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Anguispira alternata

What do they look like?

Flamed discs are medium-sized snails, typically ranging from 17 to 25 mm in diameter. Shells average 20 mm wide and 12 mm tall, and are wider than they are tall. The shells are pale yellow to brown in color, with reddish-brown and brown blotches on the upper surface, and reddish-brown streaks on the bottom surface. The shells have 5.5 to 6 whorls, or spirals. Flamed discs have two pairs of tentacles, with eyes at the tips of the upper tentacles. The head and eye stalks can be a light grayish-blue color, and the body can be brown or brownish-black. Body color is typically duller during the late summer. The body of the snail, which it uses to move around on, is called the foot. The foot is wide and short, and can be white. These snails produce mucus that may be reddish in color. ("The International Union for the Conservation of Nature and Natural Resources", 2013; Baker, 1939; Burch and Jung, 1988; Pilsbry, 1948)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    17 to 25 mm
    0.67 to 0.98 in

Where do they live?

Anguispira alternata, a land snail commonly called the flamed disc, is native to North America. It is found as far north as New Brunswick, Canada, south to northern Florida, and west to northeastern Texas, Kansas and western Minnesota. It has also occasionally been recorded further west, in Oregon, Alberta, and central Saskatchewan. ("Anguispira alternata", 2003; Hubricht, 1985)

What kind of habitat do they need?

Flamed discs are terrestrial snails found in many different habitats. These include forests, weedy roadsides, and along railroads, as well as gardens or vacant lots in urban areas. They are usually found around logs, hollow trees, and rocks in wooded areas. Flamed discs can survive in temperatures as low as -14°C, though they usually prefer warmer temperatures. (Burch and Jung, 1988; Hubricht, 1985; Riddle and Miller, 1988)

How do they grow?

Land snails lay their eggs in moist areas. They produce a sticky substance that makes the group of eggs stick to a surface, or they bury them in holes a couple centimeters deep. Eggs have been measured at 2 to 3 mm in diameter. The eggs typically hatch within 30 to 45 days, but this depends on other conditions such as temperature. Some studies suggest that the young grow very quickly during their first summer, almost reaching adult-size by the fall. ("Carnegie Museum of Natural History", 2013; Burch and Pearce, 1990; Douglas, 1963; Elwell and Ulmer, 1971; Tompa, 1984)

How do they reproduce?

Flamed discs are hermaphrodites, meaning that each individual snail has both male and female genitals. Mates can be found by following their mucus trails. Once a mate is found, a courtship ritual usually takes place, which can last a few hours. After the ritual, they then mate. One snail climbs on top of the shell of the other, and each snail uses its male genitalia to insert a spermatophore into the other. A spermatophore contains sperm. Each snail will produce fertilized eggs after mating. (Asami, et al., 1998; Burch and Pearce, 1990; Tompa, 1984)

In addition to two snails mating, flamed discs can also reproduce by self-fertilizing. Since they are hermaphrodites and have both male and female parts, a single snail can use its male genitalia to fertilize its own eggs. Reproduction takes place during the warmer months of the year, and make occur more when it is raining. Flamed discs are old enough to breed when a structure called the lip forms on the opening of the shell, usually 2 to 3 years after hatching. In cooler or drier areas, growth and development is slower than in warmer, moist regions. This means that flamed discs in cooler regions takes longer to grow, so they are not able to breed until later in their lives. Flamed discs generally lay 2 to 25 eggs per season, but can lay as many as 40 eggs. Eggs are laid in leaf litter, usually in moist areas. More eggs hatch in the spring than any other time of the year. ("Carnegie Museum of Natural History", 2013; Burch and Pearce, 1990; Douglas, 1963; Elwell and Ulmer, 1971; Perez and Cordiero, 2008; Tompa, 1984)

  • How often does reproduction occur?
    Flamed discs breed yearly.
  • Breeding season
    Flamed discs breed during the warmer months of the year.
  • Range number of offspring
    2 to 25
  • Average number of offspring
    40
  • Range gestation period
    30 to 45 days
  • Range age at sexual or reproductive maturity (female)
    2 to 3 years
  • Range age at sexual or reproductive maturity (male)
    2 to 3 years

After land snails lay their eggs, they leave them and do not give any parental care. ("Anguispira alternata", 2003; "Carnegie Museum of Natural History", 2013)

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning

How long do they live?

