Strange Animals Podcast

Further reading:

Is the Javan tiger Panthera tigris sondaica extant? DNA analysis of a recent hair sample

The Sunda tiger [photo by Alfonsopazphoto – Own workAnimaisFotos, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=16029853]:

Show transcript:

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

We’re going to learn about a mystery tiger this month, but first we have to learn about the place where it’s supposed to live. Java is a large island that was formed by volcanic activity millions of years ago, and it’s been home to humans and our ancestors for over a million years. Its soil is rich and the climate is tropical, but the island’s ecosystems include tall mountains, savannas, rainforests, and mangrove forests. Naturally, lots and lots of animals live on Java that are found nowhere else in the world. Unfortunately, a whole lot of people live on Java too, which means that many animals and their habitats are threatened by habitat loss and pollution. Many animals have gone extinct in the last few hundred years. That includes the Java tiger.

The Java tiger was small compared to tigers in other areas, although even a small tiger is a big animal. A big male tiger can grow about ten feet long, or 3 meters, and the Java tiger could grow about 8 feet long, or almost two and a half meters. The Java tiger was lightly built, though, and rarely weighed much more than 300 pounds, or about 140 kilograms. Despite its relatively small size, it was extremely strong and had paws as big as the much larger Bengal tiger. It also had lots of thin stripes.

Originally scientists thought the Java tiger was a separate subspecies of tiger, but in 2017 it was reclassified as a population of Sunda tigers that have only been isolated from other populations for around 12,000 years. That doesn’t mean it wasn’t important, though. It showed differences from other Sunda tigers that weren’t yet significant enough to warrant it being a separate subspecies, but which definitely indicated it was on its way to evolving into a separate subspecies.

Unfortunately, the Java tiger’s habitat was largely destroyed to make way for farming and logging, and as a result its usual prey animals became rare or went extinct. People would also poison or shoot any tiger they could. It only survived in a few small nature preserves, but the last tiger footprints were spotted in 1989 and since then, no tigers have been officially seen on Java. A 1999 expedition that set up camera traps in hopes of spotting a few tigers mostly got photos of poachers hunting in what was supposed to be a protected area. The Java tiger was declared extinct.

Rumors persisted that tigers still lived on Java, though. Sometimes I think people claim to see recently extinct animals as a way to feel less guilty about humans having driven an animal to extinction. But in 2019 someone saw a tiger outside a village in western Java and reported the sighting to some local foresters. The foresters investigated and discovered footprints, claw marks, and a single hair on a fence.

The foresters collected the hair carefully and gave it to a team of geologists who were working in the area. The geologists sent it to the West Java Nature Conservation Authority, which sent it for genetic analysis. They also sent some tiger hairs from other types of tigers to compare it to, including hairs from a museum specimen of a tiger killed on Java in 1930.

The hair discovered in 2019 was definitely from a tiger, and its genetic signature most closely matched the genetic signature of the 1930 Java tiger specimen.

This doesn’t 100% mean the Java tiger isn’t extinct, but it does mean that there’s hope that it’s still around.

Java is part of Indonesia these days, and a few days ago as this episode goes live, the Indonesian government announced a plan to search for signs of the tiger, with an expedition getting underway soon to place camera traps. Conservationists are hoping that the tiger is discovered, which will allow it to be protected.

The Sunda tiger is critically endangered, only surviving in the wild on the island of Sumatra, with possibly fewer than 400 of them left alive. Another population of Sunda tigers, the Bali tiger, was declared extinct in the 1940s. A few hundred captive tigers living in zoos around the world show congenital health issues as a result of inbreeding. If the Java tiger is still alive, it could mean the difference between extinction and survival of the entire Sunda tiger subspecies. Fingers crossed that the camera traps reveal a healthy, safe population of tigers on Java!

Thanks for your support, and thanks for listening!

Further reading:

What gives bees their sweet tooth?

