Differentiation in the Pteropod Clio pyramidata L., 1767 forma sulcata (Pfeffer, 1879)

Pteropods are hermaphrodite animals. The reproductive system is composed of a hermaphrodite gland (gonad), a gonoduct, an accessory gland with one genital opening, a seminal groove and a penis. KNOWER (1894), however, discovered in Cavolinia longirostris (Lesueur, 1821), two separate sexual openings and a closed ciliated tube running from the accessory gland to the penis, in which this species differs from all other Pteropods, in KNOWER’s opinion. The closing of the seminal groove, by which a ciliated tube is formed, causes a better transport of the male products and on the other hand a female opening (vagina) becomes a necessity.