Barth's myochordotonal organ as a receptor for auditory and vibrational stimuli in fiddler crabs (Uca pugilator and U. minax)

Abstract

The sensitivity of fiddler crabs to air‐ and substrate‐borne acoustic stimuli (pure tones) was studied, using responses of interneurons in the supra‐oesophageal ganglion for the measurements. Intact Uca pugilator could detect stimuli as both air‐borne (sound) and vibrational energies, but were much more sensitive to the latter. This finding, coupled with previous measurements of its own courtship sounds, indicated that only sound carried through the substrate was important for intraspecific communication. Destruction of Barth's Myochordotonal organ in the walking legs of both U. pugilator and U. minax decreased sensitivity to vibration by 8–20 dB. The effect was evident across the entire sensitivity spectrum, but most pronounced at the higher frequencies. The external anatomy of the receptor is described, as revealed by scanning EM study.