Mechanical response of the tympanal membranes of the tree cricket Oecanthus henryi

Mhatre, Natasha and Montealegre-Z, Fernando and Balakrishnan, Rohini and Robert, Daniel (2009) Mechanical response of the tympanal membranes of the tree cricket Oecanthus henryi. Journal of Comparative Physiology A, 195 (5). pp. 453-462. ISSN 0340-7594

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Official URL: http://dx.doi.org/10.1007/s00359-009-0423-x

Abstract

Crickets have two tympanal membranes on the tibiae of each foreleg. Among several Weld cricket species of the genus Gryllus (Gryllinae), the posterior tympanal membrane (PTM) is signiWcantly larger than the anterior membrane (ATM). Laser Doppler vibrometric measurements have shown that the smaller ATM does not respond as much as the PTM to sound. Hence the PTM has been suggested to be the principal tympanal acoustic input to the auditory organ. In tree crickets (Oecanthinae), the ATM is slightly larger than the PTM. Both membranes are structurally complex, presenting a series of transverse folds on their surface, which are more pronounced on the ATM than on the PTM. The mechanical response of both membranes to acoustic stimulation was investigated using microscanning laser Doppler vibrometry. Only a small portion of the membrane surface deXects in response to sound. Both membranes exhibit similar frequency responses, and move out of phase with each other, producing compressions and rarefactions of the tracheal volume backing the tympanum. Therefore, unlike Weld crickets, tree crickets may have four instead of two functional tympanal membranes. This is interesting in the context of the outstanding question of the role of spiracular inputs in the auditory system of tree crickets.

Item Type:Article
Additional Information:Crickets have two tympanal membranes on the tibiae of each foreleg. Among several Weld cricket species of the genus Gryllus (Gryllinae), the posterior tympanal membrane (PTM) is signiWcantly larger than the anterior membrane (ATM). Laser Doppler vibrometric measurements have shown that the smaller ATM does not respond as much as the PTM to sound. Hence the PTM has been suggested to be the principal tympanal acoustic input to the auditory organ. In tree crickets (Oecanthinae), the ATM is slightly larger than the PTM. Both membranes are structurally complex, presenting a series of transverse folds on their surface, which are more pronounced on the ATM than on the PTM. The mechanical response of both membranes to acoustic stimulation was investigated using microscanning laser Doppler vibrometry. Only a small portion of the membrane surface deXects in response to sound. Both membranes exhibit similar frequency responses, and move out of phase with each other, producing compressions and rarefactions of the tracheal volume backing the tympanum. Therefore, unlike Weld crickets, tree crickets may have four instead of two functional tympanal membranes. This is interesting in the context of the outstanding question of the role of spiracular inputs in the auditory system of tree crickets.
Keywords:Auditory organ, Cricket, Orthoptera
Subjects:C Biological Sciences > C990 Biological Sciences not elsewhere classified
C Biological Sciences > C770 Biophysical Science
Divisions:College of Science > School of Life Sciences
ID Code:6474
Deposited By: Fernando Montealegre-Z
Deposited On:08 Oct 2012 21:46
Last Modified:26 Feb 2013 20:48

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