Biotremology.

Animal communication, including that among humans, is fascinating in its efficiency, diversity and its complexity. The evolution of a communication signal requires that the encoded content sent by an organism (sender) is detected and decoded by a receiver, who then must respond in such a way that the fitness of the sender is increased. The signal could be visual, such as bright coloration or some stereotypical movement that attracts attention through the sense of sight. It could be chemical, such as a pheromone we detect by smell or taste, or it could be tactile, involving direct physical touch. It could be an acoustic wave, detected by an auditory organ as sound and perceived through the sense of hearing, or it could be a vibrational wave detected by a vibration receiver of another sort. The medium through which the signal is transmitted could be any that exists on the Earth (solid, liquid or gas), and each type of medium influences the type of signal that is able to most efficiently move through it.