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Name: Ruhamah S.
Status: student
Age: 13
Location: N/A
Country: N/A
Date: 
Thursday, June 06, 2002



Question:
Do all animals need ears to hear?


Replies:
A definition of "hearing" is "perception of sound made possible by vibratory changes in air pressure on the ear drums" (Encarta Dictionary) so in that sense ears are required to "hear." However the sound waves that change air pressure on ear drums can also affect other parts of the body. Insects, for example, do not have ears and ear drums like mammals and birds, but do perceive sound waves.

J. Elliott


This depends upon what you define as a "ear". If by that you mean the ability to sense vibrations of the medium surrounding the animal, the answer is NO. Fish, worms, and many other species do not have "ears" in the sense of the anatomical structure most mammals possess. Even we humans can "feel" frequencies of air movement less than 10 hertz, the typical cutoff frequency of sound -- for example a large bass drum. Do we "hear" that? Is it sound? A similar thing occurs with light. We can "feel" a hot burner on a stove from several feet even though it is not "glowing". It is infrared radiation. Are we "seeing" it? It is a matter of how you want to define the terms.

Vince Calder


Ruhamah,

It depends upon your definition of ears. Most birds and mammals have ears by tranditional definitions. However, reptiles, fish, amphibians and invertebrates do not really have ears. We can follow the evolutionary developmenbt through these animals and that is a real interesting topic! I suggest you look up the frog and how it hears. This will explain most amphibians. Fish and inveterbrates have several methods in detecting vibrations (sound is really just vibrations). This is a great library research project.

Steve Sample


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