“The platypus is an anthology of weirdness. It has a leathery duck-like bill, a flattened tail and webbed feet. The males have a venomous claw on their hind feet, and the females lay eggs. And if you look inside a platypus, you’ll find another weird feature: its gullet connects directly to its intestines. There’s no sac in the middle that secrete powerful acids and digestive enzymes.
In other words, the platypus has no stomach.”
Read more from Ed Yong at Phenomena: Not Exactly Rocket Science.