Radix natalensis
Encyclopedia
Radix natalensis is a species
of freshwater snail
, an aquatic
gastropod mollusc in the family
Lymnaeidae
.
It is widely distributed in Africa. It is a major intermediate host
for Fasciola gigantica
in Africa. Placement of this species in the genus Radix was confirmed by Correa et al. (2010).
The type locality is in "pools in Port Natal", which today is Durban
, South Africa.
in 1848.
The shape of the shell
is elongate ovoid. The shell is colorless or light brown in color. The height of the aperture
covers about 3/4 of the shell height. The lip of the aperture is thin and sharp. The umbilicus is closed. The width of the shell is about 5.75-7 mm. The height of the shell is 4.6-19.2 mm.
The reproductive system
and radula
was described by Wright (1963) in detail.
or bedrock as a substrate.
Laboratory experiments have shown that some larger snails of Radix natalensis can survive on a wooden surface without water for up to 21 days. Some smaller snails of Radix natalensis have survived desiccation
on a soil surface up to 60 days on "black" soil. Some smaller snails of Radix natalensis were able to survive for up to 90 days on soil among sedges (Cyperus
) or in the "black" soil exposed to sun or in the soil with stones.
Parasites of Radix natalensis include:
Predators of Radix natalensis include leeches Helobdella nilae and Alboglossiphonia conjugata.
Snails of the non-indigenous species Marisa cornuarietis
eliminated Radix natalensis and other two native snail species from a small pond in Tanzania in an experiment in 1982.
Oil extract of the gum myrrh Commiphora myrrha
has molluscicidal
activity against Radix natalensis.
shows the phylogenic relations of species in the genus Radix:
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of freshwater snail
Freshwater snail
A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine habitat. The majority of freshwater gastropods have a shell, with very few exceptions....
, an aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
gastropod mollusc in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Lymnaeidae
Lymnaeidae
Lymnaeidae is a taxonomic family of small to large air-breathing freshwater snails, aquatic pulmonate gastropod mollusks, that belong to the clade Hygrophila....
.
It is widely distributed in Africa. It is a major intermediate host
Intermediate host
A secondary host or intermediate host is a host that harbors the parasite only for a short transition period, during which some developmental stage is completed. For trypanosomes, the cause of sleeping sickness, humans are the primary host, while the tsetse fly is the secondary host...
for Fasciola gigantica
Fasciola gigantica
Fasciola gigantica is a parasitic flatworm of the class Trematoda, which causes tropical fascioliasis. It is regarded as one of the most important single platyhelminth infections of ruminants in Asia and Africa...
in Africa. Placement of this species in the genus Radix was confirmed by Correa et al. (2010).
Distribution
Radix natalensis is a widespread species in Africa and occurs from northern Africa to southern Africa:- Northern Africa: Algeria, Tunisia, Egypt, Sudan. There are also findings of distribution of Radix natalensis in Algeria 8-10,000 years ago.
- Western Africa: Benin, Burkina Faso, Côte d'Ivoire, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Niger, Nigeria and Senegal,
- Eastern Africa: Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Malawi, Mozambique, Somalia, Tanzania, Uganda, Zambia and Zimbabwe.
- Central Africa: Angola, Cameroon, Central African Republic, Chad, Democratic Republic of the Congo, Republic of the Congo, Equatorial Guinea and Gabon.
- Southern Africa: Botswana, Namibia, South Africa and Rhodesia.
- Madagascar
The type locality is in "pools in Port Natal", which today is Durban
Durban
Durban is the largest city in the South African province of KwaZulu-Natal and the third largest city in South Africa. It forms part of the eThekwini metropolitan municipality. Durban is famous for being the busiest port in South Africa. It is also seen as one of the major centres of tourism...
, South Africa.
Description
Radix natalensis was described by German scientist and traveller Christian Ferdinand Friedrich KraussChristian Ferdinand Friedrich Krauss
Christian Ferdinand Friedrich Krauss , was a German scientist, traveller and collector.-Early life:...
in 1848.
The shape of the shell
Gastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...
is elongate ovoid. The shell is colorless or light brown in color. The height of the aperture
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
covers about 3/4 of the shell height. The lip of the aperture is thin and sharp. The umbilicus is closed. The width of the shell is about 5.75-7 mm. The height of the shell is 4.6-19.2 mm.
The reproductive system
Reproductive system of gastropods
The reproductive system of gastropods varies greatly from one group to another within this very large and diverse taxonomic class of animals...
and radula
Radula
The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...
was described by Wright (1963) in detail.
