ADW: Margaritiferidae: INFORMATION

<!DOCTYPE html> <html xmlns:og="http://ogp.me/ns#" lang="en" xml:lang="en"> <head> <title>ADW: Margaritiferidae: INFORMATION</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="canonical" href="https://animaldiversity.org/accounts/Margaritiferidae/" /> <script type="text/javascript" src="//code.jquery.com/jquery-3.6.0.min.js"></script> <script type="text/javascript" src="//code.jquery.com/jquery-migrate-3.3.2.min.js"></script> <script type="text/javascript" src="/static/js/compat.js"></script> <link rel="shortcut icon" href="https://animaldiversity.org/favicon.ico" /> <link href="//fonts.googleapis.com/css?family=Gentium+Book+Basic:400,400italic,700,700italic" rel="stylesheet" type="text/css" /> <link href="//fonts.googleapis.com/css?family=PT+Sans:400,700,400italic,700italic" rel="stylesheet" type="text/css" /> <link rel="stylesheet" type="text/css" href="/static/bootstrap/css/bootstrap.css" /> <link rel="stylesheet" href="/static/css/pica.styles.css" /> <link rel="stylesheet" href="/static/css/pica.print.css" media="print" />  <link rel="stylesheet" type="text/css" href="/static/colorbox/colorbox.css" /> <meta property="og:url" content="https://animaldiversity.org/accounts/Margaritiferidae/" /> <meta content="Margaritiferidae" property="og:title" /> <meta content="website" property="og:type" /> <meta content="Animal Diversity Web" property="og:site_name" /> <meta content="https://animaldiversity.org/collections/contributors/Grzimek_inverts/Bivalvia/Margaritifera_margaritifera/medium.jpg" property="og:image" /> <meta name="twitter:card" content="summary" /> <meta name="twitter:site" content="@AnimalDiversity" /> <meta name="twitter:title" content="Margaritiferidae" /> <meta name="twitter:description" content="Read about Margaritiferidae on the Animal Diversity Web." /> <meta name="twitter:image:src" content="https://animaldiversity.org/collections/contributors/Grzimek_inverts/Bivalvia/Margaritifera_margaritifera/medium.jpg" /> <meta name="twitter:image:height" content="422" /> <meta name="twitter:image:width" content="640" /> <meta name="twitter:url" content="https://animaldiversity.org/accounts/Margaritiferidae/" /> <script type="text/javascript" src="/static/js/Hyphenator.js"></script> <link rel="stylesheet" href="/static/social-likes/social-likes_birman.css" /> <style> .social-likes { margin: 0; } .social-likes__widget { margin: 0; } </style>   </head> <body> <div id="outerwrap"> <div id="header" aria-role="header"> <h1> <a id="homelink" href="/">Animal Diversity Web</a> </h1> <div class="umlinks"> <div class="relative"> <a href="https://lsa.umich.edu/ummz/" id="ummzlink">University of Michigan Museum of Zoology</a> <a href="https://www.umich.edu/" id="umlink">University of Michigan</a> </div> </div> </div> <div id="wrap" class="gradient"> <div class="container-fluid"> <div class="row-fluid"> <div class="span2 sidebar left"> <ul class="nav nav-tabs nav-stacked" id="sitemap"> <li> <a href="/">Home</a> </li> <li> <a href="/about/">About Us</a> </li> <li> <a href="/animal_names/">About Animal Names</a> </li> <li> <a href="/teach/">Educational Resources</a> </li> <li> <a href="/collections/">Special Collections</a> </li> <li> <a href="/glossary/">Glossary</a> </li> <li> <a href="/accounts/Animalia/">Browse Animalia</a> </li> </ul> <h2 class="offscreen">More Information</h2> <div class="well"> <h3>Additional Information</h3> <ul class="unstyled"> <li> <a href="http://eol.org/search/?q=Margaritiferidae&search=Go">Encyclopedia of Life</a> </li> </ul> </div> </div> <div class="span7_5 blahblahblah main" aria-role="main"> <h2 class="rank-family">Margaritiferidae</h2> <div class="social-likes" data-counters="no"> <div class="facebook" title="Share link on Facebook">Facebook</div> <div class="twitter" title="Share link on Twitter">Twitter</div> </div> <div class="snapshots" aria-hidden="true"> <ul> <li> <a href="/accounts/Margaritiferidae/pictures/collections/contributors/Grzimek_inverts/Bivalvia/Margaritifera_margaritifera/"> <img alt=" " src="/collections/contributors/Grzimek_inverts/Bivalvia/Margaritifera_margaritifera/button.jpg" border="0" /> </a> </li> </ul> </div> <div class="byline">By Lisa Winhold</div> <nav class="contents"> <ul> <li> <a href="#diversity">Diversity</a> </li> <li> <a href="#geographic_range">Geographic Range</a> </li> <li> <a href="#habitat">Habitat</a> </li> <li> <a href="#physical_description">Physical Description</a> </li> <li> <a href="#development">Development</a> </li> <li> <a href="#reproduction">Reproduction</a> </li> </ul> <ul> <li> <a href="#lifespan_longevity">Lifespan/Longevity</a> </li> <li> <a href="#behavior">Behavior</a> </li> <li> <a href="#communication">Communication and Perception</a> </li> <li> <a href="#food_habits">Food Habits</a> </li> <li> <a href="#predation">Predation</a> </li> <li> <a href="#ecosystem_roles">Ecosystem Roles</a> </li> </ul> <ul> <li> <a href="#economic_importance_positive">Economic Importance for Humans: Positive</a> </li> <li> <a href="#economic_importance_negative">Economic Importance for Humans: Negative</a> </li> <li> <a href="#conservation_status">Conservation Status</a> </li> <li> <a href="#contributors">Contributors</a> </li> <li> <a href="#references">References</a> </li> </ul> </nav> <div class="inner-wrap"> <section class="hyphenate"> <h3 id="diversity">Diversity</h3> <p audience="advanced intermediate">The family <span class="taxon-link rank-family">Margaritiferidae</span> is commonly referred to as pearl mussels, naiads, or margaritiferids. No more than 15 species in 3 genera have been described, which is nearly 5% of the <a class="taxon-link rank-order" href="/accounts/Unionoida/">Unionoida</a> species in the Holarctic (Smith, 2001b). <span class="citations"> (<a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>)</span></p> <p audience="advanced intermediate">In general, <span class="taxon-link rank-family">Margaritiferidae</span> are acephalic (no head), bivalved mollusks usually with the beak (the elevated portion of the dorsal margin) slightly anterior. When present, the pseudocardinal teeth are anterior to the beak and the lateral teeth are posterior. The species in this family have a foot rather than a byssus, fibrous structures found in other mussel families. Along with <a class="taxon-link rank-family" href="/accounts/Unionidae/">Unionidae</a>, another family included in the order <a class="taxon-link rank-order" href="/accounts/Unionoida/">Unionoida</a>, <span class="taxon-link rank-family">Margaritiferidae</span> does not have true siphons. Unlike the family <a class="taxon-link rank-family" href="/accounts/Unionidae/">Unionidae</a>, the inhalant aperture (opening in the posterior end of the mantle border where water enters the mussel) of <span class="taxon-link rank-family">Margaritiferidae</span> has branched papillae (bumps). The shells are elongate, thick, black, rhomboidal and often arcuate (arched) and range in size from 80 to over 200 mm in length (Smith, 2001b). <span class="citations"> (<a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>)</span></p> </section> <section class="hyphenate"> <h3 id="geographic_range">Geographic Range</h3> <p audience="advanced intermediate">Members of the family <span class="taxon-link rank-family">Margaritiferidae</span> are found throughout the Holarctic. There are three genera and up to five species found in North America, two genera and two species in Europe, one species in North Africa, one species in Syria, one genus and three species in northeast Asia, and one species in southeast Asia (Smith, 2001b). <span class="citations"> (<a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>)</span></p> <p audience="advanced intermediate">Before the supercontinent of Pangaea divided, <span class="taxon-link rank-family">Margaritiferidae</span> were dispersed throughout. Today most of the <span class="taxon-link rank-family">Margaritiferidae</span> are found in high altitude streams due most likely to the expanse of the <a class="taxon-link rank-family" href="/accounts/Unionidae/">Unionidae</a> in the higher order rivers (Smith, 2001b). <span class="citations"> (<a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>)</span></p> <ul class="keywords donthyphenate "> <li class="keywords-header">Biogeographic Regions</li> <li> <a class="gloss" href="#20020914235803">nearctic</a> <ul> <li> <a class="gloss" href="#20020904145365">native</a> </li> </ul> </li> <li> <a class="gloss" href="#20020915001330">palearctic</a> <ul> <li> <a class="gloss" href="#20020904145365">native</a> </li> </ul> </li> <li> <a class="gloss" href="#20020915001348">oriental</a> <ul> <li> <a class="gloss" href="#20020904145365">native</a> </li> </ul> </li> </ul> <ul class="keywords donthyphenate last"> <li class="keywords-header">Other Geographic Terms</li> <li> <a class="gloss" href="#200304045530">holarctic</a> </li> </ul> </section> <section class="hyphenate"> <h3 id="habitat">Habitat</h3> <p audience="advanced intermediate">Margaritiferids are found in permanent freshwater sources with moving water such as streams and rivers. They are most abundant in depths less than 2 m, but will populate waters as deep as 7 m (Smith, 2001a). Large rivers tend to contain a wider diversity of mussel species and larger populations than smaller streams (Cummings and Mayer, 1992). Watters (1992) found a relationship between the size of the drainage basin and the fish diversity. He also found a linear correlation between the fish diversity and the mussel diversity. Rivers tend to have a more abundant food supply and higher dissolved oxygen content than bodies of water with little or no current. They may also provide a more preferred substrate and water chemistry. <span