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Unless otherwise noted, information contained in each edition of the Kansas School Naturalist reflects the knowledge of the subject as of the original date of publication.

Volume 61, Number 2 - December 2014

Checklist of the Aquatic Snails of Kansas

Vol. 61, No. 2 - December 2014 - Checklist of the Aquatic Snails of Kansas


Back cover of Vol 61, No 2

Front and Back Covers: Planorbella trivolus from Lyon County Kansas (photos by Greg Seivert)

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ISSN: 0022-877X




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Acknowledgements: I appreciate the taxonomic perspectives of Jeremy Teimann (Illinois Natural History Survey) and Clint Goodrich (Ks. Dept. of Health and Environment). I am, of course, responsible for variations on the themes. The photos in Figures 5 and 13 are used by permission of Dr. Kathryn E. Perez and copyright by the University of Wisconsin La Crosse, taken by Chris Lynum, and modified by the author.


Dr. Joe Arruda is a Professor of Biology at Pittsburg State University where he teaches introductory biology and upper-division courses in environmental science and field ecology. His education includes B.S. in biology from UMass-Dartmouth and the M.S. and Ph.D. from Kansas State University.

Contribution Card

Checklist of the Aquatic Snails of Kansas

by Joe Arruda


There are over 600 species of aquatic snails in North America (Johnson 2009, Johnson et al. 2013). In Kansas, there may be 20 to 30 species. Kansas aquatic snails fall into two major groups based on shell characteristics and breathing – prosobranchs (water breathers) and pulmonates (air breathers).

Prosobranch snails have a single gill for breathing and a cover called an operculum. When out of the water, the cover shuts the animal off and protects it from drying. The operculum is also used in identification. The prosobranchs vary in size, but all have stoutly built shells – not thin and flimsy. They are more commonly encountered in flowing waters – streams and rivers, either swifter or slower areas of flow. Because they have gills, they are more sensitive to water quality problems than the pulmonate snails.

Pulmonate snails have a “lung” of sorts for breathing in air but no operculum. Their shells are generally thinner than the prosobranchs and they are more commonly encountered in standing water environments – lakes, slow areas of streams, and wetlands.

We do not know enough about the distribution and abundance of aquatic snails in Kansas. Hopefully, this edition of the Kansas School Naturalist will help inspire more collecting and advance our understanding.

Where Do You Find Aquatic Snails?

Aquatic snails are found in both standing and flowing waters. Standing waters include ponds, lakes, and wetlands. Look along the shoreline and backwaters in and on aquatic vegetation, rocks, and sediments.

In the backwater area of lakes and around wetlands, examine the wet soils around exposed vegetation and the vegetation as well. Turn rocks around and examine crevices (Figure 1) for snails and their eggs.

Figure 1

Figure 1. The Pyramid Elmia on rocks from Shoal Creek (Cherokee County, KS)

Flowing waters are streams and rivers where snails may be found in various habitats - slower or faster current, clearer or murkier, softer sediments in pools, on or under streamside rocks (Figure 2).

Figure 2

Figure 2. View of Shoal Creek (Cherokee County, KS).

Keeping Aquatic Snails

Aquatic snails are easily collected from their habitats. Most are readily apparent, but some need a closer look to find them, requiring sifting sediments and vegetation. While some will do well in aquaria, it is best to leave snails where you find them. If you bring some into the classroom or home for observation, be sure to return them to where they were found.

Ecological Role

Aquatic snails are grazers and important links in aquatic food webs. They glide on surfaces with their foot  and use a specialized device called a radula (Figure 3) to scrape surfaces.

Figure 3

Figure 3. The radula of a non-native snail.
Photo: Greg Sievert.

A radula is a “belt” of tissue with teeth. As the teeth are worn away, a new belt and teeth are made to replace them. They scrape any surface (rocks, aquatic plants, sediments) for their food – algae and other organisms in the “slime zone” including bacteria and protozoa.

In turn, snails are food for fish, crayfish, turtles, and waterfowl, thus completing an important link in the chain of life in aquatic ecosystems.

What is a Snail’s Life Like?

The life histories of the two groups vary. The prosobranchs tend to be longer-lived and grow more slowly than do pulmonate snails. (Dillon 2000, Johnson 2009).

Prosobranch snails have separate males and females with internal fertilization. Pulmonates are hermaphroditic, with each individual producing both sperm and eggs.