Show transcript:

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

Right before I left on my trip to Belize a few months ago, my aunt Janice gave me a magazine to read on the plane, the Autumn 2021 copy of LivingBird. It’s about birds and birdwatching. I actually forgot to take it with me and it was in my car the whole time I was gone, but when I got home I took it in to read.

One article caught my eye, titled “Investigating the Sweet Tooth of Songbirds.” Literally the same day that I read that article, I stumbled across another article on ScienceDaily titled “What gives bees their sweet tooth?” And a podcast episode idea was born!

You may have heard that domestic cats can’t taste sweetness, and that’s true. When your pet cat wants to drink the milk in a bowl of sugary cereal, it’s not the sugar they care about because they can’t taste it. Also, milk isn’t good for cats and even if they can’t taste the sugar, it can end up giving them cavities.

The question is, why don’t cats taste sweetness? And what other animals can’t taste it either?

Carnivores like cats don’t need to taste sweet flavors because it’s just not present in meat, which is what carnivores eat. You can test this easily if you put two saucers on the floor for your cat, one with a small amount of unseasoned chicken and a sugar cube in the other. I guarantee you the cat will eat the chicken and play with the sugar cube, which will get sugar all over the floor so maybe don’t do that after all. This is where I share with you, for no reason, that when I was in elementary school I used to eat sugar cubes while pretending I was a horse.

Horses can taste sweet flavors like sugar because they’re herbivores. Herbivores eat plants, and in fact herbivores have a whole lot of taste buds so that they can easily tell what kind of plants they’re eating. Bitter tasting plants might be toxic while sweet ones provide lots of energy. Herbivores are also keenly attuned to the taste of salt since their diet is typically low in salt and they need to seek it out.

Humans are omnivores, and omnivores eat pretty much anything. Like our great ape cousins, we also evolved to eat a lot of fruit. Ripe fruit tastes sweet so we really like our sweet foods. Omnivores like dogs, pigs, and bears also like sweet foods because they’re high in calories and therefore provide a lot of energy.

But how does an animal lose an entire sense of taste? It’s not like all tigers woke up one day and boom, the ability to taste sweetness was gone. It happens gradually as the genes responsible for an animal’s sense of taste mutate over many generations.

Let’s take as our example the bottlenose dolphin. The ancestors of the dolphin and other cetaceans were terrestrial animals related to the ancestors of modern even-toed ungulates like hippos, camels, deer, and pigs, and were probably either herbivores or omnivores. But as the dolphin’s ancestors evolved over millions of years, they shifted to a fully marine lifestyle and a fully carnivorous diet. Over the thousands and thousands of generations, the genes that control the ability to taste sweetness mutated so much that they’re now useless, but since the dolphin doesn’t need to taste sweetness the mutations don’t matter.

In the case of the bottlenose dolphin and other cetaceans, in fact, they also can’t taste bitterness or umami. Umami is what helps you taste the difference between chicken and turkey, steak and pork, tuna and trout. Basically it’s the flavor of meat or savory foods, including cheeses. You can taste the difference between cheddar and Swiss because of the umami receptors in your taste buds, which are determined by genes.

But the dolphin eats nothing but meat! Why would it lose the ability to taste meat? Researchers think it’s because the dolphin swallows fish and other animals whole, without chewing. Cetaceans and other marine carnivores like sea lions that swallow their food whole actually have almost no taste buds at all.

If you’re wondering what happens when an animal that can’t taste sweetness has to adapt to a diet where tasting sweet foods is important, that’s exactly what happened with songbirds. The ancestors of birds lost the ability to taste sweetness millions of years ago when they were dinosaurs. Then, well, you know what happened to the non-avian dinosaurs. Suddenly the ancestors of modern birds had a lot of available ecological niches to take advantage of and they evolved rapidly to fill them. This included small birds who eat berries and nectar.

Genetic studies suggest that the ancestors of songbirds regained the ability to taste sweetness around 30 million years ago in Australia. The same thing happened in hummingbirds at about the same time. In both cases, the genes that control the ability to taste umami evolved to taste sweetness instead—but songbirds and hummingbirds adapted different umami genes. That’s what you call a subtle case of convergent evolution.

