DIGESTIVE-TRACT AND FUNCTIONAL-ANATOMY OF THE STOMACH OF NAUSITORA-FUSTICULA (JEFFREYS, 1860) (BIVALVIA, TEREDINIDAE)

The configuration of the digestive tract and a detailed description of the anatomy and main ciliary currents of the stomach of Nausitora fus ticula are given and compared with other known teredinids. The stomach is of the elongate type and differs strikingly from all other known e longate stomachs in the Teredinidae by the possession of two right cae ca, both invaded by the major typhlosole. This fold is also peculiarly accompanied all along its course inside the stomach by the minor typh losole and the sorting area SA7. These three structures enter the left caecum and the anterior and posterior right caeca as well, within whi ch they segregate the openings of the normal from those of the special ized digestive diverticula, showing that those three pockets are the m ain sites where final separation of wood from suspended filtered parti cles occurs. The presence of seven well-defined sorting areas on the s tomach walls reveals a low selectivity exercised by the organs and str uctures in the pallial cavity, and specialization of the stomach to de al with a great variety of isolated particles. The moderate size of th e appendix and mid-gut, the weakly developed typhlosole of the appendi x, and absence of fecal pellets in the species are indicative of a pre dominantly suspension-feeding habit.