Locomotion, pedal retraction and extension, and the hydraulic systems of Bullia (Gastropoda: Nassaridae)

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Surface locomotion and burrowing by Bullia digitalis have been analysed by use of ciné film and electronic recording. Both movements are shown to be carried out by a series of steps in which the propodium is first extended whilst the snail is anchored by the posterior of the foot (penetration anchor) and, when buried, also by the shell; secondly the shell is drawn forwards and downwards towards the anchored propodium (terminal anchor). The extremely flattened foot of this snail contains a greatly enlarged pedal sinus containing blood and functions as a hydraulic organ. This contrasts with the foot of most gastropods, e.g. Patella, which crawl over hard surfaces and have no large fluid filled pedal cavity. During each step, or digging cycle, there are two pressure pulses, one effecting propodial extension, the second occurring as the shell is drawn forwards. The pedal haemocoel is isolated from the remainder of the circulation for at least part of the locomotory cycle so enabling the foot to function as a fluid-muscle system at constant volume. Bullia exhibits convergence with burrowing bivalve molluscs having a similar pattern of alternating anchorages in sand and in both water is ejected from the mantle cavity to liquefy the sand in front of the shell. The energy cost of burrowing by B. digitalis is estimated to be 6.6 times 10-6 J/mg dry tissue weight, a figure comparable to that of the clam Donax provided that burial occurs at a similar rate. By contrast the energy requirement for Bullia to move over the surface of sand is about one tenth of that for burial. Pedal extension involves both blood flow, so that the foot may function as a hydraulic system, and direct muscular antagonism between the fibres of a three dimensional muscle network in the opercular muscle. When the snail is extended the shell contains some sea-water which plays a dynamic role in pedal expansion and retraction independently of the pedal blood sinus. The possible role of this cavity in other prosobranchs is discussed. 10 pp., 7 figs, gr. 8.…

N° de réf. du vendeur W17452

Détails bibliographiques

Titre
Locomotion, pedal retraction and extension, and the hydraulic systems of Bullia (Gastropoda: Nassaridae)
Auteur
Trueman, E. R. & Brown, A. C.
Année de publication
1976

ConchBooks

Harxheim, Allemagne

Vendeur avec une évaluation de 4 étoiles

Vendeur AbeBooks depuis 1 mars 2007

Frais d'expédition de Allemagne vers Etats-Unis

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Founded in 1985 we are specialized in worldwide literature on Mollusca and marine invertebrates. Our publishing house has meanwhile published approximately 60 titles on that field of interest. We have stocks of most available international books on Malacology and a huge amount of antiquarian literature, even of the latter most titles are only available once.

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Weichtiere / Shells, Schnecken / Snails & Slugs, Muscheln / Bivalves, Tintenfische / Squids / Octopusses / Ammonites, Malacology, Conchology, Marine Biology