Gyraulus (Gyraulus ioanis)

Description

Gyraulus fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Gyraulus description

Gyraulus ioanis is a small species of snail in the Planorbidae family, members of which have a shell that is disc-like and flattened in appearance ⁽³⁾. The shell of Gyraulus ioanis has three to four whorls, and is glossy to silky, and also transparent. Fine growth lines can be seen on the shell ⁽²⁾.

The body of Gyraulus ioanis is light grey and is marked with small black spots ⁽²⁾. Like other members of the Planorbidae family, Gyraulus ioanis has long and slender tentacles ⁽⁴⁾.

Size

Shell height: up to 1.3 mm ⁽²⁾

Shell diameter: up to 4.7 mm ⁽²⁾

Gyraulus biology

As it is a rare, recently discovered species of aquatic snail, there is little available information on the biology of Gyraulus ioanis. However, members of the Planorbidae family are known to be hermaphroditic, with an individual snail possessing both male and female sexual organs ⁽³⁾. Planorbidae are pulmonates, meaning that they can breathe air, which enables some members of the family to survive generally unfavourable, low-oxygen conditions. Planorbidae species can also absorb oxygen directly from the water ⁽³⁾.

The diet of most Planorbidae species consists of plant matter, with some species feeding on fresh plants and algae, while others feed on decaying plant matter ^{(3) (5)}.

Gyraulus range

Gyraulus ioanis is endemic to Montenegro, where it occurs only in Šasko Lake ⁽¹⁾.

Gyraulus habitat

Only occurring in the edge zone of Šasko Lake, Gyraulus ioanis inhabits floating and emergent vegetation ⁽²⁾.

Gyraulus status

Gyraulus ioanis is classified as Critically Endangered (CR) on the IUCN Red List ⁽¹⁾.

Gyraulus threats

The entire population of Gyraulus ioanis is restricted to a single, small lake, and is therefore highly vulnerable to alterations in its habitat. The lake is currently undergoing a process known as eutrophication, which results in the depletion of oxygen in the lake and the creation of unfavourable conditions for many organisms ⁽¹⁾.

During the summer, the water level in Šasko Lake decreases due to the interruption in flow of the main river entering the lake. This drop in water level may also potentially threaten Gyraulus ioanis ⁽¹⁾.

Gyraulus conservation

Although there are no known specific conservation actions in place for Gyraulus ioanis, monitoring of this species’ habitat is recommended as a future conservation measure ⁽¹⁾.

Find out more

Find out more about Gyraulus ioanis:

• Glöer, P. and Pešić, V. (2007) Gyraulus meierbrooki, G. ioanis, and G. shasi - three new Gyraulus spp. from the Skadar Lake Basin, Montenegro (Gastropoda: Planorbidae). Mollusca, 25(2): 131-137. Available at:
  http://www.malaco.de/Sonderdrucke/Gloeer_et_Pesic_Gyraulus.pdf

Find out more about species in the Mediterranean Basin:

• ARKive - Mediterranean Basin:
  http://www.arkive.org/eco-regions/mediterranean-basin/

Authentication

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Glossary

Algae

Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.

Emergent

Aquatic plants whose stems and leaves extend beyond the water’s surface.

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Eutrophication

A process in which a water body is enriched with excessive nutrients (such as nitrogen and phosphorus) resulting in the excessive growth of aquatic plants and the depletion of oxygen, creating unfavourable conditions for other organisms, such as fish.

Hermaphroditic

Possessing both male and female sex organs.

Pulmonate

Of or belonging to the Pulmonata, a group of gastropods which are capable of breathing air through lunglike sacs. Includes terrestrial snails and slugs and certain freshwater snails.

Whorl

In animals, a spiral or coil in the shell of a snail. In plants, a set of leaves, flowers, or branches that spring from a stem at the same point and encircle it.

References

1. IUCN Red List (December, 2011)
   http://www.iucnredlist.org/
2. Glöer, P. and Pešić, V. (2007) Gyraulus meierbrooki, G. ioanis, and G. shasi - three new Gyraulus spp. from the Skadar Lake Basin, Montenegro (Gastropoda: Planorbidae). Mollusca, 25(2): 131-137. Available at:
   http://www.malaco.de/Sonderdrucke/Gloeer_et_Pesic_Gyraulus.pdf
3. Baker, F.C. (1945) The Molluscan Family Planorbidae. The University of Illinois Press, Urbana.
4. Brown, D. (2005) Freshwater Snails of Africa and their Medical Importance. Taylor & Francis, London.
5. Recknadel, F. (Ed.) (2003) Ecological Informatics: Understanding Ecology by Biologically-Inspired Computation. Springer, Berlin and Heidelberg.