Some observations on locomotory strategies and their metabolic effects in two species of freshwater gastropods, Ancylus fluviatilis Müll. and Planorbis contortus Linn.
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Locomotion in the Pulmonata may have two, distinct, negative effects on total metabolism. Energy losses may occur via mucus secretions and also as a result of muscular and ciliary activities. These aspects of pulmonate metabolism were investigated in two freshwater species; Ancylus fluviatilis and Planorbis contortus. The former is a herbivore which feeds on periphyton and the latter is a detrivore which appears able to make use of bacteria.
Speed of movement was influenced by starvation time, food availability, and water movement, although the extent to which these factors affected locomotion showed some variation with species. In still conditions P. contortus moved more rapidly than A. fluviatilis whereas the converse occurred under conditions of more violent water movement. During deprivation, however, both species showed similar responses in that their rate of locomotion increased to some maximum and then fell, and their pattern of movement became more random. These strategies were explained in terms of fitness.
Under conditions of satiation locomotion had a measurable quantitative effect on P. contortus only, and contributed ca. 20% to routine metabolism. Nevertheless, under conditions of starvation locomotion influenced the respiratory metabolism of both species and in this case there were clear differences between the respiratory rates of constrained and non-constrained subjects. These results were used to explain certain differences recorded by earlier workers on the relationship between starvation and respiration in freshwater snails.
Energy losses via mucus secretions were found to make a significant contribution to snail energetics, representing between 13–32% of the energy absorbed across the gut wall. However, the potential energy thus released may not be completely lost from the secreting system because mucus was found to stimulate the growth of those bacteria which are preferentially ingested by P. contortus. Consequently, mucus may play a provendering role and should not be ignored as a vehicle of biologically useful energy in aquatic or terrestrial ecosystems.
KeywordsRespiration Respiratory Rate Energy Loss Terrestrial Ecosystem Metabolic Effect
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- Berg, K.: On the oxygen consumption of Ancylidae (Gastropoda) from an ecological point of view. Hydrobiologia 4, 225–262 (1952)Google Scholar
- Berg, K.: The problem of respiratory acclimatization. Hydrobiologia 5, 331–350 (1953)Google Scholar
- Berg, K.: On the oxygen consumption of some freshwater snails. Verh. internat. Verein Limnol. 14, 1019–1022 (1961)Google Scholar
- Berg, K., Lumbye, J., Ockelman, K.W.: Seasonal and experimental variations of the oxygen consumption of the limpet Ancylus fluviatilis (O.F. Müller). J. exp. Biol. 35, 43–73 (1958)Google Scholar
- Berg, K., Ockelman, K. W.: The respiration of freshwater snails. J. exp. Biol. 36, 690–708 (1959)Google Scholar
- Calov, P.: The structural and functional dynamics of selected species-populations of freshwater snails: Towards a systems approach. Unpublished Ph. D., University of Leeds (1972)Google Scholar
- Calow, P.: Gastropod associations within Malham Tarn, Yorkshire. Freshwater Biology 3, 521–534 (1973a)Google Scholar
- Calow, P.: The food of Ancylus fluviatilis (Müll.) a littoral, stone-dwelling herbivore. Oecologia 13, 113–133 (1973b)Google Scholar
- Calow, P.: Field observations and laboratory experiments on the general food requirements of two species of freshwater snail, Planorbis contortus Linn. and Ancylus fluviatilis Müll. Proc. malac. Soc. Lond. 40, 483–488 (1973c)Google Scholar
- Calow, P: Evidence for bacterial feeding in Planorbis contortus Linn. Proc. malac. Soc. Lond. (in press, 1974a)Google Scholar
- Calow, P.: Some observations on the dispersion pattern of two species-populations of littoral, stone-dwelling gastropods (Pulmonata). Freshwater Biol. (in press, 1974b)Google Scholar
- Calow, P., Fletcher, L. R.: A new radiotracer technique involving 14C and 51Cr for estimating the assimilation efficiencies of aquatic, primary consumers. Oecologia 9, 155–170 (1972)Google Scholar
- Carefoot, T. H.: Growth and nutrition of 3 species of opisthobranch molusc. Comp. Biochem. Physiol. 21, 627–652 (1967)Google Scholar
- Cruikshank, R.: Medical microbiology. Edinburgh-London: Livingstone 1965Google Scholar
- Dorier, A., Vaillant, F.: Observations et expériences relatives à la resistance au courant de divers invertébrés aquatiques. Trav. Lab. Hydrobiol. Grenoble 45, 46, 9–13 (1954)Google Scholar
- Emlen, E. M.: Ecology: An evolutionary approach. Massachusets-California-London-Ontario: Addison-Wesley 1973Google Scholar
- Hubbell, S. P.: Of sowbugs and systems: the ecological energetics of a terrestrial isopod. In: Systems analysis and simulation in ecology, vol. 1, B. C. Patten, Ed., p. 269–323. London-New York: Academic Press 1971Google Scholar
- Hutchesen, L.: Analysis of the activity of the freshwater snail Viviparous malleatus (Reeve). Ecology 28, 335–345 (1947)Google Scholar
- Hyman, L. H.: The invertebrates, vol. VI, Mollusca I. New York-Toronto-London: McGraw-Hill 1967Google Scholar
- Lumbye, J.: Oxygen consumption of Theodoxus fluviatilis (L.) and Potamopyrgus jenkinsi (Smith) in brackish and freshwater. Hydrobiologia 10, 245–262 (1958)Google Scholar
- Lumbye, J., Lumbye, L. E.: The oxygen consumption of Potamopyrgus jenkinsi (Smith). Hydrobiologia 25, 489–500 (1965)Google Scholar
- Macfadyen, A.: Methods of investigation of productivity in terrestrial ecosystems. In: Secondary productivity of terrestrial ecosystems, vol. 2, K. Petrusewicz, Ed., p. 383–412. Warsawa, Krakow: Panstowe. Wydawnictwo Naukowe 1967Google Scholar
- Mosimann, J. E.: The evolutionary significance of rare matings in animal populations. Evolution 12, 246–261 (1958)Google Scholar
- Paine, R. T.: Natural history, limiting factors and energetics of the opisthobranch Navanax inermis. Ecology 46, 603–619 (1965)Google Scholar
- Paine, R. T.: Energy flow of a natural population of the herbivorous gastropod Tegula funebralis. Limnol. Oceanogr. 16, 96–98 (1971)Google Scholar
- Phillipson, J.: A miniature bomb calormeter for small biological samples. Oikos 15, 130–139 (1964)Google Scholar
- Reynierse, J. H., Manning, A., Cafferty, D.: The effect of hunger and thirst on body weight and activity in the cockroach. Anim. Behav. 20, 751–757 (1972)Google Scholar
- Tinbergen, N., Impekoven, M., Franck, D.: An experiment on spacing-out as a defence against predation. Behaviour 28, 307–321 (1967)Google Scholar
- Wilson, R. A.: An investigation into the mucus produced by Lymnaea truncatula the snail host of Fasciola hepatica. Comp. Biochem. Physiol. 24, 629–633 (1968)Google Scholar