BROADCASTS.com

Thanks to River for suggesting this week's topic, the pufferfish!\n\nFurther reading:\n\nGrass puffer fish communicate with each other using a non-toxic version of their deadly toxin\n\nMystery pufferfish create elaborate circular nests at mesophotic depths in Australia\n\nPufferfish, puffed:\n\n\n\n\n\nA starry puffer, un-puffed [picture by Diego Delso, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=116912671]:\n\n\n\nA grass puffer, un-puffed:\n\n\n\nThe mystery structure that turns out to be made by pufferfish:\n\n\n\nShow transcript:\nWelcome to Strange Animals Podcast. I\u2019m your host, Kate Shaw.\nThis week we\u2019re going to learn about a weird fish suggested by River, the pufferfish!\nLots of fish have the name pufferfish, and sometimes they\u2019re also called balloonfish, swellfish, bubblefish, or globefish. You might be able to guess from the names what they can do, but just in case you don\u2019t know, the pufferfish can puff up to make itself big and round. The question you might have at this point is why, and how do they do this?\nThere are lots of pufferfish in various genera, all of them in the family Tetradontidae. Tetradontidae means \u201cfour teeth,\u201d because obviously when you find an incredibly poisonous fish that can blow itself up like a balloon, sometimes with spikes that emerge from the skin, of course you\u2019re going to name it after its teeth.\nMost pufferfish live in the ocean, although some live in places where freshwater mixes with ocean water, and some species even live in rivers. It prefers warm, shallow water and eats invertebrates and plant material. Larger pufferfish can use their four big front teeth to crush the shells of mollusks, like clams and mussels.\nMost pufferfish are quite small and often brightly colored with spots, stripes, and other markings. You\u2019d think the biggest pufferfish has to be the one called the giant freshwater pufferfish, but while it is big, it\u2019s not the biggest. The giant freshwater pufferfish can grow up to 26 inches long, or 67 cm, which is over two feet long. But the starry puffer is almost twice that length, up to 47 inches long, or 120 cm. That\u2019s almost four feet long!\nThe starry puffer lives in tropical and subtropical parts of the Pacific Ocean, especially in the Indian Ocean and the Red Sea. It has a big head, two pairs of nostrils, and is a mottled gray and white in color with little black spots all over. It mostly eats crustaceans and mollusks, but will also eat algae, sponges, coral, urchins, and other invertebrates.\nThe pufferfish is a slow swimmer, but it has two really good defenses. If it feels threatened\u2014for instance if a big fish tries to catch it, or it\u2019s caught in a fishing net and hauled to the surface, or if a diver tries to make friends, the pufferfish will swell up until it looks like a balloon with fins. It does so by gulping air or water into its elastic stomach until it\u2019s completely full.\nIf you\u2019re wondering how this can help the fish, not only does this make the pufferfish look much larger, it also makes it harder to swallow. Not only that, the pufferfish has spines that may be hidden in the skin most of the time, but when the skin tightens as the fish expands into balloon shape, the spines poke out. Suddenly a potential predator isn\u2019t just trying to swallow a fish way bigger than its mouth is, it\u2019s pointy.\nThe pufferfish\u2019s second defense is that its body contains a deadly poison. You may have heard about fugu, which is considered a delicacy even though it\u2019s so poisonous that in Japan and some other countries, chefs have to be specially trained and licensed to prepare the fish to eat. It contains tetrodotoxin, or TTX, a neurotoxin that stops your nerves from sending the tiny electrical signals that allow muscles to move. If you\u2019re poisoned with TTX, you start to feel dizzy and sick, then you start having difficulty speaking and moving, then you have trouble breathing, and then, ultimately, you\u2019re paralyzed and can\u2019t breathe,