Electrophysiological studies of olfaction in the whip spider Phrynus parvulus (Arachnida, Amblypygi)

The olfactory response of the whip spider Phrynus parvulus from Costa Rica was examined using a technique analogous to that used for insect electroantennograms on the tarsi of the antenniform legs which bear multiporous sensilla. Responses to 42 chemicals representing different chain lengths of alkanes, carboxylic acids, alcohols, aldehydes, and ketones, as well as some esters, monoterpenes, and phenolics were examined. Fifty-four percent of the chemicals tested elicited responses. Concentration-response curves were generated for guaiacol, hexanal, methyl salicylate, benzaldehyde, octanoic acid, and linalool. Guaiacol, benzaldehyde, and hexanol elicited the greatest responses and no differences were detected between the sexes. Compounds with chain lengths of six carbon atoms generated strong responses and most monocarboxylic acids and ring compounds elicited responses. Some compounds produced increases in potential believed to arise from a hyperpolarizing effect on the neurons. The broad spectrum of chemicals to which these animals respond is similar to results of other studies examining the general olfactory sense of insects. It is possible that odor learning plays a significant role in the behavior of amblypygids.