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Strange Animals Podcast

Strange Animals Podcast

著者： Katherine Shaw
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 A podcast about living, extinct, and imaginary animals! 博物学 生物科学 科学 自然・生態学
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  • Episode 442: Trees and Megafauna

    Episode 442: Trees and Megafauna
    2025/07/21
    Further reading: The Trees That Miss the Mammoths The disappearance of mastodons still threatens the native forests of South America Study reveals ancient link between mammoth dung and pumpkin pie A mammoth, probably about to eat something: The Osage orange fruit looks like a little green brain: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. Way back at the end of 2017, I found an article called “The Trees That Miss the Mammoths,” and made a Patreon episode about it. In episode 320, about elephants, which released in March of 2023, I cited a similar article connecting mammoths and other plants. Now there’s even more evidence that extinct megafauna and living plants are connected, so let’s have a full episode all about it. Let’s start with the Kentucky coffeetree, which currently only survives in cultivation and in wetlands in parts of North America. It grows up to 70 feet high, or 21 meters, and produces leathery seed pods so tough that most animals literally can’t chew through them to get to the seeds. Its seed coating is so thick that water can’t penetrate it unless it’s been abraded considerably. Researchers are pretty sure the seed pods were eaten by mastodons and mammoths. Once the seeds traveled through a mammoth’s digestive system, they were nicely abraded and ready to sprout in a pile of dung. There are five species of coffeetree, and the Kentucky coffeetree is the only one found in North America. The others are native to Asia, but a close relation grows in parts of Africa. It has similar tough seeds, which are eaten and spread by elephants. The African forest elephant is incredibly important as a seed disperser. At least 14 species of tree need the elephant to eat their fruit in order for the seeds to sprout at all. If the forest elephant goes extinct, the trees will too. When the North American mammoths went extinct, something similar happened. Mammoths and other megafauna co-evolved with many plants and trees to disperse their seeds, and in return the animals got to eat some yummy fruit. But when the mammoths went extinct, many plant seeds couldn’t germinate since there were no mammoths to eat the fruit and poop out the seeds. Some of these plants survive but have declined severely, like the Osage orange. The Osage orange grows about 50 or 60 feet tall, or 15 to 18 meters, and produces big yellowish-green fruits that look like round greenish brains. Although it’s related to the mulberry, you wouldn’t be able to guess that from the fruit. The fruit drops from the tree and usually just sits there and rots. Some animals will eat it, especially cattle, but it’s not highly sought after by anything. Not anymore. In 1804, when the tree was first described by Europeans, it only grew in a few small areas in and near Texas. The tree mostly survives today because the plant can clone itself by sending up fresh sprouts from old roots. But 10,000 years ago, the tree grew throughout North America, as far north as Ontario, Canada, and there were seven different species instead of just the one we have today. 10,000 years ago is about the time that much of the megafauna of North and South America went extinct, including mammoths, mastodons, giant ground sloths, elephant-like animals called gomphotheres, camels, and many, many others. The osage orange tree’s thorns are too widely spaced to deter deer, but would have made a mammoth think twice before grabbing at the branches with its trunk. The thorns also grow much higher than deer can browse. Trees that bear thorns generally don’t grow them in the upper branches. There’s no point in wasting energy growing thorns where nothing is going to eat the leaves anyway. If there are thorns beyond reach of existing browsers, the tree must have evolved when something with a taller reach liked to eat its leaves. The term “evolutionary anachronism” is used to describe aspects of a plant,
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    9 分
  • Episode 441: Mean Birds

    Episode 441: Mean Birds
    2025/07/14
    Thanks 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.
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    11 分
  • Episode 440: Trilobites!

    Episode 440: Trilobites!
    2025/07/07
    Thanks 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 fos...
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    10 分

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