Snail eggs are laid in various forms – strands or masses, for example. Some leave their eggs exposed (Figure 4) and others place them under surfaces. The “apple” snails lay eggs on vegetation above the surface (Dillon 2000).

Figure 4

Figure 4. A clump of snail eggs on the side of woody debris in a stream.

Are Aquatic Snails Endangered or Threatened?

The Freshwater Mollusc Conservation Society (2014) suggests that 10% of North American species are extinct and 55% are endangered or threatened. In Kansas, there are two state-listed threatened and one state-listed endangered species. The Delta Hydrobe (Probythinella emarginata) and the Sharp Hornsnail (Pleurocera acuta) are the threatened species.

Figure 5

Figure 5. The Delta Hydrobe (left) (Source: Univ. Wisconsin) and the Sharp Hornsnail
(Source: U.S. Geological Survey).

The Delta Hydrobe (Figure 5) was listed as a threatened species in 2009 (KDWPT 2014a). It is a tiny snail (<5mm high) with a flattened apex that makes it easy to identify. The only known site for it is in the very clean water of Cedar Creek in Chase County, where it was collected in 2001 (Angelo et al. 2002).

The Sharp Hornsnail (Figure 5) was also listed as Threatened in 2009 (KDWPT 2014b). This is a larger snail (about 1 inch high), conical, and very elongate.

The Walnut and the Marais des Cygnes rivers were its historical home in Kansas. A more recent collection on the Marais des Cygnes River was made in 1998.

The Sharp Hornsnail is a snail of relatively shallow water in protected areas of larger lakes and streams and tends to live under sand and decaying leaves (KDWPT 2014a).

Figure 6

Figure 6. Slender Walker (6-7 mm).

The Kansas endangered species (since 1987) is the Slender Walker (Pomatiopsis lapidaria) (KDWPT 2014c). The Slender Walker (Figure 6) is actually not purely aquatic – it is amphibious. It is able to spend time out of the water, climbing on emergent vegetation.

The Slender Walker is found at only one location in Kansas, a marsh in Atchison County in northeast Kansas.

Two species are likely extirpated from the state. These are the Mud Amnicola (Amnicola limnosus) and the Ponderous Campeloma (Campeloma crassulum) (Angelo et al. 2002). However, there may be relic populations as yet not surveyed.

The case of the Ponderous Campeloma is complicated. There are no recent records of this species or its congener the Pointed Campeloma (Campeloma dec-isum) in Kansas (Angelo et al. 2002). But Angelo et al. (2002) did note a report of the Pointed Campeloma in Shoal Creek in Southeast Kansas although recent surveys have found none. On the other hand, there are recent records of the Pointed Campeloma in Missouri, not far from the border. It is more likely that if a species of Campeloma is to be found in Kansas, it will be the Pointed Campeloma.

There are no recent records of the Mud Amnicola in Kansas and older records were restricted to northeast Kansas (Angelo et al. 2002). The species has been found in northwest Missouri, so it is possible that there are populations hidden in northeast Kansas.

Are Aquatic Snails Pests?

Two species of snails, part of the aquarium trade and both nonnative, have been found in Kansas. They are the Chinese Mystery Snail (Cipangopaludina chinensis) and the Japanese Mystery Snail (Cipangopaludina japonica). Both of the mystery snails are large animals, reaching over 50 mm in diameter. These and other exotic species must never be released into the environment.

The New Zealand Mudsnail (Potamopyrgus antipodarum) is a new invader to the United States. It is a small snail (about 1/8 inch) and may be inadvertently carried by anyone recreating in or on the water. The closest location where they have been found is in eastern Colorado.

The transmission of some parasites, such as the one responsible for the tropical disease schistosomiasis, is linked to aquatic snails. In the U.S., the common "swimmer’s itch" is caused by a parasite that uses aquatic snails and water birds as part of the transmission cycle.

Who Are Snails Related To?

Snails are Gastropods, a large and important group of Mollusks (Figure 7). You are probably most familiar with sea shells – the marine gastropods.

Figure 7

Figure 7. Relationships among the mollusks.

Two other major groups of mollusks are the bivalves (clams and mussels) and cephalopods (squid and octopus). Kansas once had a rich fauna of fresh-water mussels and while many remain, some are still threatened or endangered.

The origin of freshwater snails is complex (Johnson et al. 2013). Marine snails are the ancestors of the prosobranch snails - those groups with an operculum and a single gill (FMCS 2014). The group does not represent one single invasion of freshwater, but likely several over time (Dillon 2000).

