Ampullariidae

Ampullariidae, common name the apple snails, is a family of large freshwater snails, aquatic gastropod mollusks with a gill and an operculum. This family is in the superfamily Ampullarioidea and is the type family of that superfamily.

The Ampullariidae are unusual because they have both a gill and a lung, the mantle cavity being divided in order to separate the two types of respiratory structures. This adaptation allows these snails to be amphibious.

Contents 1 Taxonomy 2 Genera 3 Distribution 4 Ecology 5 Importance to humans 5.1 As a common aquarium animal 5.1.1 Feeding habits 5.1.2 Times of activity 5.1.3 Temperature 5.2 As a pest 5.3 As a bio-control agent 5.4 As a human food item 6 References 7 Further reading 8 External links

Taxonomy

This family consists of two following subfamilies (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005), that used classification by Berthold (1991):^[2]

• Ampullariinae Gray, 1824
  • tribe Ampullariini Gray, 1824 - synonyms: Pilidae preston, 1915 (inv.); Lanistimae Starobogatov, 1983; Pomaceinae Starobogatov, 1983
  • tribe Sauleini Berthold, 1991
• Afropominae Berthold, 1991

Genera

Genera in the family Ampullariidae include:

Ampullariinae

• tribe Ampullariini
  • Ampullaria Lamarck, 1799 - type genus of the subfamily Ampullariinae
  • Pila Röding, 1798
  • Lanistes Montfot, 1810
  • Pomacea Perry, 1810

• tribe Sauleini
  • Saulea Gray, 1868 - type genus of the tribe Sauleini

Afropominae

• Afropomus Pilsbry & Bequaert, 1927 - type genus of the subfamily Afropominae

subfamily ?

• Asolene - includes Pomella
• Felipponea
• Marisa

Distribution

Genera Asolene, Felipponea, Marisa, and Pomacea are New World genera (native to South America, Central America, the West Indies and the Southern U.S.A.). 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 predation by 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 enemy is the Limpkin.

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.

Importance to humans

As a common aquarium animal

Apple snails are popular aquarium pets because of their attractive appearance and size. When properly cared for, some apple snail species can reach 15 cm (5.9 in) diameter. Apple snails include species that are the biggest living freshwater snails on Earth.

The most common apple snail in aquarium shops is Pomacea bridgesii, also called Pomacea diffusa, (the spike-topped apple snail). This species comes in different colours from brown to albino or yellow and even blue, purple, pink, and jade, with or without banding. Another common apple snail is Pomacea canaliculata; this snail is bigger, rounder and is more likely to eat aquatic plants, which makes it less suitable for most aquaria. This species can also have different shell and body colours. The "giant ramshorn snail" (Marisa cornuarietis) although not always recognized as an apple snail due to its discoidal shape, is also a popular aquatic pet. Occasionally, the Florida apple snail (Pomacea paludosa) is found in the aquarium trade and these are often collected in the wild from ditches and ponds in Florida. The giant Pomacea maculata is rarely used as an aquarium species.

Apple snails are often sold under the name "golden (ivory, blue, black...) mystery snail" and they are given incorrect names like Ampullarius for the genus instead of Pomacea and wrong species names like gigas instead of maculata.

These snails sometimes become inactive (especially when first introduced to a new tank, probably from the stress of moving from one habitat to another), and may not move for several days, but once the snail is acclimated it becomes active again.

Feeding habits

In captivity, as well as eating vegetables and fish food pellets, apple snails will also eat other foods if they are available. They will sometimes eat brine shrimps and other frozen foods, or dead fish and insects. Generally, they will also eat any of the microscopic vegetation that grow on the tank rocks or walls. Snails will climb out of the water to reach food that is above the waterline. Because of their ability to do this they have become a nuisance in Asia, where they feed on crops.

Times of activity

In captivity, apple snails are most active at night. During the day they usually retreat to somewhere shaded. When it is night time, the apple snail becomes active and engages in behaviors relating to feeding, as well as mating and laying eggs.

In an aquarium that is well-lit, the exterior of the shell of apple snails may grow filamentous green algae. This is one possible source of food for juvenile snails.

Temperature

The optimal aquarium water temperature for apple snails is between 18 to 28 °C (64 to 82 °F). Apple snails are more active and lively in the higher part of this temperature range. In these higher temperatures, the snails tend to eat, crawl and grow faster. At the lower end of the temperature range, 18 °C/64 °F, the snails may become inactive.

As a pest

In the 1980s, Pomacea canaliculata was introduced in Taiwan to start an escargot industry.^[3] It was thought that such food culture could provide valuable proteins for farmers, who primarily live on a rice diet. However, the snails did not become a culinary success. Additionally the imported snails (like the native apple snail population, Pila) were able to transfer a parasite called Angiostrongylus cantonensis. This parasite can infect humans if snails are eaten that have not been thoroughly cooked first.

Instead of becoming a valuable food source, the introduced snails escaped and became a serious threat to rice production and the native ecosystems. During the 1980s the introduced snails rapidly spread to Indonesia, Thailand, Cambodia,^[4] Hong Kong, southern China, Japan and the Philippines, and there are indications that they are currently invading Australia.

Hawaii experienced the same introduction of Pomacea for culinary purposes, and its taro industry is now suffering because of it.

Nevertheless, apple snails are considered a delicacy in several regions of the world, and they are often sold in East and Pacific Asian markets for consumption.

As a bio-control agent

Pomacea and Marisa species have been introduced to Africa and Asia to control snails (Planorbidae: Bulinus sp. and Biophalaria sp.) that serve as an intermediate host for trematoda parasites. These parasites can cause swimmers itch and schistosomiasis, a disease that affects over 200 million people in tropical regions. One of the species introduced as bio-agent is Marisa cornuarietis. This snail competes with other snails and preys on other species.

As a human food item

In Veracruz, Mexico, there is a subspecies of apple snail known as Pomacea patula catemacensis Baker, 1922. This subspecies is endemic to Lake Catemaco.^[5] This large snail is locally known as "tegogolo" and is prized as a food item.

References

Further reading

• Baldia JP, Pantastico JB (1991). "Environmental impact of the golden snail (Pomacea sp.) on rice farming systems in the Philippines". Wallaceana 65: 14–6. 
• Bieler R (1993). "Book Review (Vergleichende anatomie ... Berthold, T, 1991) and Cladistic Re-analysis". The Veliger 36 (3): 291–7. 
• Cazzaniga NJ (April 2002). "Old species and new concepts in the taxonomy of Pomacea (Gastropoda: Ampullariidae)". Biocell 26 (1): 71–81. PMID 12058383. 
• Cowie RH (2001). "Can snails ever be effective and safe biocontrol agents?". International Journal of Pest Management 47 (1): 23–40. doi:10.1080/09670870150215577. 
• McClary A (1962). "Surface inspiration and ciliary feeding in Pomacea paludosa (Prosobranchia: Mesogastropoda: Ampullariidae)". Malacologia 2 (1): 87–104. 
• Meenakshi VR (1956). "Physiology of hibernation of the apple-snail Pila virens (Lamarck)". Current Science 10: 321–3. 
• Jørgensen, Aslak; Kristensen, Thomas K.; Madsen, Henry (2008). "A molecular phylogeny of apple snails (Gastropoda, Caenogastropoda, Ampullariidae) with an emphasis on African species". Zoologica Scripta 37: 245. doi:10.1111/j.1463-6409.2007.00322.x. 

External links

• Applesnail website