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Campeloma decisum

What do they look like?

Pointed campeloma snails are 2 cm to 4 cm or more in length. The shells are long and spiraled, and light yellowish green to olive green in color, but can also have spots of tan, brown, or rust. Adults have spiral lines on them. Young snails have white or light translucent beige shells. This species has a structure called an operculum, which is a plate attached to the body of the snail. When the snail draws back into the shell, the operculum covers the opening of the shell and seals it off. The operculum has a horn-like color and has rings on it. The soft body of the snail is gray, with orange spots on the underside of the foot (the body of the snail, which it moves along on). The front of the foot is square, and the back end is round. In populations that reproduce by mating, females are bigger than males. Males also have a right tentacle that is shorter and thicker than the left tentacle. (Burch and Jung, 1992; Burch, 1989; Great Lakes Environmental Research Laboratory, 2008)

  • Sexual Dimorphism
  • female larger
  • Range length
    2 to 4 cm
    0.79 to 1.57 in

Where do they live?

What kind of habitat do they need?

Pointed campeloma snails are generally found in flowing waters, particularly rivers, and are also found in some slow-moving environments, such as lakes. They are more common in areas with sandy substrate at the bottom of the water. (Bovbjerg, 1952; Dillon, et al., 2006; Johnson, 1992a)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

How do they grow?

There is little known about the development of pointed campeloma snails. Young are born within the female parent and eat within a special pouch until they are released. In one study in Lousiana, more females were present in the population, and young were released from two year old snails. (Brown, et al., 1989; Burch and Jung, 1992; Johnson, 2003)

How do they reproduce?

There is little known about the mating habits of pointed campeloma snails. This species has both sexual and parthenogenic populations. Sexual populations reproduce with two individuals mating, while parthenogenic populations reproduce without mating. Mating usually takes place in the warmer months of the year. (Brown, et al., 1989)

Pointed campeloma snails give birth to live young. Different populations have different patterns of when and how they reproduce. For example, in Louisiana, this species has a shorter life cycle than northern populations, and is able to reproduce at the age of two years. Some populations reproduce by a male and female snail mating, while other populations reproduce by parthenogenesis, which is when female snails give birth without mating. Some populations reproduce both ways. (Brown, et al., 1989; Dillon, et al., 2006; Johnson, 1992b)

  • How often does reproduction occur?
    Campeloma descisum mates once a year.
  • Breeding season
    Campeloma descisum mates in the warmer months of the year.

Females provide parental care before birth. Young are born inside the female and will feed inside a yolk sac until released. Parental care stops after the snails are born. (Burch, 1989; Johnson, 2003; Burch, 1989; Johnson, 2003)

  • Parental Investment
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female

How long do they live?

The lifespan of pointed campeloma snails differs depending on where they live. Those that live in colder regions live 3 to 5 years, though some can live up to 12 years. Snails living in warmer areas live only 1 to 2 years. (Brown, et al., 1989; Burch and Jung, 1992; Dillon, et al., 2006)

  • Typical lifespan
    Status: wild
    1 to 12 years

How do they behave?

Pointed campeloma snails are usually found around decaying matter, and burrow in the substrate. Individuals gather in groups and may move up to 10 m upstream. These groups can be very large; they have been measured at 300 snails in a single square meter on average, while peaking in the summer to 600 to 800 snails per square meter. (Bovbjerg, 1952; Brown, et al., 1989; Burch and Jung, 1992)

How do they communicate with each other?

These snails have a central nervous system. They have eye spots at the base of their tentacles, which can see light. They can detect chemicals to find their food. (Burch and Jung, 1992; Burch, 1989)

What do they eat?

Pointed campeloma snails eat detritus, which is small bits of decaying matter. They are filter feeders, meaning that they filter their food particles out of the water and sediment. (Brown, et al., 1989; Great Lakes Environmental Research Laboratory, 2008)

What eats them and how do they avoid being eaten?

Pointed campeloma snails are eaten by fish, diving ducks, turtles and crayfish. Burrowing in the soil and dirt at the bottom of rivers and lakes may be a good way for these snails to avoid being eaten by predators. (Johnson, 2003; van Appledorn, et al., 2007)

What roles do they have in the ecosystem?

