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

This Article 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 Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by SEYMOUR, M. K. Search for Related Content PubMed Articles by SEYMOUR, M. K.

Journal of Experimental Biology 64,743-750 (1976)
Published by Company of Biologists 1976

Pressure Difference in Adjacent Segments and Movement of Septa in Earthworm Locomotion

MALCOLM K. SEYMOUR ¹

¹ Department of Zoology, University of Bristol; Department of Nematology, Rothamsted Experimental Station, Harpenden, Herts., England

1. The nature and timing of septal movements during gentle crawling have been examined in relation to the coelomic pressure (P_c) in and between adjacent segments.

2. Between neighbouring anterior segments the phase lag was 0.05–0.1 s and the maximum P_e difference 3.3 cm water. The mean P_e in a leading segment exceeded that in a trailing segment by 0.9 ± 0.06 cm water.

3. In forward crawling, the septa bulged maximally backward and forward when segments were half elongated and half shortened respectively, and were flat when segments were longest and shortest: the area of a septum in an elongated segment was one quarter that in a shortened one and thus a septum is strongest (small and thick) when the P_e to be longitudinally confined is highest.

4. Bulging of septa is closely related to the intersegmental P_e difference. Bulging forces acting on a septum range from o to about 1 g wt.

5. The pressure drop along a worm is not linear and the ventral foramina may act as ‘septal valves’ to equalize coelomic volume and pressure when required. The influence of gut, septum and body wall movements on each other is discussed.