Frogs are the first amphibians to be placed alongside an exclusive group of mammals, such as whales and dolphins — that have ultrasonic ability. Some persistent croakers in China have ‘switched’ to ultrasound!
Albert Feng, a professor of neuroscience at the University of Illinois, Urbana-Champaign says, “It shows a new example of independent evolutionary adaptation in the frogs for life in habitats filled with loud background noise.”
Hearing of the unusual animals in 2000 from Kraig Adler, a biologist at Cornell University, the scientists tipped off to Huangshan Hot Springs, a popular tourist destination near Shanghai, where he had found frogs with recessed ears.
It is then two years later, Feng and his colleagues discovered that the frogs were also croaking in ultrasound-sound vibrations beyond the limit of human hearing. For this finding, the scientists used wide-band recording equipment.