Periodical cicada: mechanism of sound production.
The species Magicicada septendecim and Magicicada cassini of the 17-year cicada produce sound by sequentially buckling a series of stiff ribs embedded in a flexible tymbal. Each such collapse excites a damped oscillation in a resonant cavity. By this means the cavity (an abdominal air sac) is excited 10 to 12 times per muscle contraction, which permits a normal muscle to perform a task requiring very rapid repetitive activity.
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