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Montana Field Guide

Montana Field Guides

Star Gyro - Gyraulus crista

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Native Species

Global Rank: G5
State Rank: SNR

Agency Status

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General Description
Gyraulus crista, commonly called the Star Gyro or Nautilus ramshorn, is a minute species of freshwater snail only about 3mm across, in the family Planorbidae, the ram's horn snails. These small snails have the ability to persist in intermittent ponds and lakes

Diagnostic Characteristics
Very small rarely exceeding 3mm. The minute shell is nearly planispiral in its coiling, but the spire is actually considerably sunken rather than raised (which is usually the case with gastropods). The shell has regular transverse ridges which form points extending beyond the main curve of the periphery of the shell.
Shell color is a translucent yellowy-brown.

Range Comments
The distribution of this species is Holarctic, and includes: the continents of Europe, North America and northern Asia

Observations in Montana Natural Heritage Program Database
Number of Observations: 2

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Usually found on aqautic vegetation within ponds, lakes, wetlands or other lentic waterbodies,

Food Habits
Like most snails, these are herbivorous- scrapers of algae, detritus and diatoms from other vegetation of benthic substrates

Species may be found in intermittent waters including temporary ponds and streams:

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Citation for data on this website:
Star Gyro — Gyraulus crista.  Montana Field Guide.  .  Retrieved on , from