Body Temperature and Singing in the Bladder Cicada, Cystosoma Saundersii

Abstract

ABSTRACT Body temperatures during singing were measured in the cicada, Cystosoma saundersii Westwood, both in the field and in tethered animals indoors. The temperature of the sound-producing tymbal muscle rises rapidly during singing to reach a plateau approximately 12 °C above ambient. This produces a temperature gradient in the abdominal air sac which surrounds the muscle. When singing stops, the tymbal muscle cools exponentially. Heat production during singing, estimated from the cooling curve, is 4·82 cal min−1 g muscle−1. Generation of the same temperature excess in the air sac by an artificial heat source yields an estimated heat production of 54·4 cal min−1 g muscle−1. This discrepancy may be caused by air mixing in the air sac during singing. As temperature rises, tymbal muscle twitch contractions become faster and stronger. This and heat transfer to the thorax cause changes in the song pattern: a marked decrease in the interval between the two sound pulses produced by a single tymbal buckling and a lesser decrease in the interval between bucklings. The fundamental sound period remains unaltered. These effects are consistent with earlier data on sound production.