While most jawed vertebrates evolved with stomachs, platypuses, echidnas, and many species of fish lost their stomachs through their evolutionary history.Īt some point in time, platypuses and other stomach-less species moved past the need for stomachs, but the reason remains unclear. Surprisingly, other monotremes such as the echidnas don’t have them either. If you’re looking for bizarre platypus facts, here’s one for you: they don’t have stomachs.