The Insect 'Ear', Its Molecular Basis and Evolution

The basic principles of how hearing works is fairly simple to understand in vertebrate, though hearing is associated with the balancing organ. However, it is not clear about that in invertebrate in detail. Previously, some insects escaping from their predators, helping to mate, as well as avoiding to other male territoriality with their “ears” were known. Additionally, the spiders, a close relative of insect, can also perceive the mechanical vibration with their primitive “ear”, though most invertebrates have not ears. In view of hearing is an advanced sensation of mechanosensitive forces, the origin, evolvement and adaptive evolution for this perception in invertebrate will be the purpose of this paper. The origin of insect “ear” is a mystery to us. Here we propose preliminarily a hypothesis as follows according to related knowledge available. The hearing including vibration perception is an obviously type of effects to long distance in contrast to touch feeling that is a type of effects to short distance for mechanosensation. The touch perception widely occurs in almost all animal even prokaryotes. Apparently, it is rather ancient. On the contrary the hearing including vibration perception is only exists in insects and some related species as spiders on the land. The tactile perception of cockroach seems to be a middle-distance type to mechnosensation, so that the evolutionary tendency from short- through middle- to long-distance may be plausible. Much more evidence is required to prove this inference.