Essay on Ear Development

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Ear development, like all other sensory systems, evolved from lesser structures in lesser animals. Research based on the work of Andrea Streit however places the burden of ear development solely on vertebrates (1H). Marine vertebrates evolved the first set of mechanoreceptors that could be classified as detecting sound since sound waves and pressure waves are nearly the same forms of energy. Once animals evolved to the stage where land traversing was possible the receptors were unable to accomplish the same tasks as they once did underwater, leading to the beginning of the development of the ear as we know it today. The transition from a fluid environment to an air environment triggered the development / enhancement of the middle ear and …show more content…
Also like all amphibians the salamander does not have an external ear, rather primitive vertebrates had simple openings that led to the external auditory meatus, also known as the ear canal (2H). The cartilage surrounding mammalian ears is termed the pinna and is simply there to direct sounds to the proper receptors so that directionality can be determined. The ear canal of amphibians and fish does not exist, instead the tympanic membrane is nearly in direct contact with the external environment; some frog species ear drums are situated behind the eye (2H). Beyond the external ear differences the structures become more standardized in the middle ear. The main parts of the middle ear include the tympanic membrane, the ossicles, and the middle ear cavity. The differences in appearance, function, and origin along with the inner ear will be discussed later in this paper during the comparison of several organisms. A proper evolutionary comparison dictates that the two organisms should be sufficiently distinct from one another and yet they must show similarities at a basic level. The organisms we have chosen for this are the frog and human to analyze and compare for this paper. A proper extinct organism would not have allowed us a large enough amount of information to compare with the other two and as such we have chosen to analyze the hagfish since it is a prehistoric relic of

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