Episode 095: Giant Tortoises

This week let’s learn about giant tortoises! What’s the difference between a turtle and a tortoise? The most basic difference is that the turtle lives in water and the tortoise lives on land. And there are some really, really big tortoises in the world!

A Galapagos tortoise:

Show transcript:

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

This episode was supposed to be about strange reptiles, with more awesome suggestions from listeners. I was going to include some information about a couple of giant tortoises…but the more I researched, the longer that part of the episode became, until it just took over. So here’s an episode about giant tortoises, and we’ll have the strange reptiles episode in a couple of weeks instead. I’m going to give a shout-out to listeners Leo and Finn, who have been waiting patiently to hear their suggestions. Sorry you’ll have to wait a little bit longer.

The biggest tortoise in the world is the Galapagos Tortoise, which as you probably know, or can guess from the name, lives in the Galapagos Islands off the coast of Ecuador. In fact, the islands were named after the tortoises. Galapago means tortoise in Old Spanish. There are eleven species of Galapagos tortoise alive today, but there used to be 15. The others were mostly eaten to extinction by sailors who would stop by the Galapagos Islands, capture tortoises, and sail away with them to eat later.

The biggest individual Galapagos tortoise ever measured was a male named Goliath. When he died in 2002, Goliath was 4.5 feet long, or 1.36 meters, 2 feet three inches high, or 68.5 cm, and weighed 919 pounds, or 417 kg. He was only 42 years old when he died, but Galapagos tortoises frequently live for more than 150 years. Adult tortoises have no predators except humans. They’re just too big, too heavy, too strong, and have too tough a shell for other predators to bother with.

The Galapagos tortoise eats plants, including grass, leaves, fruit, and even cacti. Its neck is long, which allows it to reach plants that are farther away, since it can’t exactly climb trees. It can survive up to six months without water, getting most of its moisture from the plants it eats, but some tortoises on more arid islands will lick dew from rocks to get moisture. Some of the boulders have been licked by tortoises so much over the centuries that they have deep grooves worn in the surface from turtle tongues.

As I’ve mentioned before in other episodes, sometimes herbivores will eat meat when they can get it. The Galapagos tortoise does this too on occasion. There’s a type of finch on the Galapagos that cleans parasites off the tortoises, and to help the finch reach as much of its skin as possible, the tortoise will stand up straight with its legs extended. The finches hop underneath and clean ticks and other parasites from the tortoise’s legs, neck, and the skin between the carapace, or upper shell, and the plastron, the lower shell. But occasionally a tortoise will suddenly pull its legs into its shell and drop, smashing the finches flat. Then it stands up and eats the squashed birds. This is not cool, tortoise. Those birds are trying to help you.

Galapagos tortoises lay round, hard-shelled eggs. The female digs a hole in the dirt that’s about a foot deep, or 30 cm, and lays about a dozen eggs in it. She covers the eggs with dirt, tamps it down with her plastron, and leaves. When the babies hatch, they have to dig their way out of the hole. This can take weeks, but fortunately the babies still have yolk sacs attached that keep them from starving.

One of the Galapagos tortoise species that went extinct recently was the Pinta Island tortoise. The last known individual was called Lonesome George. He was found in 1971 on Pinta Island and taken to the Charles Darwin Research Station on Santa Cruz Island. Although researchers tried to find more Pinta Island tortoises, even offering $10,000 if someone found a female, George turned out to be the very last one. He lived with two females of another Galapagos giant tortoise species, in hopes that they were closely related enough to produce babies, but none of the eggs the females laid ever hatched. Lonesome George died in 2012.

Since then, in 2015, DNA testing on a population of tortoises living on Santa Cruz Island showed that they are a subspecies of their own, and closely related to the Pinta Island tortoises. This had to be an “if only we’d known” moment for the conservationists, who could have paired George with females from that population to produce offspring that were genetically close to the Pinta Island tortoise.

Other Galapagos tortoise species were luckier. The Española Island tortoise was down to only 14 individuals in the wild in 1963. They were all taken to the research station on Santa Cruz Island, joined a few years later by another Española tortoise that had been living in the San Diego Zoo. The breeding program was successful and these days there are over a thousand Española tortoises on the island. Similarly, rats introduced to Pinzón Island in the late 19th century nearly drove that island’s species of tortoise to extinction by eating their eggs and hatchlings. By 1965 there were fewer than 200 adults left alive, and no babies had survived for the better part of a century. Scientists started collecting eggs to incubate in safety at the research station, and rear in captivity until they were big enough to survive rat attacks. By 2012, all the rats had been removed from the island and tortoise nests started to hatch naturally in the wild again.

But the Galapagos tortoise isn’t the only giant tortoise alive. The Aldabra giant tortoise is from the Aldabra Atoll in the Seychelles [pronounced say-SHELZ], a collection of 115 islands off the coast of East Africa. It’s about the same size as the Galapagos tortoise and looks similar, but it’s not closely related. Females lay leathery-shelled eggs in shallow nests. In hot weather, some Aldabra giant tortoises will dig burrows to shelter from the heat. It eats plants and has a long neck like the Galapagos tortoise to reach branches, but unlike the Galapagos tortoise it will sometimes rear up on its hind legs to reach leaves. This is dangerous for a tortoise, because if it topples over on its back, it might not be able to right itself and can die.

