Lecithotrophic development and metamorphosis in the Indo-West Pacific brittle star Ophiomastix venosa (Echinodermata: Ophiuroidea) |
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Authors: | DIDIER FOURGON IGOR EECKHAUT DEVARAJEN VAÏTILINGON MICHEL JANGOUX |
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Institution: | 1. Laboratoire de Biologie Marine (CP 160/15) , Université Libre de Bruxelles , Avenue F.D. Roosevelt, 50, Bruxelles, 1050, Belgium Phone: +32 (2) 650-2970 Fax: +32 (2) 650-2970 E-mail: dfourgon@ulb.ac.be;2. Aqua-lab , Institut Halieutique et des Sciences Marines, Université de Tuléar , Tuléar, 601, Madagascar;3. Laboratoire de Biologie Marine , Université de Mons-Hainaut , Mons, 7000, Belgium;4. Laboratoire de Biologie Marine , Université de Mons-Hainaut , Mons, 7000, Belgium |
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Abstract: | Summary The larval development of the ophiocomid ophiuroid Ophiomastix venosais described using SEM. The gastrula transforms into a uniformly ciliated early larva which progressively changes into a lecithotrophic late premetamorphic larva with a continuous bilateral ciliated band. This stage is short-lived and equivalent to a highly reduced ophiopluteus. Comparisons between O. venosa and other ophiuroid species whose development has been investigated suggest that, whatever the developmental mode (lecithotrophic or planktotrophic), a pluteus stage always occurs in ophiuroids with planktonic development. Two metamorphic stages were identified, the late metamorphic larva differing from the early one by the closure of the larval mouth. The appearance of the permanent mouth marks the end of the metamorphosis. The postlarva still possesses remnants of larval features. The transformation of the reduced ophiopluteus into a barrel-shaped metamorphic larva with transverse ciliated bands, a vitellaria larva, is followed. The possible occurrence of a unique type of metamorphic larva in non-brooding ophiuroids is discussed. Verification of this, however, needs further SEM investigations on metamorphic larva from species having “regular” planktotrophic development. |
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Keywords: | Ophiuroid larval development yolk larva vitellaria SEM microscopy |
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