The elktoe (''Alasmidonta marginata'') is a

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), ...

freshwater mussel Freshwater bivalves are molluscs of the order Bivalvia that inhabit freshwater ecosystems. They are one of the two main groups of freshwater molluscs, along with freshwater snails. The majority of bivalve molluscs are saltwater species that l ...

, an

aquatic Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

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 family

Unionidae The Unionidae are a Family (biology), family of freshwater mussels, the largest in the order Unionida, the bivalve molluscs sometimes known as river mussels, or simply as unionids. The range of distribution for this family is world-wide. It is a ...

, the river mussels. This species is found in southeastern

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

and the eastern

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. Like many mussels, it is threatened by water pollution from agriculture, industry, and other development, such as

acid mine drainage Acid mine drainage, acid and metalliferous drainage (AMD), or acid rock drainage (ARD) is the outflow of acidic water from metal mines and coal mines. Acid rock drainage occurs naturally within some environments as part of the rock weatherin ...

and

sedimentation Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to th ...

. It may be

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

Oklahoma Oklahoma ( ; Choctaw language, Choctaw: , ) is a landlocked U.S. state, state in the South Central United States, South Central region of the United States. It borders Texas to the south and west, Kansas to the north, Missouri to the northea ...

Description

The elktoe is a moderately sized mussel of about 4 inches. The shell is thin and triangular-shaped with an inflated center. The anterior end is elongated and round and the border of the shell is marked with fine ridges. The hinge of the two shells, or umbo, is large and located near the center of the shell. The shell is a dull yellowish-green with multiple rays and dark green spots. The interior of the shell is a glossy bluish-white and may have some salmon near the edges and beak. The beak consists of double-looped ridges lined with thin teeth. The elktoe most closely resembles the

snuffbox A decorative box is a form of packaging that is generally more than just functional, but also intended to be decorative and artistic. Many such boxes are used for promotional packaging, both commercially and privately. Historical objects are u ...

and deertoe, however, both lack a beak and teeth.

Ecology

The elktoe is most commonly found in small, fast-moving, and shallow rivers, however, it can survive in larger bodies of water. The elktoe prefers a sand or gravel substrate. Substantial populations are found from Northeastern Canada to Arkansas. It is found along the east coast from New York to Virginia but remains inland further South. The majority of the elktoe population is found in Ohio, Indiana, and Illinois. The species was once found in Alabama but is now believed to have been extirpated as there have been no recordings in the past few decades Like other mussels, the elktoe may live for many decades and up to a century buried in rocks and other sediment. They are mostly sedentary but may use their foot, a muscle on the inside of the shell, to move around by extending and contracting the mussel between the two shells. The elktoe is a filter feeder and eats mostly bacteria, algae, and other organic matter. Water is drawn into the body through the siphon, and food and oxygen are removed from the water which is then pumped out through the siphon. Mussels are gonochoristic, meaning there are separate sexes. The elktoe breeds during warm months and females will keep the larval forms, called glochidia, in the marsupia for up to eleven months. Once released, the larva must attach to the gills of a host fish, where they are parasitic on the fish until becoming a juvenile mussel. Juvenile mussels will then live in substrate and filter feed until they develop into adults.

Conservation

All freshwater mussels in North America have suffered an extreme decline in population growth and increase in extinction rate due to habitat loss, deterioration, fragmentation, and pollution. The elktoe also experiences predation and competition with invasive species. In the Mississippi River, the

Zebra mussel The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel, an Aquatic animal, aquatic bivalve mollusk in the family Dreissenidae. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally Intro ...

will attach in large numbers to native mussels, including the elktoe, and cause suffocation and eventual death. Future conservation efforts should focus on maintaining the natural habitat of the mussels from deterioration and pollution from both industrial and residential points. In addition to protecting the elktoe, the most common host fish must also be protected, such as the

White sucker The white sucker (''Catostomus commersonii'') is a species of freshwater cypriniform fish inhabiting the upper Midwest and Northeast in North America, but it is also found as far south as Georgia and as far west as New Mexico. The fish is common ...

Rock bass The rock bass (''Ambloplites rupestris''), also known as the rock perch, goggle-eye, red eye, and black perch, is a freshwater fish native to east-central North America. This red-eyed fish is a species of freshwater fish in the sunfish family (bi ...

, and

Warmouth The warmouth (''Lepomis gulosus'') is a freshwater fish of the sunfish family (biology), family (Centrarchidae) that is found throughout the eastern United States. Other local names include molly, redeye, goggle-eye, red-eyed bream, and strawber ...

."Alasmidonta marginata (Elktoe) - Michigan Natural Features Inventory". ''mnfi.anr.msu.edu''. Retrieved 2024-04-15.

References

Alasmidonta Molluscs of North America Bivalves described in 1818 Taxonomy articles created by Polbot {{Unionidae-stub