snuffbox
Snuffbox mussel
FWS Focus

Overview

The snuffbox is a small- to medium-sized mussel, with males reaching up to 2.8 in (7.0 cm) in length (Cummings and Mayer 1992, p. 162; Parmalee and Bogan 1998, p. 108). The maximum length of females is about 1.8 in (4.5 cm) (Parmalee and Bogan 1998, p. 108). The shape of the shell is somewhat triangular (females), oblong, or ovate (males), with the valves solid, thick, and very inflated. The beaks are located somewhat anterior of the middle, and are swollen, turned forward and inward, and extended above the hingeline (Cummings and Mayer 1992, p. 162). Beak sculpture consists of three or four faint, double-looped bars (Cummings and Mayer 1992, p. 162; Parmalee and Bogan 1998, p. 108). The anterior end of the shell is rounded, and the posterior end is truncated, highly so in females. The posterior ridge is prominent, being high and rounded, while the posterior slope is widely flattened. The posterior ridge and slope in females is covered with fine ridges and grooves, and the posterioventral shell edge is finely toothed (Cummings and Mayer 1992, p. 162). The ventral margin is slightly rounded in males and nearly straight in females. Females have recurved denticles (downward curved tooth-like structures) on the posterior shell margin that aid in holding host fish (Barnhart 2008, p. 1). The periostracum (external shell surface) is generally smooth and yellowish or yellowish-green in young individuals, becoming darker with age. Green, squarish, triangular, or chevron-shaped marks cover the umbone (the inflated area of the shell along the dorsal margin), but become poorly delineated stripes with age. Internally, the left valve has two high, thin, triangular, emarginate pseudocardinal teeth (the front tooth being thinner than the back tooth) and two short, strong, slightly curved, and finely striated lateral teeth. The right valve has a high, triangular pseudocardinal tooth with a single short, erect, and heavy lateral tooth. The interdentum (a flattened area between the pseudocardinal and lateral teeth) is absent, and the beak cavity is wide and deep. The color of the nacre is white, often with a silvery luster, and a gray-blue or gray-green tinge in the beak cavity. Key characters useful for distinguishing the snuffbox from other species include its unique color pattern, shape (especially in females), and high degree of inflation.

Scientific Name

Epioblasma triquetra
Common Name
snuffbox
Snuffbox mussel
FWS Category
Clams
Kingdom

Location in Taxonomic Tree

Identification Numbers

TSN:

Characteristics

Characteristic category

Overview

Characteristics

Overview

The snuffbox is an endangered species that is declining throughout its range due to habitat modification and destruction, sedimentation, and pollution. Despite this, it remains the most widespread and abundant member of the genus Epioblasma, of which the other members are now either extinct or severely imperiled.  All remaining species in this genus are also federally listed. 

Characteristic category

Habitat

Characteristics

Habitat

The snuffbox is an endangered species declining throughout its range due to habitat modification and destruction, sedimentation, and pollution. Despite this, it remains the most widespread and abundant member of the genus Epioblasma, of which the other members are now either extinct or severely imperiled.  All remaining species in this genus are also federally listed. 

River or Stream
Characteristic category

Food

Characteristics

Food

The snuffbox feeds by using a siphon to filter small organic particles, such as bacteria, algae, and detritus, out of the water column and into their gill chambers.

Characteristic category

Behavior

Characteristics

Behavior

The snuffbox feeds by using a siphon to filter small organic particles, such as bacteria, algae, and detritus, out of the water column.

Characteristic category

Physical Characteristics

Characteristics

Size & Shape

The snuffbox has a triangular, medium-sized shellThe species is sexually dimorphic, meaning males and females differ in appearance. The shell of the male has a narrow, shallow central depression or groove and the female's shell extends outward at one end. Males can grow to 70 mm with females being considerably smaller.

Color & Pattern

The snuffbox has a yellow, green or brown shell interrupted with green rays, blotches or chevron-shaped lines. The shell becomes darker and the interruptions less clear with age. The inside of the shell is white.

Characteristic category

Lifecycle

Characteristics

Lifecycle

The snuffbox has a complicated life history that is tightly linked to freshwater fishes. Fertilized eggs develop into larvae, called glochidia, which are held by the female. Glochidia, when released from the female, must come in contact with a passing fish and attach to the gills, fins, or body of that fish. During this parasitic stage, the mussel glochidia are relatively harmless to their fish host. The mussel-host fish relationship helps disperse a basically immobile creature (the mussel), within and between aquatic systems. Snuffbox are "host specific" in that their glochidia can only survive on a specific species of fish, primarily the logperch. If a glochidium attaches to a fish that is not a suitable host species, it will not survive. After several weeks, the glochidia free themselves from the host, drift to the substrate and begin their lives as juvenile mussels.

Lifespan

The snuffbox may live up to 25 years. They reach sexual maturity at around age 3.

Reproduction

The is currently considered extant in 85 streams across its geographical range within the states of Alabama; Arkansas; Illinois; Indiana; Kentucky; Michigan; Minnesota; Missouri; Ohio; Pennsylvania; Tennessee; Virginia; West Virginia; and Wisconsin, USA and Ontario, Canada. Historically, the snuffbox occurred in at least 213 streams and lakes, as well as occurred in the states Iowa; Kansas; Mississippi; and New York. The species range has since been reduced to the upper Great Lakes sub-basin; the lower Great Lakes sub-basin; the upper Mississippi River sub-basin; the Ohio River System; the Cumberland River System; the Tennessee River System; and the lower Mississippi River sub-basin.

Characteristic category

Geography

Characteristics

Range

The is currently considered extant in 85 streams across its geographical range within the states of Alabama; Arkansas; Illinois; Indiana; Kentucky; Michigan; Minnesota; Missouri; Ohio; Pennsylvania; Tennessee; Virginia; West Virginia; and Wisconsin, USA and Ontario, Canada. Historically, the snuffbox occurred in at least 213 streams and lakes, as well as occurred in the states Iowa; Kansas; Mississippi; and New York. The species range has since been reduced to the upper Great Lakes sub-basin; the lower Great Lakes sub-basin; the upper Mississippi River sub-basin; the Ohio River System; the Cumberland River System; the Tennessee River System; and the lower Mississippi River sub-basin.

Geography

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