Vibratory communication in spiders

Summary

• 1. Both amplitude and frequency contents of male courtship vibrations of Cupiennius salei change with signal propagation through a bromeliad (Fig. 3). Temporal pattern and carrier frequency of the opisthosomal signal (Fig. 1a) remain largely unchanged, however, and therefore satisfy the requirements to carry species specific information. Pedipalpal signals cover a broad range of frequencies (Fig. 3a, c); both their dispersive transmission and the frequency-dependent attenuation by the plants may provide the female with information about her distance from the male.

• 2. Parallel processing of different signal components already begins in the female's metatarsal lyriform vibration receptor. Opisthosomal signals: They mainly elicit responses from long distal slits; signal amplitude is of only minor influence (Fig. 7). Carrier frequency is represented by interspike frequencies of individual slits (Fig. 8b, d). Pedipalpal signals: They elicit responses from all slits (Figs. 6, 7a). Responses of individual slits differ and can be assigned to specific frequency components contained in a pedipalpal signal (Figs. 6, 8a, 9b).

• 3. The repetition of opisthosomal signals within the male courtship vibration improves the signal to noise ratio in the female's receptor response (Fig. 10).

• 4. For unknown reasons the intensity of the receptor response follows changes in acceleration amplitude in the case of heterospecific but not in the case of conspecific courtship vibrations (Fig. 11).