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Episode 240: The End of the Dinosaurs

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Here we go. It’s the big one, the Cretaceous-Paleogene extinction event!

Further reading:

How Birds Survived the Asteroid Impact That Wiped Out the Dinosaurs

How an asteroid ended the age of dinosaurs

Extinction event that wiped out dinosaurs cleared way for frogs

How life blossomed after the dinosaurs died

66-million-year-old deathbed linked to dinosaur-killing meteor

Show transcript:

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

Here it is, the extinction event episode that everyone’s been waiting for, or at least that everyone knows about. It’s the one that killed off the dinosaurs and ushered in the age of mammals. It’s probably the one we know most about and it’s certainly the one we have the most paintings of, usually of a T. rex staring into the sky at an approaching comet.

In episode 227 we talked about the end-Permian extinction event, which took place about 250 million years ago. The Cretaceous-Paleogene extinction event, or end-Cretaceous, took place just over 66 million years ago, which means that for almost 200 million years there was more or less smooth sailing in the world. Dinosaurs evolved during that time, and I think we can all agree that dinosaurs are fascinating animals.

The largest terrestrial animals ever to live were dinosaurs, specifically the sauropods. Sauropods were just unimaginably huge. They were like walking buildings that ate plants, and even that doesn’t give a good idea of their size. Some sauropods had extremely long tails as well as very long necks, which increased their length. Right now the largest sauropod known was probably Argentinosaurus that might have grown as long as 118 feet, or 36 meters, but paleontologists keep finding bigger and bigger sauropods. Some sauropods had extremely long necks that they held up like a giraffe. The tallest was probably Barosaurus, estimated as being 72 feet tall, or 22 meters. And we won’t even get into estimates of how much these massive animals weighed. They make the biggest elephant that ever lived look like a toy elephant.

Sauropods ate plants, with the low-necked species eating low-growing plants and the high-necked species eating tree leaves, although even saying that much is controversial. There’s a lot we don’t know about sauropods in general, since most sauropod fossils are incomplete and many species are only known from one or a few bones. But we do know some surprising things about sauropods. We have a lot of sauropod tracks, which helps us understand how their feet looked and whether they had claws, but it also tells us that some species of sauropod traveled in herds. Paleontologists do generally agree that many sauropods migrated, since animals that big would soon exhaust all the food in one area if they didn’t.

Sauropods were extremely successful and lived all over the world. There were plenty of sauropods alive 66 ½ million years ago, and then…there were no sauropods alive ever again.

These days, there’s so much evidence that a massive asteroid killed off the dinosaurs that pretty much everyone agrees, but when the idea was first proposed in 1980, it was extremely controversial. When I was a kid I remember reading dinosaur books that still said the extinction of the dinosaurs was a mystery but that many scientists thought it was due to disease or volcanoes.

The asteroid strike hypothesis was proposed by the physicist Luis Alvarez and his son, Walter. They worked with a small team of other scientists, including two chemists, Helen Michel and Frank Asaro, to investigate a strange anomaly in rock strata. Rocks dating to the end of the Cretaceous period and the beginning of the Paleogene period are separated by a thin layer of clay that’s visible throughout the world, or at least wherever the rocks remain and can be examined. It’s called the Cretaceous-Paleogene boundary, or K-Pg boundary, although in older books and websites it’s called the K-T boundary. It occurred just over 66 million years ago. The Alvarezes were curious about this layer, and during their investigations they found out that the clay is full of an element called iridium.

Iridium is a silvery-white metal chemically related to platinum, and it’s rare. At least, it’s rare on Earth. It’s a common component of asteroids, which was one of the main reasons why the Alvarezes came to their hypothesis that the K-Pg boundary was the result of a massive asteroid impact. Other scientists had made similar suggestions in the decade or so leading up to the Alvarezes’ theory, but the iridium discovery provided the proof everyone wanted.

