They have no stomach & hunt by detecting electrical impluses
At first glance, platypus hunting methods appear rather inglorious: they close their eyes, ears, and nostrils, dive down to the stream bottom, and wiggle their bill in the muck for a minute or two.
But it’s not quite that simple.
If you look closely at a platypus’s bill, you’ll see hundreds of tiny pores all over the leathery surface. Those pores are special electroreceptors, which pick up minute electrical impulses given off by platypus prey, including macroinvertebrates and small crustaceans. Platypus use this sensory information to locate their prey in the water.
Any prey they catch is stored in their cheek pouches until they return to the surface. Then, they grind it down using a hard plate in their bill, with the help of any gravel they might have also slurped up. Weirdly, little puggles are actually born with teeth, but these fall out when the leave the burrow and are replaced by the griding plate.
When it comes time to digest their meal, platypus are missing another basic part of normal mammalian anatomy: the stomach.
Animal stomachs come in a wide variety of shape and size, but they all perform the same function: they secrete acids and digestive enzymes to help break down food before it moves on to the intestines, where it’s absorbed by the body. But if you peer inside a platypus, you’ll find that their gullet connects directly to their intestines.
Platypus aren’t alone: scientists estimate that about one-quarter of fish species have also “lost” their stomach over the course of evolutionary history.
Just one more reason why they are as wonderful as they are weird.