Electricity

When hunting underwater, platypuses shut their eyes, ears and nostrils. Their bills contain about 40,000 sensors that detect faint electric fields from prey muscles. They locate food in visual darkness with a sense almost no other mammal possesses.

Pure water is an insulator. Electricity passes through water not because of the water itself, but because of dissolved ions. Tap water conducts electricity well because it contains ions like chlorine from disinfection.