''Discus macclintocki'' is a species of

land snail A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial molluscs, terrestrial gastropod mollusks that have gastropod shell, shel ...

in the family Discidae known commonly as the Iowa Pleistocene snail and Pleistocene disc. It occurs in

Iowa Iowa ( ) is a U.S. state, state in the upper Midwestern United States, Midwestern region of the United States. It borders the Mississippi River to the east and the Missouri River and Big Sioux River to the west; Wisconsin to the northeast, Ill ...

and

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its ...

in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. It is a federally listed

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

.Iowa Pleistocene Snail (''Discus macclintocki'').
Endangered Species. USFWS Midwest Region. 2013.

Biology

This snail is limited to patches of algific talus slope habitat. It is a

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

species from the last

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and g ...

. Much of its remaining habitat is located on the Driftless Area National Wildlife Refuge in Iowa. Known from fossil evidence about 400,000 years old, it is one of many glacial relict species that remain in the

Driftless Area The Driftless Area, also known as Bluff Country and the Paleozoic Plateau, is a topographic and cultural region in the Midwestern United States that comprises southwestern Wisconsin, southeastern Minnesota, northeastern Iowa, and the extreme ...

, a

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

-eroded plateau that now makes up parts of Iowa, Illinois,

Minnesota Minnesota ( ) is a U.S. state, state in the Upper Midwestern region of the United States. It is bordered by the Canadian provinces of Manitoba and Ontario to the north and east and by the U.S. states of Wisconsin to the east, Iowa to the so ...

, and

Wisconsin Wisconsin ( ) is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest of the United States. It borders Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michig ...

. Much of the area was covered by glaciers about 500,000 years ago, while parts of the Driftless Area were unglaciated. The algific talus slope habitat that harbors the snail is a landscape cooled by air and water emerging from masses of subterranean ice. The ground temperature rarely exceeds , even in summer. Here the snail feeds on

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...

from trees (mainly birch, maple and dogwood) and shrubs. During the winter, it burrows underground and becomes dormant. It breeds from March to August, laying two to six eggs in the litter. Juveniles emerge in about 28 days. The life span of the snail is 5 to 7 years. The adult is about 5–8 millimeters wide,Driftless Area National Wildlife Refuge: Wildlife & Habitat.
USFWS. with a brownish or greenish shell.

Conservation status

The Iowa Pleistocene snail was thought to be extinct until it was discovered in 1955 by a scientist working in northeastern Iowa. It was listed as endangered by the United States in 1978. The main cause of the snail's decline is

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

, as it is restricted to patches of cold habitat in warmer surroundings. The snail is considered to be a relic of the ice age. About 75% of this snail’s original habitat has been destroyed since 1850. Other causes include

loss of habitat Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

logging Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidder, skidding, on-site processing, and loading of trees or trunk (botany), logs onto logging truck, trucksquarry A quarry is a type of open-pit mining, open-pit mine in which dimension stone, rock (geology), rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some juri ...

ing,

livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...

pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...

s, the construction of roads, and predation by

shrew Shrews ( family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to dif ...

s.''Discus macclintocki''.
Status of Listed Species and Recovery Plan Development. USGS. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

assessed the snail as a species of least concern for the Red List, because its populations are apparently stable and none were lost in the decade prior to the assessment.

Driftless Area National Wildlife Refuge

The Driftless Area National Wildlife Refuge was established in 1989 to protect native flora and fauna, including endangered and

threatened species A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensatio ...

such as the Iowa Pleistocene snail. The refuge conserves the algific talus slope habitat and other local habitat such as cold, moist

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are also known as shakeholes, and to openings where surface water ...

s. Other glacial relict snails occur on the refuge, including the Midwest Pleistocene vertigo (''Vertigo hubrichti''). Rare plants include the northern blue monkshood (''Aconitum noveboracense''), which thrives in the same cool talus habitat as the snail.

References

External links

Iowa Pleistocene snail (''Discus macclintocki'').
Environmental Conservation Online System. USFWS.

Biology

Conservation status

Driftless Area National Wildlife Refuge

References

External links

Further reading