Gyraulus (Gyraulus ioanis)

Gyraulus ioanis shell
Loading more images and videos...

Gyraulus fact file

Gyraulus description

GenusGyraulus (1)

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).

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).

IUCN Red List species status – Critically Endangered


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:

Find out more about species in the Mediterranean Basin:



This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:



Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.
Aquatic plants whose stems and leaves extend beyond the water’s surface.
A species or taxonomic group that is only found in one particular country or geographic area.
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.
Possessing both male and female sex organs.
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.
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.


  1. IUCN Red List (December, 2011)
  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:
  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.

Image credit

Gyraulus ioanis shell  
Gyraulus ioanis shell

© Peter Gloeer

Peter Gloeer


Link to this photo

ARKive species - Gyraulus (Gyraulus ioanis) Embed this ARKive thumbnail link ("portlet") by copying and pasting the code below.

Terms of Use - The displayed portlet may be used as a link from your website to ARKive's online content for private, scientific, conservation or educational purposes only. It may NOT be used within Apps.

Read more about



MyARKive offers the scrapbook feature to signed-up members, allowing you to organize your favourite ARKive images and videos and share them with friends.

Play the Team WILD game:

Team WILD, an elite squadron of science superheroes, needs your help! Your mission: protect and conserve the planet’s species and habitats from destruction.

Conservation in Action

Which species are on the road to recovery? Find out now »

This species is featured in:

This species is featured in the Mediterranean Basin eco-region

Help us share the wonders of the natural world. Donate today!