Songbirds and hummingbirds adapted to a diet high in sugar because it’s a good source of energy and easily found in flowers. In turn, flowers needed to be pollinated and have their seeds spread around, so they evolved to provide even more sugars in nectar and berries. But birds aren’t the only animals that pollinate flowers and are attracted to nectar. Insects can all detect sweetness. However, bees are exceptionally attuned to sweetness and have two taste neurons instead of one per taste bud.

Insects don’t have taste buds the same way we do, of course. In mammals, reptiles, and birds, taste buds are located on the tongue, in a few parts of the mouth, and at the top of the throat. In insects, taste receptors can be in any number of places. They’re on an insect’s mouthparts but often also on their feet, legs, and antennae.

Some amphibians have taste receptors on the body as well as concentrated in the mouth, and many fish have taste receptors all over their body. Catfish in particular have the most taste buds known, up to 175,000. Humans have about 10,000. Cats only have about 500.

Before you start feeling sorry for your cat for not being able to taste sweet foods and not having a great sense of taste in general, cats have a taste receptor we don’t. It’s the water sense. To us, a nice cold glass of water tastes refreshing but doesn’t really have a flavor. A cat or dog, and many other animals whose diet is mostly meat even if they aren’t specifically carnivores, have the ability to taste water in a way we can’t even imagine. Because meat is high in salt content, having taste buds attuned to water helps the animal drink enough water to process all that salt.

If you gave me the choice, I’d choose sweetness over the ability to taste water. But my cats would probably disagree.

Thanks for your support, and thanks for listening!

Further reading:

https://www.audubon.org/news/like-finding-unicorn-researchers-rediscover-black-naped-pheasant-pigeon-bird

https://www.sci.news/paleontology/confuciusornis-shifan-11528.html

The black-naped pheasant-pigeon:

Confuciusornis:

Show transcript:

We’re going to learn about two birds that have been in the news lately.

The first is the black-naped pheasant-pigeon. The word nape refers to the back of the neck, and this bird does have a black neck. It’s a dark blue-black all over, in fact, with reddish-brown wings, a red bill, red eyes, and long yellow legs. It looks almost identical to the other three species of pheasant-pigeons known, although some scientists think they’re subspecies. Those three are the white-naped, the green-naped, and the grey-naped pheasant-pigeons, and if you’re wondering if the spot of color on the back of the neck is the easiest way to tell these birds apart, you are exactly right. All four species are native to parts of New Guinea or small islands nearby.

Pheasant-pigeons look a lot like pheasants and are about the size of a chicken, although they’re actually pigeons. They live in forests and eat seeds and fruit, and while they can fly they spend almost all of the time on the ground. We don’t know a whole lot about them because they’re so secretive and hard to spot in the wild, although the white-naped and green-naped birds are sometimes kept in zoos. In the case of the black-naped pheasant-pigeon, all scientists knew about it was from two specimens collected in 1882. It hadn’t been seen since…until September of 2022.

A team of scientists visited Fergusson Island off the east coast of Papua New Guinea in September, as part of a worldwide collaboration of scientists called The Search for Lost Birds. This is similar to the Search for Lost Frogs that has been active for over a decade, discovering lots of new amphibians and rediscovering even more. The 2022 search was actually a follow-up to a 2019 expedition that had failed to find the bird, although it did make other discoveries.

In 2022, the team brought more people and equipment, determined to make the best effort possible to find the black-naped pheasant-pigeon. They consulted with local hunters to find the best places to search, and talked to lots of residents to see if anyone had seen one, and spent day after day hiking through forested mountains. For weeks they had no luck. Then, in a remote mountain village, they finally met some people who were familiar with the bird. One man led them to the right part of the forest and they set up camera traps, but at that point they only had a few days left before they had to leave the island.

When they checked the pictures captured by the camera traps, though, they’d found it! Two of the cameras had taken pictures and video of what were definitely black-naped pheasant-pigeons, and since the cameras were several kilometers apart the pictures were probably of different individuals. The black-naped pheasant-pigeon wasn’t extinct, which means it can be protected. Habitat loss, especially from commercial logging, and feral domestic cats are the two main threats to birds in the area.

