The Blue whale – The largest animal of our
time and the largest animal that ever lived. And yes, that includes Dinosaurs and other
Ocean-Giants like Megalodon and Mosasaur. How enormous Blue whales are exactly and how
their managed to become so large, that’s what this episode will be about. Granted, Blue whales are probably not the
longest animal of all time. But measuring relative size in length would
be somewhat problematic given the various shapes and forms life on earth has already
produced. That would lead to misleading statements like:
“Pythons are with a length of over 7m or 23ft larger than an African elephant” or
“the bootlace-worm, with 55m or 180ft - according to the Guinness-book - the longest animal
in the world, is larger than every dinosaur. When comparing the size of many anatomically
different animals, weight is therefore the easiest and most fair measurement to use. With that out of the way, let’s begin to
visualize just how big blue whales really are. Let’s begin with an animal that everyone
has seen before – a horse. This gives us a good reference point. Depending on the type of horse the weight
of course varies quite significantly, but your typical western horse weights about 500
kg or 1100 pounds - so about as much as 7 average humans. About twice as big, with a weight of 1 metric
ton, is the American Bison, the largest animal in North America. Interestingly, of all the land animals the
Bison is still relatively closely related to modern whales. They belong, just like the terrestrial ancestors
of whales, to the order of even-hoofed-animals, so mammals that bear weight equally on two,
the third and fourth, of the five toes. Other examples of even hoofed animals are
pigs, camels, deer, cattle, sheep, goats, giraffes and most importantly the Hippo. These 1.5 metric ton animals are more closely
related to whales than to any land animal. But the largest living land animal is of course
the African Bush Elephant. Particularly big bulls with a shoulder height
of close to 4 meters or 13 ft. can reach a weight of 8 metric tons: So about as much
as 100 humans. Among the extinct animals, notable examples
in this weight class are animals like Stegosaurus and T-Rex. But when it comes to sheer size, one extraordinary
group dominates – the Sauropods. This group of herbivorous dinosaurs were by
far the largest land animals that ever lived. They include famous examples like Diplodocus,
with a length of 27m and a weight of roughly 16 metric tons or Brachiosaurus, which weight
a staggering 35 metric tons. But the largest Sauropods, the Titanosaurs,
were once again significantly larger. Patagotitan for example was an over 30m long
dinosaur with a weight of roughly 70 metric tons. Argentinosaurus, the biggest described Titanosaurs,
weight, according to the newest studies, even more than 80 tons making it the largest dinosaur
and largest land animal known from uncontroversial evidence. In the oceans we have Giants like Killer Whales,
which are with 6 metric tons roughly as big as an African elephant and the biggest of
the dolphins. This makes them about twice as big as the
Pygmy Right Whale. This small whale from the Antarctic is the
smallest of today’s baleen whales, the group to which blue whales belong. Roughly 4 times larger is the whale shark,
which is similar to baleen whales, are harmless filter feeder. With a weight of 12metric tons it is the largest
shark, the largest fish, and the largest animal on earth that isn’t a whale, at least today. In the past there were of course fish and
marine reptiles that were considerably bigger still: Mosasaurus for example. These 15 metric ton reptiles were roughly
170 times heavier than today’s komodo-Dragon and are the biggest Lizard that ever lived. They were also one of the largest marine reptiles. In fact only one group seemed to have exceeded
them considerably in size: The Ichthyosaurs. The largest described species had a length
of 20m or 65 ft. and a weight of 30-40 tons. Only one animal that lived in the oceans,
that wasn’t a whale was still bigger: Megalodon. The largest specimens could possibly reach
a weight of 50-60 metric tons, about as much a sperm whale bull, the biggest of the toothed
whales. But all these records, on land and in the
water, are dwarfed by one animal and with that we have finally arrived at the star of
this video: the Blue whale. With an average length of 25m or 80ft and
an average weight of 110 metric tons adult Blue Whales are already the largest animals
that ever lived. However, they still can get considerably larger
than that. Today, Blue Whales in the southern hemisphere
live separated from those in the northern hemisphere. Like their northern relatives they spend the
summer months in the food-rich Polar Regions and feed on the abundant and dense patches
of krill found there to build up a thick layer of fat reserves for the winter. At the end of every fall they begin an up
to 5000 km long migration into warmer but less rich subtropical and tropical waters
