dcsimg

Distribution

    Distribution
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    The elktoe is found in the upper Mississippi drainage in the Ohio, Cumberland and Tennessee River systems as well as the Susquehanna River. In the Great Lakes region it is in the St. Lawrence drainage from Lake Huron to the Ottawa River. In general its range spans from western New York and Pennsylvania, west to Wisconsin, and south to northern Alabama.

    In Michigan this species is found in rivers in both the upper and lower peninsulas, but may be absent from the coldwater rivers and streams in the northwest part of the state.

    Biogeographic Regions: nearctic (Native )

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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    Alasmidonta_marginata/geographic_range

Morphology

    Morphology
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    The elktoe is up to 10 cm (4 inches) long , and is elongate and quadrate. The shell is usually fairly thin and inflated. The anterior end is rounded, the posterior end is bluntly ended in a squarish point. The dorsal margin is slightly rounded and the ventral margin is nearly straight.

    Umbos are broad and elevated above the hinge line. The beak sculpture is three to five heavy, raised, double-looped ridges.

    The periostracum (outer shell layer) is smooth, yellow-brown with broad green rays and dark green dots. The posterior end of the shell is usually lighter.

    On the inner shell, both left and right valves have a thin, elongated, pseudocardinal tooth. Lateral teeth are absent but there is a swelling on the hinge line.

    The beak cavity is moderately deep. Although the nacre is white, occasionally it is has a salmon tint near the beak.

    In Michigan, this species can be confused with the snuffbox, slippershell, and deertoe. The snuffbox is generally smaller, more square, and females have teeth ridges at the posterior margin. Slippershells are smaller, therefore growth lines are closer together. The deertoe has a more rounded ventral margin. The elktoe is spotted with dark green dots, which are absent in the other species. The foot of a live elktoe also tends to have an orangish color.

    Range length: 10 (high) cm.

    Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

    Sexual Dimorphism: sexes alike

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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Habitat

    Habitat
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    The elktoe is usually found in larger creeks the upper reaches of rivers. Substrates where it was found are described as mixed sand and gravel.

    Habitat Regions: freshwater

    Aquatic Biomes: rivers and streams

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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    Alasmidonta_marginata/habitat

Trophic Strategy

    Trophic Strategy
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    In general, unionids are filter feeders. The mussels use cilia to pump water into the incurrent siphon where food is caught in a mucus lining in the demibranchs. Particles are sorted by the labial palps and then directed to the mouth. Mussels have been cultured on algae, but they may also ingest bacteria, protozoans and other organic particles.

    The parasitic glochidial stage absorbs blood and nutrients from hosts after attachment. Mantle cells within the glochidia feed off of the host’s tissue through phagocytocis.

    Plant Foods: algae; phytoplankton

    Other Foods: detritus ; microbes

    Foraging Behavior: filter-feeding

    Primary Diet: planktivore ; detritivore

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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    Alasmidonta_marginata/food_habits

Associations

    Associations
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    While freshwater mussels require a host fish for metamorphosis, the host for the elktoe is unknown.

    Ecosystem Impact: parasite

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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    Alasmidonta_marginata/ecosystem_roles
    Associations
    provided by Animal Diversity Web

    Unionids in general are preyed upon by muskrats, raccoons, minks, otters, and some birds. Juveniles are probably also fed upon by freshwater drum, sheepshead, lake sturgeon, spotted suckers, redhorses, and pumpkinseeds.

    Unionid mortality and reproduction is affected by unionicolid mites and monogenic trematodes feeding on gill and mantle tissue. Parasitic chironomid larvae may destroy up to half the mussel gill.

