Painted rocksnail
Encyclopedia
The painted rocksnail, scientific name Leptoxis taeniata, is a species
of freshwater snail
with a gill and an operculum
, an aquatic
gastropod mollusk in the family Pleuroceridae
.
This species is endemic to the United States
, specifically the state of Alabama
. The snail has been listed as threatened on the United States Fish and Wildlife Service list of endangered species
since October 28 1998.
that measures about 19 mm (0.8 in) in length, and is subglobose to oval in shape. The aperture
is broadly ovate, and rounded anteriorly. The shell coloration varies from yellowish to olive-brown, usually with four dark bands. Some shells do not have these dark bands, and some have the bands broken into square or oblong patches (see Goodrich, 1922 for a detailed description).
All of the rocksnails that historically inhabited the Mobile
Basin had broadly rounded apertures, oval shaped shells, and variable coloration. Although the various species were distinguished by relative sizes, coloration patterns, and ornamentation, identification could be confusing. The painted rocksnail is the only known survivor of the 15 rocksnail species that historically occurred in the Coosa River
drainage.
, downstream into the mainstem of the Alabama River
to Claiborne
, Monroe County, Alabama
, and the Cahaba River
below the Fall Line in
Perry
and Dallas counties, Alabama
.
Surveys by Service biologists and others in the Cahaba River, unimpounded portions of the Alabama River, and a number of free-flowing Coosa River tributaries have located only three localized Coosa River drainage populations.
The painted rocksnail is currently known from the lower reaches of three Coosa River tributaries: Choccolocco Creek, Talladega County, Alabama
; Buxahatchee Creek, Shelby County
; and Ohatchee Creek, Calhoun County, Alabama
.
Basin's larger rivers (Coosa River, Alabama River and Cahaba River for Painted rocksnail) is primarily due to extensive construction of dam
s, and the subsequent inundation 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.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of freshwater snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
with a gill and an operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
, an aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
gastropod mollusk in the family Pleuroceridae
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....
.
This species is endemic to the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, specifically the state of Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
. The snail has been listed as threatened on the United States Fish and Wildlife Service list of endangered species
United States Fish and Wildlife Service list of endangered species
This list contains only the bird and mammal species described as endangered by the United States Fish and Wildlife Service. It contains species not only in the U.S. and its territories, but also species only found abroad. It does not contain fish, amphibians, reptiles, plants, or invertebrates,...
since October 28 1998.
Description
The painted rocksnail is a small to medium-sized pleurocerid snail with a shellGastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...
that measures about 19 mm (0.8 in) in length, and is subglobose to oval in shape. The aperture
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
is broadly ovate, and rounded anteriorly. The shell coloration varies from yellowish to olive-brown, usually with four dark bands. Some shells do not have these dark bands, and some have the bands broken into square or oblong patches (see Goodrich, 1922 for a detailed description).
All of the rocksnails that historically inhabited the Mobile
Mobile River
The Mobile River is located in southern Alabama in the United States. Formed out of the confluence of the Tombigbee and Alabama rivers, the approximately river drains an area of of Alabama, with a watershed extending into Mississippi, Georgia, and Tennessee. Its drainage basin is the...
Basin had broadly rounded apertures, oval shaped shells, and variable coloration. Although the various species were distinguished by relative sizes, coloration patterns, and ornamentation, identification could be confusing. The painted rocksnail is the only known survivor of the 15 rocksnail species that historically occurred in the Coosa River
Coosa River
The Coosa River is a tributary of the Alabama River in the U.S. states of Alabama and Georgia. The river is about long altogether.The Coosa River is one of Alabama's most developed rivers...
drainage.
Distribution
The painted rocksnail had the largest range of any rocksnail in the Mobile River Basin. It was historically known from the Coosa River and tributaries from the northeastern corner of St. Clair County, AlabamaSt. Clair County, Alabama
St. Clair County is a county of the U.S. state of Alabama.It is a part of the Birmingham–Hoover–Cullman Combined Statistical Area. Its name is in honor of General Arthur St...
, downstream into the mainstem of the Alabama River
Alabama River
The Alabama River, in the U.S. state of Alabama, is formed by the Tallapoosa and Coosa rivers, which unite about north of Montgomery.The river flows west to Selma, then southwest until, about from Mobile, it unites with the Tombigbee, forming the Mobile and Tensaw rivers, which discharge into...
to Claiborne
Claiborne, Alabama
Claiborne is a ghost town on a bluff above the Alabama River in Monroe County, Alabama. Situated near the Federal Road, Claiborne began during the Mississippi Territory period with a ferry over the river. During the Creek War a large stockade fort, named Fort Claiborne, was established at the...
, Monroe County, Alabama
Monroe County, Alabama
Monroe County is a county of the U.S. state of Alabama. Its name is in honor of James Monroe, fifth President of the United States. As of 2010, the population was 23,068. Its county seat is Monroeville. It is a dry county, in which the sale of alcoholic beverages is restricted or...
, and the Cahaba River
Cahaba River
The Cahaba River is the longest free-flowing river in Alabama and is among the most scenic and biologically diverse rivers in the United States. The Cahaba River is a major tributary of the Alabama River and part of the larger Mobile River Basin...
below the Fall Line in
Perry
Perry County, Alabama
Perry County is a county of the U.S. state of Alabama. It was established in 1819, and is named in honor of Commodore Oliver Hazard Perry of Rhode Island and the United States Navy. As of 2010 the population was 10,591...
and Dallas counties, Alabama
Dallas County, Alabama
Dallas County is a county of the U.S. state of Alabama. Its name is in honor of United States Secretary of the Treasury Alexander J. Dallas. The county seat is Selma.- History :...
.
Surveys by Service biologists and others in the Cahaba River, unimpounded portions of the Alabama River, and a number of free-flowing Coosa River tributaries have located only three localized Coosa River drainage populations.
The painted rocksnail is currently known from the lower reaches of three Coosa River tributaries: Choccolocco Creek, Talladega County, Alabama
Talladega County, Alabama
Talladega County is a county of the U.S. state of Alabama. Talladega is a Muscogee Native American word derived from TVLVTEKE, which means "border town." As of 2010, the population was 82,291...
; Buxahatchee Creek, Shelby County
Shelby County, Alabama
Shelby County is a county of the U.S. state of Alabama and a part of the Birmingham–Hoover–Cullman Combined Statistical Area. It is named in honor of Isaac Shelby, Governor of Kentucky. The county seat of Shelby County is Columbiana. As of 2010 U.S. Census the population was 195,085. Shelby...
; and Ohatchee Creek, Calhoun County, Alabama
Calhoun County, Alabama
Calhoun County is a county in the U.S. state of Alabama. Its name is in honor of John C. Calhoun, famous member of the United States Senate from South Carolina. As of 2010 the population was 118,572. It is included in the Anniston-Oxford Metropolitan Statistical Area...
.
Reasons for the decline
The Painted rocksnail has disappeared from more than 90 percent of its historic range. The curtailment of habitat and range for this (and few other snail species) species in the MobileMobile River
The Mobile River is located in southern Alabama in the United States. Formed out of the confluence of the Tombigbee and Alabama rivers, the approximately river drains an area of of Alabama, with a watershed extending into Mississippi, Georgia, and Tennessee. Its drainage basin is the...
Basin's larger rivers (Coosa River, Alabama River and Cahaba River for Painted rocksnail) is primarily due to extensive construction of dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
s, and the subsequent inundation 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.