where they breed and give birth. Because the seasons in the southern hemisphere
are offset from those in the northern hemisphere, the migrations of the respective blue whale
populations are similarly offset. Southern hemisphere blue whales are generally
larger than northern hemisphere animals and females are once more about 6% longer than
males. Therefore, if one wants to find an exceptionally
large whale, looking for a particularly old and well-fed female in the southern hemisphere
at the end of summer is probably the best approach. The longest whale measured by scientists was
a female 29.9 meters (98 ft.) long that weight about 180 metric tons and possibly could have
reached a weight of about 210 metric tons during the late summer. The longest whales ever recorded were two
females measuring 33.6 and 33.3 meters (110 and 109 ft.). The weight of such giants would most likely
approach 250 metric tons. These measurements however, should be treated
with a bit of caution at least, as they came from whalers and not scientists. Additionally, you can’t verify them anymore,
as commercial whaling in the last century decimated baleen populations and very probably
removed most, if not all, of the super old blue whales out there. In the Antarctic Ocean Blue whales were hunted
until the 1970s, which reduced their population there by close to 99.9%. Globally the blue whale population was reduced
from 350-400 thousand individuals at the turn of the twentieth century to less than 5000
sixty years later. Even today, more than 50 years after blue
whale hunting was banned internationally, they only managed a minor recovery and only
a few whales likely now exceed 30m or 100ft. in length. Still, even a 30m Blue whale weights more
than: 2 Argentionsaurus, 3 Megalodons, 5 Brachiosaurus,
20 T-Rex, 25 African Elephants, 350 Horses, or 2300 average humans. One reason that it is so hard to imagine just
how large Blue Whales really are probably has to do with the lack of reference points
in the ocean. If you were to put a blue whale next to an
Airbus-A320, one of the most common medium range airliners – their size would become
a lot more apparent. A similar comparison with the new Tesla Model
3, a NBA Field or the Space Shuttle would make it even clearer – Blue whales are Gigantic. Of course, such a huge animal can also be
expected to have some record-breaking organs. The heart for instance, is the largest known
in any animal. It is big enough that a human could stand
in it and weights as much as a horse. With each of its 5-6 beats per minute it pumps
about 500 liters or 130 gallons of blood into the bloodstream. The aorta that transports the blood through
the body is thick enough that a human could squeeze through it and ensures that the roughly
8000 liters or 2000 gallons of blood the whale has reach even the furthest body parts : the
penis for instance. On average around 2,5m or 8ft long and 30cm
or 1 ft. in diameter it too is the largest in the animal kingdom. In particularly well-endowed individuals and
can even reach a length of up to 5meter or 16 ft. and a weight of half a metric ton. But perhaps the most impressive feature of
the Blue Whale is its gigantic mouth which allows it to take in huge volumes of water
to filter for food. When feeding, blue whales dive below the surfaces
to depth of one-two hundred meters and then lunge into swarms of tiny krill above them
at several meters per second. As they strike, they open their mouths at
a wide - almost 90°- angle allowing tens of thousands of liters of prey-filled waters
to flow in. Dozens of parallel running pleated throat
grooves that extend all the way to the belly give the whale the ability to stretch its
throat enough to take in its own bodyweight in water – up to 200.000 liters or 50k gallons
Of course that means that, when feeding, the biggest blue whales temporarily weight around
400 metric tons -- more than a 747 Because the giant volumes of water rushing
in could potentially rip its jaw apart while doing this the whale initially has to actively
control the flow of the water with its tongue and certain muscles in its jaw. After the jaws have closed around the engulfed
water it uses its giant tongue which alone weighs as much as an African elephant to forces
the water out again through a special comb-like structure on the upper jaw called baleen,
filtering out everything edible, primarily of course krill. But small fish and squid too are sometimes
inevitably caught that way. A human, however, couldn’t be swallowed
by a blue whale despite is enormous size as they can't swallow anything wider than a beach
ball. The Blue whales technique of filter-feeding
is called lunge feeding and is one reason for the incredible success of today’s baleen
whales. But this technique is only worth the effort
when enough prey is available as every lunge costs huge amounts of energy. Because opening its jaws is essentially like
opening a big parachute underwater, it grinds the whale to an almost complete halt within
