Snuffbox

Epioblasma triquetra

SARA Status
No Status
NS
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

SARA Status

  • No Status NS
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX
COSEWIC Status
Not at Risk
NR
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

COSEWIC Status

  • Not at Risk NR
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

Description

The Snuffbox (Epioblasma triquetra) is one of Canada’s 54 freshwater mussel species and the most widely distributed member of the genus Epioblasma. It is a small, unique-looking mussel with the following features:

  • shell is solid and thick, triangular in shape in males, somewhat longer and “puffed-up” in females;
  • males may reach seven cm, females may reach six cm in length;
  • the raised part at the top of the shell (beak) is swollen and sculptured with three or four faint double-looped ridges;
  • the shell is rounded at both ends, while top and bottom edges are nearly parallel;
  • outside shell is smooth, yellowish to yellow-green and marked with many dark green rays that are often broken into triangular spots that look like “dripping paint”;
  • inside shell (nacre) is white and shiny on the back half and has a grey-blue tinge in the depression inside the beak; and
  • there are deep scars on the inside of the shell where the muscles that hold the two shell-halves together attach

Habitat

Historically, the Snuffbox was found in Ontario in lakes Erie and St. Clair and the Ausable, Grand, Niagara, Sydenham and Thames rivers. It is currently known to occur only in a 93 km reach of the East Sydenham River as well as at five sites within a 91 km reach of the Ausable River. The Snuffbox was also known from 18 American states, but is now thought to be lost from Iowa, Kansas, New York and Mississippi. Overall, the Snuffbox has been lost from 60 per cent of historically occupied rivers and streams in North America and remaining populations are small and isolated from each other.

The Snuffbox is typically found in small- to medium-sized rivers in “riffles,” shallow areas with clear, swift-flowing water over coarse, firmly packed rubble/ gravel/sand substrates. The Snuffbox is a moderately long-lived, sexually dimorphic species (males and females look different from each other), with a lifespan of at least ten years. It is believed that spawning occurs in late summer and the glochidia (larvae) are released the following May–June. Like most other freshwater mussels, the glochidia are parasitic on fishes. Using its shell, the female Snuffbox grabs and holds a host fish while releasing glochidia into the fish’s mouth. The glochidia then attach to the host fish as they flow through its gills. Here they will remain until they reach their juvenile, free-living stage and drop off onto the substrate below. Adult Snuffbox are sedentary and spend their lives completely or partially burrowed in the substrate. Throughout their lives, they may move only a few metres through the substrate.

In Canada, the Logperch (Percina caprodes) is the main host fish identified for this mussel, but other possible host fishes include the Iowa Darter, Mottled Sculpin, Largemouth Bass, Brook Stickleback and Rainbow Darter.

Like all species of freshwater mussels, the Snuffbox filters its food from the water. Bacteria and algae are its primary food sources.

Threats

The major threats to the Snuffbox continue to be habitat loss and destruction from increasing municipal, industrial, and agricultural activities. Disturbances to Snuffbox habitat, such as flooding of riffle areas and the impoundment of large rivers, have also destroyed much of its habitat over the last century. More recently, the Zebra Mussel has devastated the Great Lakes Snuffbox populations, while the Round Goby may pose a new threat by competing with the mussel’s known host fishes and feeding on juvenile mussels.

Further Information

Under SARA, a recovery strategy and an action plan have been developed to prevent the loss of the Snuffbox in Canada and to return healthy self-sustaining populations of this species to the Ausable, Grand, Sydenham and Thames rivers and the Lake St. Clair delta.

Research, land and water stewardship, monitoring and awareness activities are underway. Provincial legislation regulating agricultural nutrients and protecting clean water in Ontario have been enacted. Critical habitat for the Snuffbox has also now been identified under SARA, allowing for greater protection and recovery of its habitat.

Text Sources: COSEWIC Status Report on the Snuffbox (Epioblasma triquetra) in Canada, 2011; Fisheries and Oceans Canada. Action Plan for the Sydenham River in Canada [proposed], 2012; Fisheries and Oceans Canada. Recovery Strategy for Northern Riffleshell, Snuffbox, Round Pigtoe, Mudpuppy Mussel and Rayed Bean in Canada [proposed], 2012; Metcalfe-Smith et al. Photo Field Guide to the Freshwater Mussels of Ontario, 2005.

For more information, visit the SARA Registry at Species at Risk (SARA) Public Registry Profile.

Snuffbox

Snuffbox (Epioblasma triquetra - Rafinesque, 1820)

Epioblasma triquetra
Male (left) | Female (right)
Photo credit: Environment Canada

Scientific Name: Epioblasma triquetra
SARA Status: Endangered
COSEWIC Status: Endangered
Region: Ontario

Snuffbox distribution as described in the following paragraphs

Map showing the Snuffbox distribution in Canada. The map indicates areas of current and historic sites in southern Ontario.

Did You Know?

Freshwater mussels are molluscs, soft-bodied animals without a skeleton (invertebrates), that live on the bottom of streams, rivers, lakes and ponds. They use a muscular foot to burrow and crawl and have a pair of hinged shells. Mussels are filter feeders — nature’s water purifiers — and are food for other wildlife like fishes, otters, mink, muskrats and some birds. They are also among the most endangered creatures in the world.

Some molluscs are hermaphroditic, meaning that members of a species possess both male and female reproductive organs. Others—like the Snuffbox—are sexually dimorphic, meaning that males and females have distinctly different physical characteristics.

Snuffbox

Photo Credit: Shawn Staton

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