The spiny river snail,

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 ...

''Io fluvialis'', is a

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 ...

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), ...

, an aquatic

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

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 ...

family. This is the only species in the genus ''Io''. 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 USA.

Ecology

Distribution

This species is

to the

Tennessee River The Tennessee River is a long river located in the Southern United States, southeastern United States in the Tennessee Valley. Flowing through the states of Tennessee, Alabama, Mississippi, and Kentucky, it begins at the confluence of Fren ...

and its larger

tributaries A tributary, or an ''affluent'', is a stream or river that flows into a larger stream ('' main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which the ...

, but it has been largely extirpated due to pollution and the 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 ...

Habitat

These snails live in rapidly flowing, well-oxygenated waters of shoals and riffles of rivers, but not in slack water below shoals. The species preferred water depth of up to 1.5 m.

Behavior

These snails feed on the algal coating on rocks. Females lay between 20 and 100 eggs, which begin to hatch after 15 days.

Description

The shell morphology is very variable, with some individuals totally lacking spines. For this reason, it was formerly thought that many species existed within this genus.

Human relevance

The shells are found abundantly in shell middens along the rivers within their range, indicating they were exploited as a food source by Native American cultures. Additionally, this snail has served as the emblem for the American Malacological Society since 1960.https://web.archive.org/web/20110817075159/http://www.malacological.org/about/75_years_of_molluscs.pdf

References

Molluscs of the United States Pleuroceridae Gastropods described in 1825 Taxonomy articles created by Polbot Taxa named by Isaac Lea {{Pleuroceridae-stub