The spiny river snail,

scientific name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''Io fluvialis'', is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

freshwater snail Freshwater snails are gastropod mollusks which 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 ...

, an aquatic

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

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. Reprodu ...

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

endemic Endemism is the state of a species being found 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 found elsew ...

to the USA.

Ecology

Distribution

This species is

to the

Tennessee River The Tennessee River is the largest tributary of the Ohio River. It is approximately long and is located in the southeastern United States in the Tennessee Valley. The river was once popularly known as the Cherokee River, among other names, ...

and its larger

tributaries A tributary, or affluent, is a stream or river that flows into a larger stream or 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 drain the surrounding drainage b ...

, 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, a ...

Habitat

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

Behavior

These snails feed on the algal coating on rocks. Females lay between 20-100 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 its 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.

References

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