The plicate rocksnail,

scientific name In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

''Leptoxis plicata'', is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

freshwater snail Freshwater snails are gastropod mollusks that live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs t ...

with a gill and an operculum, an

aquatic Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the family

Pleuroceridae Pleuroceridae, common name pleurocerids, is a family of small to medium-sized freshwater snails, aquatic gilled gastropod mollusks in the superfamily Cerithioidea.These snails have an operculum and typically a robust high-spired shell. Reproduc ...

. This species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to 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 ...

, specifically the state of

Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...

. The snail has been listed as endangered on the

United States Fish and Wildlife Service list of endangered species This is a list of the bird and mammal species and subspecies described as endangered by the United States Fish and Wildlife Service. It contains species and subspecies not only in the U.S. and its territories, but also those only found in other ...

since October 28, 1998. Leptoxis plicata shell

Description

The plicate rocksnail is a pleurocerid snail with a

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

that grows to about 20 mm (0.8 in) in length. Shells are subglobose with broadly rounded

apertures In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image of ...

. The

body whorl The body whorl is part of the morphology (biology), morphology of the gastropod shell, shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk ...

may be ornamented with strong folds or plicae. Shell color is usually brown, occasionally green, and often with four equidistant color bands. The

columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...

(central column or axis) is smooth, rounded, and typically pigmented in the upper half. The aperture is usually bluish-white, occasionally pink or white. The operculum (plate that closes the shell when the snail is retracted) is dark red, and moderately thick.Goodrich C. 1922. ''The Anculosae of the Alabama River Drainage''. Miscellaneous Publications, Museum of Zoology, University of Michigan (7):1-57. Although morphologically similar to the basin's other three surviving rocksnail species, the plicate rocksnail is genetically distinct.

Distribution

The plicate rocksnail historically occurred in the

Black Warrior River The Black Warrior River is a waterway in west-central Alabama in the southeastern United States. The river rises in the extreme southern edges of the Appalachian Highlands and flows 178 miles (286 km) to the Tombigbee River, of which the ...

, the

Little Warrior River Little Warrior River is a river in Blount County, Alabama. It is a tributary of the Locust Fork of the Black Warrior River The Locust Fork River, in the U.S. State of Alabama, is one of three major tributaries of the Black Warrior River, st ...

, and the

Tombigbee River The Tombigbee River is a tributary of the Mobile River, approximately 200 mi (325 km) long, in the U.S. states of Mississippi and Alabama. Together with the Alabama, it merges to form the short Mobile River before the latter empties i ...

. Recent status surveys have located plicate rocksnail populations only in an approximately 88 km (55 mi) reach of the

Locust Fork of the Black Warrior River The Locust Fork River, in the U.S. State of Alabama, is one of three major tributaries of the Black Warrior River, stretching across Blount, and some portions of Etowah, Jefferson, and Marshall Marshall may refer to: Places Australia *Ma ...

Jefferson Jefferson may refer to: Names * Jefferson (surname) * Jefferson (given name) People * Thomas Jefferson (1743–1826), third president of the United States * Jefferson (footballer) * Jefferson (singer) or Geoff Turton (born 1944), British s ...

and Blount counties, Alabama. The latest survey information indicates that the snail has recently disappeared from the upstream two-thirds portion of that habitat and now appears to be restricted to an approximately 32 km (20 mi) reach in Jefferson County.

Reasons for the decline

The plicate rocksnail has disappeared from more than 90 percent of its historic range. The curtailment of habitat and range for this species (and a few other snail species) in the Mobile Basin's larger rivers – (Black Warrior River, the Little Warrior River, and the Tombigbee River for the plicate rocksnail) is primarily due to extensive construction of

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...

s, and the subsequent

inundation A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant concern in agriculture, civi ...

of the snail's shoal habitats by the impounded waters. This snail has disappeared from all portions of its historic habitats that have been impounded by dams. Dams change such areas by eliminating or reducing currents, and thus allowing sediments to accumulate on inundated channel habitats. Impounded waters also experience changes in water chemistry, which could affect survival or reproduction of riverine snails. For example, many reservoirs in the Basin currently experience eutrophic (enrichment of a water body with nutrients) conditions, and chronically low dissolved oxygen levels. Such physical and chemical changes can affect feeding, respiration, and reproduction of these riffle and shoal snail species.

Ecology

Habitat

Plicate rocksnails inhabit shallow gravel and cobble shoals in the flowing waters of rivers.

Life cycle

Although the precise longevity has not been well documented, individuals have survived 2 years in captivity.P. Johnson, Tennessee Aquarium Research Institute, pers. comm., 2002 in U.S. Fish and Wildlife Service. 2005
''Recovery Plan for 6 Mobile River Basin Aquatic Snails''
U.S. Fish and Wildlife Service, Jackson, Mississippi. 46 pp. pages 13-14.

References

This article incorporates public domain text (a

public domain The public domain (PD) consists of all the creative work to which no Exclusive exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly Waiver, waived, or may be inapplicable. Because no one holds ...

work of the United States Government A work of the United States government is defined by the United States copyright law of the United States, copyright law, as "a work prepared by an officer or employee of the United States Government as part of that person's official duties".: ...

) from the reference. U.S. Fish and Wildlife Service. 2005
''Recovery Plan for 6 Mobile River Basin Aquatic Snails''
U.S. Fish and Wildlife Service, Jackson, Mississippi. 46 pp. pages 13-14 and page 15. {{Taxonbar, from=Q3138499 Leptoxis Endemic molluscs of the United States Endemic fauna of Alabama ESA endangered species Gastropods described in 1834 Taxa named by Timothy Abbott Conrad Taxonomy articles created by Polbot