Tonic immobility in terrestrial isopods: intraspecific and interspecific variability

By

Quadros, Aline Ferreira de
Bugs, Priscila Silva
Araujo, Paula Beatriz.

Type

Article

Date of Publication

2012

Original Publication

ZooKeys

Volume

176

Pages

155-170

Subjects

anti-predator strategies , Crinocheta , Death-feigning

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/zookeys.176.2355

 

Abstract

Many arthropods, including terrestrial isopods, are capable of entering a state of tonic immobility upon a mechanical disturbance. Here we compare the responses to mechanical stimulation in three terrestrial isopods Balloniscus glaber, B. sellowii and Porcellio dilatatus. We applied three stimuli in a random order and recorded whether each individual was responsive (i.e. showed tonic immobility) or not and the duration of the response. In another trial we related the time needed to elicit tonic immobility and the duration of response of each individual. Balloniscus sellowii was the least responsive species and P. dilatatus was the most, with 23% and 89% of the tested individuals, respectively, being responsive. Smaller B. sellowii were more responsive than larger individuals. Porcellio dilatatus responded more promptly than the Balloniscus spp. but it showed the shortest response. Neither sex, size nor the type of stimulus explained the variability found in the duration of tonic immobility. These results reveal a large variability in tonic immobility behavior, even between closely related species, which seems to reflect a species-specific response to predators with different foraging modes.