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Haplotrema concavum

What do they look like?

Gray-foot lancetooth snails are 11 to 21 mm in diameter, with 4.5 to 5.5 spirals in their shells. The height of an adult shell ranges from 5 to 10 mm. Their shells, which are shades of white, greenish, tan, or yellow, are glossy and smooth. The shell shape is round or flat like a disc. The shell opening is crescent-shaped. Within the shell, gray-foot lancetooth snails have a thick, coarse skin, which may be checkered in appearance. Two pairs of tentacles are found on the head, and the body is broad and heavy. There is a flap of skin on the right part of the neck. (Burch and Jung, 1988; Pilsbry, 1946)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    12 to 13 mm
    0.47 to 0.51 in

Where do they live?

Haplotrema concavum, also known as the gray-foot lancetooth snail, lives in the eastern United States and southeastern Canada. These snails are found from Maine and central Ontario south to Florida's panhandle. They are found as far west as eastern Iowa and eastern Texas (with small populations reported in a few areas farther west), and as far east as the coastline of the Atlantic Ocean. ("Haplotrema concavum Say, 1821", 2013; "Haplotrema concavum", 2003; Hubricht, 1985)

What kind of habitat do they need?

Gray-foot lancetooth snails live in moist areas of forests, as well as river valleys. They are often found around plants such as cinnamon fern (Osmunda cinnamomea), Virginia creeper (Parthenocissus quinquefolia), bracken fern (Pteridium aquilinum), greenbrier (Smilax rotundifolia), and poison ivy (Toxicodendron radicans), and are also found in debris on the forest floor, and on the underside of logs. (Burch and Jung, 1988; Hubricht, 1985; Painter, 2013)

How do they grow?

Land snails lay their eggs in moist areas, and produce a sticky substances that makes their eggs stick to surfaces. The eggs usually hatch after 7 to 10 days, but this depends on moisture and temperature. The snails grow, and they are considered adults when the outer lip on the opening of the shell forms. ("Illinois Snails and Slugs", 2009; Burch and Pearce, 1990)

How do they reproduce?

Gray-foot lancetooth snails are hermaphrodites, meaning that each individual snail has both male and female genitalia. Mates may be found by following the mucus trails snails leave behind. The snails typically perform a courtship ritual before mating. After the ritual takes place, one snail climbs on top of the other snail. The snails gnaw on each other for a few minutes before each snail inserts its male genitalia into the other snail. Mating can last for a long time; in one instance it was observed going on for 10 hours. Afterwards, the snails separate, and both will lay eggs. (Burch and Pearce, 1990; Tompa, 1984; Webb, 1943)

In addition to two snails mating, gray-footed lancetooths are also able to reproduce by self-fertilization. Since the snails have both male and female parts, a snail is sometimes able to use its own sperm to fertilize its own eggs. Mating is likely to be most common during the warmer months of the year, and the snails also mate more when it is raining. Land snails lay about 20 eggs at a time. Snails are able to mate when the lip at the opening of the shell forms. In cooler or drier regions, growth can take longer, so snails are not able to mate until later in life than snails that live in warmer regions. ("Illinois Snails and Slugs", 2009; Burch and Pearce, 1990; Tompa, 1984; Webb, 1943)

  • How often does reproduction occur?
    Gray-foot lancetooth snails mate multiple times a year.
  • Breeding season
    Breeding season for this species has not been clearly identified; it is likely that breeding occurs during spring and fall months.
  • Average number of offspring
    20
  • Range gestation period
    7 to 10 days

Land snails lay their eggs and then leave. They provide no parental care. ("Illinois Snails and Slugs", 2009)

  • Parental Investment
  • no parental involvement

How long do they live?

Gray-foot lancetooth snails probably live about 1 to 2 years. ("Haplotrema concavum", 2003)

How do they behave?

Gray-footed lancetooth snails are nocturnal, and are also more active when the temperature is cooler and humidity is higher. To survive the winter, land snails can decrease the amount of water in their body and form a membrane over the opening of the shell. This membrane prevents any further water loss. This membrane can also be produced during dry conditions, to seal off the shell and keep moisture in. As predators, gray-foot lancetooth snails are more solitary than other land snails. (Atkinson, 2013; Burch and Pearce, 1990; Pearce, 1989)

Home Range

Home range size is unknown for this species, but other related land snails live in about 40 square meters of space. (Pearce, 1990)

How do they communicate with each other?

Land snails leave mucus trails, which are used as a form of communication. The mucus allows the snails to detect their own species (to find mates) and other species. Gray-foot lancetooth snails are known to follow mucus trails of their prey. The front tentacles of these snails detect chemicals. These snails can find food by using their sense of smell. Eyes located at the tops of the tentacles can detect light and may also be used for sensing forms at night. (Atkinson, 2013; Burch and Pearce, 1990; Nordsieck, 2011)

What do they eat?