class="citations"> (<a href="#55e629cce1f4435134ecdd93227acd0a" class="citation">Cummings and Mayer, 1992</a>; <a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>; <a href="#104ac2a2e86e98444c7a2b253ffdfe11" class="citation">Watters, 1992</a>)</span></p> <p audience="advanced intermediate">Margaritiferids tend to thrive in neutral to weakly acidic water, but may be found in slightly alkaline water (Smith, 2001b). Acidic water tends to dissolve the calcium content in the shells. As an adaptation to the soft water, <span class="taxon-link rank-family">Margaritiferidae</span> shells are thick, containing nearly 30% of the mussel's organic content (Bauer, 2001a). <span class="citations"> (<a href="#7c338419e365b0f661d94305b785e949" class="citation">Bauer, 2001a</a>; <a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>)</span></p> <ul class="keywords donthyphenate "> <li class="keywords-header">Habitat Regions</li> <li> <a class="gloss" href="#20020904145595">temperate</a> </li> <li> <a class="gloss" href="#20020904145747">freshwater</a> </li> </ul> <ul class="keywords donthyphenate "> <li class="keywords-header">Aquatic Biomes</li> <li> <a class="gloss" href="#20020904145431">benthic</a> </li> <li> <span>rivers and streams</span> </li> </ul> <ul class="keywords donthyphenate last"> <li class="keywords-header">Other Habitat Features</li> <li> <a class="gloss" href="#20020904145842">riparian</a> </li> <li> <a class="gloss" href="#20020904145633">intertidal or littoral</a> </li> </ul> </section> <section class="hyphenate"> <h3 id="physical_description">Physical Description</h3> <p audience="advanced intermediate">In general, members of the <span class="taxon-link rank-family">Margaritiferidae</span> family are acephalic (not having a true head), have two calcium carbonate/organic shells called "valves" (bivalved) attached at the hinge by an elastic <a class="rewrite" href="/resources/biodidac/bivashell1.jpg/medium.jpg">ligament</a>. They have an <a class="rewrite" href="/resources/biodidac/bivashell1.jpg/medium.jpg">umbo</a> (beak) along the dorsal margin and slightly anterior to the hinge and are bilaterally symmetrical along a plane running between the two valves. Individuals do not have true siphons. Instead, they have two openings in the mantle along the posterior margin that act as the inhalant and exhalant apertures (Smith, 2001a). Unlike the <a class="taxon-link rank-family" href="/accounts/Unionidae/">Unionidae</a>, which have two openings in the mantle for the exhalant aperture, <span class="taxon-link rank-family">Margaritiferidae</span> has only one opening. The mantle margin along the inhalant aperture is lined with branched papillae (<a class="taxon-link rank-family" href="/accounts/Unionidae/">Unionidae</a> have unbranched papillae or bumps) (Smith, 2001b). The exhalant aperture has crenulations (grooves) along the mantle margin (Smith, 2001b). Under each mantle, is a gill made up of two demibranchs. Each demibranch is composed of two <a class="rewrite" href="/resources/biodidac/lamellae.jpg/medium.jpg">lamellae</a> fused at the ventral surface but open at the dorsal surface forming a "W." The ax-shaped foot is found on the anterior end of the organism and between the demibranchs in the two valves. The majority of the median visceral mass in the posterior portion of the organism is primarily dorsal and not as confined in the anterior portion (Smith, 2001a). As acephalic organisms, mussels have a simplistic sensory system. Their <a class="rewrite" href="/resources/biodidac/bivanerv.jpg/medium.jpg">nervous system</a> is comprised of three pairs of ganglia: cerebropleural, pedal, and visceral. With one on each side of the esophagus, the cerebropleural ganglia are located on the posterior side of the anterior adductor muscle and are connected by a short commissure. In the foot and fused is the pair of pedal ganglia and anterior to the posterior adductor muscle is the partially fused visceral ganglia. The ganglia are connected by long commissures and each pair is the source of the nerve fibers for the surrounding organs (Smith, 2001a). Near the pedal ganglia is a pair of statocysts, which are ovid or spherical. These statocysts are filled with fluid and lined with sensory cells. They also contain a solid sphere called a statolith (Smith, 2001a). Osphradia are specialized epithelium concentrated in two small regions on the roof of the cloacal chamber (the posterior end of the suprabranchial chamber in the gills where it is fused) (Smith, 2001a). <span class="citations"> (<a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>; <a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>)</span></p> <p audience="advanced intermediate">Adults can range anywhere from 80 to over 200 mm (Bauer, 2001a; Smith, 2001a; Smith, 2001b) in length. Mussel species found in low order streams where the stream flow is more turbulent, tend not to have external shell sculpturing (Bauer, 2001a). Sculptures, such as pustules and ridges, aid in the mussel's ability to burrow into the sediments (Bauer, 2001a). Headwater streams have fewer sediment deposits due to the steeper channel gradient and flow rate of the stream. Margaritiferids tend to be found in these headwater habitats and so do not have external sculptures. Margaritiferids tend to have elongate, compressed, thick shells that are rhomboidal and often arcuate (arched) in shape. The periostracum does not contain rays or any other external color pattern, is light brown to a greenish brown in young mussels and black in adults (Smith, 2001b). <span class="citations"> (<a href="#7c338419e365b0f661d94305b785e949" class="citation">Bauer, 2001a</a>; <a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>; <a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>)</span></p> <p audience="advanced intermediate">Aside from the exterior surface of the shell, researchers involved in identifying mussel species examine various aspects of the interior of the shell, as well. In fact, because of the high individual variability of the exterior, the interior characteristics are relied more heavily upon in identification. Probably the most important interior features are the size, shape, number, and orientation of the hinge <a class="rewrite" href="/resources/biodidac/bivashell2.jpg/medium.jpg">teeth</a>. Pseudocardinal teeth are situated slightly anterior to the beak and are generally short and triangular in shape. Lateral <a class="rewrite" href="/resources/biodidac/bivashell2.jpg/medium.jpg">teeth</a> are the long, slender, raised ridges posterior to the beak. In young individuals, the teeth are well-developed, while in some older individuals, the teeth are reduced (Smith, 2001b). Another internal shell characteristic of <span class="taxon-link rank-family">Margaritiferidae</span> is the presence of mantle attachment scars extending from the beak cavity posterior-dorsally to the <a class="rewrite" href="/resources/biodidac/bivashell2.jpg/medium.jpg">pallial line</a> (Smith, 2001b). Most species cannot be identified by merely one characteristic. In reality, it is a combination of several characteristics which distinguish one species from another. <span class="citations"> (<a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>)</span></p> <p audience="advanced intermediate">Glochidia are the parasitic stage of the larvae and are generally dependent on a host to survive. Mature glochidia are an average of 0.08 mm in diameter (Wachtler et al, 2001). They are circular to ovid bivalves, which are typically attached by a single adductor muscle (Smith, 2001a). Most glochidia have sensory hairs lining their mantle and have reduced or absent hooks (Wachtler et al, 2001). Those species without hooks usually attach to the gills (Smith, 2001a; Wachtler et al, 2001). <span class="citations"> (<a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>; <a href="#47d491ad2ac85b311b6bad46c59eaba6" class="citation">Wachtler, et al., 2001</a>)</span></p> <p audience="advanced intermediate">Measurements are generally taken of the length, height, and width. The length is the distance from the anterior to the posterior margin. The height is the distance from dorsal to ventral margin, usually at the beak. Width is the widest point when the mussel valves are together, which is usually below the beaks. In addition, some identification keys will use the length to height ratio as a way to distinguish some species.