Iridium wasn’t the only thing found in the K-Pg boundary layer, either. There were other platinum-group metals present in high concentrations—much higher than found on Earth, and in fact these elements are referred to as rare-earth metals for that reason. In some places, the K-Pg boundary contains grains of shocked quartz and microtektites. We’ll discuss those in a minute.

As we’ve discussed before in various episodes, the earth’s surface is always moving around. It’s slow to us, with continents moving around at the same dizzying speed that our fingernails grow, but over millions of years that adds up. Continents move around and crash into each other, forming new mountain ranges that then wear down to plains, and where continental plates pull apart or push together the crust can weaken and allow magma to erupt through as volcanoes. Ocean levels rise and fall. In other words, a crater made 66 million years ago might have disappeared as all this geologic activity goes on.

But then, we found the crater. The crater.

The Chicxulub crater is in Mexico, specifically the Yucatán Peninsula at the southern portion of the Gulf of Mexico. You can’t see it when you’re walking around because it’s buried under 2,000 feet of soil, or 600 meters, that has built up over the last 66 million years. Two geophysicists found it in the 1970s while surveying for petroleum, but it wasn’t until 1990 that they were able to verify that it was a crater. Asteroid impacts leave clues behind that the geophysicists recognized.

The first clue is shocked quartz. Quartz is a common crystalline mineral throughout the world, and it has a certain structure that’s familiar to geologists. In shocked quartz, that structure has been deformed by intense pressure, but not high temperature. It was first noticed after nuclear bomb tests, and after that scientists recognized it in meteor craters.

The second clue is little pieces of glass called tektites. They’re different from obsidian, which is a type of glass formed by volcanic activity. Tektites are usually shaped like droplets or little blobs, but sometimes they’re round. They’re only found around big impact sites and only for relatively recent meteor impacts, because they don’t last forever.

The Chicxulub crater is actually kind of old for its tektites to still be around, except for two things. First, the tiniest tektites, the microtektites, ended up in the K-Pg boundary layer, as I mentioned earlier. Second, we actually have a fossil site in North Dakota, in the middle of North America up near Canada, that seems to date to literally the day of the asteroid impact, and there are tektites all over the site, including clogging the gills of fish. The tektites match the chemical signatures of the Chicxulub crater so we know that’s where they came from.

Before we talk about the North Dakota fossil bed, let’s discuss what exactly happened on the day the asteroid hit the earth. Because we’ve found the asteroid’s crater, we know a lot about the asteroid itself. Most researchers estimate that it was about 6 miles across, or 10 km. It approached the earth at an angle, traveling about 12 km a second. That’s 7.5 miles per second. It hit the earth right on the coast, partly in the ocean, partly on land, forming a crater about 110 miles across, or 180 km, and 12 miles deep, or 19 km.

The asteroid smashed into the Earth so fast that it was completely buried in about the time it takes you to blink. There really wasn’t time for any dinosaurs to look up and wonder what that bright light was, because the time between the asteroid entering earth’s atmosphere and smashing into the earth was maybe five seconds.

The megatsunami resulting from the impact would have been unbelievably huge. Waves may have been a mile high, or over 1.5 km. The initial impact would have thrown water more than 7.5 miles into the air, or 12 km, and when that water fell back down it would have set up another megatsunami. Not only that, the impact actually shook the whole earth like a massive earthquake, which caused landslides all over the place and set up even more tsunamis. It’s like shaking a snowglobe to watch the fake snow swirl around and around, only instead of fake snow it was ocean.

At the same time, everything near the impact site was instantly on fire. It was on fire because the asteroid was traveling so fast that it was glowing white-hot with incandescent heat just from pushing against air molecules, and when it hit the Earth, all that heat had to go somewhere. Also, everything exploded. The water exploded up and outward, the land exploded up and outward. A lot of water turned instantly to steam. The asteroid itself disintegrated and tiny bits of it were carried high into the atmosphere along with ash, dust, molten glass created by the blast, and anything else that was nearby and not instantly incinerated.

