Ferrissia (synonym Gundlachia) are small, limpet-shaped snails, often with semi-transparrent shells that are easily overlooked (if you don’t have a microscope). Small individuals have fragile shells, but with increasing size the shells become more thickened and coloured. The limpet shape is asymetrical but not as paua-shaped as the larger native limpet Latia.
Ferrissia are most common in slow-flowing, weedy streams where they often attach to submerged plant surfaces. Some populations also occur on stony bottom streams.
Like most snails they are grazers, scraping biofilms from submerged surfaces.
- Hard bottom: 3
- Soft bottom: 2.4
The tolerance values (ranging from 0 to 10) give an indication of which are the sensitive taxa (values of 8 or more) and which are the tolerant taxa (values of 3 or less). For more information see: Indicator species
Ferrissia can be abundant in farmland streams with moderate to poor water quality. They have been assigned tolerance values of 3 (hard bottom sites) and 2.4 (soft bottom sites).