Why are freshwater crustaceans a favourite food of platypuses?

Freshwater crustaceans are a favorite food of the platypus primarily because the platypus is highly adapted to hunt for bottom-dwelling invertebrates along the beds of rivers, streams, and lakes.1

While foraging, the platypus uses its flat bill to shovel through streambed debris. It relies on a sophisticated electromechanical system of electroreceptors and touch receptors to detect the minute electrical signals generated by the muscles of its prey, which allows it to navigate and hunt effectively while submerged.1