The shockwaves from the impact acted as a magnitude 12 earthquake, with follow-up shocks estimated at about magnitude 9 occurring across the entire planet. Volcanoes erupted as a result, pumping even more ash and gases into the atmosphere. All the trees were flattened for about 930 miles around the impact, or 1500 km.

Within a few hours of the impact, fireballs of molten rock and glass were falling across the world, setting fires on land and heating the surface of the ocean to boiling temperature in many areas. And it was already getting really dark as the massive amounts of debris and dust and ash and smoke and everything else spread across the earth.

Okay, deep breath. This happened a long, long time ago and most animals died so quickly they didn’t feel anything. Look out the window if you’re feeling stressed and see how calm it is? Maybe it’s raining where you live or maybe it’s night-time and you can hear frogs or crickets calling, maybe an owl if you’re lucky. It might be daytime and you can hear cars passing by, or a dog barking somewhere, people talking. Whew. Okay, back we go to that awful day 66 million years ago, back to the fossil site found in North Dakota.

Back then, the middle of North America was a shallow sea. The first tsunami wave was probably 30 feet tall, or 9 meters, when it reached the mouth of a river emptying into the sea. It pushed the river backwards and washed hundreds of freshwater fish onto a sand bar. To add insult to injury, or just injury to injury, while the fish were stranded and flopping around trying to get back in the water, globs of molten glass and rocks rained down on them. Then another wave pushed up the river and covered the dead and dying fish with a lot of sand and sediment, which preserved them.

The site was discovered in 2013 and the findings were published in 2019. It’s not just fish at the site, although there are unbelievable numbers of fish. There are also tree trunks and branches that show evidence of burning, ammonites and other marine animals that were washed up the river, even part of a triceratops and a hadrosaur. One charred trunk is covered in amber, which is fossilized tree resin. The amber is full of tektites, which were caught in the resin when it was soft.

Every time I say tektite I think of those spidery things in Zelda, which makes this whole situation seem even worse.

None of the animals at the site show evidence of being eaten by anything. Some researchers estimate that the event took place less than an hour after the asteroid impact. There’s also a layer of clay on top of the sediment that contains high levels of iridium.

In all, roughly 75% of all life on earth went extinct following the asteroid impact. Many animals that survived the immediate aftermath of the impact died out months or years later, and many more scraped along for hundreds or thousands of years before finally going extinct. The massive amounts of dust and ash in the atmosphere blocked sunlight for the next several years or even longer, which means plants died throughout the world. Poisonous gases in the atmosphere led to acid rain that killed more plants and animals. The ocean temperature dropped considerably, as did the overall temperature of the earth, leading to freezing temperatures that would have killed off even more animals. Deep-sea animals fared better than most, but many plankton went extinct very soon after the impact and that meant animals that ate the plankton also went extinct.

But, of course, not everything went extinct. If it had, I wouldn’t be recording this episode and you wouldn’t be listening to it. Awful as it sounds, the Cretaceous-Paleogene extinction event wasn’t nearly as bad as the end-Permian extinction. Full recovery is estimated to have taken as much as 9 million years, when it took 50 million years for the earth to fully recover from the end-Permian extinction.

One thing that isn’t generally known is that things had been getting rough on earth for a couple of million years before the asteroid hit. Some species were already in decline due to climate change. The asteroid just made everything intensely worse.

The first plants to recolonize the blasted wastelands were ferns, lots and lots and lots of ferns. Ferns are tough plants and thrive in areas where nothing else can grow, and ferns grow quickly and provide food for lots of animals. Within a hundred years of the impact the world was carpeted with ferns.

Some dinosaurs did survive, of course, but we call them birds. They would have looked very birdlike even 66 million years ago. Most birds that survived were ones that lived on the ground instead of in trees. Researchers think many birds survived because they were able to eat seeds, which would have remained as a food source even after the plants that dropped the seeds had all died. Insects and other invertebrates that eat rotting leaves would have been just fine, and many birds could find and eat them too.

Mammals also survived the asteroid impact, of course. Look, here we are! We’ve done quite well for ourselves. 66 million years ago most mammals were small and rodent-like, and the ones that survived probably mostly lived in burrows and ate seeds and other plant material or small animals like insects.