</p> <ul class="keywords donthyphenate "> <li class="keywords-header">Other Physical Features</li> <li> <a class="gloss" href="#20020916131519">ectothermic</a> </li> <li> <a class="gloss" href="#20020904145642">bilateral symmetry</a> </li> </ul> <ul class="keywords donthyphenate last"> <li class="keywords-header">Sexual Dimorphism</li> <li> <span>sexes alike</span> </li> </ul> </section> <section class="hyphenate"> <h3 id="development">Development</h3> <p audience="advanced intermediate">Embryonic mussels develop within the marsupia, or specialized portions of the gills, of the female. Once fully developed, they are released from the female and must attach to a host within a few days or they will die. Because margaritiferids lack developed hooks, they must attach to the gills of the host. Generally species that must attach to the gills rather than the fins tend to be more host-specific (Wachtler et al, 2001). Margaritiferids tend to be specific to <a class="taxon-link" href="/accounts/Salmonidae/">salmon and trout</a> (Watters, 1994b). Attachment to a wrong species will cause the death of the glochidia from an immune system attack (Watters, 1998). Within a couple of days, the hosts' dermal tissue will encapsulate each glochidium forming a nodular cyst. While encysted, the glochidia will metamorphose, allowing the organs to develop more like an adult's organs (Meglitsch and Schram, 1991). There is a mortality rate of over 99.99% (1 in 100,000,000 survive on average) from the time the glochidia are released from the mother to the time the metamorphosed juveniles reach the sediments (Jansen et al, 2001; McMahon, 1991). <span class="citations"> (<a href="#43ceb9ca5d5a6979d38ea1ac7f341a96" class="citation">Jansen, et al., 2001</a>; <a href="#48de59a597ed1d293c5cdf3d7093ecee" class="citation">McMahon, 1991</a>; <a href="#90c1221ae45f6f1b82ae0326bc321b64" class="citation">Meglitsch and Schram, 1991</a>; <a href="#47d491ad2ac85b311b6bad46c59eaba6" class="citation">Wachtler, et al., 2001</a>; <a href="#5513482355da1e3133b6045a011d01ce" class="citation">Watters, 1994b</a>; <a href="#d12c933a5d58dff2e6ed389665ce86a3" class="citation">Watters, 1998</a>)</span></p> <p audience="advanced intermediate">The period of encystment can range from 3 to 10 months (Wachtler et al, 2001). Unlike <a class="taxon-link rank-family" href="/accounts/Unionidae/">Unionidae</a>, <span class="taxon-link rank-family">Margaritiferidae</span> glochidia tend to increase in size during metamorphosis (Wachtler et al, 2001). After this period, metamorphosis will be complete and the glochidia will break from the cysts and drop from the host. The third and final stage of development occurs in the sediments of the stream or lake and may last up to twelve years before the juvenile is sexually mature (McMahon, 1991). In this juvenile stage, the young mussel will complete its internal development, create the adult shell, and begin to live independently on the bottom of the stream or lake (Smith, 2001a). <span class="citations"> (<a href="#48de59a597ed1d293c5cdf3d7093ecee" class="citation">McMahon, 1991</a>; <a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>; <a href="#47d491ad2ac85b311b6bad46c59eaba6" class="citation">Wachtler, et al., 2001</a>)</span></p> <p audience="advanced intermediate">As in most bivalves, the shell is composed of three layers: the periostracum, the prismatic layer, and the nacre. The periostracum is the outermost layer and is composed of an organic material. The prismatic layer is the middle layer and is composed of thin blocks of a prism-like calcium carbonate, which are oriented perpendicular to the mantle and the other two layers. The nacre, or mother of pearl, is the innermost layer, which is composed of thin, alternating, laminae (flakes or sheets) of calcium carbonate and an organic material (Smith, 2001a). The mantle is responsible for generating new shell as the mussel ages. A mantle flap is pressed against the interior of each valve and ends in three folds. The periostracum forms at the outer margin and the prismatic layer forms at the outer border. The nacre forms along the entire surface of the mantle. Muscle scars form where the muscle attaches to the shell, disrupting the formation of the nacre. Instead of the shell forming along the dorsal edge where the hinge is located, an elastic hinge ligament composed of conchiolin (a protein-rich substance) forms, binding the two valves together (Meglitsch and Schram, 1991). <span class="citations"> (<a href="#90c1221ae45f6f1b82ae0326bc321b64" class="citation">Meglitsch and Schram, 1991</a>; <a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>)</span></p> <p audience="advanced intermediate">Growth of the mussel begins at the elevated portion called the <a class="rewrite" href="/resources/biodidac/bivashell1.jpg/medium.jpg">umbo or beak</a>. Because new shell is added along the entire edge of the mantle, concentric rings form around the beak. In some species, these rings may be grouped closer together in some areas than others, forming ridges. These ridges indicate the period of diapause during the winter or unfavorable environmental conditions, such as lower water level or lack of food. The period of growth in northern populations is typically from April to September. The growth rate depends mostly on environmental conditions such as water temperature, food supply, and the chemical composition of the water (Smith, 2001a). <span class="citations"> (<a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>)</span></p> <ul class="keywords donthyphenate last"> <li class="keywords-header">Development - Life Cycle</li> <li> <a class="gloss" href="#20020904145364">metamorphosis</a> </li> <li> <a class="gloss" href="#20020913223809">diapause</a> </li> </ul> </section> <section class="hyphenate"> <h3 id="reproduction">Reproduction</h3> <p audience="advanced intermediate">Some margaritiferids are occasional or permanent simultaneous hermaphrodites (self-fertilizing); while others are dioecious (sexes are separate) (Bauer, 1987; Smith, 2001b). Bauer (1987) suggested that hermaphroditism occurs when the population density is low or gene flow is limited. In these cases, the female is the only one of the two sexes that can become hermaphroditic. Despite the dioecious nature of most mussels, males and females do not make contact with each other. The male's sperm leaves the suprabranchial chamber of each demibranch and exits the organism through the exhalant aperture to be carried by the water current to a nearby female. Because sperm cannot swim against the current, the receiving female must be downstream (Watters, 1994a). The sperm enters the female through the inhalant aperture and fertilizes the eggs stored in the demibranch (Smith, 2001a). <span class="citations"> (<a href="#971124ae6ad219a969412fba89b8039b" class="citation">Bauer, 1987</a>; <a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>; <a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>; <a href="#cb509ee4a3012c7c8a5302f279703316" class="citation">Watters, 1994a</a>)</span></p> <ul class="keywords donthyphenate last"> <li class="keywords-header">Mating System</li> <li> <a class="gloss" href="#20020904145483">polygynandrous (promiscuous)</a> </li> </ul> <p audience="advanced intermediate">Margaritiferids can take up to 12 years to reach full sexual maturity (McMahon, 1991). They are tachytictic (short term) breeders, which means they will release the glochidia in the same year, usually by July or August (Watters 1998), and may have multiple reproductive events each year (Smith, 2001b). Matteson (1948) was convinced that the membrane surrounding the developing embryos provides all of the necessary nutrients, rather than the female transferring food to the developing young. His conclusion was based on a lack of connective structure from the gills to the young and that the fertilization membrane surrounding each embryo, which prevents the passing of any materials, remains until development is complete. <span class="citations"> (<a href="#68312b5a25d1849e50c57a75f7e35a58" class="citation">Matteson, 1948</a>; <a href="#48de59a597ed1d293c5cdf3d7093ecee" class="citation">McMahon, 1991</a>; <a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>; <a href="#d12c933a5d58dff2e6ed389665ce86a3" class="citation">Watters, 1998</a>)</span></p> <ul class="keywords donthyphenate last"> <li class="keywords-header">Key Reproductive Features</li> <li> <a class="gloss" href="#20020904145554">iteroparous</a> </li> <li> <a class="gloss" href="#20020904145584">seasonal breeding</a> </li> <li> <span>gonochoric/gonochoristic/dioecious (sexes separate)</span> </li> <li> <span>simultaneous hermaphrodite</span> </li> <li> <a class="gloss" href="#20020904145786">sexual</a> </li> <li> <a class="gloss" href="#20020904145546">fertilization</a> <ul> <li> <a class="gloss" href="#20020904145427">internal</a> </li> </ul> </li> <li> <a class="gloss" href="#20020904145610">ovoviviparous</a> </li> </ul> <p audience="advanced intermediate">Margaritiferid embryos spend the first stage of development in the marsupial portion of the female unionid's gills, where they develop into glochidia, the parasitic stage. Once the first stage is complete, usually in the spring, the female will release the glochidia into the water to begin the second stage as a parasite. The number of glochidia in one brood typically depends upon the size of the glochidia and the size of the female. Since <span class="taxon-link rank-family">Margaritiferidae</span> glochidia are generally small (0.08 mm) and the average female is relatively large (80 to 200 mm), the individual female can incubate an average of 3 to 4 million and up to 17 million glochidia at a time (Wachtler et al, 2001; Smith, 2001b; McMahon, 1991). The glochidia are incubated in both pairs of gills and remain there for only a few weeks before being released (Wachtler et al, 2001; Bauer, 2001a). <span class="citations"> (<a href="#7c338419e365b0f661d94305b785e949" class="citation">Bauer, 2001a</a>; <a href="#48de59a597ed1d293c5cdf3d7093ecee" class="citation">McMahon, 1991</a>; <a href="#46f62e3581f144ab39e42e26315ae7d9" class="citation">Smith, 2001b</a>; <a href="#47d491ad2ac85b311b6bad46c59eaba6" class="citation">Wachtler, et al., 2001</a>)</span></p> <ul class="keywords donthyphenate last"> <li class="keywords-header">Parental Investment</li> <li> <a class="gloss" href="#20020904145398">precocial</a> </li> <li> <a class="gloss" href="#20020904145746">female parental care</a> </li> </ul> </section> <section class="hyphenate"> <h3 id="lifespan_longevity">Lifespan/Longevity</h3> <p audience="advanced intermediate">For small organisms, mussels are long-lived (Cummings and Mayer, 1992). Margaritiferids have a much longer lifespan than <a class="taxon-link" href="/accounts/Unionidae/">unionids</a>, with a range of 40 to well over 100 years (Bauer, 2001a). The record for a <a class="taxon-link rank-species" href="/accounts/Margaritifera_margaritifera/">Margaritifera