.
GOLDBOGEN: And the oceans went through a rapid series of changes.
Thousands of small invertebrate organisms swarm through ocean waters.
GOLDBOGEN: The effect of those changes creates a lot of whale food and,
Goldbogen speaks in his office.
GOLDBOGEN: …really, these enormous patches—super, super dense—and that's what makes their filter feeding mechanism so efficient and allows them to evolve massive body sizes incredibly rapidly in just a small amount of geological time.
A diagram shows a blue whale with fully inflated pouch. Text reads, “Two-quarter Ellipsoid Engulfment Model.” Mathematical formulas indicate the volume of the rear portion and the front portion of the pouch.
SHIREL KAHANE-RAPPORT (Ph.D. student, Hopkins Marine Station of Stanford University): This diagram shows a blue whale with its pouch, the engulfment capacity, fully expanded and it shows the model that we have created to measure how much water it can swallow in one gulp.
Kahane-Rapport stands in front of a computer monitor displaying the engulfment diagram. Animated text identifies her as Shirel Kahane-Rapport, Ph.D. student, Hopkins Marine Station of Stanford University.
KAHANE-RAPPORT: And whales, when they engulf water like this, they're also engulfing prey. So, the more prey you can engulf at once, the more efficient you are,
Underwater camera tag footage shows a whale swimming off to the side of the tagged whale. The whale off to the side opens its mouth for a feeding lunge and its pouch expands tremendously.
KAHANE-RAPPORT: …and you get so much more energy for that singular effort. And so, we think that whales have gotten so big because they're able to engulf huge amounts of energy in a really efficient way.
Cade organizes equipment on board a rubber boat.
CADE: Last week we put out 14 different types of tags.
Researchers on a boat hold a reception antenna. Cade examines a whale tag.
CADE: If you're putting a camera on a whale, you can only tell so much.
A researcher stands in the prow of a rubber boat and stretches a long pole out over the water. The camera tag is at its tip and the researcher slaps it on a whale’s side as it momentarily surfaces.
CADE: You have to have the context, the interpretation of what's actually happening here.
Cade speaks from his office.
CADE: The most common whale behavior is just gliding, just hanging out.
Split screen footage shows the front and back views of a whale camera tag.
CADE: And if you have to just watch this video with no context, you could spend your whole career just basically watching whales do nothing, right.
Below the split screen footage, there is now a color-coded graph showing variables (like depth, speed, pitch, and roll) over time.
CADE: So, one of the things that's really important in the work that we do is do the interpretation.
An arrow indicates a blue line that begins at zero then dips lower as time progresses.
CADE: The blue line here is the depth sensor of the whale. So, that's a pressure sensor that measures how much pressure is being applied to that whale.
Cade speaks in front of his computer monitor, as it plays the footage of the whale tag cameras.
CADE: And so, then you can interpret that as depth and how deep that whale actually is.
An arrow now indicates an orange line that oscillates up and down fairly rapidly.
CADE: The orange line here is the animal's speed. When the animal is going faster that line is a little bit higher.
Cade speaks from his office.
CADE: This red line here is where we are in the video.
The arrow now indicates a vertical red line, moving horizontally across the graph as the video plays. Above the graph, the footage shows the whale approaching the ocean’s surface and then breaching.
CADE; So, right now the whale is coming back up towards the surface. It's about to break the surface here. And then goes back down. You can see that it's going to do about one, two, three, four, five breaths…
Cade speaks in his office.
CADE: …and then go back down.
An arrow indicates a spiky pink line, running the length of the graph’s x-axis.
CADE: The pink line here is a measurement- we call it the animal's jerk. Jerk is the rate of change of acceleration.
Cade speaks in his office.
CADE: In addition to the video we can use all those sensors to actually construct a model of what that whale is doing in space and time.
In a computer-generated 3D graphic, a simulated whale goes through the motions of the actual whale, as recorded by the tag’s sensors.
CADE: How is it actually oriented in relation to the surface, in relation to everything else?
Cade speaks in his office.
CADE: So, if I'm looking for interesting areas of this whale's behavior, I’m looking at this graph and saying, like, “Okay, well, what's interesting? What's unique? What's actually going on here in interesting environments?”
In a close-up of the graph displayed on his computer monitor, Cade’s finger indicates a spike in the graph.
CADE: And the first thing that catches my eye is this peak and speed here with a rapid deceleration phase.
Cade speaks in his office.
CADE: So, I know that something's going on there. I know that you have a big event going on at that moment.
Split screen footage of the front and rear whale tag cameras is shown above the graph indicating time, speed, depth, etc. The whale is heading back towards the surface at great speed.
CADE: And that is the feeding event. So, the whale here is doing its acceleration phase—really pumping its tail, accelerating up there, opening its mouth, and then feeding as it decelerates.
In the split screen footage, the whale’s jaw opens wide.
CADE: There's that pouch. It inflates with water and it slows that whale down from all that drag. Imagine, like, trying to force equal to your body weight amount of water.
Cade speaks from his office.
CADE: That whale is using its momentum and then forcing that water forward as it then starts to filter that water out.
Credits roll:
The “Marine Biology” Seminars on Science is made possible by OceanX, an initiative of the Dalio Foundation, as a part of its generous support of the special exhibition Unseen Oceans and its related educational activities.
Director / Producer
Karen Taber
Producer / Editor
Ben Tudhope
Post Producer
Kate Walker
Title Design
Timothy J. Lee
Illustrations
Alex Boersma
Special Thanks
The Goldbogen Lab at Hopkins Marine Station of Stanford University.
All footage & images taken under permit NMFS 16111/21678.
© American Museum of Natural History
Massive blue whales feed on very tiny prey called krill. How do they manage to get enough to eat? Hint: it involves literally doubling in size! In Part Three of our four-part Giants of the Sea series, we’ll hitch a ride on the back of a blue whale to learn about its incredible feeding mechanism. In only 3-5 million years (a short time on the geological scale), blue whales evolved from dolphin-sized ancestors. Scientists think their size and filter-feeding mechanism evolved to help them take advantage of changes that were happening in the oceans. These researchers are using advanced sensor tech to help them understand how blue whales engulf their prey.