Louisiana pearlshell (Margaritifera hembeli)
Where Listed: WHEREVER FOUND
The Louisiana pearlshell mussel is oblong and kidney shaped. Umbos (the inflated dorsal part of the shell) are even with or slightly extended past the hinge line. The anterior end, typically buried in the substrate, is rounded; whereas, the exposed posterior end of the shell is pointed and may have some corrugated sculpturing along the surface of the shell. The periostracum or outer shell color is brown to black, while the nacre or inner shell color is white to purple, with the nacre surface being pitted. Large adults are approximately 100 mm (3.9 in) long, 50 mm (2.0 in) high, and 30 mm (1.2 in) wide.
- States/US Territories in which the Louisiana pearlshell, Wherever found is known to or is believed to occur: Louisiana
- US Counties in which the Louisiana pearlshell, Wherever found is known to or is believed to occur: View All
- Countries in which the the Louisiana pearlshell, Wherever found is known to occur: United States
|Status||Date Listed||Lead Region||Where Listed|
|02/05/1988||Southeast Region (Region 4)||Wherever found|
» Federal Register Documents
|02/26/1993||58 FR 11579 11581||ETWP; Proposed Rule to Reclassify the Louisiana Pearlshell (Margaritifera hembeli) from Endangered to Threatened|
|09/24/1993||58 FR 49935 49937||ETWP; Determination To Reclassify the Louisiana Pearlshell (Margaritifera Hembeli) From Endangered to Threatened|
|08/30/2016||81 FR 59650 59652||5-Year Status Reviews of 22 Southeastern Species; Notice of initiation of reviews; request for information.|
|02/05/1988||53 FR 3567 3570||Final End. Status for Louisiana Pearlshell (Margaritifera hembeli); 53 FR 3567-3570|
|09/08/2006||71 FR 53127 53129||Endangered and Threatened Wildlife and Plants; 5-Year Review of 14 Southeastern Species|
|04/24/1987||52 FR 13794 13797||Proposed End. Status for Louisiana Pearlshell (Margaritilera hembeli); 52 FR 13794-13797|
|Date||Title||Plan Action Status||Plan Status|
|12/03/1990||Louisiana Pearlshell||View Implementation Progress||Final|
|Date||Citation Page||Title||Document Type|
|09/08/2006||71 FR 53127 53129||Endangered and Threatened Wildlife and Plants; 5-Year Review of 14 Southeastern Species||
|08/30/2016||81 FR 59650 59652||5-Year Status Reviews of 22 Southeastern Species; Notice of initiation of reviews; request for information.||
|02/22/2011||Louisiana Pearlshell Mussel 5-Year Review|
» Critical Habitat
No critical habitat rules have been published for the Louisiana pearlshell.
» Conservation Plans
No conservation plans have been created for Louisiana pearlshell.
» Life History
The Louisiana pearlshell mussels require clear, relatively shallow headwater streams, with a moderately swift current and rocky outcroppings. They are usually associated with the riffle area of the stream and not typically found in stagnant pools or deeper sandy areas.
The diet of the Louisiana pearlshell mussel is likely similar to that of other freshwater bivalves, including food items such as detritus (disintegrated organic debris), algae, diatoms, and bacteria. Adult freshwater mussels are filter feeders and generally orient themselves on or near the substrate surface to take in food and oxygen from the water column. Juveniles lack developed filter feeding structures and are typically pedal feeders that burrow completely beneath the substrate surface and bring food particles that adhere to the extended foot inside the shell for ingestion.
The reproductive biology of the Louisiana pearlshell mussel is similar to other dioecious (having separate male and female sexes), freshwater mussel species, in that fertilization occurs after females siphon and filter sperm that males release into the water during the spawning period. The sexes are monomorphic (males and females appear the same). Females brood developing embryos on the marsupia of all four gills until releasing fully developed glochidia into the water. These glochidia must then attach to a species-specific host fish within a short time after being released into the water or the released glochidia will die. Once glochidia successfully attach to the gills of the host fish, glochidial metamorphosis takes place. The length of metamorphosis is not yet known. After glochidial metamorphosis is complete, the newly metamorphosed mussels are released from the host fish and float downward to settle on the streambed. Once reaching the sediment in suitable habitat, the final developmental stage into a sexually mature adult begins. It is not yet certain at what age the Louisiana pearlshell mussels reach sexual maturity. Several fish species have been suggested as potential host for the Louisiana pearlshell mussel, but until 2016 all reports of potential host fish were made from observing glochidia encysted on the gills of wild caught fish, with none confirmed from observation of metamorphosis into transformers. The U.S. Fish and Wildlife Service's Nachitoches National Fish Hatchery confirmed the reproductive timing of the species, and in April 2016 the pickerel was documented as the host fish, confirmed by glochidial metamorphosis in a hatchery setting.
» Other Resources
NatureServe Explorer Species Reports -- NatureServe Explorer is a source for authoritative conservation information on more than 50,000 plants, animals and ecological communtities of the U.S and Canada. NatureServe Explorer provides in-depth information on rare and endangered species, but includes common plants and animals too. NatureServe Explorer is a product of NatureServe in collaboration with the Natural Heritage Network.
ITIS Reports -- ITIS (the Integrated Taxonomic Information System) is a source for authoritative taxonomic information on plants, animals, fungi, and microbes of North America and the world.
FWS Digital Media Library -- The U.S. Fish and Wildlife Service's National Digital Library is a searchable collection of selected images, historical artifacts, audio clips, publications, and video.