Campeloma decisum

Geographic Range

The pointed campeloma, Campeloma decisum, is a freshwater snail found in eastern North America. It ranges from Nova Scotia, southern Ontario and southern Manitoba, south to eastern Texas, Louisiana, Mississippi, Alabama, and northern Georgia and Virginia. ("Campeloma decisum", 2003; Burch, 1989)


Campeloma decisum is generally found in flowing waters, particularly rivers, and is also found in lentic environments, such as lakes. It is more abundant in areas with sandy substrate. (Bovbjerg, 1952; Dillon, et al., 2006; Johnson, 1992a)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

Physical Description

Campeloma decisum is 2 cm to 4 cm or more in length. The spire of the shell is elongate, the body whorl rounded, and the aperature length is greater than the width. The shell is light yellowish olive to olive colored, but can have deposits of tan, brown or rust. Adults have spiral lines. Newborn young have a opaque white or light translucent beige shell. This species has an operculum, which is a calcareous plate attached to the foot. When the snail retracts into it's shell, the operculum seals off the aperture. The operculum has a horn-like color and has concentric rings radiating from the center. The soft parts of the animal are gray, with orange spots on the underside of the foot. The anterior of the foot is squarish and extends beyond the short and narrow rostrum (snout). The posterior end of the foot is roundish. In populations that are not parthenogenic, this species is sexually dimorphic, with females bigger than males. Males also have a right tentacle shorter and thicker than the left tentacle, which is modified as a penis sheath. (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


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


There is little information on the mating habits of Campeloma decisum. This species has both sexual and parthenogenic populations. Mating usually takes place in the warmer months of the year. In a Louisiana population, sex ratios were skewed toward females. (Brown, et al., 1989)

Campeloma decisum is viviparous. Different populations of Campeloma decisum have different patterns of sexual maturity and reproduction. In Louisiana, this species has a shorter life cycle than northern populations, and these Louisiana populations reach sexual maturity at the age of two years. Some populations reproduce parthenogenically, while others are sexual and some are both. Populations can also be iteroparous or semelparous. (Brown, et al., 1989; Dillon, et al., 2006; Johnson, 1992b)

  • Breeding interval
    Campeloma descisum mates once a year.
  • Breeding season
    Campeloma descisum mates in the warmer months of the year.

Females of Campeloma decisum provide significant parental care before birth. Young are born inside the parent and will graze for food inside a yolk sac until released. There is no parental care after the snails are born. (Burch, 1989; Johnson, 2003)

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


The lifespan of C. descisum differs with latitude. Temperate populations generally live 3 to 5 years, although some may live up to 12 years. Subtropical populations live only one to two years. (Brown, et al., 1989; Burch and Jung, 1992; Dillon, et al., 2006)

  • Typical lifespan
    Status: wild
    1 to 12 years


Campeloma descisum is usually found around decaying organic matter, and burrows in the substrate. Individuals aggregate and may move up to 10 m upstream. These aggregations can be very large; average densities in Louisiana populations were measured at 300 per square meter, peaking in the summer to 600 to 800 snails per square meter. (Bovbjerg, 1952; Brown, et al., 1989; Burch and Jung, 1992)

Communication and Perception

Gastropods in general have a centralized nervous system. Campeloma decisum has eye spots at the base of its tentacles, which perceive light. Chemosenses are likely also used to find its food. (Burch and Jung, 1992; Burch, 1989)

Food Habits

Campeloma decisum is a deposit or filter feeder. This species is a detritivore, feeding primarily on particulates in soft sediments. (Brown, et al., 1989; Great Lakes Environmental Research Laboratory, 2008)


Campeloma decisum is eaten by fish, diving ducks, turtles and crayfish. Burrowing in the sediment may be a way for these pointed campeloma snails to avoid predation. (Johnson, 2003; van Appledorn, et al., 2007)

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)

Ecosystem Roles

Freshwater snails in general are an important link in aquatic ecosystems, cycling nutrients by feeding on algae and other detritus in the water. Campeloma decisum is a significant food source for fish, diving ducks, turtles and crayfish. Freshwater snails are often intermediate hosts for trematodes. Campeloma decisum is a known host for the fluke Sanguinicola occidentalis, which infects yellow perch. These snails are also the intermediate hosts for the trematode, Leucochloridiomorpha constantiae, which infects water fowl. This trematode is found in the female reproductive system in parthenogenic populations. (Johnson, 1992a; Johnson, 2003; Muzzall, 2000)

Commensal/Parasitic Species
  • fluke, Sanguinicola occidentalis
  • trematode, Leucochloridiomorpha constantiae

Economic Importance for Humans: Positive

There are no know positive effects of Campeloma decisum on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of Campeloma decisum on humans.

Conservation Status

Campeloma decisum currently has no special conservation status. However, the invasive zebra mussel, Dreissena polymorpha, settles on this snail, impeding movement and possibly growth. This may impact future populations of C. decisum, and could require more research and possible conservation efforts. (van Appledorn, et al., 2007; van Appledorn, et al., 2007)


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



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


an animal that mainly eats decomposed plants and/or animals


particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature


a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.


mainly lives in water that is not salty.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


development takes place in an unfertilized egg

seasonal breeding

breeding is confined to a particular season


remains in the same area


offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


associates with others of its species; forms social groups.


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate


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.