Conversations Encore: The misfit mammal that defies biological conventions
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May 7, 2026 Jack Ashby, British zoologist and Assistant Director at Cambridge Museum of Zoology, and author of Platypus Matters. He tells vivid stories about first encountering platypus specimens and seeing wild platypuses in Tasmania. He explains the platypus’s weird anatomy—electroreceptive bill, cheek pouches, webbed digging feet and venomous spurs. He also reflects on echidnas, historical reactions to Australian mammals, and conservation concerns.
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Why Platypuses Are Mammals
- Platypuses are unequivocally mammals despite lacking nipples because they have mammary glands that secrete milk into fur patches.
- Young lap milk from fur; evolutionary constraints (a bill) likely prevented nipple evolution in platypuses.
Bill Is A Living Electro-Sensor
- The platypus bill is a soft, leathery sensory organ with electroreceptors that detect prey electrical signals underwater.
- They close eyes and ears underwater and sweep the bill like a metal detector, finding prey by electrical impulses.
Platypus Tooth Replacement Trick
- Adult platypuses lack teeth but use constantly regrowing horny keratin ridges to crush hard prey like crayfish.
- Juveniles hatch with teeth then reabsorb them, showing evolutionary tooth-loss and replacement with keratin 'plates'.