The other bird we’re going to talk about today hasn’t been seen in even longer: 119 million years, in fact. The article about this fossil was only released a few days ago as this episode goes live. You can check the show notes for links to this article and a good one about the pheasant-pigeon too.

Paleontologists discovered the bird’s fossil remains in northeastern China, in fossil beds that contain incredibly well-preserved animals and plants. The Jiufotang Formation in China dates to the early Cretaceous, between about 122 and 119 million years ago, and researchers think it’s from an area that was once a shallow lake surrounded by forests. Every so often, a nearby volcano would erupt and the resulting ash would fall into the lake, causing anoxic conditions that helped preserve animals that died and sank into the mud at the bottom of the lake. There are lots of fish, pterosaurs, birds, and dinosaurs among the fossils discovered, most of them small but a few quite large. This includes a type of tyrannosaur that probably grew around 33 feet long, or 10 meters. A few early mammals have been discovered too. In one case, the remains of 40 individual birds were found on one big slab of stone, and scientists think an entire flock of birds was killed by a volcanic ashfall or poisonous gases from the volcano.

The newly described fossil we’re talking about today was almost complete and almost completely articulated, preserved with the impression of feathers around its body. The bird has been named Confuciusornis shifan and was a little smaller than a modern crow. It had a toothless beak and a short tail, although it probably had long tail feathers. Other Confuciusornis species have been discovered with the impressions of long tail plumes.

All of the Confuciusornis fossils discovered so far were birds that could fly well but probably nowhere near as well as any bird today. But C. shifan had an adaptation in its wings not seen in any other bird, living or extinct. It had a small extra bone in the wing that acted like a cushion and probably helped the wings withstand the stresses of flight.

The most interesting thing about the different Confuciusornis species is that if we could go back in time and see them when they were alive, they probably wouldn’t have looked unusual to most people, except to bird experts who would instantly freak out. For the most part, they just looked like birds. Some specimens show preserved melanosomes under electron microscopy that indicate the feathers were various colors including white, brown, red, and black. There’s even evidence of a pattern of spots and streaks on some feathers. Their feet were adapted for perching the way many modern songbird feet are. But Confuciusornis wasn’t a direct ancestor of modern birds as far as we know.

Even though we have lots of beautifully preserved Confuciusornis fossils, the fossils can only tell us so much. We have a pretty good idea of what the birds looked like, but we don’t know much about how they lived. One specimen was found with the remains of a tiny fish inside its body, so researchers think the birds may have eaten fish or might have just been omnivores that weren’t picky about what they ate. One specimen was found with an egg beside it that was the right size to have fit through its pelvic opening, but we can’t know for sure if the egg belonged to the bird or was from another bird and just happened to have settled near the dead bird when it fell in the water.

Still, even though we only have fossil remains, that’s much better than having no knowledge of these early birds at all.

Thanks for your support, and thanks for listening!

Further reading:

Rare pterosaur fossil reveals crocodilian bite 76m years ago

Show transcript:

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

Let’s learn about a type of pterosaur that lived around 75 million years ago in what is now Canada, and we’ll specifically learn about an individual young pterosaur that had a very bad day, a bad day that’s preserved in the fossil record.

Pterosaurs were flying reptiles that lived alongside dinosaurs, but weren’t actually dinosaurs. Some of them got as big as small airplanes while some were barely the size of chickens. Cryodrakon was one of the biggest ones, with an estimated wingspan of 33 feet, or 10 meters, for an adult animal—maybe even bigger. We don’t know the adults’ size for sure because we only have a few fossils of adult Cryodrakons, and those are incomplete. Mostly we have fossils of young individuals. The older juveniles had a wingspan of around 16 feet, or 5 meters, which is still pretty darn big.

Cryodrakon was the first pterosaur discovered in Canada, with fossils found in Alberta in 1972. Since then more fossils have been discovered in the same province, especially in what’s called the Dinosaur Park Formation.