Like the Galapagos tortoise, some species of Aldabra giant tortoise have gone extinct in the recent past, and for the same reasons. This included Arnold’s giant tortoise, which lived on one of the central Seychelles islands.

In 1995, the Nature Protection Trust of Seychelles was told about two unusual tortoises in a hotel garden. A couple of scientists went to investigate. The tortoises were both male, extremely old, and appeared to fit the description of Arnold’s giant tortoise, which had supposedly gone extinct over a hundred years before. Where had they come from?

It turns out that the hotel had recently bought the tortoises from a very old local man. They had been in the man’s family for longer than anyone alive could remember. Originally there had been three tortoises, but one had died only a matter of months before the scientists discovered them. They were able to get the dead tortoise’s skeleton for study, which proved that these weren’t just regular old Aldabra giant tortoises, they were Arnold’s giant tortoises—possibly the last two alive in the world.

But the researchers weren’t going to give up that easily. They started digging into reports of other unusual tortoises on the islands. Not only did they eventually find a handful of other Arnold’s giant tortoises, they found a second subspecies that had supposedly gone extinct in 1840, referred to as hololissa after its scientific name, Aldabrachelys hololissa.

As if that wasn’t awesome enough, after all this excitement in the tortoise studying community, the Blackpool Zoo in England took a closer look at the Aldabra giant tortoise that had been living there for the last 25 years, named Darwin. It turns out that Darwin was a hololissa tortoise all along. After that, other zoos brought in experts to examine their giant tortoises, and more hololissa and Arnold’s individuals turned up. The problem is that these tortoises all look pretty much alike except to experts. The tortoises have been placed in a successful captive breeding program in the Seychelles.

Researchers used to think that giant tortoises grew so big due to island gigantism, where a species isolated on an island evolves to become larger. In addition to the Seychelles and the Galapagos, giant tortoises used to live on the Canary Islands and the Mascarene islands, including on Mauritius. You know, where the dodo used to live.

But giant tortoises used to be common all over the world, not just on islands where they mostly live today. Big as these living tortoises are, there used to be giant tortoises even bigger.

The biggest known giant tortoise lived in what is now India and Pakistan, and probably in other places too. It lived around two million years ago and may have only gone extinct about 100,000 years ago, or maybe even more recently. It was twice the size of the Galapagos tortoise, possibly as much as nine feet long, or 2.7 meters, and six feet high, or 1.8 meters.

The giant land tortoise, Hesperotestudo crassiscutata, lived even more recently in North and Central America. It was a little bit larger than the Galapagos tortoise, maybe six feet long, or 1.8 meters, but it went extinct only 12,000 years ago. Researchers think humans may have played a part in driving that tortoise to extinction too, by eating it and its eggs. Since I’m recording this episode on Thanksgiving day in the United States, I’m feeling a little guilty about eating so much turkey. Fortunately, turkeys, unlike giant tortoises, are not endangered.

I’m thankful that some species of giant tortoises have survived until today. They’re awesome animals.

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!

Episode 094: The Koala and the Monato del Monte

Thanks for this week’s topic suggestion from Jideobi! This week we’re going to learn all about koalas and some of their strange friends!

The Blood on the Rocks podcast (not for kids) where you can hear a segment by me in the WWI megasode!

An unlocked Patreon episode about wombats

So cuddly, little koala:

I am dying of cute y’all:

I have actually died. I am ded because this mama koala is feeding her baby a leaf:

I came back to life but then I died again because of this monito del monte:

Show transcript:

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

It’s another listener suggestion week! But before we get started, a quick shout-out to the podcast Blood on the Rocks. I was one of about a dozen podcasters who participated in their recent epic World War I megasode. It’s not a podcast for kids since it covers dark topics like true crime and the more gruesome bits of history, but if you are a grown-up type person who finds that sort of thing interesting, I’ll put a link in the show notes so you can check it out. My part of the show was a short segment about the animals of WWI. I also released a different version of the segment as a patreon bonus episode earlier this month.

Anyway, let’s start off this week’s episode about koalas. Thanks to Jideobi, who suggested we learn about the koala. I can’t believe I haven’t covered koalas on the podcast before. They’re such amazing, weird animals.

Many people call the koala a koala bear, but it’s not related to bears. The koala is a marsupial—you know, where the babies stay in their mama’s pouch. It’s most closely related to the wombat, and I was going to talk about the wombat in this episode until I remembered I had a whole Patreon episode about the wombat. I’ve unlocked it so anyone can listen to it. There’s a link in the show notes and you can click on it and listen in your browser, no login needed.

The koala lives near the coasts of eastern and southern Australia in eucalyptus trees. It’s gray, gray-brown, or brown in color, with no tail, short floofy ears, a flat face with a big black nose, and long claws that help it cling to tree trunks. You may already know all this about the koala, and you probably know that almost all it eats is the leaves of the eucalyptus tree. But there is so much more to learn about the koala.

