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Gastrocopta armifera

By Renee Mulcrone

Geographic Range

Armed snaggletooth snails, Gastrocopta armifera, are native to the Nearctic region. They are found from Arkansas and Florida in the south, to Vermont, Michigan, northeastern Wisconsin, and Nebraska in the north. They may also be found in southern Quebec and Ontario in Canada, mainly near Lake Erie and Lake Ontario. ("Gastrocopta armifera", 2013a; Hubricht, 1985)

In Michigan, specimens have mainly been collected from the southern half of the lower peninsula. (Burch and Jung, 1988)

Habitat

In general, land snails are found in soil and leaf litter. Armed snaggletooth snails are commonly found living in rotten logs and leaf litter on calcium-rich soils, as well as beneath limestone outcroppings. In the Great Lakes region, this species was found to be a habitat generalist. More tolerant of dry conditions than other land snails, Gastrocopta armifera may be found in prairie regions, although less commonly. (Baker, 1939; Basch, et al., 1961; Burch and Pearce, 1990; Nekola, 2003; Riddle and Miller, 1988)

Armed snaggletooth snails tolerate relatively high temperatures, to about 44°C, particularly when previously acclimated to temperatures of 30°C. This species tolerates lower temperatures of -20°C. (Riddle and Miller, 1988; Riddle, 1990)

Physical Description

Gastrocopta armifera has a shell that is whitish in color. These snails average 3.0 to 5.0 mm in length and 2.0 to 2.6 mm in diameter, with 6 to 7 convex whorls. Shell shape is oval, widening toward the base. The base of the shell has a perforation where the whorls do not join. The shell lip is thin, expanded and reflected. The shell aperture has lamellae (calcareous teeth-like projections). Two larger lamellae (parietal and angular) on the upper portion of the aperture are fused, but have two projections at the tip. The columular lamella, located at the left side of the aperture, is well-developed and deep-set. The basal lamella is low and inconspicuous. There are three palatal folds on the right side of the aperture. (Baker, 1939; Burch and Jung, 1988; Burch and Pearce, 1990; Hubricht, 1972; Pilsbry, 1948)

When fully extended, the soft body is almost as long as the shell, and is usually mottled. Armed snaggletooth snails have two pairs of tentacles, with eyes at the tips of the upper tentacles. Individuals of this species have a simple penis without an appendix and an unforked penial retractor muscle, and also possess female reproductive organs. Tricuspid teeth are located in the center of the radula, and are significantly narrower than the bicuspid lateral teeth. (Baker, 1939; Burch and Jung, 1988; Burch and Pearce, 1990; Pilsbry, 1948)

  • Range length
    3.0 to 5.0 mm
    0.12 to 0.20 in

Development

Land snails deposit their eggs in moist areas and secrete a substance to make the egg masses stick; eggs of this species are covered with a gelatinous, hydroscopic material. The time it takes for eggs to hatch depends on moisture and temperature; it may take longer for snails to reach maturity in drier areas. Eggs of this species are relatively large, averaging 1.0 to 1.2 mm in diameter. Maturity is usually reached when the lip of the shell is formed. (Burch and Pearce, 1990; Gugler, 1963; Tompa, 1984)

Reproduction

Land snails belonging to the clade Stylommatophora, such as armed snaggletooths, are hermaphroditic. Although they usually mate with other snails, they may also self-fertilize. Mating partners may be located by following mucus trails. After a courtship ritual, the snails will copulate, with each snail inserting spermatophores into the other. (Burch and Pearce, 1990; Gugler, 1963; Tompa, 1984)

Generally, land snails breed in the warmer months of the year, and rain may bring on increased mating. Sexual maturity is likely reached when the lip at the aperture forms. In captivity, Gastrocopta armifera deposited loose clusters of 3 to 6 eggs on soil. In one study, armed snaggletooth snails were brought into a laboratory setting from solidly frozen soil; these individuals began to lay eggs within 8 to 15 days, indicating that this species likely lays eggs in the spring in the wild. Individuals in this study laid their eggs at night, retracting into their shells, depositing an egg into the body whorl, and pushing the egg through the aperture. (Burch and Pearce, 1990; Gugler, 1963; Tompa, 1984)

  • Breeding interval
    Armed snaggletooth snails likely breed once a year.
  • Breeding season
    Armed snaggletooth snails breed during the warmer months of the year.
  • Range number of offspring
    3 to 6