Like other pterosaurs in the family Azhdarchidae, Cryodrakon had long legs and a very long neck with long jaws. Most scientists think it spent a lot of time on land, hunting small animals. It could fold the longest part of its wings up out of the way in order to walk on all fours.

A flying animal’s wing, whether it’s a pterosaur or a bird or a bat, is a modified arm. Insects are different because they’re invertebrates. In bats, the fingers are elongated with strong skin stretched between them to form a wing. In birds, the fingers are fused into a sort of stump and most of the flying surface is feathers. In pterosaurs, one or two fingers were elongated like a bat’s, but the other fingers were short and blunt. These are the fingers that azhdarchids could walk on when the rest of the fingers, and therefore the wing, was folded up so it wouldn’t get in the way. We know it’s possible for a winged animal to walk this way because vampire bats do it just fine, and they’re able to run around quite fast on the ground.

An adult Cryodrakon walking on all fours would have been about as tall as a modern giraffe because of its long neck. Its neck was strong and its head large, so it could easily grab a little running dinosaur and swallow it whole, maybe giving it a good chomp with its toothless jaws first. While azhdarchids probably couldn’t run, because the hind legs weren’t very strong and the feet were small, it could probably walk pretty quickly. And, of course, it could fly extremely well. Scientists think it launched into the air by pushing off the ground with its wings, not its back legs.

In older episodes we’ve talked about some other species of pterosaur from this same family, especially Quetzalcoatlus, a genus of exceptionally large pterosaurs discovered in North America. The largest individuals may have had a wingspan potentially more than 36 feet, or 11 meters. But in 2002 a remarkably complete pterosaur fossil was discovered in Romania, and while we don’t have the complete wing bones, estimates suggest this new species might even be larger than Quetzalcoatlus. Some estimates put its wingspan at 39 feet across, or 12 meters. It had a shorter neck than other azhdarchids but a massive head. Its neck was about 5 feet long, or 1.5 meters, while its skull was at least that long and possibly as much as 8 feet long, or 2.5 meters.

The Romanian specimen was named Hatzegopteryx but the specimen has been nicknamed Dracula (also the name of my cat). Some scientists initially argued that Dracula was just an especially big Quetzalcoatlus, but while it was probably a close relative, it’s too different to be the same species.

Despite their huge size, pterosaur bones were delicate because the animals had to be light enough to fly. That means they had air pockets or spongy internal structures in their bones, and that means their bones were much less likely to preserve. The most likely reason we have so many more fossils from young pterosaurs than old ones is because many species of pterosaur appear to have nested together. It’s a sad fact of life for wild animals that many young ones don’t survive, so the fossils of young pterosaurs probably come from nesting areas.

And that brings us to our young Cryodrakon who had a terminally bad day. In 2023, researchers found a neck bone of a cryodrakon that had a puncture right through it. The hole in the bone is about 4 mm across and circular, and the scientists who examined it think it’s from a crocodilian tooth. We don’t know if the baby pterosaur was chomped to death by a crocodilian or if it was already dead and the crocodilian was scavenging it.

That’s not even the only Cryodrakon fossil that shows tooth marks. In 1995 the fossils of a young animal were found in a scattered state, with tooth marks on some of the bones. Even better from a scientific standpoint, but definitely not from a cryodrakon standpoint, a little piece of chipped-off tooth was found embedded in one of the bones. Researchers think the tooth comes from a small dromaeosaurid dinosaur found in the same area, Saurornitholestes. It only stood about two feet tall, or 60 cm, so if it was running around biting baby cryodrakons, I hope it was really fast. The mother pterosaur would eat a dinosaur that size like a potato chip.

Thanks for your support, and thanks for listening!

The sewellel is a little rodent:

The superflea is a big flea (left, compared to a regular flea, right):

Show transcript:

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

Let’s learn about a rodent you may never have heard of, unless you live where it does, and a parasite that makes that rodent its host. It’s not an ordinary parasite, but don’t worry, it’s not icky. You can continue to snack.