The lifespan of this species is unknown.

How do they behave?

Flamed discs are commonly found climbing or at the bases of trees at night, likely seeking food. They have been observed creating burrows by using their foot to move loose soil, then dragging their shells into the newly made hole. In Kansas, flamed discs were observed living in groups ranging from 16 to 75 snails per square foot, burrowing together to spend the winter. Young and juvenile snails are often found in large groups as well. In the fall, these snails decrease the amount of water in their bodies, and get rid of all the food in their guts. This makes it easier to survive in cold temperatures. They also form a structure called an epiphram, which seals the shell shut, and prevents the snails from drying out in the cold weather. ("Carnegie Museum of Natural History", 2013; Douglas, 1963; Elwell and Ulmer, 1971; Hotopp, 2005; Pearce, 1990; Perez and Cordiero, 2008; Riddle, 1981)

  • Average territory size
    40 m^2

Home Range

One study found that a single flamed disc lives in about 40 square meters of habitat. (Pearce, 1990)

How do they communicate with each other?

Generally, land snails leave mucus trails that are used as a form of communication between other snails. By smelling the mucus trail, other snails can tell if the snail leaving the trail was a member of their own species, or a different species. The eyes on the top of the tentacles can detect light, and the tentacles can also detect chemicals. Flamed discs may also use smell to locate food. ("Carnegie Museum of Natural History", 2013; Atkinson, 2003; Atkinson, 2013; Nordsieck, 2011; Pearce, 1997; Shearer and Atkinson, 2001)

What do they eat?

Flamed discs feed on decaying plant material and fungi. Since they are often found in trees, they also likely graze on algae that lives on the bark. Cannibalism of eggs by adults has also been observed. The radula is a toothed organ used by land snails to feed, by scraping or grinding food with it. ("Carnegie Museum of Natural History", 2013; Atkinson, 2003; Burch and Pearce, 1990; Elwell and Ulmer, 1971; Hotopp, 2005; Perez and Cordiero, 2008; Shearer and Atkinson, 2001)

  • Animal Foods
  • eggs
  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems
  • bryophytes
  • lichens
  • algae

What eats them and how do they avoid being eaten?

Predators of land snails include lampyrid beetle larvae or other insects, birds, rodents, and small mammals, particularly chipmunks, voles and shrews. Carnivorous land snails will also prey on flamed discs. (Burch and Pearce, 1990; Elwell and Ulmer, 1971; Painter, 2013)

What roles do they have in the ecosystem?

Land snails are often responsible for seed dispersal, meaning that they move seeds from one location to another, and the seeds can grow in this new location, thanks to the help from the snails. Land snails also break down organic and decaying matter found in forests, such as old leaves and logs. Flamed discs may also carry parasites, including trematodes and nematodes, which go on to infect other animals. ("Carnegie Museum of Natural History", 2013; Barger, 2012; Burch and Jung, 1988; Burch and Pearce, 1990; MDNR wildlife diseases laboratory, 2013)

  • Ecosystem Impact
  • disperses seeds
Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

Flamed discs do not cause any problems for humans. (MDNR wildlife diseases laboratory, 2013)

How do they interact with us?

Flamed discs do not benefit humans specifically, but they do break down organic and decaying matter in forests, keeping those ecosystems healthy and balanced. Humans can then benefit from healthy forests. (Burch and Pearce, 1990)

Are they endangered?

Flamed discs are not an endangered species. ("The International Union for the Conservation of Nature and Natural Resources", 2013)

Contributors

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

References

2003. "Anguispira alternata" (On-line). Encyclopedia of Life. Accessed May 16, 2013 at http://eol.org/pages/452610/maps.

2013. "Carnegie Museum of Natural History" (On-line). Virginia land snails: Anguispira alternata (Say, 1816). Accessed November 25, 2013 at http://www.carnegiemnh.org/science/default.aspx?id=19014.

2013. "The International Union for the Conservation of Nature and Natural Resources" (On-line). Accessed August 19, 2013 at http://www.iucnredlist.org/search.

