Apple snails
| Apple snails | ||||||||||||
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Pomacea diffusa in the aquarium |
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| Scientific name | ||||||||||||
| Ampullariidae | ||||||||||||
| Gray , 1824 |
As apple snails (Ampullariidae) a family is called tropical or sub-tropical freshwater snails. According to the status of systematic processing in 2015, there are 175 species of apple snails in 9 genera . Various apple snails are kept as aquarium animals. Colored cultivated forms of the pointed apple snail ( Pomacea diffusa ) are particularly popular .
Occurrence and characteristics
The home of the apple snails are the fresh waters of the tropical climate zone in America, Africa and Asia.
Characteristic features of all species of the family are the housing cover ( operculum ) and a pair of lip buttons on the mouth, which the snails have in addition to the feelers .
Since they prefer stagnant water and swamps, which are low in oxygen in this climate zone and sometimes dry out, apple snails have developed a lung sac in addition to their gill , into which they absorb air on the surface of the water. To do this, they have developed a fold on the edge of the jacket, which they can shape into an open channel, a funnel or a closed tube. The species of the genus Pomacea , Pila and Marisa form a closed tube with the Sipho and exchange the air in the lung bag through this "snorkel" with pumping movements of the front body. In Asolene and Lanistes , the Sipho forms a short but wide funnel. In order to breathe, these animals therefore have to lift their housing a little out of the water.
The eyes are on small bumps at the base on the outside of the antennae. The ability to see is described as moderate, with the possibility of distinguishing between light and dark.
Reproduction
Apple snails are not hermaphrodites , but the sexes are difficult to distinguish in most species. During mating, the male “sits” on the female and inserts his lobed penis into the female's genital opening. The siphon is to the left of the head while the penis is on the right. The apple snails of the genera Pomacea and Pila lay their eggs outside of the water. Your eggs are protected from damage and drying out by a chalky shell. In some Pomacea species, they are bright red, orange or green in color. Most of the time, the eggs are white. In the Pomacea species, females usually stick them to parts of plants or stones in dense egg packets with up to 1000 eggs above the water. But there are exceptions. Pomacea urceus keeps its eggs under the housing and the young hatch there while the mother buries in the ground during the dry season. Pila ampullacea also sticks its eggs to solid surfaces outside of the water. It also covers its clutch with a layer of chalky scales. Their clutches include between 15 and 50 eggs. Some Pila species lay their eggs in pits on the shores of their home waters. In the genera Marisa, Lanistes, Felipponea , Saulea and Asolene , the eggs are deposited in spawning balls in the water. They adhere to parts of plants and can be found, for example, under the floating leaves of water lilies. In these clutches, the eggs are embedded in a gelatinous mass.
The development of the eggs takes between 2 and 4 weeks, depending on the temperature and the type of apple snail.
food
Apple snails are omnivores. In many species, vegetable food is the predominant part of the diet, but carnal food is also consumed. While some apple snail species are content with dead plant remains and leaves ( Asolene spixi , Pomacea diffusa ), other species also eat healthy plants ( Pomacea canaliculata , Pomacea haustrum, Pila ampullacea ). Usually the entire plant is eaten and not even the fibrous stems or rhizomes are spurned. Algae and microorganisms are also part of the apple snail diet, as well as carrion, other snails, fish clutches, etc.
Importance to humans
Apple snails are very popular in the aquarium hobby. Many color forms have been bred from the pointed apple snail ( Pomacea diffusa ) in particular . The cultivated forms with a white body and brown, striped or monochrome yellow housing are very widespread. Less common are "blue" animals with a white shell through which a black body shines through, pure white animals or shapes with a pink shell that looks pink in animals with a white body and purple in animals with a dark body.
Apple snails are eaten in South America, Africa, and Asia. In some regions they are an important staple food and are grown in large numbers and traded on markets.
While apple snails in their natural ecosystem, e.g. B. in the Pantanal swamp in South America, have natural enemies, introduced Pomacea canaliculata , Pomacea haustrum and Pomacea insularum have become a plague in Asia. The animals cause massive damage to rice and taro, which are indispensable staple foods for the rural population. The apple snail Pomacea canaliculata is an extremely invasive species. The animals overwinter in regions with mild frost, buried in the ground under ice. In Europe, Pomacea insularum has caused great damage in some regions of Spain, in rice fields in the Ebro Delta . Therefore, importation and trade of all species of the genus Pomacea within the EU were banned on January 1, 2013. Studies have shown that other species of this genus, which cannot be reliably differentiated taxonomically, also cause damage to aquatic plants. On the recommendation of the European Food Safety Authority (EFSA), the European Commission issued an implementing decision prohibiting the import and trade of the genus Pomacea and plants contaminated with it within the member states of the European Union with effect from January 1, 2013. The decision is implemented in Germany by the plant protection services of the federal states. The main focus is on preventing the spread of apple snails into endangered areas of southern Europe by commercial and private owners and propagators.
Apple snails can be carriers of parasitic worms. When eating inadequately cooked or raw snails, humans can be infected with the nematode Angiostrongylus cantonensis and develop eosinophilic meningoencephalitis .
