Pomacea spp.

Family

Ampullariidae

Species

Pomacea canaliculata (Lamarck, 1822)

P. glauca (Linnaeus, 1758)

P. insularum (d'Orbigny, 1835)

P. lineata (Spix, 1827)

P. haustrum (Reeve, 1856)

P. diffusa (Blume, 1957)

Common name

Apple snails

Pomacea canaliculata: Golden applesnail, South American ampullarid, Channeled applesnail, Miracle snail

P. insularum: Island applesnail

Description

Pomacea spp.

Traditionally, apple snails have been diagnosed by characters of the shellShell:
A hard, inflexible, calcareous or chitinous structure that vary in size and may either completely encasing the animal, covering some part of it or be internal.
, operculumOperculum:
A rigid structure that blocks the opening/aperture of the shell (partially/wholly) when the body of the snail is retracted. This structure is often attached dorsal to the tail of the animal. It can be chitinous, proteinaceous or calcareous. Often observed in aquatic species. (See also epiphragm).
and siphonSiphon:
In aquatic and semi-terrestrial gastropods, this is a narrow breathing tube formed by an extension of the mantle.
. In recent years, these characters have been proven to be unreliable in differentiating species. As such, molecular techniques have been developed to distinguish between species.

The globoseGlobose:
Shell shape: to be roughly spherical or globular in shape.
shell of this group of snails ranges from 45-75 mm in heightHeight:
The height of the shell is a measure of the distance between the apex and the most basal part of the shell OR the measurement taken from the apex of the shell to the base, when measured parallel to the axis of the shell.
and 40-60 mm in widthWidth:
The width of the shell is the maximum distance across the shell (including the aperture).
, with 4-6 whorlsWhorls:
Pleural of whorl. A whorl is a complete spiral turn/growth of the shell of a mollusc. The whorls are counted from the apex outwards.
, depending on the species. The apertureAperture:
The major opening of a shell that the body of the animal may be retracted.
is oval to round. The color of this species also varies: yellow to green to brown. There may or may not be brown-black spiralSpiral:
Directional term: direction of the coils of the whorls of a shell; opposite of axial.
bands on the shellShell:
A hard, inflexible, calcareous or chitinous structure that vary in size and may either completely encasing the animal, covering some part of it or be internal.
.

There is a single native species of apple snail in the U.S, Pomacea paludosa. It can be found in wetlands in Florida, Georgia and more recently, Alabama. This should not be confused with the introduced species. A species comparison follows:

Pomacea paludosa: Clutch size: up to 30; Egg Color: freshly laid eggs are salmon colored in a gelatinous matrix then they become pink-white and calcified; Incubation Period: 15-28 days; Time to Maturity: undocumented; Longevity: undocumented.

P. canaliculata: Clutch size: 25-1000; Egg Color: bright pink; Incubation Period: 7 days - 6 weeks; Time to Maturity: 55 days to 12 months; Longevity: up to 5 years.

P. glauca: Clutch size: 30-90; Egg Color: green; Incubation Period: 14-17 days - 6 weeks; Time to Maturity: 8-13.5 months; Longevity: up to 3 years.

P. insularum: Clutch size: undocumented; Egg Color: pink-red; Incubation Period: undocumented; Time to Maturity: undocumented; Longevity: undocumented.

P. lineata: Clutch size: 100; Egg Color: pink-red; Incubation Period: 15 days; Time to Maturity: undocumented; Longevity: undocumented.

P. haustrum: Clutch size: 236; Egg Color: bright green and polygon-shaped; Incubation Period: 9-30 days; Time to Maturity: approximately 1 year; Longevity: undocumented.

P. diffusa: Clutch size: undocumented; Egg Color: tan to salmon (white when just laid) and honey-comb shaped; Incubation Period: undocumented; Time to Maturity: undocumented; Longevity: undocumented.

Native range

South America

Distribution

North America:

• U.S.: Alabama, Arizona, California, Florida, Georgia, Texas

South and Central America

Pacific Islands: Hawaii, Guam

Caribbean: Dominican Republic

Australasia: Papua New Guinea

S.E. Asia: China, Singapore, Sri Lanka

Africa

Ecology

Apple snails are serious pests of aquatic ecosystems. They are generally found in fresh water habitats, though these species are known to tolerate low levels of salinity. This group is often dispersed by human activity through the pet trade or through their use as a food source. These snails are a threat to wetland ecosystems as they are generalist feeders and as such they have the potential to outcompete and displace other snail species. These snails are omnivorous and will consume vegetation, and all life stages of other snail species. Apple snails are known to be amphibious; however they will spend considerable periods in terrestrial habitats. This behavior facilitates disperal in both terrestrial and aquatic habitats. Pomacea canaliculata species is of concern to the U.S. as they may pose a risk to the rice producing area of the U.S. (e.g., Texas and Louisiana).They often are pest of rice and taro in other regions of the world.

Generally Pomacea species prefer standing or slow moving water (e.g., marshes, lakes and rivers). It has been reported that Pomacea canaliculata inhabits standing water, but P. insularum prefers faster moving water (e.g., rivers). Also, both species may be separated by egg characteristics: the eggs of P. canaliculata are larger and fewer than P. insularum (which lays more than 1000 eggs per clutch). Apple snails are dieciousDiecious:
Being sexually distinct. Male and female genitalia do not occur in the same specimen.
, meaning that both sexes occur separately. Sexual dimorphism has also been documented in some species; in the females the shells are often larger than that of males. Pomacea spp. prefer to lay their eggs above the water line on vegetation or on other substrates like rocks.

Synonyms

Pomacea canaliculata:

• Ampullaria canaliculata Lamarck, 1822.

References

Barker 2002; Barnes et al. 2008; Cowie 2000; Cowie 2001; Cowie et al. 2009; Pain 1960; Peebles et al. 1972; Rawlings et al. 2007; Thiengo 1987