Gray-foot lancetooth snails are carnivores, and feed mostly on other snails. They also chew on dead shells to get calcium. They will cannibalize their own species, but studies have shown that these snails prefer young snails of other species, such as flamed discs (Anguispira alternata). Younger individuals will eat the eggs of their own and other species, but begin to eat whole snails once reaching 6 to 7 mm in diameter. Gray-foot lancetooth snails prefer larger prey items with softer shells, such as juvenile oval ambersnails (Novisuccinea ovalis). This species will also eat nematodes and plants. To catch their prey, gray-foot lancetooth snails follow their slime trails. They attack smaller prey by climbing on top or turning the shell. To attack larger snails, they crawl inside their prey's shell. The snail may eat its prey there, or move it to another location by dragging it along. A meal may take several hours to eat. (Atkinson and Balaban, 1997; Atkinson, 1998; Hotopp, 2006; Hubricht, 1985; Painter, 2013; Shearer and Atkinson, 2001)

  • Animal Foods
  • mollusks
  • terrestrial worms
  • Plant Foods
  • leaves

What eats them and how do they avoid being eaten?

In general, land snails are preyed on by lampyrid beetle larvae and other insects, birds, reptiles, rodents, and other small mammals, particularly voles and shrews. (Burch and Pearce, 1990; Painter, 2013)

What roles do they have in the ecosystem?

Gray-foot lancetooths are predators of other snails, and are also prey to a number of other insects, birds, reptiles, and small mammal predators. They may also carry brain worms (Parelaphostrongylus tenuis), which cause a disease called cerebrospinal nematodiasis in various hoofed animals. (Burch and Pearce, 1990; MDNR wildlife diseases laboratory, 2013)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

Gray-footed lancetooth snails do not cause any problems for humans. (MDNR wildlife diseases laboratory, 2013)

How do they interact with us?

Gray-foot lancetooth snails eat some snail species that can do damage to crops. By preying on these snails, gray-foot lancetooth snails decrease crop damage. ("Haplotrema concavum Say, 1821", 2013)

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

Gray-foot lancetooth snails are not an endangered species. (IUCN, 2013)

Contributors

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

References

2013. "Haplotrema concavum Say, 1821" (On-line). Global Biodiversity Information Facility. Accessed December 05, 2013 at http://data.gbif.org/species/2295986/.

2003. "Haplotrema concavum" (On-line). Encyclopedia of Life. Accessed May 22, 2013 at http://eol.org/pages/455034/maps.

Illinois Department of Natural Resources. Illinois Snails and Slugs. 1. Springfield, IL: Illinois Department of Natural Resources. 2009. Accessed December 09, 2013 at http://www.dnr.state.il.us/publications/pdf/00000656.pdf.

2013. "Virginia land snails: Haplotrema concavum" (On-line). Carnegie Museum of Natural History. Accessed December 09, 2013 at http://www.carnegiemnh.org/science/default.aspx?id=21573.

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

Atkinson, J. 1998. Food Manipulation and Transport by a Carnivorous Land Snail, Haplotrema concavum. Invertebrate Biology, 117/2: 109-113. Accessed August 21, 2013 at http://www.jstor.org/stable/3226962.

Atkinson, J., M. Balaban. 1997. Size-related change in feeding preference in the carnivorous land snail Haplotrema concavum (Pulmonata: Stylommatophora). Invertebrate Biology, 116/2: 82-85. Accessed August 21, 2013 at http://www.jstor.org/stable/3226972.

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

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.

Hotopp, K. 2006. "Haplotrema concavum (Say, 1821)" (On-line). Pennsylvania land snails. Accessed June 14, 2013 at http://www.carnegiemnh.org/science/default.aspx?id=16827.

Hubricht, L. 1985. The distributions of the native land mollusks of the Eastern United States. Fieldiana, Zoology New Series, 24: 1-191. Accessed August 21, 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 13, 2013 at http://www.iucnredlist.org/search.

MDNR wildlife diseases laboratory, 2013. "Brainworm (meningeal worm)" (On-line). Michigan Department of Natural Resources. Accessed May 23, 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 05, 2013 at http://www.fcps.edu/islandcreekes/ecology/disc_cannibal_snail.htm.

Pearce, T. 1989. Loping locomotion in terrestrial gastropods. Walkerana, 3/10: 229-237. Accessed August 21, 2013 at http://www.carnegiemnh.org/uploadedFiles/CMNH_Site/Mollusks/Downloads/Pearce1989.pdf.

Pearce, T. 1990. Spool and line technique tracing field movements of terrestrial snails. Walkerana, 4/12: 307-316. Accessed August 21, 2013 at http://www.carnegiemnh.org/uploadedFiles/CMNH_Site/Mollusks/Downloads/Pearce-1990-Spooling.pdf.

Pearce, T., A. Gaertner. 1996. Optimal foraging and mucus-trail following in the carnivorous land snail Haplotrema concavum (Gastropoda: Pulmonata). Malacological Review, 29: 85-99. Accessed August 21, 2013 at http://www.carnegiemnh.org/uploadedFiles/CMNH_Site/Mollusks/Downloads/Pearce-Gaertner-1996.pdf.

Pilsbry, H. 1946. Land mollusca of North America (North of Mexico), volume 2, part 1. Monographs of the Academy of Natural Sciences of Philadelphias, 3: 1-520.

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 August 21, 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.

Webb, G. 1943. The mating of the landsnail Haplotrema concavum (Say). American Midland Naturalist, 30/2: 341-345. Accessed August 21, 2013 at http://www.jstor.org/stable/2421286.

 
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Mulcrone, R. 2014. "Haplotrema concavum" (On-line), Animal Diversity Web. Accessed November 01, 2014 at http://www.biokids.umich.edu/accounts/Haplotrema_concavum/

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