Systematics
In the past, the Ampullariidae were placed in the now no longer listed order of middle snails (Mesogastropoda). In the nomenclature currently used, the family of apple snails (Ampullariidae) belongs to the Caenogastropoda parentage and is divided into 9 genera:
- Afropomus :Represented in West Africawith only one species ( Afropomus balanoidea Pilsbry & Bequaert 1927)
- Asolene : 8 species in Venezuela, Guyana, Suriname, eastern Bolivia, southern Brazil, Paraguay, Montevideo, northern Argentina
- Felipponea : 2 species in Paraguay, northern Argentina, Montevideo, southwest Bolivia, southern Brazil
- Forbesopomus : The genus Forbesopomus only includes the species Forbesopomus atalanta, which is endemic to Lake Lanao in Mindanao (Philippines).
- Lanistes : 43 species in Senegal, Gambia, Guinea-Bissau, Guinea, Sierra Leone, Liberia, Ivory Coast, Ghana, Togo, Benin, Nigeria, Niger, Cameroon, Equatorial Guinea, Gabon, Congo, Angola, Democratic Republic of the Congo, Zambia, Zimbabwe, Mozambique, Malawi, Tanzania, Uganda, Kenya, Somali, Ethiopia, South Sudan, Sudan, Egypt and Zanzibar and Madagascar
- Marisa : 2 species in Venezuela, Guyana, Suriname, Eastern Bolivia, Brazil, Paraguay
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Pila : The genus Pila occurs both in Africa and in Asia, each with its own species.
- 9 African species in Senegal, Gambia, Guinea-Bissau, Guinea, Sierra Leone, Liberia, Ivory Coast, Ghana, Togo, Benin, Nigeria, Niger, Cameroon, Equatorial Guinea, Gabon, Congo, Democratic Republic of the Congo, Zambia, Zimbabwe, Mozambique , Malawi, Tanzania, Uganda, Kenya, Somali, Ethiopia, South Sudan, Sudan, Egypt and Madagascar
- 19 Asian species in India, Sri Lanka, Bangladesh, Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia, Sumatra, Java, Borneo, Sulawesi, Philippines
- Pomacea : 89 species in Florida, Cuba, Dominican Republic, southern Mexico, Guatemala, Belize, Honduras, El Salvador, Nicaragua, Cosa Rica, Panama, Colombia, Ecuador, Venezuela, Guyana, Suriname, French Guiana, Brazil, Peru ( Lowlands), Bolivia, Paraguay, Montevideo, Northern Argentina
- Saulea : Only one species ( Saulea vitrea (Born 1778) Gray 1861) is present in West Africa.
Individual evidence
- ↑ a b R. H. Cowie: The recent apple snails of Africa and Asia (Mollusca: Gastropoda: Ampullariidae: Afropomus, Forbesopomus, Lanistes, Pila, Saulea): a nomenclatural and type catalog. The apple snails of the Americas: addenda and corrigenda.- Zootaxa. 2015 Mar 27; 3940: 1-92 .
- ↑ IW Ramnarine (2003): Induction of spawning and artificial incubation of eggs in the edible snail Pomacea Urceus (Muller) .- Aquaculture 215 (1-4), 163-166 .
- ↑ Machfudz Djajasamita (1987): The apple snail Pila ampullacea: its food and Reproduction (Gastropoda: Ampullariidae) or Keong Gongdang Pila ampullacea: Makanan dan reproduksinya (Gastropda: Ampullaitoae) .- Berita Biologi (7) Oct. 1987 342 - 346 .
- ^ EY Low, SK Tan and TH Ng (2013): Pila conica (Wood, 1828), or Pila scutata (Mousson, 1848)? The correct name for the native apple snail of Singapore (Gastropoda: Ampullariidae) .- Nature in Singapore 2013 6: 55-60 .
- ↑ http://www.aquaristik-spezial.net/index.php/Wirbellose/Pomacea-bridgesii-Apfelschnecken.html
- ^ RH Cowie (2002): Apple Snails (Ampullariidae) as Crop Pests: Their Biology, Impacts and Management . In: GM Barker (Ed.): Molluscs as Crop Pests . S. 145-192 .
- ^ I. Kenji (2002): Environmental factors influencing overwintering success of the golden apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae), in the northernmost population of Japan.- Applied Entomology and Zoology 37 (4), 655-661 .
- ↑ MDR: The Tricks of Survival ( Memento from January 17, 2017 in the Internet Archive )
- ↑ EFSA Scientific Opinion on the evaluation of the pest risk analysis on Pomacea insularum, the island apple snail, prepared by the Spanish Ministry of Environment and Rural and Marine Affairs
- ↑ Implementing decision of the Commission of November 8, 2012 regarding measures to protect against the introduction of the genus Pomacea (Perry) into the EU and its spread in the EU (PDF)
- ↑ Hollingsworth, RG and Cowie, RH: Apple snails as disease vectors. AGRIS record, 2006. online
literature
- Maike Wilstermann-Hildebrand: Apple snails. The family of the Ampullariidae . Nature and Animal, Münster 2009, ISBN 978-3-86659-128-8 .