Surprisingly, frogs did really well after the asteroid impact. Frogs are small and can survive in small microhabitats. While most of the frogs in North America went extinct, plenty of frogs survived in other parts of the world that weren’t so close to the impact site, and as soon as conditions improved, more species evolved than ever before. That’s why frogs across the world look so similar. They may not all be closely related, but they all faced the same environmental pressures at the same time.

Once plants started to recover, things took a turn for the better as birds, fish, mammals, reptiles, amphibians, insects, and other animal groups suddenly didn’t have to watch out for dinosaurs or the other big predators that had gone extinct. Sauropods and other giant herbivores weren’t eating up all the plants. Life evolved rapidly to fill the available ecological niches, and animals started getting bigger and bigger.

In late 2019, scientists released details of a fossil site found in Colorado, in the western United States. It has an unbroken record of rocks dating from before the asteroid impact to about a million years afterwards. It gives us an excellent record of the changes that took place.

In the years after the impact, there’s not a lot to see, just lots of ferns and some rat-sized mammals. Within 200,000 years palm forests had replaced the ferns and cat-sized mammals were common. By 400,000 years after the impact, plants and trees with nuts evolved and many mammals were the size of dogs. By 700,000 years after, the relatives of modern bean and pea plants appeared, forests were varied and healthy, and the mammals were the size of wolves or bigger. There were animals other than mammals too, including a five-foot-long crocodilian, or 1.5 meters, with teeth adapted to crush turtle shells.

The ancestors of whales evolved about 50 million years ago around what is now India and its neighbors, when a little animal called Indohyus spent a lot of time in the water. It was about the size of a raccoon, which it resembled in some ways, except that its bones were unusually heavy for its size. This helped it stay underwater without effort. The hippopotamus has the same kind of heavy bones for the same reason, and Indohyus was actually related to the hippo’s distant ancestor. Within five million years, descendants of animals like Indohyus were fully aquatic and looked a lot like dolphins with small legs. As whales got bigger and faster, predators evolved too, including the largest shark that ever lived, Megalodon. The first baleen whales evolved around 25 million years ago and ultimately grew to the gigantic sizes of some of the whales alive today.

Every time you feel sad that you’ll never see a real live dinosaur like a sauropod, remember that you live at the same time as the undisputed largest animal that has ever lived, the blue whale. It can grow up to 98 feet long, or 30 meters, and possibly longer. That’s as long as a ten-story building is high. It’s twice the length of Megalodon! If you have the money and time, you can actually charter a boat that will take you out to look at blue whales because they’re still alive!

I guarantee you that millions upon millions of years from now, in some far-distant future that we can’t even imagine, there will be scientists who study whales and write whatever those future people use as books, and there will be young people who read those books and look longingly at drawings of whales. They’ll know about dinosaurs, sure, and those will always be popular, but it’ll be the whales that really catch people’s imagination. There will be the far-future equivalent of movies where people successfully clone whales or bring them back from the past, and the details will be all wrong but no one will know because no one in that far future time will actually know what whales really look like! But you know, and that is the most amazing fact I can ever share with you.

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. There are links in the show notes to join our mailing list and to our merch store.

Thanks for listening!

Episode 211: The Magnificent Fin Whale

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This week let’s venture into the ocean and learn about the fin whale!

Further reading:

The songs of fin whales offer new avenue for seismic studies of the oceanic crust

Fin whales’ big gulp

The fin whale can hold a whole lot of water in its mouth (illustration from the second article linked above):

A fin whale underwater. Look at that massive tail. That’s pure muscle:

A fin whale above water. It’s like a torpedo:

Show transcript:

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

It’s been too long since we had an episode about whales. Yes, okay, two weeks ago we talked about a couple of newly discovered whales, but I want to really learn about a particular whale. So this week, let’s look at the fin whale.

