Physics Application: Found in underground tunnels, this Israelian species of mole rat is found to be blind, communicating through the use of senses other than the eliminated optical apparatus, including a sense of smell and vocalization for small distances. However, for long distance communication, the moles use seismic waves by thumping their flattened heads against the walls of their tunnels. The signals are not heard, but are felt through the skin and travel to the brain by bone conduction and are processed by the auditory system, as experiments proved when the moles were subject to deafening, which resulted in the eventual elimination of head drumming.

Each species of the Blind Mole rat possesses its own, specific thumping rhythm which may prevent intraspecies breeding, as well as the prevention of overcrowding and competition.

Species: Hippopotamus amphibias, Choeropsis liberiensis (Hippopotamus, Pygmy hippopotamus)

Physics Application: The hippopotamus, Greek for "river horse", is known as the third largest mammal, just after the elephant and rhinoceros, and also is known to use infrasonic calls. Sounds emitted above the surface are from the nostrils which we can hear except for the infrasound undertones, but as the waves travel through the air, infrasound calls travel through the water. Sounds in the water are not audible to the human ear, though they may be in the audible range, and are detected by the jaw of the hippopotamus. In the air, the calls travel for 6.4 km (4.0 miles) and are received by the ear, where sounds in the water travel five times faster and are received first, traveling up to 32.2 km (20.0 miles). Using such a system enables the hippopotamus to judge the distance of objects and other living organisms, including their rivals. In the case of an earthquake, they, too, may be able to hear grinding rock under the earth’s surface.

Physics Application: Infrasonic calls.