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Episode 281: The Humpback Whale

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Thanks to Clay for suggesting the topic of this week’s episode, the humpback whale!

Happy birthday to Emry!

Further reading:

How humpback whales catch prey with bubble nets

Study: Humpback whales aren’t learning their songs from one another

Stanford researchers observe unexpected flipper flapping in humpback whales

Ancient baleen whales had a mouthful

The humpback’s long, thin flippers help it maneuver:

Humpbacks are active, jumpy whales:

A humpback whale’s big mouth:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

Thanks to Clay for suggesting this week’s topic, the humpback whale!

But first, we have a birthday shout-out! A great big happy birthday to Emry! I hope your birthday is so epic that in the future, when people look up birthday in the dictionary, your name is listed there.

I’m amazed we haven’t talked about the humpback whale before because when I was little, it was my favorite whale until I learned about the narwhal. Sorry, humpback, you’re now my second favorite whale.

The humpback is a baleen whale, specifically a rorqual, which is a group of related baleen whales. I don’t think I’ve mentioned the term rorqual before because I find it really hard to pronounce. Rorquals are long, slender whales with throat pleats that allow them to expand their mouths when they gulp water in. We talked about this in episode 211 about the fin whale, which is another rorqual. I’ll quote from that episode to explain again what the throat pleats are.

A baleen whale eats tiny animals that it filters out of the water through its baleen plates, which are keratin structures in its mouth that take the place of teeth. The baleen is tough but thin and hangs down from the upper jaw. It’s white and looks sort of like a bunch of bristles at the end of a broom. The whale opens its mouth wide while lunging forward or downward, which fills its huge mouth with astounding amounts of water. As water enters the mouth, the skin stretches to hold even more, until the grooves completely flatten out.

After the whale fills its mouth with water, it closes its jaws, pushing its enormous tongue up, and forces all that water out through the baleen. Any tiny animals like krill, copepods, small squid, small fish, and so on, get trapped in the baleen. It can then swallow all that food and open its mouth to do it again. This whole operation, from opening its mouth to swallowing its food, only takes six to ten seconds.

The humpback mostly eats tiny crustaceans called krill, and little fish. Since gulp feeding takes a lot of energy, finding a lot of food in a relatively small space is important to the whale. Many little fish that live in schools will form what are called bait balls when they feel threatened, where the fish swim closer together and keep moving around. Any given individual fish has a good chance of avoiding being eaten when behaving this way. Think about last week’s episode, where the spinner shark swims straight up through a bait ball, biting biting biting. It eats some fish, but most are fine. But a big filter feeder like the humpback can gulp a whole lot of fish at once, so it really likes bait balls.

To help maneuver prey animals into a small area, groups of humpbacks sometimes employ a strategy called bubble-net feeding. The whales will dive below the fish or krill and swim in a ring, blowing bubbles the whole time. The bubbles startle the animals, who move away from them. But since the bubbles are all around them, and the whales swim closer and closer together so that the ring of bubbles shrinks, eventually the fish or krill are all clustered in a small space as though they’re caught in a net. Then the whales open their mouths and gulp in lots of food. This is actually a simplified explanation of how bubble-net feeding works, which requires several different types of bubbles and various actions by the whales to make it work right.

The humpback is closely related to the fin whale and the blue whale. In episode 211 we learned that fin and blue whales sometimes interbreed and produce offspring, and in at least one case a marine biologist identified a whale that appeared to be the hybrid of a blue whale and a humpback.

The humpback grows up to 56 feet long, or 17 meters, with females being a little larger than males on average. It’s mostly black in color, with mottled white or gray markings underneath and on its flippers. Its flippers are long and narrow, which allows it to make sharp turns. It also has tubercles on its jaws and the fronts of its flippers which are probably sensory organs of some kind, since they contain nerves attached to a very thin hair in the middle that’s about an inch long at most, or almost 3 cm.

This is a good time to remind you that even though they look very different from other mammals, all whales are mammals. Mammals are warm-blooded animals that produce milk for their babies. Mammals also have hair, unless they don’t have hair, except that the humpback whale does have hairs in its tubercles. So there you go, humpback whales have hair.

Despite its huge size, the humpback is an active whale. It frequently breaches, meaning it rises up out of the water almost its full length, then crashes back down into the water with a huge splash. It also often slaps its flippers or its tail on the surface. Some researchers think these behaviors may have something to do with communication with other whales, or that the whale is trying to get rid of parasites, or that the whale is just having fun.