The fin whale is a baleen whale that’s only a little less enormous than the blue whale. The longest fin whale ever reliably measured was 85 feet long, or just a hair shy of 26 meters, but there are reports of fin whales that are almost 90 feet long, or a bit over 27 meters. An average American school bus is half that length, so a fin whale is as long as two school buses. Even a newborn fin whale calf is enormous, as much as 21 feet long, or 6.5 meters. Females are on average larger than males.

It’s a long, slender whale that’s sometimes called “the greyhound of the sea,” because it’s also really fast. It can swim up to 29 mph, or 46 km/hour, and possibly faster. If that doesn’t sound too fast, consider that the Olympic gold-medal swimmer Michael Phelps topped out at about 4.7 miles per hour, or 7.6 km/h.

Like other baleen whales, the fin whale has a pair of blowholes instead of just one. On its underside, it has up to 100 grooves that extend from its chin down to its belly button. Yes, whales have belly buttons. They’re placental mammals, and all mammals have belly buttons because that’s where the umbilical cord is attached when a developing baby is in its mother’s womb. I don’t know what a whale’s belly button looks like. Also, the proper term for belly button is navel, and if you’re wondering, that’s where navel oranges get their name, because they have that weird thing on one end that looks like a belly button. It’s not, though. I don’t know what it is. You’ll have to find a podcast called Strange Plants to explain it.

Anyway, the grooves on the fin whale’s underside act as pleats, or accordion folds. Other baleen whales have these pleats too. 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. The water it can hold in its mouth is about equal to the size of a school bus.

Technically, though, a lot of that water isn’t in the whale’s mouth. It’s in a big pocket between the body wall and the blubber underneath the skin. The ballooning out of the pocket stretches the nerves in the mouth and tongue to more than twice their length, and then the nerves have to fold back up tightly after the water is pushed out. The nerves fold in a complicated double layer to minimize damage during all this stretching.

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 for another big bite. Even more amazing, this whole operation, from opening its mouth to swallowing the food, only takes six to ten seconds.

Because it only eats small animals, the fin whale’s esophagus (which is the inside part of the throat) is actually quite narrow considering what a huge animal it is. In other words, it could not possibly swallow a human, in case you were worried. I was worried. If you did end up in a fin whale’s mouth, it would just spit you back out.

Baleen whales have a sensory organ on the chin that’s found in no other animal. It’s about the size of a grapefruit and situated between the tips of the jaws. It probably helps the whale determine how much potential food is in the water, which saves it from wasting time and energy gulping in water and filtering it out when there’s nothing much to eat.

The fin whale looks a lot like the blue whale and the two species are closely related, so much so that they sometimes interbreed and produce hybrid babies. It usually lives in small groups of up to around 10 individuals and a female fin whale has one baby every two or three years. It probably migrates seasonally to new feeding grounds, but we don’t actually know a whole lot about where it goes and whether all fin whales migrate.

Fin whales have extremely loud vocalizations, but most humans would barely be able to hear them, or wouldn’t be able to hear them at all, because they’re at the very bottom or below the range of sounds that the human ear can detect. The calls can be up to 188 decibels, a measure of loudness, which may be the loudest sounds made by any animal alive today. Technically the blue whale is louder, at 190 decibels, but on average the fin whale is louder. In comparison, a jet plane taking off is measured at 150 decibels. Of course, sound through water is different from sound through air, because water is much denser. A better comparison is with an offshore drill rig at 185 decibels or a supertanker ship at 190 decibels. The fin whale is about as loud as both, although of course the fin whale doesn’t make those noises all the time like drill rigs and ships do. The male fin whale makes short pulses of sound that last a second or two in specific patterns, which he repeats sometimes for days. Since the sounds travel long distances underwater, researchers think a female can hear a male’s calls and follow the sound so she can find him to mate. Of course, this means that females may have trouble finding a male these days since the ocean is full of noise from human-made things like offshore drill rigs and supertanker ships.

The fin whale is not only one of the loudest animals known, its vocalizations are among the lowest in frequency of any animal ever recorded. It turns out that this combination has a surprising benefit to human knowledge in a very specific way.