margaritifera</a> was over 200 years (Bauer, 2001a). Bauer (2001b) suggested life span is dependent upon metabolic rate. Mussels with a higher metabolic rate tend to have a shorter life span. Those in larger rivers or streams would have a higher metabolic rate due to the abundance of food, and would be expected to have a short life. Margaritiferids tend to thrive in low order streams (closer to the headwaters than the mouth), and so tend to live longer than the unionids in the higher order streams. This is possibly because mussels that thrive further upstream may have adapted to a limited food supply by decreasing their metabolic rate. Although metabolic rate is a key factor affecting the longevity in some species, it is not a universal constant. Some species with similar metabolic rates may have very different lifespans. <span class="citations"> (<a href="#7c338419e365b0f661d94305b785e949" class="citation">Bauer, 2001a</a>; <a href="#476941098a032e369a80799457803813" class="citation">Bauer, 2001b</a>; <a href="#55e629cce1f4435134ecdd93227acd0a" class="citation">Cummings and Mayer, 1992</a>)</span></p> </section> <section class="hyphenate"> <h3 id="behavior">Behavior</h3> <p audience="advanced intermediate">For the most part, mussels are sedentary, but they are capable of a restricted form of locomotion. They move around by a series of muscular motions of the <a class="rewrite" href="/resources/biodidac/bivamuscl.jpg/medium.jpg">foot</a> located at the anterior end of each individual. The foot is thrust forward first. It then swells and shortens at the same time, causing the body and shell to pull forward slightly. This process is repeated until the mussel has reached its destination. Some species have been recorded to move up to several feet within an hour. Researchers are still unsure what causes this migration, but they suspect the movement is caused by a drop in water level or some other unfavorable change in the surrounding environment (Smith, 2001a). <span class="citations"> (<a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>)</span></p> <p audience="advanced intermediate">Like unionids, margaritiferids are solitary organisms. The only intra- or inter-species interactions occur during reproduction. Once it drops from the host, the mussel becomes a solitary individual and lives partially buried in the sediments. As juveniles, mussels burrow into the sediments along the bottom of the stream, which protects them from predators. Once mature, more of the organism must protrude from the substrate in order for the inhalant and exhalant apertures to bring in and expel water. Because more of the shell is visible, they are more susceptible to predation (Smith, 2001a). <span class="citations"> (<a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>)</span></p> <p audience="advanced intermediate">During winter months and aestivation periods (Matteson, 1955; van der Shalie, 1940), mussels will burrow into the substrate until only the apertures are protruding. They then go into a state of dormancy where the apertures only open on occasion. Some genera are able to survive in this dormant state among the dry to moist sediments for months at a time (Smith, 2001a). <span class="citations"> (<a href="#05107de44c87a60a004d87cf7dd01345" class="citation">Matteson, 1955</a>; <a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>; <a href="#e5dbfa520e94f215df414b0b01b217fe" class="citation">Van der Shalie, 1940</a>)</span></p> <ul class="keywords donthyphenate last"> <li class="keywords-header">Key Behaviors</li> <li> <a class="gloss" href="#20020904145661">fossorial</a> </li> <li> <a class="gloss" href="#20020904145767">parasite</a> </li> <li> <a class="gloss" href="#20020904145472">motile</a> </li> <li> <a class="gloss" href="#20020904145569">nomadic</a> </li> <li> <a class="gloss" href="#20020904145585">sedentary</a> </li> <li> <a class="gloss" href="#20020904145403">hibernation</a> </li> <li> <span>aestivation</span> </li> <li> <a class="gloss" href="#20020904145381">solitary</a> </li> </ul> </section> <section class="hyphenate"> <h3 id="communication">Communication and Perception</h3> <p audience="advanced intermediate">Mussels use specialized structures to visually attract potential fish hosts. The combination of the statocysts and the statolith aids the mussel in maintaining equilibrium by sensing gravity. They may also be able to detect vibrations (Meglitsch and Schram, 1991). Although the function of the osphradia is uncertain, some researchers believe that they detect foreign particles brought in through the inhalant aperture (Smith, 2001a). Drastic changes in the intensity of the light in the environment can be detected by the mantle border (Smith, 2001a). Glochidia can usually detect light changes with ocelli, but the eyes are generally lost after metamorphosis (Meglitsch and Schram, 1991). Many mussel species also have tactile cells lining the exposed portion of the mantle, which aid in the organism's sense of touch (Meglitsch and Schram, 1991). The glochidia are especially sensitive to touch, which helps in the attachment to a host as it comes close to them (Arey, 1921). <span class="citations"> (<a href="#de44813f278decc6ef16bc50d42f92cf" class="citation">Arey, 1921</a>; <a href="#90c1221ae45f6f1b82ae0326bc321b64" class="citation">Meglitsch and Schram, 1991</a>; <a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>)</span></p> <ul class="keywords donthyphenate last"> <li class="keywords-header">Perception Channels</li> <li> <a class="gloss" href="#20020913180829">infrared/heat</a> </li> <li> <a class="gloss" href="#20020915004137">polarized light</a> </li> <li> <a class="gloss" href="#20020904145500">tactile</a> </li> <li> <a class="gloss" href="#20020904145852">vibrations</a> </li> <li> <a class="gloss" href="#20020904145606">chemical</a> </li> </ul> </section> <section class="hyphenate"> <h3 id="food_habits">Food Habits</h3> <p audience="advanced intermediate">Adult freshwater mussels are filter feeders; they continuously filter food particles out of the water (Watters, 1998; Allen, 1921). Water is constantly pumped into the inhalant aperture, through the <a class="rewrite" href="/resources/biodidac/biva002b.gif/small.jpg">gills</a>, and out the exhalant aperture by cilia. The cilia lining the inner surface of the mantle, demibranchs, and visceral mass create a current by beating in a coordinated manner. Organic and inorganic particles suspended in the water surrounding the inhalant aperture are brought in by the current and caught in the mucus lining the demibranchs. The constant current created by the cilia moves the mucus with any trapped particles to the cilia lining the <a class="rewrite" href="/resources/biodidac/biva002b.gif/small.jpg">labial palps</a>. The labial palps remove the inorganic particles and push them toward the ventral margin where they drop off. There they are moved by the cilia backward, and released between the valves just below the inhalant aperture (Smith, 2001a). The organic particles are separated by size in sorting areas on the labial palps and are then directed into the mouth. From the mouth, particles are moved through a short esophagus to the digestive gland surrounding the stomach. Food particles enter the stomach through the subdivided pores of the large digestive gland (Meglitsch and Schram, 1991). Small particles are digested intracellularly as they enter the stomach. The intestinal glands are responsible for phagocytosis, intracellular digestion, food absorption, secretion of enzymes and excretion (Meglitsch and Schram, 1991). The intestine coils behind and below the stomach before it extends dorsally and empties into the mantle cavity through the anus located just above the exhalant aperture. <span class="citations"> (<a href="#4a03171b0649618c975e7d950eb978e4" class="citation">Allen, 1921</a>; <a href="#90c1221ae45f6f1b82ae0326bc321b64" class="citation">Meglitsch and Schram, 1991</a>; <a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>; <a href="#d12c933a5d58dff2e6ed389665ce86a3" class="citation">Watters, 1998</a>)</span></p> <p audience="advanced intermediate">The exact type of food consumed by adult freshwater mussels has been debated for some time now. Some researchers have suggested mussels eat algae and diatoms (Allen, 1914), while others suggest bacteria, protozoans and other organic particles were ingested (Watters, 1998). A few studies have even suggested ingesting silt somehow enhances the survival of the organism (Watters, 1998). Current views suggest mussels feed on the bacteria and microphytoplankton but nothing larger (Smith, 2001a; Cummings and Mayer, 1992). <span class="citations"> (<a href="#fec985d8d459bd7430f529767c1ddb2c" class="citation">Allen, 1914</a>; <a href="#55e629cce1f4435134ecdd93227acd0a" class="citation">Cummings and Mayer, 1992</a>; <a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>; <a href="#d12c933a5d58dff2e6ed389665ce86a3" class="citation">Watters, 1998</a>)</span></p> <p audience="advanced intermediate">The phagocytic mantle cells of the glochidia feed off of the host's tissue (Meglitsch and Schram, 1991). Before attachment, glochidia must locate a proper host. In most cases, they end up in the stream or lake sediments with the open end of the valves up awaiting a fish to brush up against the mud allowing the larvae to attach themselves to the fins. The glochidia of other species swim around in the water by clapping the valves together. <span class="citations"> (<a href="#90c1221ae45f6f1b82ae0326bc321b64" class="citation">Meglitsch and Schram, 1991</a>)</span></p> <ul class="keywords donthyphenate "> <li class="keywords-header">Primary Diet</li> <li> <a