Ecology
Radix natalensis lives in permanent water bodies. An estimated density of Radix natalensis in a natural habitat in Tanzania was 34 snails per m². The snails lived mainly in the shallow water in depths of 0-4 cm, mainly between 20-30 cm from the shoreline. They prefer plant detritusDetritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
or bedrock as a substrate.
Laboratory experiments have shown that some larger snails of Radix natalensis can survive on a wooden surface without water for up to 21 days. Some smaller snails of Radix natalensis have survived desiccation
Desiccation tolerance
Desiccation tolerance refers to the ability of an organism to withstand or endure extreme dryness, or drought-like conditions. Plants and animals living in arid or periodically arid environments such as temporary streams or ponds may face the challenge of desiccation, therefore physiological or...
on a soil surface up to 60 days on "black" soil. Some smaller snails of Radix natalensis were able to survive for up to 90 days on soil among sedges (Cyperus
Cyperus
Cyperus is a large genus of about 600 species of sedges, distributed throughout all continents in both tropical and temperate regions. They are annual or perennial plants, mostly aquatic and growing in still or slow-moving water up to 0.5 m deep. The species vary greatly in size, with small species...
) or in the "black" soil exposed to sun or in the soil with stones.
Parasites of Radix natalensis include:
- Fasciola hepaticaFasciola hepaticaFasciola hepatica, also known as the common liver fluke or sheep liver fluke, is a parasitic flatworm of the class Trematoda, phylum Platyhelminthes that infects the livers of various mammals, including humans. The disease caused by the fluke is called fascioliasis . F...
- Fasciola giganticaFasciola giganticaFasciola gigantica is a parasitic flatworm of the class Trematoda, which causes tropical fascioliasis. It is regarded as one of the most important single platyhelminth infections of ruminants in Asia and Africa...
- Trichobilharzia sp.
- some cercariaTrematode lifecycle stagesTrematodes are small parasitic flatworms that use vertebrates as their definitive host, and molluscs as their intermediate host. In order to accomplish this, they have several varied lifecyle stages....
from Echinostomatidae - some xiphidiocercaria from Plagiorchiidae
- four trematodeTrematodaTrematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
larvaLarvaA larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e in Zambia
Predators of Radix natalensis include leeches Helobdella nilae and Alboglossiphonia conjugata.
Snails of the non-indigenous species Marisa cornuarietis
Marisa cornuarietis
Marisa cornuarietis, common name the giant ramshorn snail, is a species of large freshwater snail with an operculum, an aquatic gastropod mollusk in the family Ampullariidae, the apple snail family....
eliminated Radix natalensis and other two native snail species from a small pond in Tanzania in an experiment in 1982.
Oil extract of the gum myrrh Commiphora myrrha
Commiphora myrrha
Common myrrh or gum myrrh is a tree in the Burseraceae family. It is one of the primary trees used in the production of myrrh, a resin made from dried tree sap...
has molluscicidal
Molluscicide
Molluscicides, also known as snail baits and snail pellets, are pesticides against molluscs, which are usually used in agriculture or gardening to control gastropod pests like slugs and snails that can damage crops by feeding on them....
activity against Radix natalensis.
Phylogeny
A cladogramCladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
shows the phylogenic relations of species in the genus Radix:
External links
- Siwela A. H., Nyathi C. B. & Naik Y. S. (2010). "A comparison of metal levels and antioxidant enzymes in freshwater snails, Lymnaea natalensis, exposed to sediment and water collected from Wright Dam and Lower Mguza Dam, Bulawayo, Zimbabwe". Ecotoxicology and Environmental Safety 73(7): 1728-1732. , doi:10.1016/j.ecoenv.2010.08.001.
- Pilsbry H. A.Henry Augustus PilsbryHenry Augustus Pilsbry was an American biologist, malacologist and carcinologist, among other areas of study. He was a dominant presence in many fields of invertebrate taxonomy for the better part of a century...
& Bequaert J. C.Joseph Charles BequaertJoseph Charles Bequaert was an American naturalist of Belgian origin, born 24 May 1886 in Torhout and died on 12 January 1982 in Amherst ....
(1927). "The aquatic mollusks of the Belgian Congo, with a geographical and ecological account of Congo malacology". Bulletin of the American Museum of Natural HistoryBulletin of the American Museum of Natural HistoryThe Bulletin of the American Museum of Natural History is a peer-reviewed scientific journal in the fields of zoology, paleontology, and geology...
53(2): 69-602. PDF. page 110, 111-114, 568.