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Strange Animals Podcast
Hosted by Katherine Shaw · EN
A podcast about living, extinct, and imaginary animals!
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Episode 441: Mean Birds
Jul 14, 202500:11:25Tap to summarizeThanks to Maryjane and Siya for their suggestions this week! Further reading: Look, don’t touch: birds with dart frog poison in their feathers found in New Guinea The hooded pitohui: The rufous-naped bellbird: The regent whistler: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. This week we’re going to learn about some birds that by human standards seem pretty mean, although of course the birds are just being birds. Thanks to Maryjane and Siya for their suggestions this week! We’ll start with Maryjane’s suggestion, the Northern shrike. It lives in North America, spending winter in parts of Canada and the northern United States. In summer it migrates to northern Canada. It’s a lovely gray and black bird with a dark eye streak, white markings on its tail and wings that flash when it flies, and a hooked bill. It’s a strong bird about the size of an American robin, and both the male and female sing. They will sometimes imitate other bird songs, and during breeding season a pair will sing duets. The Northern shrike looks very similar to the loggerhead shrike that lives farther south, in the southern parts of Canada and throughout most of the United States and Mexico. Most important to us today, the Northern shrike is sometimes called the butcher bird, because in the olden days, butchers would hang meat up to cure–but we’ll get to that part. It prefers to live in the edges of a forest near open spaces, and in the summer it lives along the border of the boreal forest and tundra. While it’s just a little songbird, in its heart it’s a falcon or hawk. It eats a lot of insects and other invertebrates, especially in summer, but it mainly kills and eats other songbirds and small mammals like mice and lemmings, even ones that are bigger and heavier than it is. The shrike has ordinary feet for a perching bird, not talons, but its feet are strong and can hold onto struggling prey. Its beak is deadly to small animals. The bill has a sharp hook at the end and is notched so that it has two little projections that act like fangs. It will hover and drop onto its prey, or grab a bird in mid-flight and bear it to the ground to kill it. Sometimes it will hop along the ground until it startles a bird or insect into flying away. It will even flash the white patches on its wings to frighten hidden prey into moving. If the shrike kills a wasp or bee, it will remove the stinger before eating it. It will pick off the wings of large insects and will sometime beat a dead insect against a rock or branch to soften it up and break off parts of the hard exoskeleton before eating it. Shrikes are territorial and will chase away birds that are much bigger than them, like ducks and even geese. During nesting season, the female takes care of the eggs and the male provides food for her. To prove that he can provide lots of food for the female while she’s incubating the eggs, he will cache food throughout his territory in advance. This is something shrikes do anyway, but it’s especially important during nesting season. If a shrike catches an animal it doesn’t want to eat right away, it will store it for later. It will cram it into a crack in a rock, impale it on a thorn or other sharp item like the points of a barbed wire fence, or wedge it into the fork of a tree branch. Then it can come back and eat it in a day or two when it’s hungry, or take the food to its mate. When the eggs hatch, both parents help feed the babies. When the babies are old enough to leave the nest, the parents go their separate ways, but they will often each take some of the fledglings with them so they can continue to feed them and help them learn to hunt. Since a nest can have as many as nine babies, it’s not always possible for one parent to take all the babies. The siblings stick together even once they’re mostly grown and independent, often through their first winter. This is what a Northern shrike sounds like: [Northern shrike call] We talked about some poisonous birds in episode 222, but Siya wanted to learn more about them. In that episode we mostly talked about the hooded pitohui, but since then, two more poisonous birds have been discovered in New Guinea. Let’s refresh our memories about the hooded pitohui, mostly because its discovery by scientists is such a fun story. The hooded pitohui lives in forests throughout much of New Guinea and eats seeds, insects and other invertebrates, and fruit. It’s related to orioles and looks very similar, with a dark orange body and black wings, head, and tail. It’s a social songbird that lives in family groups where everyone works to help raise the babies. The people who live in New Guinea knew all about its toxicity, of course. They mentioned this to European naturalists as long ago as 1895, but weren’t believed, because the scientists had never heard of a toxic bird. It wasn’t until 1989 that a grad student studying birds of paradise made a surprising discovery. Jack Dumbacher was trying to net some birds of paradise to study but kept catching pitohuis in his nets. He would untangle the birds and let them fly away, but naturally they were upset and one scratched him. He was in a hurry so he just licked the cuts clean. His tongue started to tingle, then burn, and then it went numb. Fortunately the effects didn’t last long, but he mentioned it to another researcher who had had a similar experience. They realized something weird was going on, so Dumbacher asked some of the local people what the cause might be. They all said, “Yeah, don’t lick the pitohui bird.” Dumbacher did, though, because sometimes scientists have to lick things. The next time his nets caught a pitohui, Dumbacher plucked one of its feathers and put it in his mouth. His mouth immediately started to burn. Dumbacher was amazed to learn about a toxic bird, but it took a year for anyone else to take an interest, specifically Dr. John W. Daly, an expert in poison dart frogs in Central and South America. Back in the 1960s while he was studying the frogs, in order to determine which ones were actually toxic and which ones weren’t, he frequently poked a frog and licked his finger, so Daly completely understood Dumbacher putting a feather in his mouth. Maybe don’t put random stuff in your mouth. Both Dumbacher and Daly were lucky they didn’t die, because it turns out that poison dart frogs and pitohuis both contain one of the deadliest neurotoxins in the world, called batrachotoxin. A chemical analysis determined that both animals excrete the same toxin. In captivity, poison dart frogs lose their toxicity. Daly was the one who figured this out, but he couldn’t figure out why except that he was pretty sure they absorbed the toxins from something they were eating in the wild. He thought the same might be true for the pitohui. Dumbacher agreed, and after he achieved his doctorate he started making expeditions to New Guinea to try to find out what. Both he and Daly thought it was probably an insect. But there are a lot of insects in Papua New Guinea and he couldn’t stay there and test insects for toxins all the time. He came and went as often as he could, and to make his trips easier he left his equipment in a village rather than hauling it back and forth with him. What he didn’t know is that...