For one thing, its diet. Eucalyptus trees are mostly native to Australia, although people in other parts of the world grow them as ornamentals, although they need warm climates to survive. Koalas eat the leaves of many different types of eucalyptus trees, but they prefer about 30 species, typically ones whose leaves contain higher levels of protein. But eucalyptus leaves contain toxins that make other animals avoid them—toxins that can poison even large animals like horses and cattle if they eat any. Even handling eucalyptus leaves with your bare hands can irritate your skin.

The koala’s liver produces a type of protein called cytochrome P450, which breaks down the toxins and stops them from making the koala sick. Still, researchers have observed that the koala does avoid certain leaves or parts of leaves that contain higher concentrations of the toxins.

Researchers recently sequenced the koala genome, which gives us new genetic understanding of its biology. One thing the genome reveals is the koala genes associated with taste receptors. For most mammals, a bitter taste is a warning that something you’re eating might be toxic. That’s why things like coffee and strong tea are acquired tastes, because they contain compounds that can make the drink taste bitter, especially if it’s not prepared properly. That’s why I put a whole bunch of sugar and milk into my coffee. The koala has more bitter taste receptors than almost any other animal studied, which means it can probably taste the level of toxins in every leaf. This helps it choose the least toxic leaves. Interestingly, the koala also has taste receptors for sweetness and for umami, which is the flavor mostly associated with meat. So it’s likely that the ancestors of the koala had a broad diet that probably included fruit and meat.

Because eucalyptus leaves aren’t all that high in protein, the koala has a low metabolic rate and spends a lot of its time asleep. It sleeps as much as eighteen to twenty hours a day, curled up in the fork of a tree. That sounds so nice. It’s mostly active at night. It spends almost all its time in trees, but when it wants to move to a different tree, it just climbs down and walks to a tree it likes better. Sometimes the leaves it eats don’t give it quite enough moisture, so it will climb down from its tree to drink from a stream.

The koala eats a lot of leaves, something like two and a half pounds of them a day, or almost 1.2 kilograms, and it even has cheek pouches where it can store leaves to eat later. Its digestive system is really long, which helps it extract as many nutrients from its food as possible.

If you’re not from Australia, you may not know that eucalyptus leaves have a pungent smell. The leaves contain eucalyptus oil, which has a number of health benefits for humans if used properly in things like cough drops, ointments, or mouthwashes. And since the koala eats eucalyptus leaves all day every day, guess what it smells like. That’s right. The koala smells like a cough drop.

Naturally, a koala needs access to a lot of trees in order to get enough to eat, about 100 trees per koala. These days it’s threatened by habitat loss as forests in Australia are chopped down to build houses or create farmland. Another threat to the koala is being hit by cars while wandering around looking for a new tree to climb. Recently, the Queensland Dept of Transport and Main Roads started building special tunnels under roads and ledges across roads designed specifically to allow koalas to cross safely. A tracking study to see if koalas are using the new structures show that yes, they are. In fact, even though the koala has a small brain in comparison to its body size, it’s a pretty smart animal in some ways. It started using the tunnels and ledges as soon as they were installed.

Another threat to the koala is a bacterial disease called koala chlamydia. It can cause blindness, pneumonia, and infections that stop koalas from being able to have babies. A newly developed vaccine for the disease has proven effective, but the problem is getting the vaccine to wild animals that live way up in trees. Currently, anytime someone brings an injured koala to a zoo hospital, veterinarians make sure to vaccinate it while it’s being treated for its injuries.

The koala has weird feet that look and act a lot like primate hands. It has five digits on its forefeet, three fingers and what are basically two thumbs—two opposable digits that help it grasp tree limbs more securely. Its hind feet have four toes, two regular toes, one opposable thumb toe with no claw, and one toe that is made up of two toes that are fused together, although it still has two claws at the end. It mainly uses the fused toes to groom its fur. It also has friction ridges on its toe pads, otherwise known as fingerprints, that are unique to each individual like those of humans and other primates.

Even the koala’s butt is kind of weird. It has a pad made of cartilage at the end of its spine that gives it a built-in chair for sitting in branches.

The koala has a good sense of smell, excellent hearing, and poor vision. Its eyes are small and have slit pupils like a cat’s. Male koalas mark their trees with scent from a gland on the chest, which is bare of fur.

From pictures, koalas look pretty small, maybe a little larger than a rabbit, but it’s actually closer to the size of a dog. It’s two to three feet long, or around 60 to 90 cm, with males larger than females. It also looks really cuddly, but it can be dangerous because its claws are so long and sharp. The koala just wants to be left alone to sleep and eat leaves.

There used to be an even bigger species of koala, which went extinct around 50,000 years ago. It’s called the giant koala, but it actually wasn’t all that much bigger than the koalas alive today, maybe twice its size at the most. It probably looked and acted like modern koalas, it lived in the same places as modern koalas, and it lived at the same time as modern koalas, which have been around for close to a million years. When researchers found this out, they were really surprised because they had assumed modern koalas were smaller descendants of the giant koala. We’re still not sure why the giant koala went extinct while the modern koala is still around.