Appel, D. 2008. "Anguispira alternata (Say)" (On-line). Accessed May 11, 2013 at https://bioweb.uwlax.edu/bio210/2011/appel_doug/index.htm.

Asami, T., R. Cowie, K. Ohbayashi. 1998. Evolution of mirror images by sexually asymmetric mating behavior in hermaphroditic snails. The American Naturalist, 152/2: 225-236. Accessed November 25, 2013 at http://www.jstor.org.proxy.lib.umich.edu/stable/10.1086/286163.

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

Atkinson, J. 2003. Foraging strategy switch in detour behavior of the land snail Anguispira alternata (Say). Invertebrate Biology, 122/4: 326-333. Accessed August 19, 2013 at http://www.jstor.org/stable/3227069.

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

Barger, M. 2012. Life span of cercariae of Postharmostomum helicis (Trematoda: Brachylaimidae) under different temperatures and relative humidity. Comparative Parasitology, 79/2: 169=172.

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.

Douglas, C. 1963. Population analyses, variation and behavior of Anguispira alternata alternata. Transactions of the Kansas Academy of Science, 66/2: 186-194. Accessed October 31, 2013 at http://www.jstor.org/stable/3626559.

Elwell, A., M. Ulmer. 1971. Notes on the biology of Anguispira alternata. Malacologia, 11/1: 199-215. Accessed November 26, 2013 at http://archive.org/stream/malacologia111971inst/malacologia111971inst_djvu.txt.

Hotopp, K. 2005. "Anguispira alternata (Say, 1816)" (On-line). Pennsylvania land snails. Accessed April 14, 2013 at http://www.carnegiemnh.org/science/default.aspx?id=16811.

Hubricht, L. 1985. The distributions of the native land mollusks of the Eastern United States. Fieldiana, Zoology New Series, 24: 1-191. Accessed August 19, 2013 at http://archive.org/stream/distributionsofn24hubr#page/n3/mode/2up.

MDNR wildlife diseases laboratory, 2013. "Brainworm (meningeal worm)" (On-line). Michigan Department of Natural Resources. Accessed May 11, 2013 at http://www.michigan.gov/dnr/0,4570,7-153-10370_12150_12220-26502--,00.html.

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.

Painter, T. 2013. "Disc cannibal snail (Haplotrema concavum)" (On-line). Study of Northern Virginia Ecology. Accessed December 06, 2013 at http://www.fcps.edu/islandcreekes/ecology/disc_cannibal_snail.htm.

Pearce, T. 1990. Spool and line technique tracing field movements of terrestrial snails. Walkerana, 4/12: 307-316.

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 October 31, 2013 at http://mollus.oxfordjournals.org/content/63/3/389.full.pdf.

Perez, K., J. Cordiero. 2008. A guide for terrestrial gastropod identification. American Malacological Society: Terrestrial gastropod identification workshop, 1: 1-73. Accessed November 26, 2013 at http://www.uwlax.edu/biology/faculty/perez/Perez/PerezLab/Research/Publications/AMS_Workbook_KEP_FINAL.pdf.

Pilsbry, H. 1948. Land mollusca of North America (North of Mexico). Monographs of the Academy of Natural Sciences of Philadelphias, 3: 1-1113.

Riddle, W. 1981. Cold hardiness in the woodland snail, Anguispira alternata (Say) (Endodontidae). Journal of Thermal Biology, 6: 117-121.

Riddle, W., V. Miller. 1988. Cold-hardiness in several species of land snails. Journal of Themal Biology, 13/4: 163-167. Accessed August 19, 2013 at http://www.sciencedirect.com/science/article/pii/0306456588900289.

Shearer, A., J. Atkinson. 2001. Comparative analysis of food-finding behavior of an herbivorous and carnivorous land snail. Invertebrate Biology, 120/3: 199-205. Accessed October 31, 2013 at http://www.jstor.org/stable/3227244.

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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Mulcrone, R. 2014. "Anguispira alternata" (On-line), Animal Diversity Web. Accessed December 18, 2018 at http://www.biokids.umich.edu/accounts/Anguispira_alternata/

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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