Plants and Animals

Fontigens nickliniana Watercress snail

Key Characteristics

The watercress snail is a small, freshwater snail with a 3.5 to 4.5 mm long, narrowly conic, shiny, black shell with 4.5 to 7.5 well-rounded whorls and deep sutures where whorls border one another. The operculum (lid that seals the aperture) is roundly ovate with 4-5 rapidly enlarging spirals (paucispiral), and is about 1 mm in width.

Status and Rank

US Status: No Status/Not Listed
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G5 - Secure
State Rank: S2S3 - Rank is uncertain, ranging from imperiled to vulnerable


CountyNumber of OccurrencesYear Last Observed
Allegan 1 2021
Barry 2 1996
Berrien 2 1918
Calhoun 3 2021
Cass 4 2019
Emmet 1 Historical
Huron 2 1943
Kalamazoo 7 2022
Kalkaska 1 2021
Kent 7 2023
Montcalm 1 Historical
Ottawa 1 Historical
St. Joseph 2 2009
Van Buren 3 1947

Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


This species is found on watercress (Naturtium officianale or Rorippa naturtium-aquaticum) in small lakes and ponds, springs, and spring-fed streams. Since watercress is an exotic invasive species of European origin and has only become common in our streams since the early 1900's, it is unlikely that the snail is limited to this plant species.

Natural Community Types

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Management Recommendations

Draining, filling, and other hydrologic alterations should be avoided. This species is likely sensitive to pollution and contaminants. Other invasive plants that may crowd out watercress such as purple loosestrife should be controlled.

Active Period

Active from first week of May to first week of September

Survey Methods

This species can be surveyed using several techniques. One survey method consists of sweeping aquatic vegetation or scraping the substrate with a fine mesh aquatic sampling net or dip net (e.g., D-frame net). Visual surveys of watercress in suitable habitat also can be conducted to look for the watercress snail. Vegetation samples also can be collected and examined later for snails. Another survey technique consists of vigorously shaking aquatic vegetation over a pail of water causing the various snails clinging to the plants to drop to the bottom of the pail.

Shaking vegetation survey

Survey Period: From first week of May to first week of September

Time of Day: Daytime
Water Level: Low Water Levels
Water Turbidity: Low Turbidity

Sweep with dip net

Survey Period: From first week of May to first week of September

Time of Day: Daytime
Water Level: Low Water Levels
Water Turbidity: Low Turbidity

Visual surveys

Survey Period: From first week of May to first week of September

Time of Day: Daytime
Water Level: Low Water Levels
Water Turbidity: Low Turbidity


Survey References

  • Berry, E.G. 1943. The Amnicolidae of Michigan: Distribution, Ecology, and Taxonomy. University of Michigan Press, Ann Arbor. 68pp.
  • Clarke, A.H. 1981. The Freshwater Molluscs of Canada. National Museum of Natural Science, National Museums of Canada, Ottawa. 446pp.

Technical References

  • Burch, J.B. and Y. Jung. 1992. Freshwater snails of the University of Michigan Biological Station area. Walkerana 6(15).
  • Dillon, R.T. Jr. 2000. The Ecology of Freshwater Molluscs. Cambridge University Press, Cambridge, UK. 509pp.
  • Goodrich, C. 1932. The Mollusca of Michigan. The University of Michigan Press, Ann Arbor. 121pp.