Spiny river snail

The spiny river snail, scientific name Io fluvialis, is a freshwater snail species, an aquatic mollusk in the Pleuroceridae family. This is the only species in the genus Io.^[3] This species is endemic to the USA.

Spiny river snail
A live individual of Io fluvialis
A live individual of Io fluvialis
Conservation status
Endangered  (IUCN 2.3)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Caenogastropoda
Superfamily:	Cerithioidea
Family:	Pleuroceridae
Genus:	Io Lea, 1831[2]
Species:	I. fluvialis
Binomial name
Io fluvialis (Say, 1825)

Ecology

Distribution

This species is endemic to the Tennessee River and its larger tributaries, but it has been largely extirpated due to pollution and the construction of dams.

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.^[4]