>>JEREMY GOLDBOGEN: Blue whales are absolutely awe-inspiring.
By all standards they are the largest animals of all time.
There's all these examples of giants in the fossil record. We have giant rodents.
We have huge dinosaurs.
We don't have the opportunity to study those animals in
the way that we can study the modern giants.
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: 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: 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. When
you get bigger your metabolism becomes much more efficient. So, that means you
can fast for longer periods of time and you can put on lipid stores very, very rapidly.
>>CADE: You can avoid predators better. You have a lower cost of transport—it's easier to walk or
move long distances. You can potentially have longer lifespans because of that.
But the downside is that it can take more energy
and that on land there's a kind of a limit to how much mass you can actually hold on your legs.
>>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 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.
>>CADE: The blue whale is essentially neutrally buoyant, meaning that they can just kind of float
there. 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. 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: 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. And so scaling is how something grows proportionally as its length increases.
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, but it also is
true for things like bridges or bones. And so, in this case we apply it to an animal like a whale.
We have found their body mass and their engulfment capacity—which are volumes—do not cube. So,
they engulf more than we expected and that's what allows them, we think, to get so large.
>>GOLDBOGEN: There are about 80 to 90 species of whales. 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.
Blue whales are rorqual whales and rorquals are characterized by their unique lunge
filter-feeding mechanism. 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, where they open their mouth to tremendous gape angles
and they have this huge expandable throat sac that basically engulfs the water and prey.
Then once the mouth closes around that prey-laden water, 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. So, they're born in
warmer tropical waters where they're with their mothers, learning how to feed in these waters. 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. 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
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.
There's still so much that we don't know and just their sheer size inspires this sense of awe. 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?