Land snails provide provisioning in their eggs and produce a gelatinous substance to cover them. They leave their eggs after they are deposited and there is no further parental care. (Burch and Jung, 1988)

  • Parental Investment
  • pre-fertilization
    • provisioning

Lifespan/Longevity

The lifespan of this species is likely about one year. (Burch and Jung, 1988; Burch and Pearce, 1990)

Behavior

Light intensity, relative humidity, and temperature influence much of a land snail's behavior, since these factors affect the snail's water retention. In general, land snails are nocturnal, and more active with increased relative humidity and decreased temperature. In temperate climates, snails may reduce their water content and form an epiphram over the shell aperture as they aestivate over the winter. During dry periods, this same membrane will form to prevent desiccation. Snails may also move in a "loping" fashion to avoid rough substrates or retain water. (Burch and Pearce, 1990; Pearce, 1989; Riddle and Miller, 1988; Riddle, 1990)

  • Range territory size
    10 (high) m^2

Home Range

Home ranges of land snails vary, but smaller ones such as armed snaggletooth snails typically only disperse throughout areas up to 10 squared meters. (Burch and Pearce, 1990; Nekola, 2012)

Communication and Perception

Land snails leave mucus trails, which are used as a form of communication. The mucus allows the snails to detect their own and other species. Some land snails may grow more slowly when exposed to mucus trails of the same species. The upper tentacles of stylommatophoran snails are sensitive to light and chemicals. Snails can find food in still air by following an olfactory gradient. Eyes at the top of the tentacles can detect light, and may also be used for sensing forms at night. Their anterior tentacles are chemosensory and their labia detect both touch and chemical signals. (Atkinson, 2013; Nordsieck, 2011; Pearce, 1997)

Food Habits

Pupillid snails (Family Pupillidae), such as armed snaggletooths, generally feed on fungi and decaying plant matter. The radula, a toothed feeding organ, is used to scrape or grind food. (Baker, 1939; Burch and Pearce, 1990)

Predation

Specific predators are not known for this species, but in general, land snails are preyed on by lampyrid beetle larvae and other insects, birds, rodents, and small mammals, particularly voles and shrews. Gastrocopta armifera has denticles on its shells' apertures, which helps to protect its soft body. ("Illinois Snails and Slugs", 2009; Burch and Pearce, 1990)

Ecosystem Roles

Generally, land snails disperse fungal spores and plant seeds, and break down detritus in the forest. While many snails are vectors for nematodes, records for this particular species are not currently available in the literature. (Burch and Pearce, 1990)

Economic Importance for Humans: Positive

There are no known positive effects of Gastrocopta armifera on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of armed snaggletooth snails on humans.

Conservation Status

Armed snaggletooth snails do not have any special conservation status; however, NatureServe has listed this species as extirpated in Louisiana and vulnerable in North Carolina. More research and possible conservation efforts are necessary to combat this and ensure that other populations are stable. ("Gastrocopta armifera", 2013a; "Gastrocopta armifera", 2013b; IUCN, 2013)

Contributors

Renee Mulcrone (author), Special Projects, Jeremy Wright (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

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.

biodegradation

helps break down and decompose dead plants and/or animals

chemical

uses smells or other chemicals to communicate

detritivore

an animal that mainly eats decomposed plants and/or animals

detritus

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

ectothermic

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

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

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.

internal fertilization

fertilization takes place within the female's body

iteroparous

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).

motile

having the capacity to move from one place to another.

mycophage

an animal that mainly eats fungus

native range

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

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

solitary

lives alone

tactile

uses touch to communicate

temperate

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).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

2013. "Gastrocopta armifera" (On-line). International Union for Conservation of Nature and Natural Resources. Accessed August 20, 2013 at http://www.iucnredlist.org/search.

2013. "Gastrocopta armifera" (On-line). NatureServe. Accessed August 20, 2013 at http://www.natureserve.org/explorer/servlet/NatureServe?searchSciOrCommonName=gastrocopta+armifera&x=0&y=0.

2003. "Gastroptera armifera" (On-line). Encyclopedia of Life. Accessed April 16, 2013 at http://eol.org/pages/453144/overview.

Illinois Department of Natural Resources. Illinois Snails and Slugs. 1. Springfield, IL: Illinois Department of Natural Resources. 2009. Accessed December 16, 2013 at http://www.dnr.state.il.us/publications/pdf/00000656.pdf.

