A Quantitative Study of Copulation and Spawning in the South American Apple-Snail, Pomacea canaliculata (Prosobranchia: Ampullariidae)

ALBRECHT, E.A; CARREÑO, N.; CASTRO-VAZQUEZ, A.

VELIGER

Año: 1996 vol. 39 p. 142 - 147

0042-3211

Copulation and spawning of male-female pairs of the South American apple-snail Pomacea canaliculata werw periodically observed in aquaria. Copulation occurred under water (2.9 ± 0.3 times/week, mean ± SEM) and was more frequently recorded in the ,orning (45%) and afternoon (37%) than in the evening (18%). Most copulations were recorded in one or two subsequent observations, although some were recorded in up to five subsequent observations (encompassing more than 30 h); some of these long copulations were interrupted by spawning and then resumed, Vich suggests that some copulation may indeed be series of several copulatory episodes. Spawning occurred above water level (1.4 ± 0.1 times/week) and mostly at ninght (93%). The number of eggs per spawn was 101.0 ± 6.8 eggs (mean SEM), its mean volume was 9.9 ± 0.2 mm3, and the percentage of fertile eggs was 42.6 ± 2.7. The number of eggs produced, the men egg volume, and the percent of fertile eggs did not differ significantly between the first and second spawn produced directly alter copulation. When several spaws (up to five) were produced in sucesión, without intervening copulations, the number of eggs per spawn was whitin the normal range, but the fertility of the eggs produced varied from normal to null values. The adaptative significance of these findings in comparison with what in know in other ampullariid gastropods is discussed.