Pulmonate aquatic snails, the air breathers, are descended from land ancestors (FMCS 2014), probably due to a single invasion (Dillon 2000). The pulmonates breathe inside the shell using their mantle tissue (that also makes the shell) in the same way as their terrestrial counterparts. Unlike land snails, though, the eyes of the pulmonates are at the base of the tentacles not at the top of the tentacles (Figure 8).

Figure 8

Figure 8. Aquatic snail (top) with eyes at base and land snail (bottom) with eyes at tip of tentacle.

Because of their use of water for oxygen, prosobranchs are considered to be more sensitive to environmental impacts compared to the air-breathing pulmonates (Angelo et al. 2002).

Note that the terms "prosobranch" and "pulmonates" are terms of convenience, no longer of specific taxonomic rank (although taxonomy is in flux).

Major Features of Kansas Aquatic Snails

The major characters to observe in aquatic snails are the type of coils (elevated, flat, or absent), presence or absence of an operculum, and handedness of the aperture (left or right).

Operculum – The operculum is a horny plate that closes the aperture (the opening of the shell) with the animal withdrawn inside. The prosobranch snails have opercula that can be seen when alive (Figure 9). When dead, the operculum which was attached to the animal’s body, is lost (Fig. 10)

Figure 9

Figure 9. Elimia potosiensis alive with its operculum.

Figure 10

Figure 10. Elimia potosiensis

Type of Coil and Spire – this is an easily seen character.

Elevated - The winding of the snail’s coil (whorls) rises to the apex as in Figure 10 for the prosobranch Elimia and Figure 11 for the pulmonate Physella.

Figure 11

Figure 11. Physella.

Flat (planospiral) – The winding of the coil stays in the same plane, like a cinnamon roll. Some Planorbid snails, including Planorbella trivolus (Figure 12), are examples. The "spire" is actually sunken below the upper edge of the body whorl.

Figure 12

Figure 12. Planorbella trivolus

None – Limpets have no coil at all, the shell is one piece with a slight peak, or apex (Fig. 13).

Figure 13

Figure 13. A limpet. (Source: Univ. Wisconsin)

Handedness – hold the snail with the spire upwards and observe the location of the aperture. The snail is either right-handed (Figure 10) or left-handed (Figure 11). The Planorbid snails are not usually evaluated as to handedness, but they are left-handed as in Planorbella (Figure 12).

About The Kansas Checklist

Current taxonomic issues and perspectives make developing a checklist a challenge. The need for more extensive collections and suitable molecular analysis is great. A further challenge is that aquatic snails display a great deal of morphological plasticity – even in the same reach or water body, regionally, or due to changes in size/age. Data are needed to assess local and regional geographic variability in order to better define species and their ranges.

As a result, any checklist must be considered to be tentative. This list is a conservative working list based on Johnson et al. (2013) considering the earlier work of Leonard (1959) for Kansas and Wu et al. (1997) for Missouri as well as Angelo et al. (2002) and Burch (1989).

This list has 30 species, but probably only 28 are extant, with Campeloma crassulum not recently collected. Amnicola limosus has not been collected recently (Angelo et al. 2002).

In addition, the status of the Lymnaeds has not been worked out. The six species listed here might well be only two or some intermediate number. This could bring the state list down to 24 species without Campeloma or Amnicola. Physid phylogeny is also being debated.

Checklist of Kansas Aquatic Snails

(Th = threatened, En = Endangered, In = invasive)

Prosobranch Snails


Amnicola limosa 1 (Mud Amnicola)


Cincinnatia integra (Midland Siltsnail)

Probythinella emarginata (Delta Hydrobe, Th)


Elimia potosiensis (Pyramid Elimia)

Pleurocera acuta (Sharp Hornsnail, Th)


Pomatiopsis lapidaria (Slender Walker, En)


Campeloma crassulum 1 (Ponderous Campeloma)

Cipangopaludina chinensis (Chinese Mystery Snail, In)

Cipangopaludina japonica (Japanese Mystery Snail, In)


Pulmonate Snails

Ancylidae 2

Ferrissia fragilis 3 (Fragile Ancylid)

Ferrissia rivularis 3 (Creeping Ancylid)

Laevapex fuscus (Dusky Ancylid)


Galba bulimoides 4 (Prairie Fossaria)

Galba dalli 4 (Dusky Fossaria)

Galba rustica 5 (a freshwater snail)

Galba obrussa 5 (Golden Fossaria)