Humpback whales are famous for their elaborate songs, which are produced by males. The whales breed in winter, and the males start singing as winter gets closer, so the songs must have something to do with mating season. Scientists aren’t sure what, though. Females don’t seem to be very interested in individual males who are singing, but they will sometimes be attracted to a group of singing males. Some researchers suggest that singing might be a general call to attract all whales in the area to the breeding grounds. Then again, sometimes a male will interrupt another male who is singing and the two will fight.

The songs vary and new song elements can spread quickly through a population. Generally, researchers think males hear a new element and incorporate it into their own songs, but results of a study published in 2021 found that similar new song elements often show up in whales that could not have heard other whales sing it. This indicates that instead of copying other songs, each whale modifies his own song individually and sometimes the changes are similar. That’s just one study, though. It’s probable that the way males change their songs depends on many factors, only one of which is hearing and imitating other songs.

The study suggests that the way we think about whale songs might be wrong to start with. Researchers generally think that a whale probably sings for the same reasons that birds sing: to stake out a territory, to advertise to potential mates that it’s healthy enough to spend energy singing, and to warn rivals away. But because whales live in an environment so different from birds, and so different from what we as humans understand, it’s possible that whalesong carries meanings and intentions that we can’t interpret. A different study published in 2019 discovered that male humpbacks sometimes sing in feeding grounds, especially when a population of whales decides to overwinter at their feeding grounds instead of migrating, as sometimes happens.

What, precisely, a whale’s song means to other whales is something that only the whales know for sure. This is what a humpback song sounds like:

[humpback song]

Humpbacks make other sounds other than songs, though. Mothers and calves need to communicate so that the calves get the care they need and don’t stray too far away, but since any sounds could attract predators, they have to communicate very quietly. They make little grunting sounds to each other.

The main predator of the humpback whale is the orca, which will attack and kill calves and sometimes even adults. As a result, the humpback really does not like orcas. Humpbacks will sometimes protect seals and other animals from orca attacks.

Humpbacks migrate from their summer habitats in either the Antarctic or the Arctic, depending on what hemisphere they live in, to their winter breeding grounds in tropical waters. Then they return to colder waters in summer where there’s more food, since krill is a cold-water species. These migrations can be as long as 5,000 miles, or 8,000 kilometers. Unlike some animals that migrate in huge herds, humpbacks mostly travel in small groups that are often widely spaced.

The humpback was almost driven to extinction by commercial whaling, but after it was declared a protected species, its numbers have increased. It still has the same human-caused dangers that many other marine animals face, including habitat loss and water pollution, climate change, drowning after being entangled in nets, and noise pollution that can keep whales from communicating.

There’s always a lot we don’t know about any given species of whale, since whales are hard to study. For instance, a 2017 study discovered that humpbacks sometimes swim in a way never documented in whales before. Whales swim by flexing their massively powerful tails, and use their flippers to maneuver. Think of the tail as the engine of a car and the flippers as the power steering system. The humpback’s flippers are uniquely shaped, which as we mentioned earlier means it can maneuver skillfully, turning much more quickly than a great big whale would otherwise be able to turn. But in video studies of whales in the wild, very rarely a whale would flap its flippers like a bird flapping its wings—or, more accurately, like a seal or sea lion swimming with its flippers. The researchers who analyzed the videos suggest that the flapping is used for accelerating quickly, and because it takes a lot of energy, the whales don’t do it often. The researchers also think the humpback may be the only whale species that can accelerate using the motion of its flippers, since other whales have much smaller flippers relative to their size.

As far as we know, baleen whales don’t use sonar the way toothed whales do. Their songs and sounds are for communication, not navigation. But while humpbacks mostly hunt for food near the surface of the water where there’s plenty of light, they do occasionally dive deeper and hunt for food near the bottom. They especially like an eel-like fish called the sand lance, which spends a lot of time buried in the sand on the sea floor. In 2014, a study of humpbacks diving to find these fish indicated that when a whale dives alone, it remains silent, but when it dives to hunt with some friends, they communicate with a sound described as a tick-tock. Not the app, just a sound like the ticking of a clock. Sometimes more humpbacks come to join the whales when they hear their tick-tock sounds. But we still don’t know how the whales find the fish in the first place, since there’s no light for them to hunt by. It’s possible they can detect the fish’s chemical signature in the water when they’re close enough to one.

Baleen whales don’t have teeth, although when a baby whale is developing in its mother’s womb it does grow teeth. But at some point during its development, these embryonic teeth are reabsorbed and baleen plates form instead.

The extinct ancestors of modern baleen whales still had teeth. One genus was called Aetiocetus, which lived between about 34 and 23 million years ago in the north Pacific Ocean. It probably wasn’t directly related to modern whales, since baleen whales do actually appear in the fossil record before Aetiocetus. It was a small whale that probably only grew about 11 feet long, or 3.5 meters, although some species might have grown twice that length. The first Aetiocetus fossils were discovered in the 1960s and it was initially described as a toothed whale, since it had teeth.

