BROADCASTS.com

Thanks to Eilee for suggesting the sea louse this week!\n\nFurther reading:\n\nSecrets of the Whale Riders: Crablike \u2018Whale Lice\u2019 Show How Endangered Cetaceans Evolved\n\nParasite of the Day: Neocyamus physeteris\n\nA whale louse [By \xa9 Hans Hillewaert, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=19259257]:\n\n\n\nThe salmon sea louse [By Thomas Bj\xf8rkan - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7524020]:\n\n\n\nShow transcript:\nWelcome to Strange Animals Podcast. I\u2019m your host, Kate Shaw.\nIt\u2019s now officially August, so we\u2019re officially kicking off Invertebrate August with two invertebrates with the word louse in their names, even though neither of them are technically lice. Thanks to Eilee for suggesting sea lice, and thanks to our patrons because I used some information from an old Patreon episode for the first part of this episode.\nThat would be the whale louse. The whale louse isn\u2019t actually a louse, although it is a parasite. Lice are insects adapted for a parasitic lifestyle on the bodies of their hosts, but whale lice are crustaceans\u2014specifically, amphipods specialized to live on whales, dolphins, and porpoises.\nThere are many species of whale louse, with some only living on a particular species of whale. In the case of the sperm whale, one species of whale louse lives on the male sperm whale while a totally different species of whale louse lives on the female sperm whale and on calves. This was a fact I found on Wikipedia and included in the Patreon episode, but at the time I couldn\u2019t find out more. It\u2019s puzzled me ever since, which is one of the reasons I wanted to revisit this topic. I couldn\u2019t figure out how the male calves ended up with male sperm whale lice, and I couldn\u2019t figure out why males and females would have different species of lice. I\u2019m happy to report that I now know the answers to both questions, or at least I can report what experts hypothesize.\nMale sperm whales spend more time in polar waters while females spend more time in warmer waters to raise their calves. Sperm whales are actually host to three different whale lice species, but one species prefers colder water and is much more likely to live on males, while another species prefers warmer water and is much more likely to live on females and calves. Any sperm whale might have lice from any of the three species, though, and whale lice are spread when whales rub against each other. This happens when the whales mate, but it also happens when males fight or when whales are just being friendly.\nThe whale louse has a flattened body and legs that end in claws that help it cling to the whale. Different species are different sizes, from only five millimeters up to an inch long, or about 25 mm. Typically the lice cling to areas where water currents won\u2019t sweep them away, including around the eyes and genital folds, ventral pleats, blowholes, and in wounds. Barnacles also grow on some whales and the lice live around the barnacles. But even though all that sounds horrible, the lice don\u2019t actually harm the whales. They eat dead skin cells and algae, which helps keep wounds clean and reduces the risk of infection.\nThe right whale is a baleen whale that can grow up to 65 feet long, or almost 20 meters. Right whales have callosities on their heads, which are raised patches of thickened, bumpy skin. Every whale has a different pattern of callosities. Right whales are dark in color, but while the callosities are generally paler than the surrounding skin, they appear white because that\u2019s where the whale lice live, and the lice are white. This allows whales to identify other whales by sight. It\u2019s gross but it works for the whales. Right whales also usually host one or two other species of louse that don\u2019t live on the callosities.\nDolphins typically have very few lice, since most dolphins are much faster and more streamlined than whales and the lice have a harder time not getting washed off.