The rodent is called the sewellel, Aplodontia rufa. It’s also called the mountain beaver even though it doesn’t always live in the mountains and it isn’t a beaver. It doesn’t even look like a beaver. For one thing, it only has a little nub of a tail and it only grows around 20 inches long, or 50 cm. It has small eyes and ears, short legs, a chunky body, and long claws. This body shape should give you a hint about its lifestyle: the sewellel is a digger, although it can also swim just fine and can even climb small trees to eat young twigs and leaves.

The sewellel is an aplodont, a large group of rodents that have been common in Europe, Asia, and North America for 40 million years. But it’s the only one left. All the other aplodonts went extinct several million years ago at least. We’ve actually talked before about one of the sewellel’s extinct relations, the horned gopher (which was not a gopher), in the Patreon episode about animals with nose horns.

The sewellel itself hasn’t been around all that long, only appearing in the fossil record a few million years ago. It lives in a small area of northwestern North America, in parts of British Columbia, Washington state, Oregon, and a few parts of California. It lives in forests where it doesn’t get too cold in the winter, since it doesn’t hibernate and isn’t as good at keeping itself warm as other rodents are. It also needs to drink more water than other rodents and prefers to live in wet climates as a result.

In fact, the sewellel is sometimes referred to as a living fossil since it lacks many features that all other living rodents have. Its teeth resemble a simpler version of squirrel teeth, so some researchers think it may be most closely related to squirrels, but even if that’s the case, it isn’t very closely related. The sewellel’s ancestors were more adapted to live in trees and a study published in 2018 determined that it had a larger brain than the sewellel. Since the sewellel is nocturnal and spends most of its life underground, it doesn’t need to see very well, and the part of the brain that processes vision is much smaller than in its ancestors.

The sewellel mostly eats ferns, although it also eats other plants, and some of its favorite plants are toxic to other animals. It’s a solitary, mostly nocturnal animal that digs deep, complex burrows, and it stays as close as possible to the burrow entrance so it can hide easily if it needs to. Everything eats the sewellel, from owls to coyotes to bobcats to eagles.

And that brings us to the parasite associated with the sewellel. Many animals have parasites that are specific to that particular species. The Patreon episode about whale lice has some information about how specific this can get. The male sperm whale has a different species of louse than the species that lives on female sperm whales, for instance. Also, the whale louse isn’t a louse, it’s a type of crustacean.

The sewellel’s parasite is a type of flea. Big deal, you say, fleas are all about the same.

Are they, though? Because the sewellel’s flea is actually kind of a big deal. It is, in fact, the largest flea known, called the superflea. It can grow up to 8 mm long (and possibly longer, reports vary). I just measured, and that’s the length of my little fingernail, from the base to the quick. Most species of flea are 3 mm long at most.

The superflea is only found on the sewellel. It looks like an ordinary flea except for its size, meaning it’s laterally flattened with legs that allow it to jump long distances. So why is it so big compared to other fleas, especially considering that it lives on an animal that’s about the size of a chonky cat? No one knows. No one has even the slightest idea why this flea is so big.

There used to be even bigger fleas, some up to two cm long. That’s 20 mm, or just a little more than twice the length of the superflea. Of course, those 20 mm fleas lived 165 million years ago and probably lived on dinosaurs. Also, they couldn’t jump and instead of being flattened laterally, or side to side, like modern fleas, they were flattened dorsoventrally, or top to bottom. So they weren’t very much like modern fleas.

That’s all we know about the superflea, but let’s have one last sewellel fact before we go. With all this talk of the sewellel being a primitive rodent whose closest relations are all extinct, you might think there’s nothing really special about it beyond its giant fleas. You would be wrong, though, because the sewellel’s front paws have opposable thumbs. It’s not as mobile as our opposable thumbs, but it allows the sewellel to manipulate food more easily. It will sometimes sit up on its big round bottom to eat, just like a really weird squirrel.

Thanks for your support, and thanks for listening!