seconds. That means for every new attempt Blue whales
have to accelerate their massive bodies again, which costs up to 2000 calories. This is also thought to be the reason why
Blue whales are only capable of relatively short dives compared to other whales like
sperm whales for example. However, if enough food is available, there
is not better method to ensure quick and easy hunting success. A good catch can yield the whale half a ton
of krill – 500 000 calories in one gulp. During a typical 10 minute dive, during which
a blue whale makes on average 3-4 of these lunges, it might catch and swallow up to 2.000.000
calories worth of krill or the equivalent of 6600 cheeseburgers. A single dive can therefore provide enough
food to cover the whale’s daily energy requirement of 1.5 million calories. During the summer they typically eat around
40 million krill a day so roughly 3-4 metric tons. These 4 million calories allow the whale to
build up the giant fat reserves it needs to survive the winter in the tropics where they
breed and give birth but where there is next to no food for them. Even as babies, blue whales are enormous and
the biggest in the animal kingdom. At birth, they are with a length of 7m and
a weight almost 3 metric tons already as big as an adult great white. Since they are mammals blue whale calves are
nursed during the first few months of their lives. The milk they drink has a very high fat concentration
of 30-50 % (10 times higher than that of human or cow milk) which gives it an almost toothpaste-like
consistency. This has two reasons: On the one hand, it
makes feeding under water easier as the milk doesn’t so easily dissolve into the water. On the other hand, it provides the necessary
nutrients and energy the calf needs to quickly grow large enough to survive the challenging
migrations. A calf drinks between 200-400 litres of milk
a day – that’s around 90 gallons. This allows it to grow at a rate unparalleled
in the animal world: Nearly 100 kilos (200 pounds) do they gain per day - that’s a
whopping 4 kilos or 9 pounds per hour. By the time the calf is weaned, 7-9 months
later, it will have reached a length of 15 meters or 50ft and a weight between 20-25
metric tons making it already larger than any other animal that isn’t a whale. Of course, all these records raise the obvious
question why and how Blue whales became so large in the first place. ____________________________________________
Initially it was believed that it simply must be easier underwater to reach such sizes,
because ocean animals don’t have to hold up their own weight and that whales therefore
continuously grew larger and larger over the course of their evolution. However, as we now know, this is not correct. While it is true that the weightlessness under
water allows an animal to grow much faster than on land, it isn’t the reason they grow. In actuality it is possibly even more difficult
under water to surpass a certain size threshold due to the lack of said reasons. A certain body size is of course a strict
requirement in marine mammals, primarily because of the increased heat loss under water. Cold water drains heat away from the body
25 times faster than air. Smaller animals are more affected by this
because the smaller you are, the more your body surface increases in relation to its
volume. Evolving a large round body, paired with a
thick layer of fat to insulate it, is an easy way to solve this problem effectively. Beyond that, however, increased size quickly
becomes a problem - Especially in the oceans. The biggest land animals today and in the
past were almost exclusively herbivores. Plants make up the lion's share of the Earth's
biomass - They outweigh humans 10.000 to 1 and account for 80 percent of all biomass,
thereby presenting an almost endless food supply for large land animals. In the oceans however, their biomass is comparably
small, and most of it is made up of microscopic algae, unusable for large fish or marine mammals. The evolution of a large body underwater therefore
becomes a big energy management problem. How do you supply the additional body mass
with enough fuel? On land, larger size means protection from
predators while plants provide an easy food source to supply the addition bodyweight with
energy – ideal conditions to increase in size. In the oceans, however, every large animal
inevitably has to become a predator itself. For them an excessive increase in size would
more of than not create more problems than advantages:
That is because, as they grow in length their volume and consequently their energy demand
grows exponentially, increasing the food demand similarly. At the same time, above a certain body mass,
agility and speed start to decrease making hunting more difficult. This paradox usually prevents ocean animals
to grow beyond a certain point. The sweet spot for most marine mammals seems
to be 500 kg or 1100 lbs and even for large apex predators like sharks, toothed whales