But not everyone agreed. Aetiocetus showed some adaptations to filter feeding seen in modern baleen whales. For instance, its lower jaw bones weren’t fused at the chin end as they are in toothed whales. Modern baleen whales don’t have connected lower jaw bones, and in fact they have a sensory organ at that spot that scientists think helps the whale keep from engulfing too much water and hurting itself.

Recently, a team of scientists examined a CT image of a skull of Aetiocetus weltoni and discovered something surprising. Baleen is made of keratin, and keratin is only preserved in fossils very rarely, but in baleen whale fossils, the upper jawbones do show grooves where the baleen once connected. These grooves were present in the Aetiocetus skull, even though it also had teeth.

Researchers think Aetiocetus may have used its teeth to filter larger fish from the water the way some animals like crab-eater seals do today. Its teeth interlocked, which would allow it to trap fish in its mouth while pushing water out between its teeth. Its baleen probably helped catch smaller fish and other animals. The baleen was far enough away from the teeth that the whale would have still been able to bite at fish and other prey without accidentally biting its own baleen. But, as the researchers mention in their 2021 paper, Aetiocetus had a really crowded mouth.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 072: Weird Whales

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It’s been too long since we discussed whales, so this week let’s learn about how whales evolved and some especially strange or mysterious whales!

Pakicetus was probably kind of piggy-looking, but with a crocodile snout:

Protocetids were more actually whale-like but still not all that whale-like:

Now we’re getting whaley! Here’s basilosaurus, with a dinosaur name because the guy who found it thought it was a reptile:

Here’s the skull of a male strap-toothed whale (left). Those flat strips are the teeth:

Another view. See how the teeth grow up from the lower jaw and around the upper jaw?

A dead pygmy right whale:

The walrus whale may have looked sort of like this:

The half-beak porpoise had a chin that just would not quit:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week’s topic is weird whales and some of their relations. If you think about it, all whales are weird, but these are the weirdest whales we know of. Some are living, some are extinct, and some…are mysteries.

Whales, dolphins, and porpoises are most closely related to—wait for it—HIPPOPOTAMUSES. About 48 million years ago an ancestor of both modern hippos and whales lived in Asia. It’s called Inodhyus and it was about the size of a cat, but looked more pig-like. It was at least partially aquatic, probably as a way to hide from predators, but it was an omnivore that probably did most of its hunting and foraging on land.

The earliest whale is generally accepted to be Pakicetus. It lived around the same time as Inodhyus and its fossils have been found in what is now Pakistan and India. It was about the size of a big dog, but with a long, thick tail. Its skull was elongated, something like a short-snouted crocodile with big sharp triangular teeth. It had upward-facing eyes like a crocodile or hippo, and it also had four long, fairly thin legs. It probably hunted on both land and in shallow water, and like the hippo it probably didn’t have much hair.

That doesn’t sound much like a whale, but it had features that only appear in whales. These features became more and more exaggerated in its descendants. At first, these ancestral whales looked more like mammalian crocodiles. It’s not until Protocetids evolved around 45 million years ago that they started to look recognizably like whales. Some protocetids lived in shallow oceans throughout the world but probably still gave birth on land, while others were more amphibious and lived along the coasts, where they probably hunted both in and out of water. But they had nostrils that had migrated farther back up their snouts, although they weren’t blowholes just yet, reduced limbs, and may have had flukes on their large tails. But they still weren’t totally whale-like. One protocetid, Rodhocetus balochistanensis, still had nail-like hooves on its forefeet.

By around 41 million years ago, the basilosaurids and their close relations had evolved, and were fully aquatic. They lived in the oceans throughout the tropics and subtropics, and their nostrils had moved almost to the location of modern whales’ blowholes. Their forelegs were basically flippers with little fingers, their hind legs had almost disappeared, and they had tail flukes. They were also much bigger than their ancestors. Basilosaurus could grow up to 60 feet long, or 18 meters, and probably looked more like a gigantic eel than a modern whale. It was long and relatively thin, and may have mostly lived at the ocean’s surface, swimming more like an eel or fish than a whale. It ate fish and sharks. SHARKS.

