How Did Blue Whales Get So Big?
A blue whale swims near the surface of clear, sparkling ocean water. The Museum’s logo unfolds across the screen, reading “150 Years | American Museum of Natural History.” It fades away. The whale spouts.
JEREMY GOLDBOGEN (Assistant Professor of Biology, Hopkins Marine Station of Stanford University): Blue whales are absolutely awe-inspiring. By all standards they are the largest animals of all time.
A two- or three-person inflatable boat, running between two blue whales is shown from overhead.
The camera pans over large skeletons in the Museum’s Hall of Primitive Mammals.
GOLDBOGEN: There's all these examples of giants in the fossil record. We have giant rodents. We have huge dinosaurs.
A model of a Xiongguanlong baimoensis, a tyrannosauroid dinosaur.
Jeremy Goldbogen interviewed in an office space, with computer monitors behind. Text animates on screen, identifying him as Jeremy Goldbogen, Assistant Professor of Biology, Hopkins Marine Station of Stanford University.
GOLDBOGEN: We don't have the opportunity to study those animals in the way that we can study the modern giants.
A blue whale surfaces and spouts, before diving back under. An animated title reads “Giants of the Sea, Part 1: How did blue whales get so big?”
GOLDBOGEN: Today we have the largest animals of all time, throughout the entire history of life on Earth. By better studying these ocean giants we can ensure that these species will persist for future generations.
David Cade interviewed in an office space. Images of whales decorate the walls. Text animates on screen, identifying him as David Cade, Postdoctoral Researcher, Institute of Marine Sciences, UC Santa Cruz.
DAVID CADE (Postdoctoral Researcher, Institute of Marine Sciences, UC Santa Cruz): The defining characteristic of a blue whale is that it's the biggest animal that's ever lived, certainly by mass—up to 140 tons of whale in one animal. When you're up next to one of these things, you really see that. This whale surfaces and then goes and goes and goes and goes and goes and goes and goes and then you see the flukes and the flukes are 10 or 12 feet across.
Goldbogen speaks in his office.
GOLDBOGEN: It's widely recognized that body size is one of the most important determinants of how you function and how you interact with your environment.
A hippo munches on a grassy field.
GOLDBOGEN: When you get bigger your metabolism becomes much more efficient.
Giraffes, zebras, and wildebeests roam over a broad savannah.
GOLDBOGEN: So, that means you can fast for longer periods of time and you can put on lipid stores very, very rapidly.
A blue whale swims near the surface. A rhinoceros strolls in an area with trees.
Cade speaks in his office.
CADE: You can avoid predators better. You have a lower cost of transport—it's easier to walk or move long distances.
A herd of elephants crosses a plain with a mountain looming in the background.
CADE: You can potentially have longer lifespans because of that.
Cade speaks in his office.
CADE: But the downside is that it can take more energy and that on land…
An Indian elephant chews grassy plants and moves its trunk around.
CADE: …there's a kind of a limit to how much mass you can actually hold on your legs.
A blue whale breaches the surface, spouts, and goes back under.
GOLDBOGEN: If you're in water you don't have to deal with gravity in the same way. You have the support of the aquatic medium.
Goldbogen speaks in his office.
GOLDBOGEN: And that might allow you to evolve much larger size and you don't have to bear that weight with limbs as you would on land.
A blue whale is seen from above, moving only slightly, near the surface of the ocean.
CADE: The blue whale is essentially neutrally buoyant, meaning that they can just kind of float there.
Cade speaks in his office.
CADE: No matter how big you are, if your tissue is about the same density as water, you don't have that same mass of gravity laying on you. So, the ocean allows for these big animals to exist.
A blue whale floats near the surface, spouting.
CADE: And what are the procedures and mechanics that allow them to get that big? It’s been pretty well unknown until now.
Shirel Kahane-Rapport is interviewed in an office setting. A whiteboard with equations is in the background. Animated text identifies her as Shirel Kahane-Rapport, Ph.D. student, Hopkins Marine Station of Stanford University.
SHIREL KAHANE-RAPPORT (Ph.D. student, Hopkins Marine Station of Stanford University): One of my research questions is how whales got to be so big and I'm choosing to answer that question using basic physical principles, one of which is called scaling.
Kahane-Rapport indicates a diagram on a monitor. Text reads “10 x Length > 100 x Skin > 1000 x Volume.” Beneath the text a small circle on the left and a much larger circle on the right are separated by an arrow pointing to the larger circle.
KAHANE-RAPPORT: And so, scaling is how something grows proportionally as its length increases.