Freshwater snails are an important part of aquatic ecosystems. They cycle nutrients by eating and digesting algae and other decaying matter. Pointed campeloma snails are a significant food source for fish, diving ducks, turtles and crayfish. Freshwater snails are often hosts for parasitic flatworms called flukes or trematodes. Pointed campoloma snails are hosts for the fluke Sanguinicola occidentalis. After the fluke develops in the snail's body, it goes on to infect yellow perch. These snails are also hosts for the trematode Leucochloridiomorpha constantiae, which infects water fowl after it has develop inside the snail. This trematode is found in the female reproductive system in populations that reproduce by parthenogenesis. (Johnson, 1992a; Johnson, 2003; Muzzall, 2000)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • fluke, Sanguinicola occidentalis
  • trematode, Leucochloridiomorpha constantiae

Do they cause problems?

Pointed campeloma snails do not cause any problems for humans.

How do they interact with us?

Pointed campeloma snails do not have any positive effects on humans.

Are they endangered?

Pointed campeloma snails are not an endangered species. However, their populations could decrease in the future due to the effects of the invasive zebra mussel, Dreissena polymorpha. The zebra mussel settles on the snail, making it harder for it to move and grow. If this causes many snails to die, then research and conservation efforts could be needed in the future to keep this species from becoming threatened. (van Appledorn, et al., 2007)


Renee Mulcrone (author), Special Projects, Angela Miner (editor), Animal Diversity Web Staff.


2003. "Campeloma decisum" (On-line). Encyclopedia of Life. Accessed May 29, 2013 at

Bovbjerg, R. 1952. Ecological aspects of dispersal of the snail Campeloma decisum. Ecology, 33/2: 169-176.

Brown, K., D. Varza, T. Richardson. 1989. Life histories and population dynamics of two subtropical snails (Prosobranchia: Viviparidae). J. N. Am. Benthol. Soc., 8: 222-228.

Burch, J. 1989. Freshwater snails of North America. Hamburg, Michigan: Malacological Publications.

Burch, J., Y. Jung. 1992. Freshwater Snails of the University of Michigan Biological Station Area. Walkerana, 6/15: 1-218.

Dillon, R., B. Watson, T. Stewart, W. Reeves. 2006. "Campeloma decisum (Say 1817)" (On-line). The freshwater gastropods of North America. Accessed May 29, 2013 at

Great Lakes Environmental Research Laboratory, 2008. "Viviparidae" (On-line). Great Lakes water life photo gallery. Accessed May 30, 2013 at

Johnson, P. 2003. Sustaining America's aquatic biodiversity - Freshwater snail biodiversity and conservation. Virginia Cooperative Extension, Publication no. 420-530: 1-7. Accessed October 11, 2013 at

Johnson, S. 1992. Spontaneous and hybrid origins of parthenogenesis of Campeloma decisum (freshwater prosobranch snail). Heredity, 58: 253-261.

Johnson, S. 1992. Parasite-Induced Parthenogenesis in a Freshwater Snail: Stable, Persistent Patterns of Parasitism. Oecologia, 89/4: 533-541.

Karowe, D., T. Pearce, W. Spaller. 1993. Chemical communication in freshwater snails: Behavioral responses of Physella parkeri to mucous trails of P. parkeri (Gastropoda: Pulmonata) and Campeloma decisum (Gastropoda: Prosobranchia). Malacological Review, 26: 9-14.

Laman, T., N. Boss, H. Blankespoor. 1984. Depth distribution of seven species of gastropods in Douglas Lake, Michigan. Nautilus, 98: 20-24.

Muzzall, P. 2000. Occurrence of Sanguinicola occidentalis Van Cleave and Mueller, 1932 in Perca flavescens and Campeloma decisum from a Michigan Creek. Journal of Parasitology, 86/6: 1360-1362.

van Appledorn, M., D. Lamb, K. Albalak, C. Bach. 2007. Zebra mussels decrease burrowing ability and growth of a native snail, Campeloma decisum. Hydrobiologia, 575: 441-445.

University of Michigan Museum of ZoologyNational Science Foundation

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Mulcrone, R. 2014. "Campeloma decisum" (On-line), Animal Diversity Web. Accessed October 23, 2017 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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