Transcribe →Episode 440: Trilobites!
Jul 7, 202500:10:27Tap to summarizeThanks to Micah for suggesting this week’s topic, the trilobite! Further reading: The Largest Trilobites Stunning 3D images show anatomy of 500 million-year-old Cambrian trilobites entombed in volcanic ash Strange Symmetries #06: Trilobite Tridents Trilobite Ventral Structures A typical trilobite: Isotelus rex, the largest trilobite ever found [photo from the first link above]: Walliserops showing off its trident [picture by TheFossilTrade – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=133758014]: Another Walliserops individual with four prongs on its trident [photo by Daderot, CC0, via Wikimedia Commons]: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. This week we’re going to learn about an ancient animal that was incredibly successful for millions of years, until it wasn’t. It’s a topic suggested by Micah: the trilobite. Trilobites first appear in the fossil record in the Cambrian, about 520 million years ago. They evolved separately from other arthropods so early and left no living descendants, that they’re not actually very closely related to any animals alive today. They were arthropods, though, so they’re distantly related to all other arthropods, including insects, spiders, and crustaceans. The word trilobite means “three lobes,” which describes its basic appearance. It had a head shield, often with elaborate spikes depending on the species, and a little tail shield. In between, its body was segmented like a pillbug’s or an armadillo’s, so that it could flex without cracking its exoskeleton. Its body was also divided into three lobes running from head to tail. Its head and tail were usually rounded so that the entire animal was roughly shaped like an oval, with the head part of the oval larger than the tail part. It had legs underneath that it used to crawl around on the sea floor, burrow into sand and mud, and swim. Some species could even roll up into a ball to protect its legs and softer underside, just like a pillbug. Because trilobites existed for at least 270 million years, there were a lot of species. Scientists have identified about 22,000 different species so far, and there were undoubtedly thousands more that we don’t know about yet. Most are about the size of a big stag beetle although some were tinier. The largest trilobite found so far lived in what is now North America, and it grew over two feet long, or more than 70 centimeters, and was 15 inches wide, or 40 cm. It’s named Isotelus rex. I. rex had 26 pairs of legs, possibly more, and prominent eyes on the head shield. Scientists think it lived in warm, shallow ocean water like most other trilobites did, where it burrowed in the bottom and ate small animals like worms. There were probably other species of trilobite that were even bigger, we just haven’t found specimens yet that are more than fragments. Because trilobites molted their exoskeletons the way modern crustaceans and other animals still do, we have a whole lot of fossilized exoskeletons. Fossilized legs, antennae, and other body parts are much rarer, and preserved soft body parts are the rarest of all. We know that some trilobite species had gills on the legs, some had hairlike structures on the legs, and many had compound eyes. A specimen with preserved eggs inside was also found recently. Some incredibly detailed trilobite fossils have been found in Morocco, including details like the mouth and digestive tract. The detail comes from volcanic ash that fell into shallow coastal water around half a billion years ago. The water cooled the ash enough that when it fell onto the trilobites living in the water, it didn’t burn them. It did suffocate them, though, since so much ash fell that the ocean was more ash than water. The ash was soft and as fine as powder, and it covered the trilobites and protected their bodies from potential damage, while also preserving the body details as they fossilized over millions of years. The fossils were discovered in 2015, about 509 million years after the trilobites died, and are still being studied. Two species of trilobite have been found at this Morocco site, and the team is using non-invasive technology to study the preserved insides in one exceptionally preserved specimen. Its entire digestive system is intact, probably because the poor trilobite ended up swallowing a lot of ash before it died. The ash kept the soft tissues from decomposing. Some trilobites had spines growing from their head shields and even from the rest of the exoskeleton. Scientists think these may have helped protect the animals from being eaten, but they might also have helped them navigate more easily in the water without getting flipped over by currents. One genus of trilobite, Walliserops, even had a structure sticking out from the front of its head called a trident. The trident grew forward and slightly upward from the head, then split into three prongs. Scientists aren’t sure what it was for, but suggest that it acted as a nose spike like some modern beetles have, which allowed trilobites to fight each other for resources or mates. The tridents weren’t completely symmetrical, and one individual has even been found with a four-pronged trident. (I guess you would call that a quadrent.) Some species had long tridents, some short, but there’s no evidence that only males or only females had them. Electron microscopes and other modern imaging technology have allowed scientists to learn more about what the trilobite looked like when it was alive. This includes some