Oxygen Consumption of the Ampullariid Snail Marisa cornuarietis L. in Relation to Body Weight and Temperature

Abstract

Both in laboratory conditions and during field studies, the South-American freshwater snail Marisa cornuarietis L. depressed populations of the planorbid snail Biomphalaria glabrata Say, an intermediate host of the trematode Schistosoma mansoni Sambon, responsible for bilharziosis in Brazil (OlivierGonzalez et al. 1956, Radke et al. 1961). Demian and Lutfy (1966) showed that during laboratory conditions Marisa reduced populations of Bulinus truncatus Audouin and Lymnea cailliaudi Bourguignat by predation. The latter are freshwater snails from Egypt and transmitters of parasitic worm diseases. Before the capacity of Marisa is utilized to reduce populations of snails spreading Bilharziosis, it is important to know its biology and physiology. Hunt (1961) showed that Marisa tolerates salinities of up to 25 per cent sea water (S = 8.5 %) The anatomy of the alimentary system was studied by Demian (1964), who also investigated the respiratory organs and movements (Demian 1965). Marisa has two respiratory structures, a monopectinate ctenidium and a pulmonary sac. Demian (1965) distinguished three modes of respiration, viz. bronchial respiration, siphonal pulmonary respiration, and direct pulmonary respiration. No quantitative measurements of the oxygen consumption of Marisa cornuarietis have been performed earlier. The purpose of this investigation was to study the respiration in