In an article published in Science just a few days ago as this episode goes live in February of 2021, a team of scientists discovered that fin whale vocalizations can help with seismic imaging of the oceanic crust.

The oceanic crust isn’t just the sea floor but what the earth below the sea floor is made up of. Scientists measure the reflections of a sound wave, and since sound waves travel at different speeds through different materials, and bounce off various types of rocks and other structures at different speeds and angles, the reflections can tell us a lot. Scientists use sensitive seismometers on the ocean floor to read the reflections. The problem is how to get the sound wave in the first place. Researchers usually use a giant air gun to make sound waves, but not only can this be dangerous to ocean life because it’s so loud, it’s also expensive and can’t be used in all areas.

But the fin whale does almost as good a job as an air gun. A pair of researchers studying earthquakes off the Oregon coast in North America noticed that when fin whales were around, their seismometers picked up extra signals. They figured out that the signals were actually from the fin whales’ vocalizations, and were surprised to find that the reflections matched those from the air gun sound waves. As an added benefit, the researchers could pinpoint exactly where each whale was since its signals were picked up by multiple seismometers.

Fin whale vocalizations are at the perfect frequency and strength for sound waves to travel through the ocean floor and be picked up by the seismometers. Best of all, fin whales live throughout almost all of the world’s oceans, including places where air guns can’t be used. Researchers just have to put the seismometers in place and the whales produce as many sound waves as the scientists need.

Because the fin whale makes such low-frequency noises, its hearing is different from other animals’. Big as a fin whale is, the low-frequency vocalizations it makes actually form a sound wave that’s longer than its body, which means the whale actually can’t hear it through its ears. But for a long time, scientists weren’t sure how the fin whale and other big baleen whales could hear those sounds.

Then, in 2003, a fin whale beached in California and died despite attempts to save it. Scientists were allowed to collect the body for research, and they took the head to an X-ray CT scanner designed for rocket motors to get a 3D image they could study. It turns out that the fin whale’s skull has acoustic properties that makes it sensitive to low frequency sounds and actually amplifies the sound waves as the bones of the skull vibrate. So fin whales hear each other with their skull bones instead of their ears.

Absolutely nothing can top that amazing fact, so that’s the end of this episode.

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 just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us that way.

Thanks for listening!

Episode 008: The Loneliest Whale and Other Strange Recordings

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This week’s episode is a collection of strange animal sounds, some unknown, others identified. We start with “the loneliest whale.”

A blue whale. Not the loneliest whale, as far as anyone knows.

A tarsier:

This fox can see into your soul and does not like you:

Show transcript:

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

One of the great things about making my own podcast is that I’m the one who gets to decide what topics to cover. I love podcasts about unexplained sounds captured on audio, so this week’s episode is just that.

With one or two exceptions, I’ve tried to keep to sounds that are definitely or probably made by animals. I’ve also tried to dig a little deeper to explore some sounds that I haven’t heard covered in other podcasts. I waded through a million pop-up ads so you don’t have to.

First, let’s talk about a whale you’ve probably heard of. It’s frequently called the loneliest whale. The story goes that this whale is lonely because its voice is too high to be heard or understood by other whales. It calls but never gets a response.

But that’s actually not the case. Its voice is higher than other blue whales, fin whales, and humpback whales, but they can certainly hear it, and for all we know, they answer. Since the individual whale hasn’t actually been spotted, we don’t know if it travels alone or with other whales.

The loneliest whale was first detected in 1989 by the US Navy listening for submarines in the North Pacific, then again in 1990 and 1991. At that time the recordings were classified due to the cold war, but in 1992, some were partially declassified, and word about the whale got out. The calls vary but are similar to blue whale calls. The main difference is the voice’s pitch. The loneliest whale calls at 52 hertz. That’s slightly higher than the lowest notes on a piano or tuba. Blue whale songs are typically around 10 to 40 hertz. The whale’s voice has deepened over the years to around 49 hertz, suggesting that it has matured.

