Physa
Encyclopedia
Physa is a genus
of small, left-handed or sinistral, air-breathing freshwater snail
s, aquatic
pulmonate gastropod mollusks in the family Physidae
.
These snails eat algae, diatom
s and detritus.
possess a complex of muscles that is unique amongst gastropods. This complex was given the name “physid musculature”. The physid musculature has two main components, the physid muscle sensu stricto and the fan muscle. The physid musculature is responsible for a unique ability of physids to rapidly flick their shells from side to side — a reaction that frequently enables them to escape predation.
that are sinistral, which means that if you hold the shell such that the spire is pointing up, then the aperture is on the left-hand side.
The shells of Physa species have a long and large aperture
, a pointed spire
, and no operculum
. The shells are thin and corneous, and rather transparent.
Synonyms:
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of small, left-handed or sinistral, 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....
s, 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 mollusks in the family Physidae
Physidae
Physidae, common name bladder snails, are a monophyletic taxonomic family of small freshwater snails, aquatic pulmonate gastropod molluscs in the clade Hygrophila....
.
These snails eat algae, diatom
Diatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
s and detritus.
Anatomy
Members of the freshwater pulmonate family PhysidaePhysidae
Physidae, common name bladder snails, are a monophyletic taxonomic family of small freshwater snails, aquatic pulmonate gastropod molluscs in the clade Hygrophila....
possess a complex of muscles that is unique amongst gastropods. This complex was given the name “physid musculature”. The physid musculature has two main components, the physid muscle sensu stricto and the fan muscle. The physid musculature is responsible for a unique ability of physids to rapidly flick their shells from side to side — a reaction that frequently enables them to escape predation.
Shell description
These small snails, like all the species in the family Planorbidae, have shellsGastropod 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...
that are sinistral, which means that if you hold the shell such that the spire is pointing up, then the aperture is on the left-hand side.
The shells of Physa species have a long and large 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....
, a pointed spire
Spire (mollusc)
A spire is a descriptive term for part of the coiled shell of mollusks. The word is a convenient aid in describing shells, but it does not refer to a very precise part of shell anatomy: the spire consists of all of the whorls except for the body whorl...
, and no operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
. The shells are thin and corneous, and rather transparent.
Species
Species in the genus include:- Physa ancillaria (Say, 1825) - Pumpkin Physa
- Physa carolinae Johns Island, South Carolina 2010 by Amy Wethington in ditch, then confirmed at the University of Alabama
- Physa concolor
- Physa fontinalisPhysa fontinalisPhysa fontinalis is a species of freshwater snail, an aquatic gastropod mollusk in the family Physidae. The shells of this species are left-handed or sinistral.-Distribution:...
- Fountain bladder snail - type species - Physa hordacea (I. Lea, 1864)
- Physa jennessi Dall, 1919
- Physa lordi (Baird, 1863)
- Physa marmorataPhysa marmorataPhysa marmorata is a species of freshwater snail, a gastropod in the Physidae family.- Further reading :* Appleton C. C. & Dana P. . "Re-examination of Physa mosambiquensis Clessin, 1886 and its relationship with other Aplexinae reported from Africa". African Invertebrates 46: 71-83....
Guilding, 1828 - synonyms: Physa mosambiquensis Clessin, 1886 and Physa waterloti - Physa megalochlamys Taylor, 1988
- Physa natricina Taylor, 1988
- Physa nuttalli
- Physa propingua (Tryon, 1865)
- Physa pumilia Conrad, 1834
- Physa siberica Westerlund, 1876
- Physa skinneriPhysa skinneriPhysa skinneri, common name the glass physa, is a species of freshwater snail, an aquatic gastropod mollusk in the family Physidae.- Distribution :This species occurs in:* Canada* Montana, USA...
Taylor, 1954 - Physa vernalis Taylor et Jokinen, 1984
- Physa sp., Lake Winnipeg Physa, lives in ManitobaManitobaManitoba is a Canadian prairie province with an area of . The province has over 110,000 lakes and has a largely continental climate because of its flat topography. Agriculture, mostly concentrated in the fertile southern and western parts of the province, is vital to the province's economy; other...
in Canada. It was classified as endangered by COSEWIC. COSEWIC recommendation has been forwarded to the Minister of the Environment of CanadaMinister of the Environment (Canada)The Minister of the Environment is the Minister of the Crown in the Canadian Cabinet who is responsible for overseeing the federal government's environment department, Environment Canada...
and a decision for listing at the List of Wildlife Species at Risk of the Canadian Species at Risk ActSpecies at Risk ActThe Species at Risk Act is a piece of Canadian federal legislation which became law in Canada on December 12, 2002. It is designed to meet one of Canada's key commitments under the International Convention on Biological Diversity. The goal of the Act is to protect endangered or threatened...
was pending in 2005.
Synonyms:
- Physa acuta Draparnaud, 1805, Physa heterostropha (Say, 1817) and Physa integra (Haldeman, 1841) are a synonyms for Physella acutaPhysella acutaPhysella acuta, common name the European physa, is a species of small, left-handed or sinistral, air-breathing freshwater snail, an aquatic gastropod mollusk in the family Physidae.-Shell description:...
(Draparnaud, 1805) - Physa columbiana (Hemphill, 1890) is a synonym for Physella columbiana (Hemphill, 1890)
- Physa gyrina (Say, 1821) is a synonym for Physella gyrinaPhysella gyrinaPhysella gyrina common name the "tadpole physa", is a species of small, left-handed or sinistral, air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Physidae.-Shell description:...
(Say, 1821)
External links
- http://www.animalbase.uni-goettingen.de/zooweb/servlet/AnimalBase/list/species?taxongenus=301
- Dillon R. T., Wethington A. R. & Lydeard C. (2011). "The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail Physa". BMC Evolutionary Biology 11: 144. doi:10.1186/1471-2148-11-144.