Pomacea canaliculata (Lamarck, 1822)
Often confused with another species that has been introduced outside of its native range, P. insularum. Also confused with a number of other closely related species including, P. lineata, P. figulina, and P. dolioides.
Pomacea canaliculata is primarily macrophytophagous, but is also known to be a voracious consumer of variety of animals, including other snails. When kept in captivity they are known to consume nearly all plant matter kept in the aquarium and will even prey upon their own young.
In the invaded range they are major consumers of macrophytes often altering the ecosystem states and functions in invaded freshwater habitats.
All ampullariids (apple snails) are dioecious (i.e. have separate sexes). Fertilization is internal with copulations lasting as long a 18 hours. During these copulations the male snail mounts the female's shell posteriorly and crawls up the body whorl (the largest part of the shell) until he reaches the edge of the shell. He then inserts the muscular penis sheath into the pallial cavity of the female. Once the male has inserted the sheath into the pallial cavity of the female, it then extrudes its thin, whip-like penis through the penis sheath canal and inserts it into the females genital opening. It has been reported that the male uses this sheath to secure himself to the female during lengthy copulations, during which the female may continue to move around and even feed. Additionally, the glands of the sheath may be involved in lubrication, adhesion and nuptial feeding.
Like many snails, female apple snails may store sperm for weeks to months, allowing them to produce fertilized eggs even in the absence of a male partner.
Mating is seasonal and triggered by rainfall and temperature. In its native range of Argentina, Uruguay, and Paraguay P. canaliculata breeds only in the warm summer months. However, outside of their native range, once released from such seasonal fluctuations, P. canaliculata may reproduce year round, particularly in artificial habitats like rice paddies and taro patches.
In Pomacea canaliculata, as in most of the species in the genus Pomacea, females deposit fertilized eggs above the water on emergent vegetation. The developing embryos are surrounded by bright pink/red perivitellins (the major component of the egg yolk) and are encased in a calcareoius shell. The perivitellins are thought to be primarily nutritive, but also serve a protective function, as the pigments block UV light. The calcareous casing prevents desiccation, but remains semi-permeable to allow oxygen penetration. In what seems somewhat odd for a freshwater snail, if the eggs are submerged in water for extended periods the embryos will die. Egg clutches may contain as many as 500 or more eggs. However, this is a small number when compared to the 1000's of eggs often deposited by P. insularum, a closely related species.