Alternation of Sexuality in Oysters

Abstract

In both the larviparous and oviparous species of oysters the primary gonad is essentially bisexual, with a strong tendency toward protandry. In Ostrea lurida there usually follows an alternating rhvthm of [female] and <[male] phases. Occasionally the primary <f phase is aborted, the first functional phase being [female]. In some individuals there is an exceptionally strong <[male] tendency. These so-called "true [male][male]" may long postpone the typical [female] phase. Both heredity and environmental conditions are thought to influence these variations in sexuality. In 0. virginica, as in 0. gigas, facultative change of sex from year to year may occur at any age.