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Mariner Group

Olfactory glomeruli must have evolved early, because these characteristic structures are present in the "olfactory brains" of modem representatives of ancient marine groups including molluscs (5) and crustaceans (6). Likewise the lampreys, which are extant representatives of the most primitive vertebrates, have relatively large olfactory bulbs with glomeruli and conspicuous mitral cells not unlike those of more advanced vertebrates (7). [Pg.173]

Cultivated marine bacteria are scattered throughout the phylogenetic tree of the domain Bacteria. However, at lower phylogenetic levels, clusters of marine bacteria have been found which are distinct from those of terrestrial origin. One example is the so-called a3-subgroup of the a-Proteobacteria subclass of the division Proteobacteria, the Roseobacter clade [20]. A marine group of Actinobacteria [21] has been described, which has, to date, however not been cultivated. [Pg.210]

Is sperm chemotaxis specific, i.e., are the chemoattractants specific for each species or are there chemoattractants common to several species There is no single answer to this question. With some exceptions, species specificity appears to be the rule in marine species [102, 103]. There, the gametes are released in to seawater, and gametes of different species may be in close proximity. Therefore, in these cases, chemotaxis may be needed as one of the means to avoid interspecies fertilization. Indeed, in some marine groups (e.g., sea urchins, hydromedusae and certain ophiuroids), the specificity of sperm chemotaxis is very high. In other groups (e.g., starfish), the specificity is at the family level and, within the family, there is no specificity. In contrast, in mollusks, there appears to be no specificity at all ([35,102,103] and references therein). [Pg.442]

Whole-rock K-Ar dates of slate and siltstones of the Mariner Group in Appendix 4.8.4.2, reported by Adams et al. (1982), range from 417 3 (Lower Devonian) to 380 3 Ma (Middle Devonian) and are lower than the age indicated by fossils (late Middle to late Late Cambrian), although they do overlap with the K-Ar dates of the Sledgers Group in Fig. 4.20. [Pg.119]


See other pages where Mariner Group is mentioned: [Pg.684]    [Pg.1092]    [Pg.1211]    [Pg.684]    [Pg.1092]    [Pg.1211]    [Pg.43]    [Pg.1210]    [Pg.217]    [Pg.9]    [Pg.294]    [Pg.418]    [Pg.867]    [Pg.395]    [Pg.118]    [Pg.118]    [Pg.119]    [Pg.119]    [Pg.136]    [Pg.110]    [Pg.723]    [Pg.760]    [Pg.176]   


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