So when did whales develop the ability to echolocate? Researchers think it happened roughly 34 million years ago, which also happens to be about the same time that baleen whales and toothed whales started to develop separately. Echolocation probably evolved to help whales track hard-shelled mollusks called nautiloids. By 10 million years ago, though, nautiloids were on the decline and mostly lived around reefs. Whales had to shift their focus to soft-bodied prey like squid, which meant their sonar abilities had to become more and more refined. Toothed whales echolocate, while baleen whales probably do not. Researchers aren’t 100% sure, but if baleen whales do use echolocation, it’s limited in scope and the whales probably mostly use it for sensing obstacles like ice or the sea floor.

Baleen whales are the ones that communicate with song, although the really elaborate songs are from humpback and bowhead whales. Of those species, humpback songs are structured and orderly, while bowhead whale song is more free-form. But humpback songs do change, and researchers have discovered that they spread among a population of whales the same way popular songs spread through human populations. This is what they sound like, by the way. A snippet of humpback song is first, then a snippet of bowhead song.

[examples of humpback and bowhead]

So now we’ve got a basic understanding of how whales evolved. Now let’s take a look at some of the weirder whales we know about. We’ll start with a living one, the strap-toothed whale. It’s one of 20-odd species of mesoplodont, or beaked whale, and we don’t know a whole lot about any of them. The strap-toothed whale is the longest beaked whale at 20 feet long, or 6.2 meters.

The strap-toothed whale lives in cold waters in the southern hemisphere. It’s rarely seen, probably since it lives in areas that aren’t very well traveled by humans. It mostly eats squid. Females are usually a little bigger than males, and adults are mostly black with white markings on the throat and back.

The weird thing about this whale is its teeth. Male beaked whales all have a pair of weird teeth, usually tusk-like, which they use to fight each other, but strap-toothed whales take the weird teeth deal to the extreme. As a male grows, two of its teeth grow up from the lower jaw and backwards, curving around the upper jaw until the whale can’t open its mouth very far and can only eat small prey. The teeth can grow a foot long, or 30 cm, and have small projections that cause more damage in fights with other males.

Most of what we know about the strap-toothed whale comes from whales that have been stranded on land and died. Males don’t seem to have any trouble getting enough to eat, and researchers think they may use suction to pull prey into their mouths. Other beaked whales are known to feed this way.

All beaked whales are deep divers, generally live in remote parts of the world’s oceans, and are rarely seen. In other words, we don’t know for sure how many species there really are. In 1963, a dead beaked whale washed ashore in Sri Lanka. At first it was described as a new species, but a few years later other researchers decided it was a ginkgo-toothed whale, which had also only been discovered in 1963. Male ginkgo-toothed whales have a pair of tusks shaped like ginkgo leaves, but they don’t appear to use them to fight each other. But a study published in 2014 determined that the 1963 whale, along with six others found stranded in various areas, belong to a new species. It’s never been seen alive. Neither has the ginkgo-toothed whale.

The pygmy right whale is a baleen whale, but it’s another one we know very little about. It lives in the southern hemisphere. Despite its name, it isn’t closely related to the right whale. It’s small for a baleen whale, around 21 feet long, or 6.5 meters, and it’s dark gray above and lighter gray or white underneath. Its sickle-shaped dorsal fin is small and doesn’t always show when the whale surfaces to breathe. It feeds mostly on tiny crustaceans like copepods, and probably doesn’t dive very deeply considering its relatively small heart and lungs.

The pygmy right whale was first described in 1846 from bones and baleen. Later studies revealed that it’s really different from other baleen whales, with more pairs of ribs and other physical differences. It also doesn’t seem to act like other baleen whales. It doesn’t breach, slap its tail, or show its flukes when it dives. It doesn’t even swim the same way other whales swim. Other whales swim by flexing the tail, leaving the body stable, but the pygmy right whale flexes its whole body from head to tail. It seems to be a fairly solitary whale, usually seen singly or in pairs, although sometimes one will travel with other whale species. In 1992, though, 80 pygmy right whales were seen together off the coast of southwest Australia. Fewer than 200 of the whales have been spotted alive, including those 80, so we have no idea how rare they are.

It wasn’t until 2012 that the pygmy right whale’s differences were explained. It turns out that it’s not that closely related to other baleen whales. Instead, it’s the descendant of a family of whales called cetotheres—but until then, researchers thought cetotheres had gone extinct completely around two million years ago. Not only that, it turns out that at least one other cetothere survived much later than two million years ago, with new fossils dated to only 700,000 years ago. But that particular whale, Herpetocetus, had a weird jaw joint that kept it from being able to open its mouth very far. It and the strap-toothed whale should start a club.

Sometimes whale fossils are found in unexpected places, which helps give us an idea of what the land and ocean was like at the time. For instance, fossils of an extinct beaked whale known as a Turkana ziphiid was found in Kenya in 1963, in a desert region 460 miles inland, or 740 kilometers. The fossil is 17 million years old. So how did it get so far inland?