Suggestions as to why this whale has a different call include the possibility that the whale is deaf, that it’s malformed in some way, or that it’s a hybrid of two different species of whale. Fin whales and blue whales do interbreed occasionally, but no one has successfully recorded a hybrid’s calls.

Whale researchers think the recordings seem to be of one individual whale, but in 2010, sensors off the coast of California picked up lonely whale type calls that might have been made by more than one whale at the same time. One suggestion is that blue and fin whale hybrids might be common enough that they band together. This seems a little far-fetched to me, but I’m not a whale expert.

The loneliest whale’s migratory patterns suggest it’s a blue whale. So do its call patterns, if not its actual voice, but no one has recorded the whale’s song since 2004.

A documentary called “52: The Search for the Loneliest Whale” is currently in production. There aren’t any dates listed on the official site, 52thesearch.com, but it’s supposed to be released some time this year, 2017. [Note from 2020: it doesn’t appear that this has ever been released.] The film’s expedition has concluded, although we don’t know yet whether the scientific and film teams actually identified the loneliest whale or recorded it.

Here is the call of the loneliest whale. This recording has been sped up 10x to make it easier to hear. The original recording is barely more than a rumble, depending on how good your hearing is and how good your speakers are.

[whale call]

And just for fun, here’s a recording of an ordinary blue whale, also sped up:

[another whale call]

Now let’s go from the largest mammal alive to one of the largest land mammals alive, the elephant. In 1984, biologist Katy Payne, a pioneer in the field of bioacoutics, was at a zoo in Portland, Oregon to give a talk about whale songs. While she was there, she visited the elephant exhibit and noticed that every so often she felt what she called a throbbing in the air. She got some recording equipment and came back to the zoo, recorded the elephants, and sped up her recording. Sure enough, the elephants were making sounds below 20 hertz.

She pursued the finding with wild elephants in Africa. It turns out that elephants communicate not only with the familiar trumpets and squeaks, but in infrasound—that is, sounds below the lower limits of human hearing.

Infrasound can travel a long distance, especially useful in forested areas with limited visibility, and at dusk and dawn when atmospheric conditions help propagate the sound waves so they can travel as far as six miles away [9.6 km]. Females in estrus make a special call to bull elephants, for instance, attracting potential mates from a long way away.

Here’s a recording of elephant rumbles—again, sped up so we can hear it:

[elephant sounds]

Other animals communicate in infrasound, generally large animals like rhinos, hippos, giraffes, and of course whales. Many more communicate in ultrasounds, sounds above the top hearing range of humans, about 20 kilohertz. Bat radar navigation and sonar navigation sounds made by many species of dolphins and toothed whales register in the ultrasonic range, as do many insect calls. But there are other much more surprising animals that communicate in ultrasound.

The Philippine tarsier is a tiny primate only about five inches tall [13 cm], a big-eyed nocturnal fluffball with long fingers. Researchers studying the tarsiers wondered why the animals frequently opened their mouths as though to make calls but produced no sound. Sure enough, they’re communicating at ranges far too high for humans to detect—higher, in fact, than has been discovered for any terrestrial mammal.

The Philippine tarsier most often communicates at 70 kHz and can hear sounds up to 90 kHz. Researchers think the tarsier uses its ultrasonic hearing to track insects, and communicates in frequencies too high for predators to hear. Here’s a tarsier call, slowed down so we can hear it. I’ll keep it short because it’s super annoying.

[tarsier call]

Another animal that uses ultrasound is the cat. Domestic cats can hear sounds up to 85 kHz. Some kitten calls fall in the ultrasonic range, so the mother cat can hear her babies but many predators can’t. Cats have evolved to hear such high sounds because many rodents communicate in ultrasound. Male mice, for instance, sing like birds to attract mates. Here’s an example, slowed down so we can hear it:

[mouse singing]

But so far these are all known animals, or in the case of the loneliest whale, probably known. What about truly mysterious sounds?