We don’t know a lot about the koala’s ancestors, for that matter. Koala fossils are rare. So let’s talk for a moment about when marsupials in general developed. An extinct marsupial called the djarthia lived in Australia about 55 million years ago, and although it was only about the size of a mouse, researchers think its descendants spread out across Australia and evolved into everything from kangaroos and koalas to thylacines and Tasmanian devils. Djarthia’s ancestors probably came from South America. But how did they get from South America all the way to Australia?

More than a hundred million years ago, the supercontinent of Gondwana included land masses that later broke up and became what we know as South America, Australia, and Antarctica, as well as Africa and India. Antarctica was in the middle of Gondwana. The oldest known marsupial appears in North America about 65 million years ago, which was part of the other supercontinent on Earth at the same time as Gondwana, called Laurasia. You can easily see how the continents today fit together like puzzle pieces if you look at a map, especially how eastern South America snugs right up against western Africa. But about the time marsupials were spreading out across Laurasia, from North America all the way to China, Laurasia and Gondwana were connected for a while along the northern edge of South America. Animals were able to cross from Laurasia to Gondwana before the two supercontinents split apart again. Marsupials spread from Laurasia and across Gondwana before the continent of Australia separated about 50 million years ago. And little djarthia survived and thrived in Australia while marsupials in other parts of the world were not doing nearly as well. In fact, marsupials did so well in Australia that researchers think that before Australia was fully separated from Gondwana, marsupials actually started spreading back out of Australia and into Gondwana again. There’s even a living marsupial in South America now called the Monito del Monte that is more closely related to the marsupials in Australia than it is to the other marsupials living in South America.

In fact, let’s talk about the monito del monte for a minute, because it’s so cute my brain might just explode if I don’t tell you about it. Its name means ‘little monkey of the mountain,’ but it’s not a monkey, of course. It only lives in trees in the Andean forests of western Argentina and Chile, and it looks like a rodent at first glance. It’s not a rodent either. It’s brown with a pale belly and little pink feet. It grows to about five inches long at most, or 13 cm, not counting its long tail, which doubles its length. Its tail is furry except for a bare patch underneath, which probably helps it get a better grip on branches as it climbs through the treetops. Its tail is prehensile, at least to some degree. The monito del monte stores fat at the base of the tail for winter, when it retreats to its tree nest of leaves lined with soft moss and hibernates. The female has a fur-lined pouch with four teats. It mostly eats insects along with fruit that grows in the very top of the tree canopy, and as a result it helps spread the seeds of plants like orchids and bromeliads.

We’ve gotten away from koalas, so here’s something else interesting about the koala. Males bellow to attract mates, a sound that is much deeper in pitch than it should be for an animal its size. Researchers have discovered that the koala has an extra pair of vocal folds outside of the larynx. No other mammal is known to have anything like this except for toothed whales, which have special structures outside of the larynx that allow them to generate clicks for echolocation. Female koalas bellow too, but not as loudly as males, and babies, called joeys, squeak.

The koala’s mating call sounds like this. This is seriously the funniest thing I’ve heard in weeks, so even though it’s long, I’m going to play the whole thing. Enjoy!

[koala mating call]

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!

Episode 093: Insects Large and Small, mostly large

Many thanks this week to listeners Bob, Nicholas, and Damian, who all suggested insects of one kind or another! So this week is an insect extravaganza, or at least we learn about some gigantic insects, the rarest insect in the world, and a tiny ant.

The Lord Howe Island phasmid:

The longest insect in the world:

The Queen Alexandra’s birdwing butterfly:

The Hercules beetle with random frog. Onward, my steed!

Further reading:

An article about phasmid eggs

Show transcript:

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

I’ve received a bunch of excellent topic suggestions this year and I’m getting behind on addressing them, so the next few weeks will mostly be listener suggestions. This week we’re going to look at a topic several listeners have suggested…insects.

Now, you know insects are not my favorite, but they are definitely interesting. So thanks to listeners Bob, Nicholas, and Damian, we’re going to learn about various horrifying, I mean fascinating, insects!

We’ll start with some very small insects. I could probably do a whole episode just about ants, and maybe one day I will, but right now let’s look at a type of ant suggested by Bob. Bob lives in California and mentioned that the type of ant common in that part of the United States is the Argentine ant. It’s native to South America, specifically lowlands around the Paraná River, but it’s spread to many other parts of the world.

The Argentine ant is only about 2 to 3 mm long and are brownish in color. The queen ants are about twice the size of the worker ants, and each colony has many queens, unlike other ant species that may only have one queen per colony. Queen ants are the only ones that lay eggs. Worker ants find food and bring it back to the colony, tend the queen and her eggs, and dig the shallow nest where the colony lives.

Argentine ants are omnivorous, eating pretty much anything, and are definitely pests. They get into people’s kitchens to find food and will even make nests inside houses. Because a colony has more than one queen, the colonies are hard to eradicate. They also displace native ant species, which can impact the entire ecosystem since other animals that depend on native ants as their primary food won’t be able to find enough to eat. Argentine ants also cause problems for farmers, partly because they eat the larvae of pollinating insects, partly because they tend aphids for the honeydew that aphids secrete. Aphids are a pest to many crops, and the last thing farmers want is more aphids around—but Argentine ants want all the aphids they can get.

