QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online July 26, 2004
Journal of Experimental Biology 207, 3043-3053 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01136

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mezoff, S. Articles by Trimmer, B. A. Search for Related Content PubMed PubMed Citation Articles by Mezoff, S. Articles by Trimmer, B. A.

The biomechanical and neural control of hydrostatic limb movements in Manduca sexta

Sheri Mezoff, Nicole Papastathis, Anne Takesian and Barry A. Trimmer^*

Department of Biology, Dana Laboratory, Tufts University, Medford, MA 02155, USA

^* Author for correspondence (e-mail: barry.trimmer{at}tufts.edu)

Accepted 14 June 2004

Caterpillars are ecologically successful soft-bodied climbers. They are able to grip tightly to foliage using cuticular hooks at the tips of specialized abdominal limbs called prolegs. The neural control of proleg retraction has been examined in some detail but little is known about how prolegs extend and adduct. This is of particular interest because there are no extensor muscles or any obvious mechanisms for directing hydraulic flow into the proleg. In restrained tobacco hornworms (Manduca sexta), adduction can be evoked by stimulating mechanosensory hairs on the medial surface of the proleg. 3-D kinematics show that extension and adduction occur simultaneously through an unfolding of membrane between the pseudo segments. Hemolymph pressure pulses are not necessary to extend the proleg; instead, the pressure at the base of the proleg decreases before adduction and increases before retraction. It is proposed that these pressure changes are caused by muscles that stiffen and relax the body wall during cycles of retraction and adduction. Electromyographic recordings show that relaxation of the principal planta retractor muscle is essential for normal adduction. Extracellular nerve and muscle recordings in reduced preparations show that medial hair stimulation of one proleg can strongly and bilaterally excite motoneurons controlling the ventral internal lateral muscles of all the proleg-bearing segments. Ablation, nerve section and electromyographic experiments show that this muscle is not essential for adduction in restrained larvae but that it is coactive with the retractors and may be responsible for stiffening the body wall during proleg movements.

Key words: caterpillar, proleg adduction, muscle, nerve, planta, retractor muscle, motor inhibition, Manduca sexta, tobacco, hornworm

This article has been cited by other articles:

				B. Trimmer and J. Issberner Kinematics of Soft-bodied, Legged Locomotion in Manduca sexta Larvae Biol. Bull., April 1, 2007; 212(2): 130 - 142. [Abstract] [Full Text] [PDF]

				C. L. Huffard Locomotion by Abdopus aculeatus (Cephalopoda: Octopodidae): walking the line between primary and secondary defenses J. Exp. Biol., October 1, 2006; 209(19): 3697 - 3707. [Abstract] [Full Text] [PDF]