What sound does a platypus make?

The platypus is typically a silent animal, but it does make a low growling noise at times. The platypus growls most often when it's upset or disturbed.

The platypus is found in eastern Australia, and it's something of an enigma in the animal world because it's one of only five species of mammals that lay eggs. It spends most of its time in the water, coming up every 10 minutes for a breath of air. When the platypus hunts, it closes its eyes and ears, dives underwater and uses electroreceptors in its bill to detect the movements of its prey.