Researchers have found out something really unusual about Argentine ants. The ants that still live in their native habitat are genetically diverse and territorial, with different colonies fighting each other for nesting sites and hunting grounds. This keeps the population under control naturally. But outside of its native habitat, all the Argentine ants in the world are so genetically similar that in many cases, ants from different colonies act as though they were from the same colony. They don’t fight for territory, and instead act like a supercolony that can stretch for hundreds of miles, killing off or displacing native ants and other insect species.

But in some parts of North America, the Argentine ant is facing an ant species that may end up beating it at its own game. The Asian needle ant has started taking territory from the Argentine ant, helped by its resistance to cold weather. Both species of ant become less active in winter, but the Asian needle ant starts reproducing and foraging much earlier in the spring than the Argentine ant. This gives it a head start every year. Plus, the Asian needle ant is aggressive and has a venomous sting. Unfortunately, the Asian needle ant is just as bad an invasive species as the Argentine ant, driving out native ant species—and, in fact, it’s worse because some people are allergic to its sting.

Now let’s go from tiny ants to an insect I was terrified of as a kid, the stick insect, also called walking sticks or phasmids. I like the word phasmid. I don’t know why the idea of a stick insect was so scary to kid me, except that I liked to climb trees and I think I thought one day I’d climb a tree and discover that some of those sticks were not actually part of the tree. Nicholas suggests the Lord Howe Island phasmid in particular, which isn’t just a stick insect, it’s the rarest insect in the world. AND it’s enormous! In fact, it’s sometimes called the land lobster or tree lobster.

The Lord Howe Island phasmid can grow eight inches long, or 20 cm, and can weigh a full ounce, or 25 grams. Males are smaller than females. It has a round head with short antennae, sort of like a cricket, but its body is long and heavy with big legs. It’s black in color with no wings. It’s thicker than most stick insects and doesn’t so much resemble a stick as a cricket on steroids. I’m looking at a picture right now of someone holding one on the palm of their hand, and the insect is literally longer than their palm and almost as long as their palm and fingers. Put it down. Don’t touch it.

These days the Lord Howe Island phasmid lives in one place. That place is not Lord Howe Island off the coast of Australia. That’s where it used to live, and it was so common and so large that fishermen used it as bait. But rats and mice invaded the island in 1918, and by 1920 they’d eaten all the phasmids, which were declared extinct in 1960. But in 1964, someone found a dead phasmid on Ball’s Pyramid, a volcanic islet 12 miles, or 20 km, away from Lord Howe Island.

Ball’s Pyramid is what’s known as a volcanic stack, the eroded remnant of a volcano which is part of the submerged continent of Zealandia. It’s basically a cliff rising straight up out of the ocean. It’s the tallest volcanic stack in the world, 1,844 feet high, or 562 meters, 3,600 feet long, or 1,100 meters, and 980 feet wide, or 300 meters. It’s surrounded by rough seas and barely submerged rocks, and there’s pretty much nothing on it, so not very many people have ever tried to land on the islet. A group of mountain climbers scaled it in 1965 and again in 1979, but in 1982 access to the islet was restricted. It’s now part of the Lord Howe Island Marine Park.

During the successful climbs of Ball’s Pyramid, and a few unsuccessful climbs, dead phasmids were photographed but no live ones found. In 2001, a couple of entomologists landed to make a survey of the islet, primarily to determine whether the Lord Howe Island phasmid was alive on the island or actually extinct. They were pretty sure it was extinct. They found some Melaleuca howeana shrubs growing in a few cracks in the rock, and incidentally that’s a subspecies of tea tree that only grows on Ball’s Pyramid and Lord Howe Island. It grows up to ten feet tall, or 4 meters, and almost as wide. And in one of the shrubs they found 24 live Lord Howe Island phasmids.

Since then, eggs have been collected from the wild and relocated to a captive breeding program, which has been successful so far. Hopefully Lord Howe Island phasmids will be rereleased onto Lord Howe Island, once the rats and mice are eradicated.

Researchers think the Lord Howe Island phasmid was able to survive in such low numbers because females are able to reproduce without being fertilized by males, called parthenogenesis. Researchers have compared DNA taken from the Ball’s Pyramid insects to museum specimens gathered from Lord Howe Island prior to 1920 and determined that they are the same species.

The term phasmid, of course, refers to an order of insects that are mostly camouflaged to look like twigs or leaves, and it contains the longest insects in the world. And that’s good, because listener Damian wants to know about the biggest insects alive today.

The longest insect is Phryganistria chinensis Zhao, a stick insect only discovered in 2014 by researcher Zhao Li of the Insect Museum of West China. Locals in the mountains had told him about a massively long phasmid and he finally tracked one down. He brought it back alive to the museum, where it laid six eggs. Can you possibly imagine how excited he must have been by those eggs? When they hatched, the smallest of the babies was 26 centimeters long, or over ten inches. The adult female measured 62.4 cm, or just over two feet long. HOLY CRAP. TWO FEET LONG. That’s more of a walking branch than a walking stick. Not only that, its legs are almost as long as its body.