    Known Predators:

    • muskrat, Ondatra zibethicus
    • mink, Neovison vison
    • raccoon Procyon lotor
    • otter, Lontra canadensis
    • turtles, Testudines
    • hellbenders, Cryptobranchus
    • freshwater drum, Aplodinotus grunniens
    • sheepshead, Archosargus probatocephalus
    • lake sturgeon, Acipenser fulvescens
    • shortnosed sturgeon, Acipenser brevirostrum
    • spotted suckers, Minytrema melanops
    • common red-horse, Moxostoma
    • catfish, Siluriformes
    • pumpkinseed, Lepomis gibbosus
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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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    Alasmidonta_marginata/predation

Behavior

    Behavior
    provided by Animal Diversity Web

    The middle lobe of the mantle edge has most of a bivalve's sensory organs. Paired statocysts, which are fluid filled chambers with a solid granule or pellet (a statolity) are in the mussel's foot. The statocysts help the mussel with georeception, or orientation.

    Mussels are heterothermic, and therefore are sensitive and responsive to temperature.

    Unionids in general may have some form of chemical reception to recognize fish hosts. Mantle flaps in the lampsilines are modified to attract potential fish hosts. How the elktoe attracts and if it recognizes its fish host is unknown.

    Glochidia respond to touch, light and some chemical cues. In general, when touched or a fluid is introduced, they will respond by clamping shut.

    Communication Channels: chemical

    Perception Channels: visual ; tactile ; vibrations ; chemical

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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Life Cycle

    Life Cycle
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    Fertilized eggs are brooded in the marsupia (water tubes) up to 11 months, where they develop into larvae, called glochidia. The glochidia are then released into the water where they must attach to the gill filaments and/or general body surface of the host fish. After attachment, epithelial tissue from the host fish grows over and encapsulates a glochidium, usually within a few hours. The glochidia then metamorphoses into a juvenile mussel within a few days or weeks. After metamorphosis, the juvenile is sloughed off as a free-living organism. Juveniles are found in the substrate where they develop into adults.

    Development - Life Cycle: metamorphosis

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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    Alasmidonta_marginata/development

Life Expectancy

    Life Expectancy
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    The age of mussels can be determined by looking at annual rings on the shell. However, no demographic data on this species has been recorded.

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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Reproduction

    Reproduction
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    Age to sexual maturity for this species is unknown. Unionids are gonochoristic (sexes are separate) and viviparous. The glochidia, which are the larval stage of the mussels, are released live from the female after they are fully developed.

    In general, gametogenesis in unionids is initiated by increasing water temperatures. The general life cycle of a unionid, includes open fertilization. Males release sperm into the water, which is taken in by the females through their respiratory current. The eggs are internally fertilized in the suprabranchial chambers, then pass into water tubes of the gills, where they develop into glochidia.

    Alasmidonta marginata is a long-term brooder. In the Huron River, it was gravid from early August to late May. It likely spawns from June to July.

    Breeding interval: The elktoe breeds once in the warmer months of the year.

    Breeding season: In Michigan, the breeding season is probably June to July.

    Range gestation period: 10 (high) months.

    Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous

    Females brood fertilized eggs in their marsupial pouch. The fertilized eggs develop into glochidia. There is no parental investment after the female releases the glochidia.

    Parental Investment: pre-fertilization (Provisioning); pre-hatching/birth (Provisioning: Female)

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Alasmidonta_marginata/reproduction

Conservation Status

    Conservation Status
    provided by Animal Diversity Web

    The IUCN has not rated the conservation status of Alasmidonta marginata because not enough is known about its abundance. The elktoe is listed as endangered in Kansas, threatened in Minnesota, and a species of special concern in Virginia and in Michigan.

    US Federal List: no special status

    CITES: no special status

    State of Michigan List: special concern

    IUCN Red List of Threatened Species: data deficient

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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    Alasmidonta_marginata/conservation_status

Benefits

    Benefits
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    There are no significant negative impacts of mussels on humans.

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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    Alasmidonta_marginata/economic_importance_negative
    Benefits
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    Mussels are ecological indicators. Their presence in a water body usually indicates good water quality.

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    Mulcrone, R. 2005. "Alasmidonta marginata" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alasmidonta_marginata.html
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    Renee Sherman Mulcrone
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    Alasmidonta_marginata/economic_importance_positive