N. P. Karaseva, V. V. Malakhov, S. V. Galkin - Morphology and anatomy of the vestimentiferan worm Oasisia alvinae Jones, 1985 (Annelida: Siboglinidae). I. External morphology, obturaculae and tentacles

BIOLOGIYA MORYA, 2011, Vol. 37, No. 6, pp. 413-422

Morphology and anatomy of the vestimentiferan worm Oasisia alvinae Jones, 1985 (Annelida: Siboglinidae). I. External morphology, obturaculae and tentacles

¹M.V. Lomonosov Moscow State University, Biological Faculty, Moscow 119991;
²Far Eastern Federal University, Vladivostok 690950;
³P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow 117997

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This study describes the tube structure, external morphology, and histological organization of the obturaculae and tentacles of a small hydrothermal-vent vestimentiferan worm Oasisia alvinae. The tubes are considerably twisted and bear collars, thus suggesting a step-like growth of the worm. The total length of the studied specimens is 32-41 mm. The trunk region comprises 75% of the total body length and is differentiated into a broadened forepart and a narrowed posterior part. The ratio between the lengths of the obturacular and vestimental regions is 0.62-0.63. The examined specimens of O. alvinae have 13 to 17 pairs of tentacular lamellae, the total number of tentacles is about 550. The muscular bands in the obturaculae of O. alvinae lie in the parafrontal planes. There is a polymorphism in the number and arrangement of the denticles of the opistosomal chaetae in O. alvinae.

Key words: vestimentifera, Siboglinidae, Oasisia alvinae, external morphology, obturaculae, tentacles.