Atkinson, J. 2013. "Michigan State University Snail Laboratory" (On-line). Accessed May 15, 2013 at https://www.msu.edu/~atkinso9/.

Baker, F. 1939. Fieldbook of Illinois land snails, Illinois Natural History Survey Manual 2. Urbana, Illinois: Illinois Natural History Survey.

Basch, P., P. Bainer, J. Wilhm. 1961. Some ecological characteristics of the molluscan fauna of a typical grassland situation in east central Kansas. American Midland Naturalist, 66/1: 178-199. Accessed August 20, 2013 at http://www.jstor.org/stable/2422876.

Burch, J., Y. Jung. 1988. Land snails of the University of Michigan biological station area. Walkerana, 3/9: 1-177.

Burch, J., T. Pearce. 1990. Terrestrial gastropoda. Pp. 201-310 in D Dindal, ed. Soil Biology Guide. New York: John Wiley and Sons.

Gugler, C. 1963. The eggs and egg-laying habits of some midwestern land snails. Transactions of the Kansas Academy of Science (1903-), 66/2: 195-201. Accessed December 15, 2013 at http://www.jstor.org/stable/3626560.

Hotopp, K. 2005. "Pennsylvania land snails: Gastrocopta armifera (Say, 1821)" (On-line). Carnegie Natural History Museum, Mollusks. Accessed June 05, 2013 at http://www.carnegiemnh.org/science/default.aspx?id=16826.

Hubricht, L. 1972. Gastrocopta armifera (Say). The Nautilus, 85: 73-77. Accessed December 15, 2013 at http://archive.org/stream/nautilus85amer/nautilus85amer_djvu.txt.

Hubricht, L. 1985. The distributions of the native land mollusks of the Eastern United States. Fieldiana, Zoology New Series, 24: 1-191. Accessed August 20, 2013 at http://www.archive.org/stream/distributionsofn24hubr/distributionsofn24hubr_djvu.txt.

IUCN, 2013. "The IUCN Red List of Threatened Species. Version 2013.2" (On-line). Accessed December 27, 2013 at www.iucnredlist.org.

Nekola, J. 2003. Large-scale terrestrial gastropod community composition patterns in the Great Lakes region of North America. Diversity and Distributions, 9: 55-71. Accessed August 20, 2013 at http://biology.unm.edu/jhbrown/Documents/511Readings/NekolaR4.pdf.

Nekola, J. 2012. The impact of a utility corridor on terrestrial gastropod biodiversity. Biodiversity and Conservation, 21: 781-785. Accessed August 20, 2013 at http://sev.lternet.edu/~jnekola/nekola%20pdf/biocon-preprint.pdf.

Nordsieck, R. 2011. "The eyes of snails" (On-line). The living world of mollusks. Accessed May 10, 2013 at http://www.molluscs.at/gastropoda/index.html?/gastropoda/morphology/eyes.html.

Pearce, T. 1997. Interference and resource competition in two land snails: adults inhibit conspecific juvenile growth in field and laboratory. Journal of Molluscan Studies, 63: 389-399. Accessed August 20, 2013 at http://mollus.oxfordjournals.org/content/63/3/389.full.pdf.

Pearce, T. 1989. Loping locomotion in terrestrial gastropods. Walkerana, 3/10: 229-237. Accessed August 20, 2013 at http://www.carnegiemnh.org/uploadedFiles/CMNH_Site/Mollusks/Downloads/Pearce1989.pdf.

Pilsbry, H. 1948. Land mollusca of North America (North of Mexico). Monographs of the Academy of Natural Sciences of Philadelphias, 3: 1-1113. Accessed August 20, 2013 at http://books.google.com/books/about/Land_Mollusca_of_North_America.html?id=EyHywT05a0QC.

Riddle, W. 1990. High temperature tolerance in three species of land snails. Journal of Thermal Biology, 15/2: 119-124.

Riddle, W., V. Miller. 1988. Cold-hardiness in several species of land snails. Journal of Themal Biology, 13/4: 163-167. Accessed August 20, 2013 at http://www.sciencedirect.com/science/article/pii/0306456588900289.

Tompa, A. 1984. Land snails (Stylommatophora). Pp. 47-139 in A Tompa, N Verdonk, J van den Biggelaar, eds. The Mollusca, Vol. 7, reproduction. London: Academic Press, Inc.

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