Hearing in the paddle crab, Ovalipes catharus

Abstract

For over 50 years, the mechanism and even existence of crustacean hearing has been debated. The lack of convincing evidence how crustaceans hear is underwhelming given the tremendous advancements made in our understanding of crustacean behavior that clearly shows crustaceans produce sounds and can respond to acoustic cues. We hypothesize that the crustacean statocyst is the primary hearing organ used by the decapod family. Using medical imaging technology, microCT, and auditory evoked potentials (AEP), we characterized the form and function of the statocyst organ in the paddle crab, Ovalipes catharus. The statocyst structure is found at the base of the antennae and is a narrow canal system with a statolith consisting of only a few grains of sand. Paddle crabs were most sensitive to the lower frequencies (100 -200 Hz). All AEP responses to both the speaker stimulus and particle motion stimulus disappeared when the statocysts was ablated. This provides strong evidence that the statocyst is indeed the primary hearing organ for the range of studied frequencies. In conclusion, we propose that there might be a fundamental difference between the statocyst structure and sensitivity of different members of the decapod order.