It turns out that at the time, that part of east Africa was near sea level and grown up with forests. The fossil was found in river deposits, so the whale probably swam into the mouth of a river, got confused and kept going, and then couldn’t turn around. It kept swimming until it became stranded and died. Because of the finding, researchers know that 17 million years ago, the uplift of East Africa had not yet begun, or if it had it hadn’t yet made much progress. The uplift, of course, is what prompted our own ancestors to start walking upright, as their forest home slowly became grassland.

As an interesting aside, the fossil was stored at the Smithsonian, but at some point, like so many other fascinating items, it disappeared. Paleontologist Louis Jacobs spent 30 years trying to find it, and eventually located it at Harvard University in 2011. After he finished studying it, he donated it to the National Museum of Kenya.

More whale fossils were uncovered in 2010 in the Atacama Desert in Chile—in this case, over 75 skeletons, many in excellent condition, dated to between 2 and 7 million years ago. Researchers think they’re the result of toxic algae blooms that killed the whales, which then washed ashore. Over 40 were various types of baleen whales. Other fossils found in the same deposit include a sperm whale, marine sloths, and a tusked dolphin known as a walrus whale.

The walrus whale lived in the Pacific Ocean around 10 million years ago, and while it’s considered a dolphin, it’s actually more closely related to narwhals. But it probably looked more like a walrus than either. Unlike most whales, it had a flexible neck. It also had a face like a walrus. You know, flattish with tusks sticking down. It probably ate molluscs. But the right tusk was much longer than the left one, possibly in males only. In the case of one species of walrus whale, one specimen’s left tusk was about 10 inches long, or 25 cm, while its right tusk was over four feet long, or 1.35 meters. Some researchers suggest that the whale swam with its head bent so that the long tusk lay along the body. Possibly it only used it for display, either to show off for females or to fight other males. But we don’t know for sure.

Speaking of narwhals, if you were hoping to hear about them, you’ll need to go way back to episode five, about the unicorn. I talk about the narwhal a lot in that episode. The narwhal happens to be one of the best animals. A lot of people think the narwhal isn’t a real animal, that it’s made up like a unicorn. In fact, about a week ago, I was talking to a coworker and the subject of narwhals came up. She actually did not realize it was a real animal. Nope, it’s real, and that horn is real, but it’s actually a tusk rather than a horn. It grows through the whale’s upper lip, not its forehead. In another weird coincidence, this afternoon when I was about to sit down and record this episode, a friend sent me a link to an article that had some narwhal sounds. So we’re not really talking about narwhals in this episode, but hey, this is what they sound like.

[narwhal calls]

Another weird whale is the halfbeak porpoise, or skimmer porpoise, which lived off the coast of what is now California between 5 and 1.5 million years ago. While it probably looked mostly like an ordinary porpoise, its chin grew incredibly long. The chin, properly called a symphysis, was highly sensitive, and researchers think it used it to probe in the mud for food.

There’s still so much to learn about whales, both living ones and extinct ones. We definitely haven’t identified all the living whales yet. There are reports of strange whales from all over the world, including a baleen whale with two dorsal fins. It was first spotted in 1867 off the coast of Chile by a naturalist, and other sightings have been made since. It’s supposedly 60 feet long, or 18 meters, so you’d think it wouldn’t be all that hard to spot…but there’s a whole lot of ocean out there, and relatively few people on the ocean to look for rare whales.

Whales can live a really long time. In 2007, researchers studying a dead bowhead whale found a piece of harpoon embedded in its skin. It turned out to be a type of harpoon that was made around 1879. Bowheads can probably live more than 200 years, and may even live longer than that.

And, of course, whales are extremely intelligent animals with complex social and emotional lives, the ability to reason and remember, tool use, creative thinking and play, self-awareness, a certain amount of language use, and altruistic behaviors toward members of other species. Whales and dolphins sometimes help human swimmers in distress, dolphins and porpoises sometimes help beached whales, and humpback whales in particular sometimes rescue seals and other animals from orcas. Humans aren’t very good at thinking about intelligence except as it pertains to us, but it seems pretty clear that other apes, whales and their relations, elephants, and probably a great many other animals are a lot more intelligent than we’ve traditionally thought.

One last interesting fact about whales and their relations. Most of them sleep with half their brain at a time. The half that isn’t sleeping takes care of rising to the surface to breathe periodically, so the whale doesn’t drown. That does not sound very restful to me. But sperm whales sleep with their bodies vertical and their heads sticking up out of the water. But they don’t sleep very long, only around ten minutes at a time—and only in the hours before midnight. I’ve had nights like that.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!