
Thursday 15 February
The World's Favourite Unloved Species 2018 - the Galapagos Racer
Kingdom | Animalia |
Phylum | Mollusca |
Class | Gastropoda |
Order | Neotaenioglossa |
Family | Pleuroceridae |
Genus | Lithasia (1) |
The Shawnee rocksnail (Lithasia obovata) is a member of the Pleuroceridae family of molluscs, which vary in colour from pale yellow to dark brown or black. Members of this family have solid, right-facing shells with the mantle opening facing towards the rear. The spiral operculum, which is the horny or calcareous plate that is attached to the foot and is used to close off the shell when the soft parts of the body are retracted, is typically not circular in shape. The Shawnee rocksnail’s eyes are located on the outer sides of the bases of the tentacles (2).
As in other Lithasia species, female Shawnee rocksnails are typically larger than males. Males of this species do not have external sex organs, and the female lays its eggs through a special egg-laying sinus found on the right-hand-side of the foot (2).
There is little information available on the biology and ecology of the Shawnee rocksnail. However, it is known to be a freshwater (1) benthic species (3) which breathes through gills (2). As with other members of the Pleuroceridae family, the Shawnee rocksnail is thought to be a feeding generalist (2), consuming detritus and other organic material scraped from a variety of substrates (2) (6). This species is believed to have a lifespan of about ten years (2).
A freshwater mollusc (1), the Shawnee rocksnail is a benthic species found in big rivers (3) and streams (2) where it is restricted to isolated, shallow, rocky habitats (2) (3) (4). This species has a relatively large ‘foot’ which is an adaptation to life in shallow areas and enables it to survive wave action (5).
The Shawnee rocksnail has yet to be assessed on the IUCN Red List.
The Shawnee rocksnail is thought to be globally secure and is not considered to be threatened with extinction, as it has a wide distribution and a presumed large population. However, this species is classified as Critically Imperiled in Illinois and as Vulnerable in Pennsylvania (3). It is believed that threatened populations are at risk as a result of the Shawnee rocksnail’s affinity for isolated, shallow habitats and its inability to travel to deeper dispersal pathways (2) (4). The Shawnee rocksnail is also sensitive to cold temperatures, meaning that it is less capable of colonising new habitats (4). In addition, the colonisation of the invasive zebra mussel (Dreissena polymorpha) poses a threat to the Shawnee rocksnail (2).
There are currently no known conservation measures in place for the Shawnee rocksnail.
Find out more about the Shawnee rocksnail:
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:
arkive@wildscreen.org.uk
Image credit
© T. Travis Brown
T. Travis Brown
ttravis.brown@gmail.com
http://www.flickr.com/photos/ttravisbrownphotos/
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Thursday 15 February
The World's Favourite Unloved Species 2018 - the Galapagos Racer
Thursday 01 February
Thursday 01 February