Physiological and biophysical properties of the auditory system of the New Zealand wetaHemideina crassidens (Blanchard, 1851) (Ensifera: Stenopelmatidae)
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Summary
- 1.
The frequency/threshold curve for the massed response of primary auditory fibres in the tympanal nerve has a peak of sensitivity at 2.0–2.5 kHz. Absolute threshold is 20–35 dB SPL in individual preparations and the roll-off is about 15 dB/octave below the optimum and about 27 dB/octave above the optimum frequency (Fig. 1).
- 2.
Occlusion of either the anterior or posterior tympanum causes a small loss of sensitivity (<8dB) only for frequencies above the hearing optimum. Occlusion of both auditory tympana reduces the sensitivity of the ear by 20–25 dB from 0.63 kHz to 5.0 kHz and by 7–15 dB up to 10 kHz (Fig. 2).
- 3.
Blocking the leg tracheae in the femur causes no change in the sensitivity of the ear to sounds of 0.63–10 kHz (Fig. 3). Shielding the tympanic membranes from external sound, with the tracheal system intact, reduces the sensitivity of the ear by about 40 dB at the optimum frequency and by more than 10 dB for other frequencies in the range 0.63–10 kHz (Fig. 4).
- 4.
Reducing the volume of the tibial air space behind the tympana by approximately 60% increases auditory thresholds for frequencies at and below the hearing optimum, whereas thresholds for higher frequencies are unchanged (Fig. 5).
- 5.
For sound frequencies from 0.63 kHz to 8.0 kHz, the intact auditory system inH. crassidens has no directional sensitivity (Fig. 6).
- 6.
Stridulatory sounds produced byH. crassidens are broad-band, having a peak in the power spectrum near 2.0 kHz and a roll-off of about 15 dB/octave towards higher frequencies (Fig. 7).
- 7.
The weta auditory system functions as a one-input pressure receiver; its characteristics are compared with the auditory systems of Gryllidae and Tettigoniidae.
Keywords
Tympanic Membrane Auditory System Biophysical Property Optimum Frequency Directional SensitivityPreview
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References
- Ander, K.: Vergleichend-anatomische und phylogenetische Studien über die Ensifera. Opusc. Entomol. Suppl. 2 (1939)Google Scholar
- Ball, E. E., Field, L.H.: Structure of the auditory system of the New Zealand wetaHemideina crassidens (Blanchard, 1851) (Orthoptera, Ensifera. Gryllacridoidea, Stenopelmatidae). 1. Morphology and histology, (submitted)Google Scholar
- Ball, E.E., Hill, K.G.: Functional development of the auditory system of the cricket,Teleogryllus commodus. J. Comp. Physiol.127, 131–138 (1978)Google Scholar
- Beier, M.: Embioidea and Orthopteroidea. Dr. H.G. Bronns Klassen und Ordnungen des Tierreichs. Vol. 5, Abt. 3, Buch 6, pp. 1–272 (1955)Google Scholar
- Blanchard, E.: Fauna Chileña. Insectos. Orden IV. Ortópteros. In: Historia fisica y politica de Chile. Gay, C. (ed.). Vol. 6, Zoologia, pp. 1–85; and Atlas Zoologico-Entomologia, Ortópteros. Pls. 1–3. Paris: Chilean Government 1851Google Scholar
- Embleton, T.F.W., Piercy, J.E., Olson, N.: Outdoor sound propagation over ground of finite impedance. J. Acoust. Soc. Am.59, 267–277 (1976)Google Scholar
- Field, L.H.: The stridulatory apparatus of New Zealand wetas in the genusHemideina (Insecta: Orthoptera: Stenopelmatidae). J. R. Soc. New Zealand8, 359–375 (1978)Google Scholar
- Field, L.H., Rind, C.: Stridulatory behaviour inHemideina crassidens, a flightless orthopteran (Stenopelmatidae) from New Zealand. Behaviour (in press)Google Scholar
- Graber, V.: Die tympanalen Sinnesapparate der Orthopteren. Denkschr. Akad. Wien, Math.-Naturwiss. Kl.36 (II), 1–140 (1876)Google Scholar
- Hill, K.G.: Carrier frequency as a factor in phonotactic behaviour of female crickets (Teleogryllus commodus). J. Comp. Physiol.93, 7–18 (1974)Google Scholar
- Hill, K.G.: Physiological characteristics of auditory receptors inHemideina crassidens (Blanchard) (Ensifera: Stenopelmatidae). J. Comp. Physiol.141, 39–46 (1980)Google Scholar
- Hill, K.G., Boyan, G.S.: Sensitivity to frequency and direction of sound in the auditory system of crickets. J. Comp. Physiol.121, 79–97 (1977)Google Scholar
- Hill, K.G., Oldfield, B.P.: Auditory function in Tettigoniidae (Orthoptera: Ensifera). (in prep.)Google Scholar
- Larsen, O.N., Michelsen, A.: Biophysics of the ensiferan ear. III. The cricket ear as a four-input system. J. Comp. Physiol.123, 217–227 (1978)Google Scholar
- Michelsen, A.: The physiology of the locust ear. III. Acoustical properties of the intact ear. Z. Vergl. Physiol.71, 102–128 (1971)Google Scholar
- Michelsen, A.: Sound reception in different environments. In: Sensory ecology. Ali, M.A. (ed.), pp. 345–373. New York: Plenum 1978Google Scholar
- Miller, L.A.: Directional hearing in the locustSchistocerca gregaria Forskål (Acrididae, Orthoptera). J. Comp. Physiol.119, 85–98 (1977)Google Scholar
- Morton, E.S.: Ecological sources of selection on avian sounds. Am. Nat.109, 17–34 (1975)Google Scholar
- Nocke, H.: Physiological aspects of sound communication in crickets (Gryllus campestris L.). J. Comp. Physiol.80, 141–162 (1972)Google Scholar
- Nocke, H.: Physical and physiological properties of the Tettigoniid (“Grasshopper“) ear. J. Comp. Physiol.100, 25–57 (1975)Google Scholar
- Paton, J.A., Capranica, R.R., Dragsten, P.R., Webb, W.W.: Physical basis for auditory frequency analysis in field crickets (Gryllidae). J. Comp. Physiol.119, 221–240 (1977)Google Scholar
- Seymour, C., Lewis, D.B., Larsen, O.N., Michelsen, A.: Biophysics of the ensiferan ear. II. The steady-state gain of the hearing trumpet in bushcrickets. J. Comp. Physiol.123, 205–216 (1978)Google Scholar
- Zeuner, F.: The prothoracic tracheal apparatus of Saltatoria (Orthoptera). Proc. R. Entomol. Soc. (London) Ser. A11, 11–21 (1936)Google Scholar