83 research outputs found

    Donneés sur la faune pélagique vivant au large des côtes du Gabon, du Congo et de l'Angola (0-18° lat. S. et 5-12° long. E.) Tuniciers pélagiques: II. Pyrosomidae

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    Two species of Pyrosoma (P. atlanticum and P. aherniosum) have been recorded in the copious plankton material collected during several oceanographic cruises undertaken by the O.R.S.T.O.M. Center at Pointe- Noire, from 1960 to 1967, in the tropical Atlantic Ocean. The distribution of the colonies has been examined relatively to the local hydrological conditions

    Données sur la faune pélagique vivant au large des côtes du Gabon, du Congo et de l'Angola (0-18° lat. S. et 5-12° long. E.) Tuniciers pélagiques: I. (suite) Salpidae

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    In a small complementary Tunicates collection from O.R.S.T.O.M. Centre at Pointe-Noire, Ritteriella picteti Apstein 1904 has been recognized as the 16th species of Salpa found in the investigated area where Salpidae distribution has been again considered in relation with the surrounding waters

    Sur deux espèces nouvellement définies du genre <i>Thalia</i>: <i>Thalia orientalis</i> Tokioka 1937 et <i>Thalia cicar</i> van Soest 1973

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    R . van Soest (1973) has recently reinvestigated on the genus Thalia and split the former species Thalia orientalis Tokioka 1937 into three species : Thalia orientalis Tokioka 1937 sensu stricto, Thalia cicar and Thalia rhomboĂŻdes Quoy and Gaimard 1824. In this paper, Thalia orientalis and Thalia cicar are especially considered with the view of controlling the stability of both species

    Stades larvaires du <i>Doliolum</i>

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    Curves on Heisenberg invariant quartic surfaces in projective 3-space

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    This paper is about the family of smooth quartic surfaces X⊂P3X \subset \mathbb{P}^3 that are invariant under the Heisenberg group H2,2H_{2,2}. For a very general such surface XX, we show that the Picard number of XX is 16 and determine its Picard group. It turns out that the general Heisenberg invariant quartic contains 320 smooth conics and that in the very general case, this collection of conics generates the Picard group.Comment: Updated references, corrected typo

    A comparison of filtration rates among pelagic tunicates using kinematic measurements

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    Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Marine Biology 157 (2010): 755-764, doi:10.1007/s00227-009-1359-y.Salps have higher filtration rates than most other holoplankton, and are capable of packaging and exporting primary production from surface waters. A method of kinematic analysis was employed to accurately measure salp feeding rates. The data were then used to explain how diverse body morphologies and swimming motions among species and lifecycle stages influence salp feeding performance. We selected five species, representing a range of morphologies and swimming styles, and used digitized outlines from video frames to measure body-shape change during a pulse cycle. Time-varying body volume was then calculated from the digitized salp outlines to estimate the amount of fluid passing through the filtering mesh. This non-invasive method produced higher feeding rates than other methods and revealed that body volume, pulse frequency and degree of contraction are important factors for determining volume filtered. Each species possessed a unique combination of these three characteristics that resulted in comparable filtration (range: 0.44 - 15.33 ml s-1) and normalized filtration rates (range: 0.21 – 1.27 s-1) across species. The convergence of different species with diverse morphologies on similar normalized filtration suggests a tendency towards a flow optimum.This work was supported by NSF project OCE-0647723
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