Since then, the babies have grown up and one of them, another female, is now the longest living insect ever measured, at 64 cm, or 25 inches. So you know what this means. It means there are some of them in the wild that are probably even longer.

Before the discovery of Zhao’s phasmid, the longest insect known was called Chan’s megastick, which was 22.3 inches long, or 56.7 cm. It was discovered in 2008 in Borneo in Southeast Asia, and only six specimens have ever been found. That means it too probably has even longer individuals living in the wild.

Many stick insects lay eggs that look like seeds. For a long time researchers weren’t sure why. After all, birds eat seeds. Why would an insect lay eggs that might attract hungry birds? But it turns out that the eggs contain a deposit of fat that attracts seed-eating ants, and the ants carry the eggs back to their nest and bury them. The eggs are then safe from birds, parasitic wasps, and other predators. We have come full circle back to ants, notice? Not only that, but researchers in Japan tested whether the protective coating on some seed-mimicking phasmid eggs would protect the eggs if they were eaten by birds. Sure enough, when they fed the eggs to the brown-eared bulbul, a bird known to eat phasmids, a few of the eggs survived and hatched. So it’s likely that phasmid eggs resemble seeds to attract ants but it’s okay if they also attract birds—in fact, it might even be a good thing since the birds would spread the eggs to new areas. Special thanks to Nicholas, who sent me links to several articles about stick insects, including the article about phasmid eggs. I’ll put a link in the show notes if you want to read the article, because it’s really interesting.

So the longest insects are phasmids, but what is the heaviest insect alive? That would be the Little Barrier Island giant weta from New Zealand, also called the wetapunga, which has weighed in at 72 grams, or over 2 ½ ounces. That’s heavier than some songbirds and mice. The wetapunga is basically an enormous cricket and somewhat resembles a gigantic, rather elongated version of one of my least favorite bugs, the cave cricket. It’s that same sort of sickly orangey tan color. If you look at it from the right angle it looks kind of like a lobster, which I also don’t like. Not only can the wetapunga be really heavy, it’s also long—not stick insect long, but a respectable four inches or so long, or 10 cm, and even longer if you count the stretched-out legs.

It eats plants and is mostly nocturnal.

Like the Lord Howe Island phasmid, the wetapunga is vulnerable to introduced predators. It only survives in the wild on Little Barrier Island, and is now the subject of a successful captive breeding program. It’s been around for 190 million years so it would be a shame to let it go extinct now.

The insect with the biggest wingspan is a butterfly called Queen Alexandra’s birdwing, which can have a wingspan almost a foot across, or over 25 cm. Its body is just over 3 inches long, or 8 cm. The female is larger than the male and has brown wings with pretty white and yellow markings. The male looks much different, with iridescent blue-green wings and a bright yellow abdomen. The butterfly is a strong flyer that spends a lot of time flying much higher that typical butterflies do. Males court females with a spectacular aerial dance.

The Queen Alexandra’s birdwing lives in eastern Papua New Guinea in a coastal rainforest, a habitat that is only about 40 square miles total, or 100 square km. Not only is it threatened by habitat loss due to palm oil plantations, which are absolutely insidious and seriously, you should stop buying products that use palm oil, but a volcanic eruption in the 1950s destroyed part of its habitat too. It’s protected and no one is supposed to buy, sell, or trade individuals, live or dead. Hopefully conservationists can work out a way to breed the butterfly in captivity.

The biggest beetle alive today is probably the Hercules beetle, which lives in the rainforests of Central and South America. It’s only longer than the titan beetle that lives in the Amazon rainforest because of its long rhinoceros-like horns, which push its length to 7 inches, or 17 cm. A male uses his horns to fight by grabbing another male with his horns and throwing him. The male Hercules beetle is black with yellowish or yellow-green wing cases. Females are usually all black and don’t have horns. Hercules beetle larvae are humongous and weigh a whopping 100 grams, or 3.5 ounces. So technically the Hercules beetle larva is the heaviest insect, but I’ve disqualified it because it’s not fully grown and anyway, it eats rotting wood. I wouldn’t be surprised if half its weight is just all the rotten wood it’s eaten. The adult beetles eat fruit.

So what about extinct insects? Were there ever insects even bigger than the ones alive today? The answer, as you may already know, is a big loud YES. Back in the early Permian era, around 290 million years ago, two species of flying insect called a griffinfly, which resembled a dragonfly, had a wingspan of almost two feet across, or 71 cm, and a body length of 17 inches, or 43 cm. Researchers estimate they may have weighed as much as a pound, or 450 grams.

If you were brave enough to listen to the spiders episode a few weeks ago, you may remember that spiders, and insects, can’t grow too big or they literally can’t get enough oxygen to function. So how did a huge active flying insect of that size manage?