Galba parva 5 (Pygmy Fossaria)

Galba techella 4 (a freshwater snail)

Pseudosuccinea columella (Mimic Lymnaea)

Stagnicola elodes (Marsh Pondsnail)

Stagnicola exilis (Flat-whorled Pondsnail)


Physella heterostropha (Pewter Physa)

Physella gyrina (Tadpole Physa)

Physella pomilia (Glossy Physa)


Gyraulus circumstriatus (Disc Gyro)

Gyraulus parvus (Ash Gyro)

Helisoma anceps (Two-ridged Ramshorn)

Planorbella trivolus (Marsh Ramshorn)

Promenetus exacuous (Sharp Sprite)

Promenetus umbilicatellus (Umbilicate Sprite)


1. These are likely extirpated, but presence in Missouri (Angelo et al. 2002) offers hope they may be found in Kansas.

2. Johnson et al. (2012) placed these species from the family Ancylidae into the Planorbidae.

3. These may be one species ("rivularis").

4. These may be one species ("bulimoides").

5. These may be one species ("humulis").

Common Kansas Aquatic Snails

The common aquatic (and semiaquatic or amphibious) snails presented here are those likely to be seen by the casual observer in suitable habitat.

There are no simple guides to identify aquatic snails. This list and basic information should help identify some of the common aquatic snails.

(A) Prosobranchs (9 species, 2 threatened, one endangered, 2 invasive)

All prosobranchs are right-handed and all have an operculum. But the operculum is absent from empty shells, making the presence of a live specimen important (but not impossible with experience).

Examples of the two species more likely to be encountered are given here.


(A1) Elimia potosiensis, the Pyramid Elimia (14-15 mm)



(A2) Cincinnatia integra, the Midland Siltsnail (5-6 mm)


(B) Pulmonates (21 species)



(B1) No spire, no coil – the limpets (3 species – as in Figure 13)


(B2) No spire, but coiled – Planorbid snails (6 species)

see caption below

Gyraulus parvus, a Gyro snail (2-3 mm).


see caption below

Planorbella trivolus, the Marsh Ramshorn (apical view, 11-12 mm)


(B3) High spire, right-handed – Lymnaeid snails (9 species)


see caption below

Galba (7-8 mm)


see caption below

Lymnaea columella, the Mimic Lymnaea (12-13 mm)


(B4) High spire, left-handed – Physid snails (3 species)

see caption below

Physella (~ 6 mm)



Angelo, R., Cringan, M. and Fry, J. 2002. Distributional revisions and new and amended occurrence records for prosobranch snails in Kansas. Transactions of the Kansas Academy of Science, 105: 246-257.

Burch, J. 1989. North American Freshwater Snails. Hamburg, MI: Malacological Publications.

Dillon, R.T. 2000. The Ecology of Freshwater Molluscs. Cambridge University Press. Cambridge, UK. 509 pp.

Freshwater Mollusk Conservation Society. 2014. Freshwater Snails – Snails Home. Retrieved December 8, 2014, from

Johnson, P. D. 2009. Sustaining America’s Aquatic Biodiversity - Freshwater Snail Biodiversity and Conservation. Publication 420-530. Virginia Cooperative Extension, Virginia Technological University and Virginia State University.

Johnson, P. D., A. E. Bogan, K. M. Brown, N. M. Burkhead, J. R. Cordeiro, J. T. Garner, P. D. Hartfield, D. A. W. Lepitzki, G. L. Mackie, E. Pip, T. A. Tarpley, J. S. Tiemann, N. V. Whelan & E. E. Strong. 2013. Conservation status of freshwater gastropods of Canada and the United States. Fisheries, 38: 247–282.

Kansas Dept. Wildlife, Parks, and Tourism. Delta Hydrobe. 2014a. Retrieved December 8, 2014, from

Kansas Dept. Wildlife, Parks, and Tourism. Sharp Hornsnail. 2014b. Retrieved December 8, 2014, from

Kansas Dept. Wildlife, Parks, and Tourism. Slender Walker. 2014c. Retrieved December 8, 2014, from

Leonard, Arthur B. 1959. Handbook of Gastropods in Kansas. With the technical assistance of E.J. Roscoe and others. Museum of Natural History Miscellaneous Publication no. 20. Lawrence: University of Kansas. 224 pp.

Wu, S.-K., Oesch, R. and Gordon, M. 1997. Missouri Aquatic Snails. Jefferson City: Missouri Department of Conservation.

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