Apple Snail

The **apple snail**, (Ampullariidae) is a of large freshwater snail, with a gill and an operculum. This family is in the superfamily Ampullarioideaand is the type family of that superfamily. These snails are unusual because they have both a gill and a lung, with the mantle cavity being divided in order to separate the two types of respiratory structures. This adaptation allows these snails to be amphibious.

## Distribution

The genera *Asolene*, *Felipponea*, *Marisa*, and *Pomacea* are New World genera that are native to South America, Central America, the West Indies and the Southern United States. The genera *Afropomus*, *Lanistes*, and *Saulea* are found in Africa.The genus *Pila* is native to both Africa and Asia.

## Ecology

Apple snails are exceptionally well adapted to tropical regions characterized by periods of drought alternating with periods of high rainfall. This adaptation is reflected in their life style; they are moderately amphibious. They have an operculum which enables the snail to seal the shell entrance to prevent drying out while they are buried in the mud during dry periods. One of the more typical adaptations of apple snails is the branchial respiration. The snail has a system comparable to the gills of a fish (at the right side of the snail body) to breathe under water as well as a lung (at the left side of the body) to respirate air. This lung/gill combination expands the action radius of the snail in search for food. It is part of the snail's natural behaviour to leave the water when the food supply below the surface becomes inadequate.

Several apple snail genera (*Pomacea*, *Pila* and *Asolene/Pomella*) deposit eggs above the waterline in calcareous clutches. This remarkable strategy of aquatic snails protects the eggs against predationby fish and other aquatic inhabitants. Another anti-predator adaptation in the apple snail genera *Pomacea* and *Pila*, is the tubular siphon, used to breathe air while submerged, reducing vulnerability to attacking birds. The apple snail's usual enemies are the birds limpkin and snail kite. Apple snails inhabit various ecosystems: ponds, swamps and rivers. Although they occasionally leave the water, they spend most of their time under water. Unlike the pulmonate snail families, apple snails are not hermaphroditic, but gonochoristic; i.e. they have separate genders.

## Adaptaions

Apple snails are exceptionally well adapted to tropical regions with periods of drought alternated with periods of excessive rainfall. This adaptation is reflected in their life style: moderately amphibious and being equipped with a shell door enabling the snail to close its shell (to prevent drying out while hiding in the mud during dry periods).
A typical adaptation of apple snails is the combination of a branchial respiration system comparable with the gills of a fish (at the right side of the snail body) and a lung (at the left side of the body). This lung/gill combination expands the action radius of the snail in search for food.

Many apple snail species deposit the eggs above the waterline in a calcareous clutch. This remarkably strategy of these aquatic snails protect their eggs against predation by fish and other water inhabitants. Another predator specific adaptation in the apple snail genera *Pomacea* and *Pila*, is the tubular siphon at their left side, used to breathe air while they stay submerged, thus making them less vulnerable to snail eating birds. Apple snails inhabit various ecosystems: ponds, swamps and rivers. Although they occasionally leave the water, they remain mainly submerged. In spite the fact that many snail species are hermaphrodite (being male and female at the same time) apple snails are definitely not: they have separated sexes (gonochoristic) and a male and a female are needed for reproduction.