hints about different species’ coloration and markings. Most trilobites had good vision and were probably as colorful as modern crustaceans. Some rare trilobite fossils show microscopic traces of spots and stripes. One species studied may have had a brown stripe that faded to white along the edges of the body. All trilobites went extinct at the end of the Permian, about 250 million years ago, during the extinction event called the Great Dying. We talked about it in detail in episode 227 so I won’t go over its causes and effects again except to say that an estimated 95% of all marine animals went extinct during that event. The Great Dying ended the trilobite’s successful 270 million year run on this amazing planet. When I was little, I found trilobites fascinating. They were so common for so long, and then they were gone. I’ve always wondered if some trilobites survived the Great Dying and were still alive in the deep sea. I’m not the only one who’s wondered that, so let’s talk a little more about why the trilobites went extinct and how some of them might have survived. Almost all trilobites we know of lived in shallow coastal water. We have trilobite tracks of an ancient low tide shore, which tells us that at least some species could leave the water and venture onto land occasionally, possibly the first animals on earth to do so. Coastal water is well oxygenated and we know trilobites had trouble surviving anoxic events, when the water where they lived had much less oxygen than usual. Anoxic events are actually what led to the Grea...
Transcribe →Episode 386: The Greater Siren and the Anhinga
Jun 24, 2024Tap to summarizeThanks to Kai and Emily for their suggestions this week! The greater siren [photo by Kevin Stohlgren, taken from this site]: The anhinga [photo by Tim from Ithaca - Anhinga, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=15526948]: An anhinga swimming [photo by Wknight94, CC BY-SA 3.0 , via Wikimedia Commons]: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. This week we’re going to learn about two animals, one suggested by Kai and the other suggested by Kai’s mom Emily. It’s so awesome to hear when families like to listen to the podcast together. This episode even includes a mystery animal I bet you’ve never heard of. Let’s start with Kai’s suggestion, the greater siren. The greater siren is an amphibian, specifically a salamander, but it’s probably not the kind of salamander you’re thinking of. For one thing, it can grow over three feet long, or about a meter, which is pretty darn big for a salamander. It’s dark green or gray in color with tiny yellow or green speckles, and while it has short front legs, those are the only legs it has or needs. It also has external gills which it keeps throughout its life, unlike most salamanders who lose their external gills when they metamorphose into adults. The greater siren lives primarily in Florida, but it’s also found in coastal wetlands throughout much of the southeastern United States. It’s mostly nocturnal and during the day it hides among water plants or under rocks, and will even burrow into the mud. At night it comes out to find food, which includes crayfish and other crustaceans, insects and spiders, little fish, other amphibians, snails, and even algae. It swallows its food whole, even snails and other mollusks. It poops out the shells and other undigestible pieces. The grater siren’s body is long but thin, sort of like an eel, with a rounded tail that’s slightly flattened to help it swim. While it does spend its whole life in the water, it has small lungs that allow it to breathe air if it needs to. It can wriggle above ground for short distances if it needs to find a new pond or river, and sometimes it will sun itself on shore. In drought conditions when its water dries up, the greater siren will burrow into the mud and secrete mucus that mixes with dead skin cells to form a sort of cocoon. The cocoon covers everything but the siren’s mouth, so it can still breathe. Then it enters a state of torpor called aestivation, and it can stay in its mud cocoon for a long time, possibly as much as five years, and still be fine once the water returns. It does lose a lot of its body fat and its gills wither away, but it regenerates them quickly once it has water, and will gain weight quickly too once it has food. In early spring, the female siren lays her eggs in shallow water. The male fertilizes them and takes care of them for the next two months, when they hatch into little bitty sirens that go off on their own right away. The greater siren has tiny eyes and probably doesn’t see very well. It has a good sense of smell instead, and it can also sense movement and vibrations around it with its lateral line system. This is an organ found in many fish and a lot of larval amphibians, although the greater siren retains it throughout its life. It allows the animal to sense the movement of water in extremely fine detail. The greater siren can probably also sense electrical impulses, which is something that all animals generate when they use their muscles. If there’s a greater siren, you may be thinking, there must be a lesser siren too. There is, and it’s very similar to the greater siren, just not as big. It only grows about two feet long at most, or 61 cm. Kai mentioned that the greater siren looks a lot like the axolotl, a critically endangered salamander found only in Mexico. I checked to see if the two salamanders were closely related and was actually surprised t...
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