Trueman e r (56 résultats)

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Etat : Good. 1st Edition. Former library copy. Pages intact with minimal writing/highlighting. The binding may be loose and creased. Dust jackets/supplements are not included. Includes library markings. Stock photo provided. Product includes identifying sticker. Better World Books: Buy Books. Do Good.…

Softcover. Etat : Very Good. Etat de la jaquette : N/A. 1st Edition. viii, 200pp. Pictorial laminated light card covers illustrated throughout with black and white illustrations and photographs. 8vo. Sun-faded covers, light chipping to edges and wear to covers. Text block edges starting to tan. Internally, neat, clean, bright and tight. Presents new material against the background of earlier studies, and shows how soft-bodied animals have been able to move about successfully in a variety of habitats. …

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hardcovr. Etat : as new. no jacket. fifth printing. 6 7/8 x 9 7/8" 271 pages (being pages 953 - 1224 of the series). This is Treatise on Invertebrate Paleontology Par N Volume 3 Mollusca 6 Bivalvia only.

Paper covers. Etat : V.g. No Jacket. Revised edition. Owner's signature. Weight: 1.0 Language: English.

Society for Experimental Biology, Seminar Series 5. Cambridge University Press. 1980. 250 S. gr.8. m. zahlr. Textabb. Kt.-2)englisch. ISBN: 0521297958.

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Donax denticulatus burrows in a similar manner to other infaunal bivalves, but also reacts to stimulation by activity and so proved to be suitable material for experiments on the control of locomotion. Tactile responses of the foot initiate burrowing and pedal stretch receptors control the duration of each digging cycle. Prevention of adduction of the valves, removal of ligament or cardinal hinge teeth, had little effect on burrowing and it is suggested that part of the digging cycle is programmed within the nervous system without peripheral feedback. Experiments on migratory behaviour are discussed and indicate that no intrinsic mechanism is required for its control beyond the adaptation of behavioural responses, common to most bivalves, to different physical conditions. 17 pp., 9 figs, gr. 8.…

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paperback. Etat : New. In shrink wrap. Looks like an interesting title.

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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.…

The pleurembolic proboscis of Bullia functions in the manner of a classical hydrostatic skeleton. Its protrusion occurs both with high pressure pulses (2 KPa) in the cephalic sinus and at a steady standing pressure (0.2 KPa). The proboscis probably functions as a haemocoelic chamber separate from the cephalic sinus and pressure pulses from within the everted proboscis, but not the sinus, suggest that muscle antagonism occurs in a manner common to hydrostatic skeletons. The advantages of the proboscis having a hydrostatic skeleton are discussed. 9 pp., 3 figs, gr. 8.…

Donax serra burrows powerfully and rapidly in the same manner as other infaunal bivalves except that the turgidity of the foot is increased by a standing pressure of up to 3 kPa in the pedal haemocoel. The standing pressure, upon which probing and adduction pulses are superimposed, is derived from muscular tension acting on the blood in the pedal haemocoel, which is held at near constant volume by the closure of Keber's valve. Blood flow through the foot is thus reduced to a minimum at the time of maximal pedal activity and it is possible that pedal respiration is anaerobic during burrowing. Extension of the foot is brought about by blood flow and antagonistic musclc action using blood in the pedal haemocoel as the fluid of a classical fluid-muscle system. There is no evidence of the presence of a muscular antagonistic system causing pedal protraction as occurs in the columellar muscle of some cyrtosome molluscs. 11 pp., 4 figs, gr. 8.…