MECHANISM OF SIGNAL PRODUCTION IN THE VIBRATORY COMMUNICATION OF THE WANDERING SPIDER CUPIENNIUS-GETAZI (ARACHNIDA, ARANEAE)

The communication with substrate vibrations produced by vibrations of the body or its appendages is widespread among arthropods, especially among spiders. Its biomechanics, however, is poorly understood. Males of the wandering spider Cupiennius getazi produce such substrate vibra tions during courtship by means of dorsoventral movements of their opi sthosoma without hitting their dwelling plant. Simultaneous recordings of the plant vibrations (accelerometry), of the opisthosoma movements (laser Doppler vibrometry) and of the electromyograms of the opisthos omal depressor muscle, revealed that the main frequency of the vibrato ry signal of about 80 Hz originates from the activity of the opisthoso mal depressor muscle. The transfer functions of the spider's body show resonances which could amplify the main frequency before it is transm itted into the plant. A low frequency component of the opisthosomal mo vement (duration c.0.3 s, displacement c.6 mm (peak-peak) corresponds to 30 degrees deflection angle, frequency 10-20 Hz) can be distinguish ed from a main frequency component (duration c. 0.1 s, displacement c. 0.5 mm corresponds to 2.5 degrees deflection angle, frequency c.80 Hz ). The main frequency component is superimposed on an upward movement of the low frequency component.