Sound communication

Sound is essential in the communication between species, but not all the species have the same range of hearing (see table 1) and do not produce the same kind of sounds. The human ear is sensitive to sounds with frequencies from about 20 Hz to 20,000 Hz, the frequencies under the 20Hz are called infrasound and the frequencies over the 20,000 Hz are called ultrasound.

African elephants and the blue whales use the infrasound for intraspecific communication. These sounds are low frequency and can travel long distances (several kilometers) through the ground or in the water and dissipate less fast in the air. The disadvantage of the infrasound is that they give less information of the ambient to the animal. In the other hand we have the bats (20–60 kHz), and dolphins that communicate using ultrasounds, this are characterized by waves of high frequencies, travel short distances but have the advantage that can give more information of the ambient to the animal. Bats use the echolocation sounds to found and catch preys at night, but nocturnal insects have also evolved ears sensitive to ultrasonic bat calls to avoid being predated.

One of the facts that surprise me during the bat nigh was that many species of frugivorous bat loss the hability of echolocate; instead they developed bigger eyes to be able to see better the fruits and the “tongue clics”. The echolocation sounds are more important for bats that need to follow and catch a prey through the forest.

The study of the sound, especially the echolocation sound (ultrasound) was the base for the construction of the sonar system ans the ultrasonic used in the medical care.

Literature

McComb, K., Moss, C., Sayialel, S. & Baker, L 2000. Unusually extensive networks of vocal recognition in African elephants. Animal Behaviour, 59, 1103-1109.

Nakano, R., T. Takanashi and A. Surlykke. 2015. Moth hearing and sound communication. Journal of Comparative Physiology A. 201: 1 (111-121).

 

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