and most marine reptiles from the past a maximum weight of a few tons seems to be the norm. Far from enormous sizes baleen whales can
reach. So what made these different? In general, exceptions from this rule are
often the result of very specific and unique condition, and are typically based on a fragile
balance that can easily be destroyed and therefore often result in an evolutionary dead end. In Whales, scientists believe, gigantism is
likely the result of two major factors. The first was the evolution of a new more
efficient way of feeding – Filter Feeding. Filtering tiny animals in bulk from the water,
like all baleen whales do, has one major advantage: Energy efficiency. Instead of having to spend energy hunting
a single prey item, energy that could be wasted if it escapes, blue whales simply glide through
dense clouds of krill like aquatic combine harvesters. Due to the small size of the prey it has no
chance of escaping, guaranteeing a successful hunt while keeping the energy consumption
comparably low. This makes filter feeding one of the most
efficient feeding strategies under water as long as enough prey is available. Observations of the feedings habits of blue
whales have shown that despite the relatively high initial outlay in energy (the result
of their massive size), the whales typically regained up to 90-times as much energy as
they spend. If a whale swims into a particularly dense
swarm it might even recover 1000 times more energy. Such a high efficiency is essential to surpass
a certain size threshold. It is no coincidence that some of the largest
ocean animals today and from the past use this kind of feeding strategy. However, the evolution of filter feeding alone
doesn’t explain the whale’s high efficiency when hunting or their gigantism in general. Baleen whales first evolved around 30 million
years ago and yet their size didn’t significantly change over the next 25 million years. Even when their species diversity drastically
increased 20 mya reaching its maximum 5 mya, most Baleen Whales were only between 5-10
m or 15-30 ft. in length. In relative terms certainly large, but compared
to today’s dimensions rather small. Only during the last 3 million years, roughly
with the start of the Pleistocene ice age, baleen whales suddenly began to grow rapidly
and up to four times independently from one another. At the same time most of the smaller species
went extinct, so that today even the smallest baleen whales are quite large compared to
the typical whale prior to this event. This suggests that the drastic changes in
the oceans ecosystem during the last ice age probably caused the gigantism in baleen whales. With the onset of the northern hemisphere
glaciation the oceans began to experience rapid fluctuations in sea levels. drops of 50-100m 150-300ft within only a few
hundred thousand years became common and repeatedly destroyed or reduced the shallow tropical
shelf areas that previously were the habitat of many baleen whale species. In addition to that, the final close of the
Isthmus of Panama had disrupted the water circulation between the pacific and the Atlantic
and had caused a drastic decline in planktonic productivity in the tropics which furthermore
impacted the baleen whale population negatively. All these factors likely drove the Caribbean-wide
regional mass extinction between 4 and 2 mya that killed among others many of the medium
size baleen whale species. At the same time, the continuous cooling of
the oceans resulted in a global shift in the wind and ocean currents which changed the
way water and nutrients were distributed. As a result, intense seasonal upwellings paired
with an accumulation of iron-dust along the ice shelves produced variable and widely scattered
zones of extreme planktonic productivity. Baleen whales had already the right tools
to capitalize on this new and abundantly food source. But it required a major shift in their lifestyle:
a shift from a more sedentary to a migratory way of life. This sudden need for long-distance migration
likely exerted a selective pressure on the remaining whale species to grow larger, as
a larger size helps to travel long distances effectively and survive longer periods of
food scarcity. So, the recent gigantism in whales is most
likely linked to the appearance of a sudden seasonal abundance of widely scattered patches
of prey that baleen whales due to their unique feeding technique were already able to take
maximum advantage of. And once the unique conditions that allowed
or required them to grow were actually met, they did so faster than any other group of
animals in history. Even if you include the 25 million years during
which baleen whales didn’t significantly increased in size, in only about five million
generations they increased their body mass 5,000 times. In only 50 million years the terrestrial ancestors
of whales that were barely larger than a housecat evolved to be the largest animals the world
has ever seen.
The Title doesn't do this any justice