Plants and Animals

Vertigo morsei Six-whorl vertigo

Key Characteristics

The six-whorl vertigo is a small land snail with a dark brown cylindrical (beehive-shaped) shell that is 2.7 mm in height with 6 to 6.5 whorls. The aperture (main opening) is relatively small, with a slight constriction in the palatal (outer shell) region, and has 8 or 9 short teeth.

Status and Rank

US Status:
State Status: E - Endangered (legally protected)
Global Rank: G3 - Vulnerable
State Rank: S1? - Critically imperiled (inexact or uncertain)

Occurrences

CountyNumber of OccurrencesYear Last Observed
Mackinac42009

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.

Habitat

The six-whorl vertigo inhabits calcareous fens occurring in organic-rich soil overlaying marl. The species also is reported to occur along the edges of ponds and marshes.

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

This species is vulnerable to foot and vehicle (ORV) traffic and road construction. Hydrological changes should be strictly avoided. Use of prescribed fire in occupied sites should be avoided, if possible, or prescribed fire should be applied very conservatively, leaving multiple refugia and using a burn interval of at least 15 years.

Active Period

Active from first week of June to fourth week of September

Survey Methods

Surveys can be conducted anytime during the growing season, but are most successful in spring and fall following rain showers or when the soil is moist, and during higher relative humidity conditions and cooler temperatures. Visual surveys consist of looking for individuals crawling on the ground, in moist leaf litter, and on or under woody debris. Litter sampling consists of collecting soil and leaf litter samples in the field and drying, sifting and looking for snail shells in the litter samples in the laboratory.

Visual survey

Survey Period: From first week of June to fourth week of September

Humidity: Humid
Precipitation: Just after rain

Litter sampling

Survey Period: From first week of June to fourth week of September

Humidity: Humid
Precipitation: Just after rain

References

Survey References

  • Nekola, J.C. 1998. Terrestrial Gastropd Inventory of the Niagaran Escarpment and Keweenaw Volcanic Belt in Michigan's Upper Peninsula. Small Grants Program, 1998 Nongame Wildlife Fund, Natural Heritage Program, Michigan DNR, Lansing. 133pp.
  • Schilthuizen, M. and H.A. Rutjes. 2001. Land snail diversity in a square kilometer of tropical rainforest in Sabah, Malaysian Borneo. Journal of Molluscan Studies 67:417-423.

Technical References

  • Hubricht, L. 1985. The Distributions of Native Land Mollusks of the Eastern US. Field Museum of Natural History. Fieldiana: Zoology, No. 24.
  • Nekola, J.C. 1998. Terrestrial Gastropd Inventory of the Niagaran Escarpment and Keweenaw Volcanic Belt in Michigan's Upper Peninsula. Small Grants Program, 1998 Nongame Wildlife Fund, Natural Heritage Program, Michigan DNR, Lansing. 133pp.
  • Nekola, J.C., T.A. Smith and T.J. Frest. 1996. Land snails of Door Peninsula natural habitats. Final report to the Wisconsin Chapter of The Nature Conservancy. 55pp.