class="gloss" href="#20020904145368">planktivore</a> </li> <li> <a class="gloss" href="#20020904145349">detritivore</a> </li> </ul> <ul class="keywords donthyphenate last"> <li class="keywords-header">Foraging Behavior</li> <li> <a class="gloss" href="#20020904145660">filter-feeding</a> </li> </ul> </section> <section class="hyphenate"> <h3 id="predation">Predation</h3> <p audience="advanced intermediate"><a class="taxon-link" href="/accounts/Ondatra_zibethicus/">Muskrats</a> are probably the most important mammals which prey on freshwater mussels (Cummings and Mayer, 1992; Smith, 2001a). These animals drag the mussels on the shore and either break the shells open with their teeth or leave them on the banks until the mussel dies and the shell opens (Smith, 2001a). In active muskrat foraging areas, there are often middens of a variety of shells which have been cleaned by the muskrats. Other common predators include <a class="taxon-link" href="/accounts/Neovison_vison/">minks</a>, <a class="taxon-link" href="/accounts/Lontra_canadensis/">otters</a>, <a class="taxon-link" href="/accounts/Procyon_lotor/">raccoons</a>, <a class="taxon-link" href="/accounts/Testudines/">turtles</a>, <a class="taxon-link" href="/accounts/Cryptobranchus/">hellbenders</a>, fish, some species of birds, and humans (Cummings and Mayer, 1992; Smith, 2001a; Watters, 1998). Some of the common fish species include the <a class="taxon-link" href="/accounts/Aplodinotus_grunniens/">freshwater drum</a>, <a class="taxon-link" href="/accounts/Archosargus_probatocephalus/">sheepshead</a>, <a class="taxon-link" href="/accounts/Acipenser_fulvescens/">lake sturgeon</a>, <a class="taxon-link" href="/accounts/Minytrema_melanops/">spotted suckers</a>, <a class="taxon-link" href="/accounts/Moxostoma/">common red-horse</a>, and <a class="taxon-link" href="/accounts/Lepomis_gibbosus/">pumpkinseed</a> (Smith, 2001a). In Europe, <span class="taxon-name rank-species">hooded crows</span> have been known to prey upon mussels. They are able to reach the soft tissue by dropping the mussels to crack the shell open (Watters, 1998). <span class="citations"> (<a href="#55e629cce1f4435134ecdd93227acd0a" class="citation">Cummings and Mayer, 1992</a>; <a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>; <a href="#d12c933a5d58dff2e6ed389665ce86a3" class="citation">Watters, 1998</a>)</span></p> <p audience="advanced intermediate">To avoid these predators, mussels will bury themselves into the lake or stream sediments. Because adults do not have true siphons, only openings in the mantle, they must leave the posterior margin out of the sediments to allow for sufficient respiration. This exposure leaves the organism vulnerable to predation, desiccation, and temperature extremes (Watters, 1998). <span class="citations"> (<a href="#d12c933a5d58dff2e6ed389665ce86a3" class="citation">Watters, 1998</a>)</span></p> <ul class="aside block-grid donthyphenate one-up"> <li> <dl> <dt>Known Predators</dt> <dd> <ul> <li>muskrats, <a class="taxon-link rank-species" href="/accounts/Ondatra_zibethicus/">Ondatra zibethicus</a> </li> <li>minks, <a class="taxon-link rank-species" href="/accounts/Neovison_vison/">Neovison vison</a> </li> <li>otters, <a class="taxon-link rank-species" href="/accounts/Lontra_canadensis/">Lontra canadensis</a> </li> <li>raccoons, <a class="taxon-link rank-species" href="/accounts/Procyon_lotor/">Procyon lotor</a> </li> <li>turtles, <a class="taxon-link rank-order" href="/accounts/Testudines/">Testudines</a> </li> <li>hellbenders, <a class="taxon-link rank-genus" href="/accounts/Cryptobranchus/">Cryptobranchus</a> spp.</li> <li>freshwater drum, <a class="taxon-link rank-species" href="/accounts/Aplodinotus_grunniens/">Aplodinotus grunniens</a> </li> <li>sheepshead, <a class="taxon-link rank-species" href="/accounts/Archosargus_probatocephalus/">Archosargus probatocephalus</a> </li> <li>lake sturgeon, <a class="taxon-link rank-species" href="/accounts/Acipenser_fulvescens/">Acipenser fulvescens</a> </li> <li>spotted suckers, <a class="taxon-link rank-species" href="/accounts/Minytrema_melanops/">Minytrema melanops</a> </li> <li>common red-horse, <a class="taxon-link rank-genus" href="/accounts/Moxostoma/">Moxostoma</a> spp.</li> <li>pumpkinseed, <a class="taxon-link rank-species" href="/accounts/Lepomis_gibbosus/">Lepomis gibbosus</a> </li> <li>hooded crows, <span rank="Species" class="taxon-name rank-species">Corvis cornix</span> </li> </ul> </dd> </dl> </li> </ul> </section> <section class="hyphenate"> <h3 id="ecosystem_roles">Ecosystem Roles</h3> <p audience="advanced intermediate">Like all other organisms, freshwater mussels play an important role within their ecosystem. Not only do they provide a food source for <a class="taxon-link" href="/accounts/Ondatra_zibethicus/">muskrats</a> and other predators, but they also aid in the decomposition of detritus and keep the bacterial and planktonic populations under control (Pusch et al, 2001; Jorgensen, 1990). They are important to the second trophic level by feeding heavily upon the phytoplankton (McMahon, 1991). Dense mussel populations rely on rapid current for survival. During periods of little or no current, these dense mussel beds can cause a depletion of the dissolved oxygen and food supply, causing a rise in the mortality rate of the mussel and other faunal populations along the basin (Jorgensen, 1990). In addition, freshwater mussels are important water filters and act as organic nutrient sinks by filtering the suspended seston (McMahon, 1991). <span class="citations"> (<a href="#b6117599199fbca89381ec8477455f35" class="citation">Jorgensen, 1990</a>; <a href="#48de59a597ed1d293c5cdf3d7093ecee" class="citation">McMahon, 1991</a>; <a href="#81d021a73ec2ae9e86a19680b9f8ea79" class="citation">Pusch, et al., 2001</a>)</span></p> <p audience="advanced intermediate">Researchers have found that the glochidia generally do not cause sufficient enough damage to the host to cause problems. Cases of over 3000 glochidia infecting a fish without apparent harm have been reported. However, there have also been cases where 30 mm fingerling trout have died of secondary bacterial infections caused by a little more than 100 glochidia (Smith, 2001a). Some fish species are able to develop an immune response to resist the glochidia causing them to pre-maturely drop off the fish. <span class="citations"> (<a href="#6bc3c9736b2573494b48afae4d4ec5c6" class="citation">Smith, 2001a</a>)</span></p> <ul class="keywords donthyphenate last"> <li class="keywords-header">Ecosystem Impact</li> <li> <a class="gloss" href="#20020904145767">parasite</a> </li> </ul> <div class="note"> <strong>Species Used as Host</strong> <br /> <ul> <li>cutthroat trout, <a class="taxon-link rank-species" href="/accounts/Oncorhynchus_clarkii/">Oncorhynchus clarkii</a> </li> <li>coho salmon, <a class="taxon-link rank-species" href="/accounts/Oncorhynchus_kisutch/">Oncorhynchus kisutch</a> </li> <li>cherry salmon, <a class="taxon-link rank-species" href="/accounts/Oncorhynchus_masou/">Oncorhynchus masou</a> </li> <li>rainbow trout, <a class="taxon-link rank-species" href="/accounts/Oncorhynchus_mykiss/">Oncorhynchus mykiss</a> </li> <li>sockeye salmon, <span rank="Species" class="taxon-name rank-species">Oncorhychus nerka</span> </li> <li>chinook salmon, <a class="taxon-link rank-species" href="/accounts/Oncorhynchus_tshawytscha/">Oncorhynchus tshawytscha</a> </li> <li>Atlantic salmon, <a class="taxon-link rank-species" href="/accounts/Salmo_salar/">Salmo salar</a> </li> <li>brown trout, <a class="taxon-link rank-species" href="/accounts/Salmo_trutta/">Salmo trutta</a> </li> <li>Danube salmon, <a class="taxon-link rank-species" href="/accounts/Hucho_hucho/">Hucho hucho</a> </li> <li>brook trout, <a class="taxon-link rank-species" href="/accounts/Salvelinus_fontinalis/">Salvelinus fontinalis</a> </li> <li>bitterling, <a class="taxon-link rank-species" href="/accounts/Rhodeus_sericeus/">Rhodeus sericeus</a> </li> <li>striped shiner, <a class="taxon-link rank-species" href="/accounts/Luxilus_chrysocephalus/">Luxilus chrysocephalus</a> </li> <li>golden shiner, <a class="taxon-link rank-species" href="/accounts/Notemigonus_crysoleucas/">Notemigonus crysoleucas</a> </li> <li>redfin shiner, <a class="taxon-link rank-species" href="/accounts/Lythrurus_umbratilis/">Lythrurus umbratilis</a> </li> <li>speckled dace, <a class="taxon-link rank-species" href="/accounts/Rhinichthys_osculus/">Rhinichthys osculus</a> </li> <li>Lahontan redside, <a class="taxon-link rank-species" href="/accounts/Richardsonius_egregius/">Richardsonius egregius</a> </li> <li>Tahoe sucker, <a class="taxon-link rank-species" href="/accounts/Catostomus_tahoensis/">Catostomus tahoensis</a> </li> </ul> </div> </section> <section class="hyphenate"> <h3 id="economic_importance_positive">Economic Importance for Humans: Positive</h3> <p audience="advanced intermediate">Long before Europeans ever arrived in North America, Native Americans were utilizing freshwater mussels and their shells for food, jewelry, tools, utensils, and pottery temper (Cummings and Mayer, 1992). Native Americans have been carving shells for implements and ornamentation for at least 3000 years. Around 1000 years ago, people in North America discovered that by tempering their pottery with crushed shells rather than sand or gravel allowed them to create a smoother, thinner vessel. During this same period, people were creating beads, hoes and spoons with the freshwater mussels (Wiant, 2000). <span class="citations"> (<a href="#55e629cce1f4435134ecdd93227acd0a" class="citation">Cummings and Mayer, 1992</a>; <a href="#bccaffc0085da780388d7a50b60dbd74" class="citation">Wiant, 2000</a>)</span></p> <p audience="advanced intermediate">Before 