Search results for "mollusca"

Feeding strategy of the sacoglossan opisthobranch Oxynoe olivacea on the tropical green alga Caulerpa taxifolia.

2007

The feeding behaviour of the shelled sacoglossan Oxynoe olivacea was investigated to better understand the role and importance of this species in influencing encroachments of the alien alga Caulerpa taxifolia in the Mediterranean sea. We tested whether this slug preferred, as preliminary field observations suggested, an aggregative feeding behaviour and which part of the algal thallus, phylloid vs rhizoid, it preferred. Results showed that O. olivacea fed in groups and actively selected phylloid. This outcome poses important questions regarding the possibility that this species, fragmenting the alga thallus, could enhance dispersion and regeneration of C. taxifolia.

Studies on bucephalid digeneans parasitising molluscs and fishes in Finland. II. The description of Rhipidocotyle fennica n. sp. and its discriminati…

1992

Rhipidocotyle fennica n. sp. (= Rhipidocotyle Type A of Taskinen et al., 1991) from the intestine of Esox lucius in central Finland is described and compared by means of a principal components analysis (PCA) with R. campanula (= Rhipidocotyle Type B of Taskinen et al., 1991). Its cercaria develops in the bivalve Anodonta anatina and the metacercaria occurs in the skin and fins of Rutilus rutilus. The metacercaria is discriminated from that of R. campanula by PCA and is described along with aspects of the chaetotaxy of the cercaria. The new species is distinguished from R. campanula, R. kovalae, R. papillosa and R. septpapillata.

Notes: FOOD AND PARASITES FROM TWO HOURGLASS DOLPHINS, LAGENORHYNCHUS CRUCIGER (QUOY AND GAIMARD, 1824), FROM PATAGONIAN WATERS

2003

Levels of heavy metals in some marine organisms from the western Mediterranean area (Spain)

1994

Larval trematode infections in freshwater gastropods from the Albufera Natural Park in Spain

1998

AbstractMalacological samplings were made from January 1994 to December 1996 in the Albufera Natural Park (Valencia, Spain) to trace the dynamics of molluscan populations and the prevalence and intensity of infection by larval trematodes. A total of 10,533 freshwater gastropods belonging to seven species (Lymnaea auricularia, L. truncatula, L. palustris, L. peregra, Bithynia tentaculata, Physa acuta and Gyraulus chinensis) was examined, and 110 (1.04%) were found to harbour some of the nine distinguishable types of cercariae, namely four echinostome cercariae (Hypoderaeum conoideum, Echinoparyphium recurvatum, Euparyphium albuferensis, and Echinostoma sp.), four furcocercous cercariae, and …

Body size and mating strategies in the simultaneous hermaphrodite Oxynoe olivacea (Mollusca, Opisthobranchia, Sacoglossa).

2004

Summary 1To better understand the role and importance of body size in hermaphroditic mating system theory, the mating behaviour of the shelled sacoglossan Oxynoe olivacea was studied. This simultaneous hermaphrodite exhibits bilateral and unilateral sperm transfer and thus it is particularly suitable for studies on hermaphrodite sexual conflict. 2In this study three hypotheses on body size were tested: that O. olivacea partner size has an effect on (i) mating mode choice, (ii) duration of mating modes, and (iii) choice of sexual role. Furthermore, we tested Charnov's hypothesis that in O. olivacea, like many simultaneous hermaphrodites, a sexual conflict exists and the male role is preferre…

Electron microscopy and biochemical characterization of a 350-kDa annular hemolymph protein from the keyhole limpet Megathura crenulata

1994

The isolation and biochemical characterization of an annular non-hemocyanin hemolymph protein from a marine gastropod, the Californian giant keyhole limpet (Megathura crenulata) is presented. By analytical ultracentrifugation, the protein has a sedimentation coefficient of 12S and molecular mass of approximately 350 kDa. The subunit mass, obtained by SDS/PAGE in the presence of -SH reagent and 8 M urea, is approximately 35 kDa, thereby indicating the presence of 10 subunits in the native molecule. By negative staining, the protein is revealed in one predominant image projection as a pentagonal approximately 8 nm ring-like structure with an approximately 2-nm stain-filled centre and, in anot…

Oxyarietites boletzkyi n. gen., n. sp., nouveau genre et nouvelle espèce d'ammonite dans le Sinémurien inférieur de Bourgogne (France) : un rare préc…

2012

13 pages; International audience; L'une des toutes premières ammonites à coquille presque oxycône observée dans les séries fossilifères après la crise faunique de la limite Trias/Jurassique est décrite. Elle provient du Sinémurien inférieur (chronozone à Semicostatum ou à Turneri) de Bourgogne (Mavilly-Mandelot, Côte-d'Or, France). Cette nouvelle forme, Oxyarietites boletzkyi n. gen., n. sp., possède une coquille involute, comprimée et carénée dont le type clairement suboxycône est nouveau pour le Sinémurien inférieur. En raison de son aire ventrale carénée, ce taxon se rattache probablement à la super-famille des Arietitoidea Hyatt, 1875 sensu Guex (1995) mais son attribution familiale est…

Relationship between egg features and maternal body size in the simultaneous hermaphrodite Oxynoe olivacea (Mollusca, Opisthobranchia, Sacoglossa)

2005

This paper provides information on spawn morphology and egg features of the stenophagous planktotrophic Mediterranean sacoglossan Oxynoe olivacea. Smith and Fretwell’s hypothesis, predicting that individuals of the same population growing in the same environmental conditions and varying in size should spawn eggs of a constant size, was tested in a population of O. olivacea living in the Straits of Messina. To determine whether (a) spawn mass size, (b) total egg number per spawn, and (c) egg size were related to parent size of O. olivacea, 21 egg masses (seven egg masses deposited by seven different 20 mm animals, seven egg masses deposited by seven different 25 mm animals and seven egg mass…

Chromosome analysis using different staining techniques and fluorescent in situ hybridization in Cerithium vulgatum (Gastropoda: Cerithiidae)

2002

In the present paper one population of the “large” subtidal mollusc Cerithium vulgatum Bruguiere, 1792 (Gastropoda: Cerithiidae) from the Northwestern coast of Sicily was investigated from a karyological point of view. The chromosome complement was Giemsa stained, conventionally karyotyped in 18 homomorphic chromosome pairs (10 bi-armed and 8 mono-armed), and subsequently analysed using silver, CMA3 and DAPI staining, and fluorescent in situ hybridization (FISH) with three repetitive DNA probes [ribosomal DNA (rDNA), (TTAGGG)n and (GATA)n]. FISH with the rDNA probe consistently mapped major ribosomal sites (18S-28S rDNA) in the terminal region of the short arms of one small sized mono-armed…