Thanks to them, they track their prey through changes in the electric field. The platypus can perceive electrical stimuli from the environment, just like sharks. Electroreceptors are located in its skin's special grooves. The beak determines the source of the electric field by comparing differences in signal strength between different receptors. This is evidenced by the fact that during the hunt it moves its head from side to side and "calculates" the distance to the prey. It uses neither smell nor sight during the hunt.
