Aplexa
Encyclopedia
Aplexa is a genus
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.

Shell description

These small snails are quite distinctive, because they have 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...

 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 Aplexa 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 relatively high and 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 Aplexa include:
  • Aplexa hypnorum
    Aplexa hypnorum
    Aplexa hypnorum, common name the moss bladder snail, is a species of small air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Physidae, a family which are sometimes known as the bladder snails....

    Linnaeus, 1758 - type species
  • Aplexa elongata (Say, 1821) - the lance aplexa
  • Aplexa rivalis
    Aplexa rivalis
    Aplexa rivalis is a species of small air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Physidae, a family which are sometimes known as the bladder snails.-Ecology:...

    Maton & R.

Further reading

  • "Genus summary for Aplexa". AnimalBase
    AnimalBase
    AnimalBase is a project brought to life in 2004 and is maintained by the University of Göttingen, Germany. The goal of the AnimalBase project is to digitize early zoological literature, provide copyright-free open access to zoological works, and provide manually verified lists of names of...

    .
  • Janus, Horst, 1965. ‘’The young specialist looks at land and freshwater molluscs’’, Burke, London
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