1890, freshwater mussels were utilized for only a few decorative items such as pistol grips, brush handles, and jewelry. Both the U.S. tariffs on imported goods (including buttons) and the rise of the new ready-to-wear clothing industry created high demand for buttons. The pearl button industry began in 1891 with the start of a new fashion trend to use shell buttons to fasten clothes. With Muscatine, Iowa as the center of the industry, pearl buttons became the major economy for hundreds of river towns along the Mississippi and other Midwestern rivers. The demand was so high that by 1900 the Illinois and Wabash rivers were depleted of mussels. The peak of the industry occurred in 1909 with a record of 2600 boats on the Mississippi River alone. By the 1940s and 1950s, the invention of and widespread use of plastics replaced the shell buttons with plastic ones, causing the collapse of this industry and the recovery of many impacted mussel populations. (Huitt and Warren, 2003) <span class="citations"> (<a href="#9f0942e26e658ff259552baf89315be1" class="citation">Huitt and Warren, 2003</a>)</span></p> <p audience="advanced intermediate">In the 1950s, the Japanese developed another use for freshwater mussel shells (Cummings and Mayer, 1992). They discovered that small beads could be carved out of the shells of freshwater mussels and inserted into oysters to artificially form pearls. This discovery was the beginning of the cultured pearl industry. Today, thousands of tons of freshwater mussel shells from North America are exported to Japan to support the pearl industry (Cummings and Mayer, 1992). <span class="citations"> (<a href="#55e629cce1f4435134ecdd93227acd0a" class="citation">Cummings and Mayer, 1992</a>)</span></p> <p audience="advanced intermediate">In addition to the many products, freshwater mussels act as water quality indicators. Because they are filter-feeders, pollutants in the water will accumulate in the tissue of mussels until they reach a toxic level killing the organism. A drastic drop in the mussel population is an indication of poor water quality.</p> <ul class="keywords donthyphenate last"> <li class="keywords-header">Positive Impacts</li> <li> <a class="gloss" href="#20020904145418">food</a> </li> <li> <span>body parts are source of valuable material</span> </li> <li> <span>research and education</span> </li> </ul> </section> <section class="hyphenate"> <h3 id="economic_importance_negative">Economic Importance for Humans: Negative</h3> <p audience="advanced intermediate">There are no reported negative effects on humans or the economy due to unionids. A hindrance on the fishing industry by the parasitic glochidia is plausible.</p> </section> <section class="hyphenate"> <h3 id="conservation_status">Conservation Status</h3> <p audience="advanced intermediate">Worldwide, freshwater mussels are one of the most endangered groups with significant population declines documented in recent surveys. In the United States, nearly 70 species of <a class="taxon-link rank-order" href="/accounts/Unionoida/">Unionoida</a> are either endangered or threatened, one of which is in the <span class="taxon-link rank-family">Margaritiferidae</span> family (<a class="taxon-link rank-species" href="/accounts/Margaritifera_hembeli/">Margaritifera hembeli</a>, the Louisiana Pearlshell, is federally threatened) (USFWS, 2003). In Europe, <span rank="Species" class="taxon-name rank-species">Margaritifera auricularia</span> (<span rank="Species" class="taxon-name rank-species">Pseudunio auricularia</span>) was once thought to be extinct until a fertile population was found. Now it is viewed as one of the most threatened invertebrates in the world and extensive conservation efforts have been developed to protect it (Araujo and Ramos, 2001). Reasons for the past decline include the effects of the pearl button industry of the late 19th and early 20th centuries and the cultured pearl industry of the past 50 years. Today, siltation from agriculture, forestry, and construction smothers the organisms inhibiting feeding and respiration. Impoundments alter the habitat, killing first the mussels that thrive in rapid currents. Dams cause an increase in silt as well as a constant cold water temperature. Since many mussel species are temperature sensitive, the cold will slow the growth and may inhibit the reproduction of the mussels that survived the initial shock of the construction. In-stream sand and gravel mining often buries, crushes, or removes the mussels in the substrate and releases silt, which affects the species downstream. Agricultural runoff is another threat to mussel populations. Many species cannot tolerate pollutants introduced in the water from pesticides, herbicides, and fertilizers. At sub-lethal concentrations these chemicals inhibit respiration and accumulate in the tissues of the organism. Mussels are also sensitive to heavy metals which accumulate in the tissues. Mine runoff creates an acidic pH in the water, which many mussel species cannot tolerate for long periods of time. Salinity from road salt runoff is lethal to glochidia (Watters, 1998). <span class="citations"> (<a href="#36b43bf9495658dc90d1403f5f6154f8" class="citation">Araujo and Ramos, 2001</a>; <a href="#69bf4efba6d9eec6c0dc6f36f9bdbdc2" class="citation">USFWS, 2003</a>; <a href="#d12c933a5d58dff2e6ed389665ce86a3" class="citation">Watters, 1998</a>)</span></p> <p audience="advanced intermediate">In addition to industrial wastes and depletion, mussels now compete for resources with introduced species. The <a class="taxon-link" href="/accounts/Corbicula_fluminea/">Asian clam</a> and the <a class="taxon-link" href="/accounts/Dreissena_polymorpha/">zebra mussel</a> are probably the two most common exotic species, which have been introduced to North American freshwaters.</p> <ul class="aside block-grid donthyphenate one-up"> <li> <dl> <dt>IUCN Red List <a href="http://www.iucnredlist.org/">[Link]</a></dt> <dd>Not Evaluated</dd> </dl> </li> </ul> </section> <section class="hyphenate"> <h3 id="contributors">Contributors</h3> <p>Renee Sherman Mulcrone (editor). </p> <p>Lisa Winhold (author), Animal Diversity Web. </p> </section> <section class="offscreen"> <h3 id="glossary">Glossary</h3> <div id="20020914235803"> <dl> <dt>Nearctic</dt> <dd> <p>living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.</p> <p align="center"> <img alt="World Map" src="/images/worldmap.2001.jpg" /> </p> </dd> </dl> </div> <div id="20020915001330"> <dl> <dt>Palearctic</dt> <dd> <p>living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.</p> <p align="center"> <img alt="World Map" src="/images/worldmap.2001.jpg" /> </p> </dd> </dl> </div> <div id="20020904145431"> <dl> <dt>benthic</dt> <dd> <p>Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.</p> </dd> </dl> </div> <div id="20020904145642"> <dl> <dt>bilateral symmetry</dt> <dd> <p>having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.</p> </dd> </dl> </div> <div id="20020904145606"> <dl> <dt>chemical</dt> <dd> <p>uses smells or other chemicals to communicate</p> </dd> </dl> </div> <div id="20020904145349"> <dl> <dt>detritivore</dt> <dd> <p>an animal that mainly eats decomposed plants and/or animals</p> </dd> </dl> </div> <div id="20020913223809"> <dl> <dt>diapause</dt> <dd> <p>a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.</p> </dd> </dl> </div> <div id="20020916131519"> <dl> <dt>ectothermic</dt> <dd> <p>animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature</p> </dd> </dl> </div> <div id="20020904145746"> <dl> <dt>female parental care</dt> <dd> <p>parental care is carried out by females</p> </dd> </dl> </div> <div id="20020904145546"> <dl> <dt>fertilization</dt> <dd> <p>union of egg and spermatozoan</p> </dd> </dl> </div> <div id="20020904145660"> <dl> <dt>filter-feeding</dt> <dd> <p>a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.</p> </dd> </dl> </div> <div id="20020904145418"> <dl> <dt>food</dt> <dd> <p>A substance that provides both nutrients and energy to a living thing.</p> </dd> </dl> </div> <div id="20020904145661"> <dl> <dt>fossorial</dt> <dd> <p>Referring to a burrowing life-style or behavior, specialized for digging or burrowing.</p> </dd> </dl> </div> <div id="20020904145747"> <dl> <dt>freshwater</dt> <dd> <p>mainly lives in water that is not salty.</p> </dd> </dl> </div> <div id="20020904145403"> <dl> <dt>hibernation</dt> <dd> <p>the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.</p> </dd> </dl> </div> <div id="200304045530"> <dl> <dt>holarctic</dt> <dd> <p>a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.</p> <p align="center"> <img alt="World Map" src="/images/worldmap.2001.jpg" /> </p> <p>Found in northern North America and northern Europe or Asia.</p> </dd> </dl> </div> <div id="20020913180829"> <dl> <dt>infrared/heat</dt> <dd> <p>(as keyword in perception channel section) This animal has a special ability to detect heat from other organisms in its environment.</p> </dd> </dl> </div> <div id="20020904145427"> <dl> <dt>internal fertilization</dt> <dd> <p>fertilization takes place within the female's body</p> </dd> </dl> </div> <div id="20020904145633"> <dl> <dt>intertidal or littoral</dt> <dd> <p>the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.</p> </dd> </dl> </div> <div id="20020904145554"> <dl> <dt>iteroparous</dt> <dd> <p>offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).</p> </dd> </dl> </div> <div id="20020904145364"> <dl> <dt>metamorphosis</dt> <dd> <p>A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.</p> </dd> </dl> </div> <div id="20020904145472"> <dl> <dt>motile</dt> <dd> <p>having the capacity to move from one place to another.