Science News reports: amorous alligator males produce a 18 to 20 Hz sub bass rumble to seduce females. But that's not all. Hidden in this sound there's an even deeper bass at half the vibrational frequency, 9 to 10 hertz, producing Faraday waves.
"When a male alligator craves company, he issues a sound from his lungs that is too low to be heard. This infrasound causes him to vibrate violently and whips the water on his back into a froth of waves and leaping fountains.
Acoustician R. Glynn Holt of Boston University saw a video of this "water dance" and was reminded of physicist Michael Faraday. In 1831 Faraday discovered that liquid above a vibrating object sometimes forms surface waves that move up and down at half the speed of the vibrations.
"We think that the shape of their scutes helps them create these waves," said Moriarty. The shapes of some backs may make better waves for signaling mates, he speculates — possibly a kind of sexual selection."
More bass seduction: Subwoofers and the animal kingdom.