An animation demonstrates how as length increases, surface area and volume increase proportionately, by showing a spheroid object growing in size. As it grows, numbers next to text reading “Length,” “Surface Area,” and “Volume” increase. E.g., as Length goes from 11.1 to 18.7, Surface Area increases from 388 to 1,100, and Volume increases from 719 to 3,431.
KAHANE-RAPPORT: When the length of an object increases, the surface area squares and the volume cubes. So, that's a basic thing that holds in sizes of circles and sizes of cubes,
Drone footage of San Francisco’s famous Golden Gate suspension bridge.
KAHANE-RAPPORT: …but it also is true for things like bridges or bones.
A paleontologist lies next to a huge, single dinosaur bone for scale. The bone is longer than the person.
A blue whale swims near the surface.
KAHANE-RAPPORT: And so, in this case we apply it to an animal like a whale.
An animated graphic shows a whale with an enlarged throat. Text reads “expected engulfment capacity: length3.”
KAHANE-RAPPORT: We have found their body mass and their engulfment capacity—which are volumes—do not cube.
An additional line of text appears, reading, “actual engulfment capacity: length3.8”, and the outline of the whale’s throat is expanded beyond the original illustration.
KAHANE-RAPPORT: So, they engulf more than we expected and that's what allows them, we think, to get so large.
A large whale propels itself forward with an open mouth, taking in a huge volume of water as its throat expands.
Goldbogen speaks in his office.
GOLDBOGEN: There are about 80 to 90 species of whales.
An evolutionary cladogram shows the relationships between various whales. They are divided into two categories: porpoises, dolphins, beaked whales, sperm whales are identified as “toothed whales,” while rorqual and gray whales, and right and bowhead whales are classified as “baleen whales.”
GOLDBOGEN: There are two major groups of what we call the great whales. We have toothed whales and baleen whales. So, toothed whales are well known for using echolocation to target single prey, whereas baleen whales are obligate filter feeders and they target patches of small-bodied prey.
Another evolutionary cladogram zooms into the rorqual whales, where several types are listed: sei whale, Bryde’s whale, blue whale, fin whale, humpback whale, and minke whale.
GOLDBOGEN: Blue whales are rorqual whales and rorquals are characterized by their unique lunge filter-feeding mechanism.
Goldbogen speaks in his office.
GOLDBOGEN: So, in contrast to other vertebrate filter feeders, which swim slowly forward and filter at really low, steady speeds, rorqual whales have this dynamic lunge filter-feeding mechanism,
In dramatic footage, a whale powers to the surface with its mouth agape. It breaches, its throat expands to a huge, bulging sac to take in a massive amount of water, and then turns below.
GOLDBOGEN: …where they open their mouth to tremendous gape angles and they have this huge expandable throat sac that basically engulfs the water and prey.
Goldbogen speaks in his office.
GOLDBOGEN: Then once the mouth closes around that prey-laden water,
An illustration of a rorqual whale shows water streaming out between the feathery slats of baleen.
GOLDBOGEN: …it pushes that water past the baleen plates that hang down from the top of the mouth, leaving the tremendous amount of prey inside the mouth.
CADE: Blue whales are migratory animals.
Near the surface, a young blue whale nudges at its mother’s side.
CADE: So, they're born in warmer tropical waters where they're with their mothers, learning how to feed in these waters.
A whale breaches, spouting. Its tail flicks above water before diving back beneath the surface.
CADE: So, up in the Northern Hemisphere where you have big dense patches of krill, in the summertime that's an ideal time for a blue whale to travel north and start feeding on these krill patches.
Cade speaks in his office.
CADE: They'll feed for three or four months and during that time they are building up energy. They're sometimes increasing their body mass by 40 or 50 percent,
Drone footage shows a mother blue whale and her calf swimming near the surface. Both come up to spout.
CADE: …and then the whale will use that energy throughout the rest of the year when the food is not as good.
GOLDBOGEN: Studying blue whales is interesting because they're so mysterious, in a way.
Goldbogen speaks in his office.
GOLDBOGEN: There's still so much that we don't know and just their sheer size inspires this sense of awe.
A blue whale swims near the surface and then vanishes out of view into deeper waters.
GOLDBOGEN: So, it's an animal that we see just for a few seconds at a time at the surface. Most of the time it's at depth. So, what is it doing down there and how can we figure that 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
Meet the largest animal that ever lived—the blue whale. What’s so great about being big? You can move faster and farther, you can avoid predators, and you can have a longer lifespan. In Part One of our four-part Giants of the Sea series, you’ll explore some of the fascinating mysteries that blue whales hold for researchers.
Body size is one of the most important factors in determining how an organism functions and interacts with its environment. Scientists are studying the blue whale to understand how it evolved to such a large size and what lessons it might hold for protecting the species in the future.