Biomphalaria sudanica
Encyclopedia
Biomphalaria sudanica is a species
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 air-breathing 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...

 pulmonate gastropod mollusk in the family
Family
In human context, a family is a group of people affiliated by consanguinity, affinity, or co-residence. In most societies it is the principal institution for the socialization of children...

 Planorbidae, the ram's horn snails.

Distribution

This species is African, and occurs mainly in East Africa:
  • Lake Victoria
    Lake Victoria
    Lake Victoria is one of the African Great Lakes. The lake was named for Queen Victoria of the United Kingdom, by John Hanning Speke, the first European to discover this lake....

    , Kenya, Uganda, (Tanzania)
  • Lake Ziway, Ethiopia
  • Lake Albert, Uganda. (Lake Albert is between Uganda and Democratic Republic of the Congo
    Democratic Republic of the Congo
    The Democratic Republic of the Congo is a state located in Central Africa. It is the second largest country in Africa by area and the eleventh largest in the world...

    )
  • Lake Kyoga
    Lake Kyoga
    Lake Kyoga is a large shallow lake complex of Uganda, about in area and at an elevation of 914 m. The Victoria Nile flows through the lake on its way from Lake Victoria to Lake Albert. The main inflow from Lake Victoria is regulated by the Nalubaale Power Station in Jinja. Another source of water...

    , Uganda
  • 13 crater lake
    Crater lake
    A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...

    s in western Uganda (listed as "Biomphalaria pfeifferi
    Biomphalaria pfeifferi
    Biomphalaria pfeifferi is a species of air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails.This snail is a medically important pest, because of transferring the disease schistosomiasis....

    /sudanica" in these crater lakes)

Phylogeny

A cladogram
Cladogram
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...

 showing the phylogenic relations of species in the genus Biomphalaria:

Ecology

Biomphalaria sudanica is found in shallow water near the shoreline in Lake Albert. Despite being a pulmonate, Biomphalaria sudanica is well adapted to use the oxygen from water (but not as well as Planorbis
Planorbis
Planorbis is a genus of freshwater air-breathing snails, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails, or planorbids. All species in this genus have sinistral or left-coiling shells.- Description :...

). This ability is useful for living in swamp habitats.

The population density
Population density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...

 of Biomphalaria sudanica varies during the year. The highest population density of Biomphalaria sudanica is in Lake Ziway, Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...

 from June to August, at the end of rainy season.

The higher densities of Biomphalaria sudanica occur in habitats with the Common Water Hyacinth Eichhornia crassipes
Eichhornia crassipes
Eichhornia crassipes, commonly known as Common Water Hyacinth, is an aquatic plant native to the Amazon basin, and is often considered a highly problematic invasive species outside its native range.-Ecology:...

 in Lake Victoria
Lake Victoria
Lake Victoria is one of the African Great Lakes. The lake was named for Queen Victoria of the United Kingdom, by John Hanning Speke, the first European to discover this lake....

.

It was experimentally detected under laboratory conditions that shells
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...

 of Biomphalaria sudanica are bigger in waters with higher concentration of calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

 than in waters with low calcium.

Parasites

Biomphalaria sudanica is an 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 Schistosoma mansoni
Schistosoma mansoni
Schistosoma mansoni is a significant parasite of humans, a trematode that is one of the major agents of the disease schistosomiasis. The schistosomiasis caused by Schistosoma mansoni is intestinal schistosomiasis....

 and for Schistosoma rodhaini.

Infestation with schistosomes in the Lake Victoria basin is about 1%, but can be up to 50% in the case of Schistosoma mansoni and up to 6 % in Schistosoma rodhaini in some localities.

Further reading

  • Magendantz M. (1972). "The biology of Biomphalaria choanomphala and B. sudanica in relation to their role in the transmission of Schistosoma mansoni in Lake Victoria at Mwanza, Tanzania". Bulletin World Health Organisation 47(3): 331–341.
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