Underwater Sound Locating Capability in the American Alligator (Alligator mississippiensis)

Article Review:

In this article, researcher Vladimir Dinets of the University of Miami, investigates the ability of American Alligators to locate the source of underwater sound.

Picking up sound waves, and especially localizing their source is much more difficult when they're transmitted underwater as opposed to through the air. The water is much more dense and scatters sound much more effectively than air. However, as living on both land and water, Crocodilians have adapted hearing to be able to function in both environments. Perhaps most the most notable Crocodilian aquatic communication is the head slap. This mating behavior is done by slapping the water with the head. This sharp (higher frequency) sound is one of the easiest to be detected.

In order to test if alligators showed a directional bias towards water based sounds, Dinets conducted two tests, one in canals, and one in lakes. In both Dinets used a submerged diving bell to produce underwater sound waves. This was crucial because to truly test only underwater 'hearing' the sound could not be audible above the water's surface.

After completing the tests, Dinets found that American Alligators do indeed show a directional bias towards water-borne sounds. His results suggest that underwater sounds, like the slaps, are used as long-distance communication because they're audible a much greater distance away than only air-borne sounds.

Dinets, Vladimir. (2013). "Underwater Sound Locating Capability in the American Alligator (Alligator mississippiensis)." Journal of Herpetology 47:4 521-523