Description: This small snail has an oval to cone-shaped shell which can range from cream to chocolate brown in colour with the upper whorls often with a hint of purple. There are 7-8 swollen, glossy whorls, and the lower whorls may have darker spiral streaks or blotches. Whorls can be smooth or ribbed and may alternate between these two surfaces, and there are fine spiral ridges on all whorls. A comma-shaped mark is usually present on the last whorl in most mature animals. There is a smooth and ribbed variety (although smooth may have some ribbed whorls and vice versa). It is usually 5 x 3 mm in size.

Habitat: Found from low water mark down to around 15 m depth. Often found on finely branching algae or coralline algae, due to their tendency to collect diatoms and detritus.

Distribution: Recorded from all coasts of Britain and Ireland.

Similar Species: There are several other Rissoa species and other small gastropods which could be confused with this species. The presence of fine spiral ridges and shape of the shell should help distinguish this.

Key Identification Features:

• Cream to chocolate brown coloured shell (5 x 3 mm).
• 7-8 swollen, glossy whorls.
• Mature individuals with comma-shaped mark on last whorl.
• Fine spiral ridges present on all whorls.

Distribution Map from NBN: Rissoa parva at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Rissoa parva at iNaturalist World Species Observations database.

GBIF data for Rissoa parva

WoRMS: Rissoa parva at World Register of Marine Species. Accepted name: Rissoa parva (da Costa, 1778). AphiaID: 141365.

Classification: Biota; Animalia; Mollusca; Gastropoda; Caenogastropoda; Littorinimorpha; Rissooidea; Rissoidae; Rissoa