Evolution de la taille des grains du tube arénacé en fonction de la croissance chezPectinaria (Lagis) koreniMalmgren (Polychète sédentaire)

Abstract

A granulometric study of the tubes of Pectinaria koreni showed that newly settled specimens use small sand grains (average diameter about 50 µ) for building the very first part of the arenaceous tube. During the growth of the worms the diameter of the sand grains collected increases rapidly, but when a tube diameter of about 4 mm is reached the preferred grain size stabilizes at 250–315 µ. A morphological and histochemical study of post-larval stages showed a negative allometrical growth of the building organ, a delayed development of the collecting tentacles, and an early development of the cementary organ first involved in the secretion of the organic primordial tube.