Platypus

The platypus is one of the most recognizable animals on Earth. You know it lays eggs and has a duck bill. What you probably don't know is the full depth of how strange it is — not just odd for a mammal, but genuinely unlike anything else that has ever lived. When the first specimen arrived in Britain in 1799, naturalist George Shaw cut the skin with scissors looking for stitches. He was convinced it was a taxidermy hoax.

Facts you didn't know

• 1

  The platypus has no stomach. It is one of the only vertebrates that lacks one entirely — food passes directly from the esophagus to the intestine. It lost its stomach somewhere in evolutionary history and never needed to regain it.

• 2

  Male platypuses have venomous ankle spurs. The venom causes immediate, intense pain that doesn't respond to morphine — and it can last for months, accompanied by hyperalgesia that makes even light touch agonizing near the sting site.

• 3

  The platypus hunts with its eyes, ears, and nose sealed shut. It navigates entirely by sensing the faint electrical fields produced by muscle contractions in prey — around 40,000 electroreceptors in its bill let it detect a shrimp's heartbeat through water.

• 4

  Platypus fur glows blue-green under ultraviolet light. This was discovered in 2020. The function is unknown. They join a small list of mammals with biofluorescent fur.

• 5

  The platypus has 10 sex chromosomes. Females have 10 X chromosomes, males have 5 X and 5 Y. The arrangement is partly similar to bird sex chromosomes — evidence that mammalian sex chromosomes evolved more than once, through different paths.