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Caterpillar crawling is distinct from that of worms and molluscs; it consists of a series of steps in different body segments that can be compared to walking and running in animals with stiff skeletons. Using a three-dimensional kinematic analysis of horizontal crawling in Manduca sexta, the tobacco hornworm, we found that the phase of vertical displacement in the posterior segments substantially led changes in horizontal velocity and the segments appeared to pivot around the attached claspers. Both of the motions occur during vertebrate walking. In contrast, vertical displacement and horizontal velocity in the anterior proleg-bearing segments were in phase, as expected for running gaits coupled by elastic storage. We propose that this kinematic similarity to running results from the muscular compression and release of elastic tissues. As evidence in support of this proposal, the compression and extension of each segment were similar to harmonic oscillations in a spring, although changes in velocity were 70° out of phase with displacement, suggesting that the spring was damped. Measurements of segment length within, and across, intersegmental boundaries show that some of these movements were caused by folding of the body wall between segments. These findings demonstrate that caterpillar crawling is not simply the forward progression of a peristaltic wave but has kinetic components that vary between segments. Although these movements can be compared to legged locomotion in animals with stiff skeletons, the underlying mechanisms of caterpillar propulsion, and in particular the contribution of elastic tissues, remain to be discovered., Introduction The movements of animals with stiff articulated skeletons, such as arthropods and vertebrates, have been studied extensively; they tend to be fast and precise, using joints with a few [...]

To examine the effectiveness of larval antipredator mechanisms and to test the assumption that diet breadth and chemistry are important predictors of predation responses, I offered 70 species of lepidopteran larvae to the predatory ant Paraponera clavata (Hymenoptera: Formicidae). Prey chemistry and diet breadth were significant predictors of rejection, as was plant chemistry but to a lesser degree. Specialist caterpillars were better protected than generalists, and prey with unpalatable extracts were frequently rejected by P. clavata, while prey with palatable extracts were rarely rejected. Specialists with unpalatable host plant extracts were more likely to be rejected than specialists that had host plants with more palatable extracts. Other significant predictors included morphology, behavior, and interactions between developmental stage and prey chemistry and between developmental stage and diet breadth. I concluded that predation could be a substantial selective force in the evolution of narrow diet breadth and that plant chemistry could be the mechanism whereby specialists are better defended. Key words: caterpillars; defenses; diet breadth; Lepidoptera; predation; Paraponera clavata; plant secondary compounds; specialization; tropics., INTRODUCTION In light of a decade of discussion about tritrophic interactions and the effects of natural enemies on plants and invertebrate herbivores (e.g., Price et al. 1980, Duffey et al. [...]

Power input increased linearly with speed and was closely associated with changes in cycle frequency. Minimum cost of transport of gypsy moth caterpillars was 4.5 times as high as predicted [...]

A Diet-Induced Developmental polymorphism in a Caterpillar MANY ORGANISMS OCCUR IN TWO or more distinct forms. Developmental polymorphisms (or polyphenisms) occur when phenotypic variation is produced by differences in environmental [...]