One theory is that the atmosphere in the Permian contained more oxygen than the current level, which made it easier for insects to get the oxygen they needed. Air today is made of about 21% oxygen, with the other 80% made up of other gases, mostly nitrogen, but in the early Permian oxygen content was around 30%, although that was down from a peak of 35% only ten million years before. By the late Permian oxygen content had plunged to 16% and even reached as low as 12% at the beginning of the Triassic, killing off many animals and fragmenting populations of the ones that survived. Because the oxygen content was so low, animals could only survive at or near sea level. Even the lowest mountains were deadly because the air at higher elevations naturally contains less oxygen. Researchers estimate that breathing air with only 12% oxygen at sea level would be like breathing air at 17,400 feet, or 5,300 meters. Humans can’t survive at elevations above about 19,500 feet, or 5,950 meters. The reduction of oxygen in the atmosphere led to a massive extinction event called the Great Dying, where 90% of all marine life and almost 75% of all life on land went extinct around 251 million years ago.

Researchers aren’t sure what caused the de-oxygenation of the atmosphere, but it’s possible the massive volcanic activity near the end of the Permian played a part by releasing carbon dioxide and other gases into the atmosphere. The rock record during the Permian shows the results in stark detail: limestone in the older rock strata that’s full of fossils and the fossilized burrows of little animals that lived in the soft mud at the bottom of shallow oceans. Then there’s a mineralized layer of rock full of pyrite, which forms in low atmospheric conditions. Above this are bands of clay full of minerals from volcanic eruptions but with no fossils present. Above that are mudstone layers where fossils finally start appearing again in small numbers as life rebounded after the extinction event.

I’ve sort of gotten away from huge insects here, so I’ll finish by pointing out that clearly the phasmids of today aren’t having any issues with growing really big. So, you know, watch out where you put your hands when you’re climbing trees.

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!

Episode 092: Marine Reptiles

This week we return to the sea to learn about some marine reptiles, both living and extinct!

A marine iguana, eatin:

Another marine iguana, swimmin:

Maybe Darwin was right about the marine iguana looking like imps of darkness:

A mosasaurus skeleton:

A plesiosaur skeleton:


Show transcript:

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

It’s been a while since we had an episode about the ocean, and I thought it would be interesting to learn about reptiles that evolved to live in a marine environment. Some marine reptiles we’ve already covered in previous episodes, including saltwater crocodiles, sea turtles, and sea snakes. But we haven’t talked much about extinct marine reptiles, and I don’t think we’ve ever had an episode about the marine iguana.

The marine iguana is only found on the Galapagos Islands. It eats seaweed and algae that grow in shallow water around the islands, so it swims and dives to find its food. It’s a large, strong iguana that can grow up to five feet long, or 1.5 meters, with short legs, a short snout, and a row of spines along its back. It’s black or gray in color, which absorbs heat from the sun and keeps the iguana warmer. Many have colorful markings, especially males during the breeding season. The markings might be red or pink, blue-green, yellow, or off-white, depending on subspecies. Some researchers think the kinds of algae eaten by the various subspecies of marine iguana also contributes to the colors of their markings. Males are larger than females.

The marine iguana is well adapted to swimming, although it’s not a fast swimmer. It uses its flattened tail and partially webbed toes to propel itself through the water, and the spines on its back keep it stable in the water. It has long claws that it uses to hold onto rocks to keep from being swept away. Newly hatched babies can swim immediately, but they stay out of the water whenever possible until they’re at least a year or two old. The water around the islands is cold, so the marine iguana will forage in the water for a short time, then come back on land to bask in the sun and warm up.

Only the biggest marine iguanas, mostly adult males, will dive for their food. Females and smaller males usually stay in shallow water, especially at low tide when the algae is easier to reach. A marine iguana can dive up to almost 100 feet, or 30 meters, and stay underwater for half an hour. During bad weather, the iguanas stay on shore, often gathered together to conserve body heat.

Researchers used to think the marine iguana evolved from land iguanas that were swept from Central or South America by storms and floated to the Galapagos islands on rafts of vegetation. Then genetic studies showed that the marine iguana started evolving separately from land iguanas around 8 to 10 million years ago. The Galapagos islands are of varying ages, formed by volcanic activity, but the oldest is only about 3.2 million years old. So obviously the two groups of iguana were separated long before the Galapagos formed. Researchers then speculated that there may have been other, older islands in the Galapagos or nearby that are now submerged, which were where the marine iguanas first started to evolve separately from land iguanas. Then new genetic studies indicated that marine and land iguanas actually separated about 4.5 million years ago, which is not that much of a difference from the oldest islands of the Galapagos, so researchers are back to the original hypothesis. As I’ve said before, science isn’t wrong or right, scientists learn new things and adapt their theories to account for the new information.

For instance, at the moment researchers aren’t sure how marine iguanas shrink during years when weather conditions keep them from finding as much food as they need. I don’t mean they lose weight, I mean they actually shrink. Results of a study published in the journal Nature say marine iguanas shrank up to 2.7 inches, or 6.8 cm, during years with El Nino weather patterns, which brings stormy weather. The iguanas’ bones actually shrunk, making them both shorter and smaller. Not only that, after weather patterns returned to normal and the iguanas were able to find more and better food, the shrinking reversed and they grew larger again. Shrinking reduces the iguanas’ dietary requirements, making them able to survive on less food without long-term health issues.

