ISSN:
1432-1351
Keywords:
Cricket
;
Hearing
;
Ontogeny
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract From behavioural experiments it is known that the thresholds for both positive and the negative phonotaxis in crickets (Gryllus bimaculatus) decrease during the first days of adult life. Neuronal recordings have shown that a part of the changes in threshold has its origin in the ears. In this study we investigate some changes of the mechanics of the ears in the days after the imaginal moult. The posterior tympanum starts to work as an acoustic window only after the imaginal moult. During the first days the vibration amplitude tends to increase, except below 4 kHz and between 6 and 12 kHz. In the mature hearing organ, the tympanal vibrations exceed those of the surrounding cuticle up to ca. 50 kHz, and peaks of vibration amplitude are found around 5 and 15 kHz (the frequencies of the calling and courtship songs). The appearance of these peaks is caused, at least in part, by a change in the mechanics of the tympanum. Sound propagation through the trachea connecting the ipsilateral acoustic spiracle and the inner surface of the tympanum does not change much during the first week of adult life. In contrast, the propagation from the contralateral spiracle improves considerably. Thus the tympanum of the newly moulted cricket receives only little sound from the contralateral spiracle, and therefore the ear lacks the sound component which is essential for directional hearing in the mature cricket.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00215112
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