</p> </dd> </dl> </div> <div id="20020904145365"> <dl> <dt>native range</dt> <dd> <p>the area in which the animal is naturally found, the region in which it is endemic.</p> </dd> </dl> </div> <div id="20020904145569"> <dl> <dt>nomadic</dt> <dd> <p>generally wanders from place to place, usually within a well-defined range.</p> </dd> </dl> </div> <div id="20020915001348"> <dl> <dt>oriental</dt> <dd> <p>found in the oriental region of the world. In other words, India and southeast Asia.</p> <p align="center"> <img alt="World Map" src="/images/worldmap.2001.jpg" /> </p> </dd> </dl> </div> <div id="20020904145610"> <dl> <dt>ovoviviparous</dt> <dd> <p>reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.</p> </dd> </dl> </div> <div id="20020904145767"> <dl> <dt>parasite</dt> <dd> <p>an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death</p> </dd> </dl> </div> <div id="20020904145368"> <dl> <dt>planktivore</dt> <dd> <p>an animal that mainly eats plankton</p> </dd> </dl> </div> <div id="20020915004137"> <dl> <dt>polarized light</dt> <dd> <p>light waves that are oriented in particular direction. For example, light reflected off of water has waves vibrating horizontally. Some animals, such as bees, can detect which way light is polarized and use that information. People cannot, unless they use special equipment.</p> </dd> </dl> </div> <div id="20020904145483"> <dl> <dt>polygynandrous</dt> <dd> <p>the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.</p> </dd> </dl> </div> <div id="20020904145842"> <dl> <dt>riparian</dt> <dd> <p>Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).</p> </dd> </dl> </div> <div id="20020904145584"> <dl> <dt>seasonal breeding</dt> <dd> <p>breeding is confined to a particular season</p> </dd> </dl> </div> <div id="20020904145585"> <dl> <dt>sedentary</dt> <dd> <p>remains in the same area</p> </dd> </dl> </div> <div id="20020904145786"> <dl> <dt>sexual</dt> <dd> <p>reproduction that includes combining the genetic contribution of two individuals, a male and a female</p> </dd> </dl> </div> <div id="20020904145381"> <dl> <dt>solitary</dt> <dd> <p>lives alone</p> </dd> </dl> </div> <div id="20020904145500"> <dl> <dt>tactile</dt> <dd> <p>uses touch to communicate</p> </dd> </dl> </div> <div id="20020904145595"> <dl> <dt>temperate</dt> <dd> <p>that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).</p> </dd> </dl> </div> <div id="20020904145852"> <dl> <dt>vibrations</dt> <dd> <p>movements of a hard surface that are produced by animals as signals to others</p> </dd> </dl> </div> <div id="20020904145398"> <dl> <dt>young precocial</dt> <dd> <p>young are relatively well-developed when born</p> </dd> </dl> </div> </section> <section class="hyphenate"> <h3 id="references">References</h3> <p id="4a03171b0649618c975e7d950eb978e4">Allen, W. 1921. Studies of the Biology of Freshwater Mussels: Experimental Studies of the Food Relations of Certain Unionidae. <span style="font-style: italic">Biological Bulletin</span>, 40(4): 210-241. </p> <p id="fec985d8d459bd7430f529767c1ddb2c">Allen, W. 1914. The Food and Feeding Habits of Freshwater Mussels. <span style="font-style: italic">Biological Bulletin</span>, 27(3): 127-146. </p> <p id="36b43bf9495658dc90d1403f5f6154f8">Araujo, R., M. Ramos. 2001. Life-History Data on the Virtually Unknown <em>Margaritifera auricularia</em> . Pp. 143-152 in G Bauer, K Wachtler, eds. <span style="font-style: italic">Ecological Studies: Ecology and Evolution of the Freshwater Mussels Unionoida</span>, Vol. 145. Berlin: Springer-Verlag. </p> <p id="de44813f278decc6ef16bc50d42f92cf">Arey, L. 1921. An Experimental Study on Glochidia and the Factors Underlying Encystment. <span style="font-style: italic">Journal of Experimental Zoology</span>, 33(2): 463-499. </p> <p id="476941098a032e369a80799457803813">Bauer, G. 2001b. Framework and Driving Forces for the Evolution of Naiad Life Histories. Pp. 233-255 in G Bauer, K Wachtler, eds. <span style="font-style: italic">Ecological Studies: Ecology and Evolution of the Freshwater Mussels Unionoida</span>, Vol. 145. Berlin: Springer-Verlag. </p> <p id="7c338419e365b0f661d94305b785e949">Bauer, G. 2001a. Life-History Variation on Different Taxonomic Levels of Naiads. Pp. 83-91 in G Bauer, K Wachtler, eds. <span style="font-style: italic">Ecological Studies: Ecology and Evolution of the Freshwater Pearl Mussels Unionoida</span>, Vol. 145. Berlin: Springer-Verlag. </p> <p id="971124ae6ad219a969412fba89b8039b">Bauer, G. 1987. Reproductive Strategy of the Freshwater Pearl Mussel Margaritifera margaritifera. <span style="font-style: italic">Journal of Animal Ecology</span>, 56: 691-704. </p> <p id="55e629cce1f4435134ecdd93227acd0a">Cummings, K., C. Mayer. 1992. <span style="font-style: italic">Field Guide to Freshwater Mussels of the Midwest, Manual 5</span>. Champaign, IL: Illinois Natural History Survey. </p> <p id="d7cb5228d583c63f1d0e670c85a5c83a">Davis, G., S. Fuller. 1981. Genetic Relationships Among Recent Unionacea (Bivalvia) of North America. <span style="font-style: italic">Malacologia</span>, 20: 217-253. </p> <p id="f41e1640127ddde9c0ba2047a0745983">Haas, F. 1969. <span style="font-style: italic">Das Tierreich Lieferung 88: Superfamilia Unionacea</span>. Berlin: Walter de Gruyter. </p> <p id="fdf6050727262a9fcbda35359c56c2cf">Haas, F. 1940. A Tentative Classification of the Palearctic Unionids. <span style="font-style: italic">Field Museum of Natural History Zool Ser</span>, 24: 115-141. </p> <p id="d6d97f95d6a04f84792a88697f486469">Heard, W., R. Guckert. 1970. A Re-Evaluation of the Recent Unionacea (Pelecypoda) of North America. <span style="font-style: italic">Malacologia</span>, 10: 333-355. </p> <p id="9f0942e26e658ff259552baf89315be1">Huitt, S., R. Warren. 2003. "Harvesting the River: Freshwater Mussels" (On-line). Illinois State Museum. Accessed August 03, 2003 at <tt><a href="http://www.museum.state.il.us/RiverWeb/harvesting/harvest/mussels/index.html">http://www.museum.state.il.us/RiverWeb/harvesting/harvest/mussels/index.html</a></tt>. </p> <p id="43ceb9ca5d5a6979d38ea1ac7f341a96">Jansen, W., G. Bauer, E. Zahner-Meike. 2001. Glochidial Mortality in Freshwater Mussels. Pp. 185-211 in G Bauer, K Wachtler, eds. <span style="font-style: italic">Ecological Studies: Ecology and Evolution of the Freshwater Mussels Unionoida</span>, Vol. 145. Berlin: Springer-Verlag. </p> <p id="b6117599199fbca89381ec8477455f35">Jorgensen, C. 1990. <span style="font-style: italic">Bivalve Filter Feeding: Hydrodynamics, Bioenergetics, Physiology, and Ecology</span>. Denmark: Olsen & Olsen. </p> <p id="411467636f2d13f3e0e74761f7b9a7f0">Kennard, A., A. Salisbury, B. Woodward. 1925. Notes on the British Post-Pliocene Unionidae with More Especial Regard to the Means of Identification of Fossil Fragments. Proceedings of the Malacological Society of London, 16: 267-290. </p> <p id="68312b5a25d1849e50c57a75f7e35a58">Matteson, M. 1948. Life History of Elliptio complanatus (Dillwyn, 1817). <span style="font-style: italic">American Midland Naturalist</span>, 40(3): 690-723. </p> <p id="05107de44c87a60a004d87cf7dd01345">Matteson, M. 1955. Studies on the Natural History of the Unionidae. <span style="font-style: italic">American Midland Naturalist</span>, 53: 126-145. </p> <p id="48de59a597ed1d293c5cdf3d7093ecee">McMahon, R. 1991. Mollusca: Bivalvia. Pp. 315-373 in J Thorp, A Covich, eds. <span style="font-style: italic">Ecology and Classification of North American Freshwater Invertebrates</span>. San Diego, CA: Academic Press, Inc.. </p> <p id="90c1221ae45f6f1b82ae0326bc321b64">Meglitsch, P., F. Schram. 1991. <span style="font-style: italic">Invertebrate Zoology, Third Edition</span>. New York, NY: Oxford University Press. </p> <p id="9eb988759376d1b5cc913ee67173c78e">Ortmann, A. 1910. A New System of the Unionidae. <span style="font-style: italic">Nautilus</span>, 23: 114-120. </p> <p id="53ed96b36a17498cad636650a1429954">Ortmann, A. 1911. The Anatomical Structure of Certain Exotic Naiads Compared with That of North American Forms. <span style="font-style: italic">Nautilus</span>, 24: 127-131. </p> <p id="81d021a73ec2ae9e86a19680b9f8ea79">Pusch, M., J. Siefert, N. Walz. 2001. Filtration and Respiration Rates of Two Unionid Species and Their Impact on the Water Quality of a Lowland River. Pp. 317-326 in G Bauer, K Wachtler, eds. <span style="font-style: italic">Ecological Studies: Ecology and Evolution of the Freshwater Mussels Unionoida</span>, Vol. 145. Berlin: Springer-Verlag. </p> <p id="6bc3c9736b2573494b48afae4d4ec5c6">Smith, D. 2001a. <span style="font-style: italic">Pennak's Freshwater Invertebrates of the United States: Porifera to Crustacea, Fourth Edition</span>. New York, NY: John Wiley & Sons, Inc.. </p> <p id="b96169a60095a65e4a7356e6ec60d5fc">Smith, D. 1980. Anatomical Studies on Margaritifera margaritifera and Cumberlandia monodonta (Mollusca: Pelecypoda: Margaritiferidae). <span style="font-style: italic">Zool J Linn Soc</span>, 69: 257-270. </p> <p id="46f62e3581f144ab39e42e26315ae7d9">Smith, D. 2001b. Systematics and Distribution of the Recent Margaritiferidae. Pp. 33-49 in G Bauer, K Wachtler, eds. <span style="font-style: italic">Ecological Studies: Ecology and Evolution of the Freshwater Mussels Unionoida</span>, Vol. 145. Berlin: Springer-Verlag. </p> <p id="64d01f35e9c2a730440d21e5acf6f94b">Smith, D., W. Wall. 1984. The Margaritiferidae Reinstated: A Reply to Davis and Fuller (1981), Genetic Relationships Among Recent Unionacea (Bivalvia) of North America. <span style="font-style: italic">Occas Pap Mollusks Mus Comp Zool Harv Univ</span>, 4: 321-330. </p> <p id="42440c57301b654a6abfed70aa1956bf">Turgeon, D., J. Quinn, A. Bogan, E. Coan, F. Hochberg, W. Lyons, P. Mikkelsen, R. Neves, C. Roper, G. Rosenberg, B. Roth, A. Scheltema, F. Thompson, M. Vecchione, J. Williams. 