Because the marine iguana eats algae and other plants that grow in the ocean, it ingests a lot of salt. It has a special gland on the nose that filters excess salt from the blood, which the iguana then expels by sneezing. Many times marine iguanas look like they have white markings on the head, but in actuality it’s just dried salt that they’ve sneezed out.

Like most of the animals that live on the Galapagos Islands, the marine iguana is found nowhere else in the world. It would have been easy for early visitors to the islands to have eaten them to extinction the way they did so many other species. But sailors considered marine iguanas so ugly that they refused to eat them. Even Charles Darwin called them disgusting imps of darkness. That’s harsh, especially since I think they’re cute, but it kept them safe until people understood the need for conservation.

Many marine reptiles are extinct, including the ichthyosaurs we talked about in episode 63. These days the top predators in the ocean are sharks and whales, but mosasaurs and plesiosaurs used to fill those ecological niches.

Mosasaurs looked a lot like sharks in some ways, and like whales in other ways, but they were reptiles. There were a lot of them, from one barely more than three feet long, or 1 meter, up to some species that grew some 50 feet long or more, or up to 17 meters.

All species of mosasaur had four flippers, long powerful tails, and small heads with short necks. Its skull resembled a snake’s in that it was flexible, allowing the mosasaur to swallow prey larger than its head. It also had double-hinged jaws that could open extremely wide. It’s also possible that the mosasaur had a forked tongue. We have skin impressions of mosasaurs, so we know at least some species had finely scaled skins like snakes. Some species had fluked tails shaped like a shark’s tail. The mosasaur used its tail to propel itself through the water, with its flippers only helping it maneuver. Some researchers think the closest living relative of the mosasaur is the Komodo dragon and other monitor lizards, but others think the mosasaur was more closely related to snakes.

The mosasaur came to the surface to breathe every so often like other marine reptiles. It also gave birth to live young. It probably swallowed its prey whole, although some species had specialized teeth that allowed them to crush mollusk shells, such as ammonites. Some studies suggest the mosasaur may even have been warm-blooded. It went extinct at the same time as the dinosaurs.

The plesiosaur looks similar to the mosasaur in many ways, including overall shape and size, but was probably more closely related to turtles than to the mosasaur. Most plesiosaurs had a broad body, a very long neck and small head, and a fairly short tail. It propelled itself with its four long flippers like sea turtles do and was probably relatively slow. Some plesiosaurs, known as pliosaurs, had shorter necks and much larger heads, and swam much faster.

Like the mosasaur, the plesiosaur may have been warm-blooded, and gave birth to live babies instead of laying eggs. The longest plesiosaur was called elasmosaur, which had an extremely long neck. Some elasmosaur species had as many as 76 neck vertebrae. This is your reminder that almost all mammals have seven neck vertebrae. While the elasmosaur could grow up to 50 feet long, or 15 meters, much of its length was neck. Researchers used to think plesiosaur necks were flexible like a goose or swan’s neck, but new findings indicate that it was probably fairly stiff and could mostly just move side to side. Skin impressions show slightly wrinkled skin and some species may have had a tail fluke.

Long-necked plesiosaurs had large eyes and probably hunted by sight. Researchers hypothesize that the long neck might have allowed it to sneak up on fish before they could sense the movement of water from the plesiosaur’s approaching body.

At least one elasmosaur was a filter feeder, with interlocking teeth that it used to filter small prey from either the water or sand, or possibly both. It shows many similarities in skull shape to early baleen whales, too. Researchers think it had a valve at the base of the nostrils that closed them while the animal was feeding, since plesiosaurs and some other marine reptiles have nostrils that open into the mouth.

Like mosasaurs, plesiosaurs died out at the same time as the dinosaurs. They did not live on as the Loch Ness Monster, okay?

While mosasaurs and plesiosaurs lived throughout the world’s oceans, the various species of thalattosaur lived around what is now North America, western Europe, and parts of China. They lived during the mid-Triassic period, up to about 250 million years ago, and we don’t know a whole lot about them because we don’t have all that many fossils. We’re not even really sure where they fit in the reptile family tree.

The thalattosaur hunted in warm, shallow water but otherwise probably lived on land. It resembled a lizard, but with some interesting adaptations to the water. It had four short legs, probably had webbed toes, its body was slender and flexible, and its long tail widened at the end to form a paddle. Some species grew up to 13 feet long, or 4 meters. Some species had nostrils near the eyes, some had snouts that point downward, some had snouts that point upward. Some probably ate jellyfish and other soft foods, others probably ate fish, and a few had teeth that could crush mollusk shells—and had teeth on the roof of its mouth.

This actually isn’t unusual in reptiles and some amphibians. Most snakes have a double row of teeth in the upper jaw, one row growing from the jaw like normal, the other row growing from the roof of the mouth. Some lizards have small teeth that grow from the roof of the mouth, as do many frogs. These help the animal grasp its prey and keep it from escaping while it’s being swallowed whole. This is pretty neat, but it’s not as neat as shrinking iguanas. Nothing beats 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!