Sound production mechanism in the Brazilian spiny lobsters (Family Palinuridae)

Strident lobsters of the Palinuridae family emit sounds in the presence of predators that can be used in the acoustic monitoring of such species. This study aims to identify sound emission and describe the structures of sound mechanism in red (Panulirus meripurpuratus) and green (Panulirus laevicauda) Brazilian spiny lobsters. The lobsters were collected in the environment, and recordings were performed in laboratory tanks with submerged hydrophones. The animals were stimulated to emit sound by the presence of an artificial octopus in the tank. The sounds emitted by the lobsters were analyzed by means of the waveform, and the structures involved (plectrum and file) were observed using scanning electron microscopy (SEM). Both species emitted a rasp sound composed of several pulses, with a rate varying from 125 to 265 pulses per second. The SEM showed that the file is similar between the species and it is covered by microscopic plates (shingles) measuring between 12.6 and 12.9 μm of medial–lateral width and 6.2 μm and 7.1 μm of anteroposterior length. This analysis also revealed for the first time the presence of pores (< 1 μm in diameter) with vestiges of cuticular setae in-between the shingles, which could be involved in the mechanosensory control of sound production in lobsters. The results of this study corroborate the morphological pattern of sound emission structure described for other lobsters of the genus Panulirus.