1998. <span style="font-style: italic">Common and Scientific Names of Aquatic Invertebrates from the United States and Canada: Mollusks, Second Edition</span>. Bethesda, MD: American Fisheries Society, Special Publication 26. </p> <p id="69bf4efba6d9eec6c0dc6f36f9bdbdc2">USFWS, 2003. "Species Information: Threatened and Endangered Animals and Plants" (On-line). USFWS Division of Endangered Species. Accessed December 20, 2003 at <tt><a href="http:endangered.fws.gov/wildlife.html#Species">http:endangered.fws.gov/wildlife.html#Species</a></tt>. </p> <p id="e5dbfa520e94f215df414b0b01b217fe">Van der Shalie, H. 1940. Aestivation of Fresh-Water Mussels. <span style="font-style: italic">Nautilus</span>, 43(3): 137-138. </p> <p id="47d491ad2ac85b311b6bad46c59eaba6">Wachtler, K., M. Dreher-Mansur, T. Richter. 2001. Larval Types and Early Postlarval Biology in Naiads (Unionoida). Pp. 93-125 in G Bauer, K Wachtler, eds. <span style="font-style: italic">Ecological Studies: Ecology and Evolution of the Freshwater Mussels Unionoida</span>, Vol. 145. Berlin: Springer-Verlag. </p> <p id="104ac2a2e86e98444c7a2b253ffdfe11">Watters, G. 1992. , Fishes, and the Species-Area Curve. <span style="font-style: italic">Journal of Biogeography</span>, 19(5): 481-490. </p> <p id="5513482355da1e3133b6045a011d01ce">Watters, G. 1994b. <span style="font-style: italic">An Annotated Bibliography of the Reproduction and Propagation of the Unionoida (Primarily of North America)</span>. Columbus, Ohio: Ohio Biological Survey: Miscellaneous Contributions, No. 1. </p> <p id="cb509ee4a3012c7c8a5302f279703316">Watters, G. 1994a. American Freshwater Mussels Part I: The Quick and the Dead. <span style="font-style: italic">American Conchologist</span>, 22(1): 4-7. Accessed August 01, 2003 at <tt><a href="http://coa.acnatsci.org/conchnet/acfwmus1.html">http://coa.acnatsci.org/conchnet/acfwmus1.html</a></tt>. </p> <p id="d12c933a5d58dff2e6ed389665ce86a3">Watters, G. 1998. "Freshwater Mussels: Biology" (On-line). Conchologists of America Conch-net web page. Accessed July 25, 2003 at <tt><a href="http://coa.acnatsci.org/conchnet/uniobio.html">http://coa.acnatsci.org/conchnet/uniobio.html</a></tt>. </p> <p id="bccaffc0085da780388d7a50b60dbd74">Wiant, M. 2000. "Native Americans: Prehistoric" (On-line). Museum Link Illinois. Accessed August 03, 2003 at <tt><a href="http://www.museum.state.il.us/muslink/nat_amer/pre/index.html">http://www.museum.state.il.us/muslink/nat_amer/pre/index.html</a></tt>. </p> </section> </div> </div> <div class="span2_5 right sidebar"> <div class="well" id="pocket-guide-link"> <a href="https://itunes.apple.com/us/app/adw-pocket-guide/id916179421?mt=8" target="_blank"><i class="icon-download icon-white" style="vertical-align: bottom"></i> ADW Pocket Guides on the iOS App Store! </a> <p>The Animal Diversity Web team is excited to announce ADW Pocket Guides!</p> <p> <a href="/news/5009059054038197651/">Read more...</a> </p> </div> <h2 class="offscreen">Search</h2> <div id="site-search"> <form action="/search" method="GET"> <label for="q" class="offscreen">Enter search text</label> <input value="" id="q" name="q" class="span12" size="15" type="text" placeholder="Search ADW" /> <button class="btn"> <i class="icon-zoom-in"></i> <span class="offscreen">Search</span> </button> <p 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class="feature-classification"> <a name="feature-classification" href="/accounts/Margaritiferidae/classification/#Margaritiferidae" id="feature-classification"> Classification </a> </dd> </dl> <div class="classification well"> <h3>Classification</h3> <ul class="unstyled"> <li> <span class="rank">Kingdom</span> <a href="/accounts/Animalia/" class="taxon-name rank-kingdom">Animalia</a> <span class="vernacular-name">animals</span> <div class="features"> <a href="/accounts/Animalia/" class="feature feature-information" rel="tooltip" data-original-title="Animalia: information (1)" data-delay="250" data-total="4749">Animalia: information (1)</a> <a href="/accounts/Animalia/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Animalia: pictures (22861)" data-delay="250">Animalia: pictures (22861)</a> <a href="/accounts/Animalia/specimens/" class="feature feature-specimens" rel="tooltip" data-original-title="Animalia: specimens (7109)" data-delay="250">Animalia: specimens (7109)</a> <a href="/accounts/Animalia/sounds/" class="feature feature-sounds" rel="tooltip" data-original-title="Animalia: sounds (722)" data-delay="250">Animalia: sounds (722)</a> <a href="/accounts/Animalia/maps/" class="feature feature-maps" rel="tooltip" data-original-title="Animalia: maps (42)" data-delay="250">Animalia: maps (42)</a> </div> </li> <li> <span class="rank">Class</span> <a href="/accounts/Bivalvia/" class="taxon-name rank-class">Bivalvia</a> <span class="vernacular-name"></span> <div class="features"> <a href="/accounts/Bivalvia/" class="feature feature-information" rel="tooltip" data-original-title="Bivalvia: information (1)" data-delay="250" data-total="82">Bivalvia: information (1)</a> <a href="/accounts/Bivalvia/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Bivalvia: pictures (68)" data-delay="250">Bivalvia: pictures (68)</a> <a href="/accounts/Bivalvia/specimens/" class="feature feature-specimens" rel="tooltip" data-original-title="Bivalvia: specimens (58)" data-delay="250">Bivalvia: specimens (58)</a> <span class="feature-off feature-sounds"></span> <a href="/accounts/Bivalvia/maps/" class="feature feature-maps" rel="tooltip" data-original-title="Bivalvia: maps (42)" data-delay="250">Bivalvia: maps (42)</a> </div> </li> <li> <span class="rank">Order</span> <a href="/accounts/Unionoida/" class="taxon-name rank-order">Unionoida</a> <span class="vernacular-name"></span> <div class="features"> <span class="feature-off feature-information"></span> <a href="/accounts/Unionoida/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Unionoida: pictures (5)" data-delay="250">Unionoida: pictures (5)</a> <a href="/accounts/Unionoida/specimens/" class="feature feature-specimens" rel="tooltip" data-original-title="Unionoida: specimens (45)" data-delay="250">Unionoida: specimens (45)</a> <span class="feature-off feature-sounds"></span> <a href="/accounts/Unionoida/maps/" class="feature feature-maps" rel="tooltip" data-original-title="Unionoida: maps (42)" data-delay="250">Unionoida: maps (42)</a> </div> </li> <li class="active"> <span class="rank">Family</span> <a href="/accounts/Margaritiferidae/" class="taxon-name rank-family">Margaritiferidae</a> <span class="vernacular-name"></span> <div class="features"> <a href="/accounts/Margaritiferidae/" class="feature feature-information" rel="tooltip" data-original-title="Margaritiferidae: information (1)" data-delay="250" data-total="2">Margaritiferidae: information (1)</a> <a href="/accounts/Margaritiferidae/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Margaritiferidae: pictures (1)" data-delay="250">Margaritiferidae: pictures (1)</a> <span class="feature-off feature-specimens"></span> <span class="feature-off feature-sounds"></span> <span class="feature-off feature-maps"></span> </div> </li> </ul> </div> <div class="related navlist well"> <h3>Related Taxa</h3> <ul class="descendants classification unstyled"> <li> <span class="rank">Species</span> <a href="/accounts/Margaritifera_margaritifera/" class="taxon-name rank-species">Margaritifera margaritifera</a> <span class="vernacular-name"></span> <div class="features"> <a href="/accounts/Margaritifera_margaritifera/" class="feature feature-information" rel="tooltip" data-original-title="Margaritifera margaritifera: information (1)" data-delay="250" data-total="1">Margaritifera margaritifera: information (1)</a> <a href="/accounts/Margaritifera_margaritifera/pictures/" class="feature feature-pictures" rel="tooltip" data-original-title="Margaritifera margaritifera: pictures (1)" data-delay="250">Margaritifera margaritifera: pictures (1)</a> <span class="feature-off feature-specimens"></span> <span class="feature-off feature-sounds"></span> <span class="feature-off feature-maps"></span> </div> </li> </ul> </div> </div> </div> </div> </div> <div id="footer" aria-role="contentinfo"> <div class="inner-footer"> <div class="page-citation"> <p class="content">To cite this page: Winhold, L. 2004. "Margaritiferidae" (On-line), Animal Diversity Web. Accessed November 25, 2024 at https://animaldiversity.org/accounts/Margaritiferidae/</p> </div> <div class="disclaimer"> <p class="content"><strong>Disclaimer:</strong> The Animal Diversity Web is an educational resource <strong>written largely by and for college students</strong>. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control. </p> </div> <div class="footer-links"> <ul class="unstyled"> <li><a href="https://www.umich.edu/">U-M Gateway</a> | <a href="https://lsa.umich.edu/ummz/">U-M Museum of Zoology</a></li> <li> <a href="https://lsa.umich.edu/eeb/">U-M Ecology and Evolutionary Biology</a> </li> <li> 漏 2020 Regents of the University of Michigan </li> <li><a href="/feedback/error_form/">Report Error</a> / <a href="/feedback/comment_form/">Comment</a></li> </ul> </div> <div class="thanks-links"> <p>This material is based upon work supported by the <a href="https://nsf.gov">National Science Foundation</a> Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services. </p> <p> The ADW Team gratefully acknowledges their support. </p> </div> </div> </div> <script></script> </div> <script src="/static/js/jquery.colorbox.js"></script> <script src="/static/js/pica.information.js"></script> <script type="text/javascript"> var gaJsHost = (("https:" == document.location.protocol) ? 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ADW: Margaritiferidae: INFORMATION