Probably the most famous mystery sound is the bloop. It was recorded by NOAA in 1997 off the tip of South America. It’s an incredibly loud sound, much louder than the loudest animal ever recorded, the blue whale, and for a long time, people speculated that it might be an enormous unknown animal. Unfortunately, or maybe fortunately because no one wants to awaken Cthulhu, NOAA has identified the bloop as the sound of an icequake. That is, massive iceburgs breaking apart. Here’s a clip of the bloop, sped up so we can hear it:

[the bloop]

Another solved mystery sound has been dubbed “bioduck,” since it sounds sort of like a robotic duck. It’s been recorded since the 1960s, when it was first reported by submarine operators in the southern ocean off the Antarctic. It’s common, heard almost year-round near Antarctica and Australia, and was not from any known human-made source. Then, in 2013, whale researchers attached suction-cup tags to two Antarctic minke whales. While the tags remained in place, they recorded not only where the whales went, but the sounds they made. And to the research team’s astonishment, both whales made bioduck calls. This finding is important, not just because it cleared up a longstanding mystery, but because it tells us a lot about the Antarctic minke whale that wasn’t known. Researchers thought the whales only lived in Antarctic waters part of the year. Now they know that some whales remain year-round while some migrate near Australia. They can also make better estimates of whale populations now that they can identify this distinctive call.

The Antarctic minke whale is a baleen whale that grows to around 40 feet [12 m], but usually much smaller. It’s gray with white belly and mostly eats krill. This is what they sound like:

[minke whale call]

In our sea monster episode a couple of weeks ago, I shared another baleen whale call, this one from an unidentified species. It’s been dubbed the bio-twang and has been recorded in the Mariana trench in the western Pacific year-round in 2014 and 2015. Researchers suspect the dwarf minke whale, but they don’t know yet.

[mystery whale call]

To get out of the water for a moment, in 2012 a supposed bigfoot recorded started going around the internet. It was supposedly recorded on a cell phone in the Umatilla Indian Reservation near Pendleton, Oregon. It’s more likely to be nothing more exotic than a red fox.

Here’s the unknown scream:

[creepy animal sound]

And here’s a recording of a red fox:

[equally creepy red fox sound]

To me the sounds are very similar. If you want to know how I know the red fox scream is actually a red fox screaming, google “red fox scream.” The first hit is a YouTube clip of a fox screaming. I pulled the audio from that one.

In 2014, an unknown animal was recorded in Lake Champlain in Vermont. Dennis Hall, who claimed to have spotted the lake monster known as Champ in 1985, and Katy Elizabeth, who runs an organization known as Champ Search, made the recording and thought it might be from a beluga whale.

But while Lake Champlain is connected to the ocean, a whale would have a hard time reaching the lake due to canals, and would most likely have been spotted either on its way to the lake or once it arrived. Certainly it would have been spotted once it died from trying to live in fresh water.

Other recordings of clicking and squeaking sounds like those of beluga whales have been recorded in the lake in the past, including by a Discovery Channel team researching Champ. In 2013, Dr. Lance Barret Lennard from the Vancouver Aquarium Marine Science Center, and an expert on whale acoustics, examined some of the echolocation patterns. He determined that not only are the recordings not of beluga whales, they’re not from any kind of whale. They’re probably not mammalian in origin.

Some turtles have been found to produce underwater signals that may be a form of echolocation, and many fish make clicking and drumming sounds. But we don’t know what’s making the sounds recorded in Lake Champlain.

Here’s the 2014 recording:

[Lake Champlain sounds]

Finally, here’s a sound that’s not mysterious, I just really like it. It’s the song of the veery, an attractive but rather plain thrush. I’ve heard it in person while hiking at high elevations in the Smoky Mountains, and it’s completely ethereal.

If you listen closely, you can hear that the veery is actually making two sounds at the same time. The avian vocal mechanism, called a syrinx, is much different from a mammal’s larynx, and allows a bird to product more than one tone at a time.

[veery call]

You can find Strange Animals Podcast online 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. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us and get twice-monthly bonus episodes for as little as one dollar a month.

Thanks for listening!