Louisiana pearlshell (Margaritifera hembeli)

Federal Register | Recovery | Critical Habitat | Conservation Plans | Petitions | Life History

Listing Status:   


General Information

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, Entire is known to or is believed to occur:  Louisiana
  • US Counties in which the Louisiana pearlshell, Entire is known to or is believed to occur:  View All
  • Countries in which the the Louisiana pearlshell, Entire is known to occur:  United States
Current Listing Status Summary
Status Date Listed Lead Region Where Listed
02/05/1988 Southeast Region (Region 4) Entire

» Federal Register Documents

Federal Register Documents
Date Citation Page Title
09/08/2006 71 FR 53127 53129 Endangered and Threatened Wildlife and Plants; 5-Year Review of 14 Southeastern Species
02/05/1988 53 FR 3567 3570 Final End. Status for Louisiana Pearlshell (Margaritifera hembeli); 53 FR 3567-3570
02/26/1993 58 FR 11579 11581 ETWP; Proposed Rule to Reclassify the Louisiana Pearlshell (Margaritifera hembeli) from Endangered to Threatened
04/24/1987 52 FR 13794 13797 Proposed End. Status for Louisiana Pearlshell (Margaritilera hembeli); 52 FR 13794-13797
09/24/1993 58 FR 49935 49937 ETWP; Determination To Reclassify the Louisiana Pearlshell (Margaritifera Hembeli) From Endangered to Threatened

» Recovery

Current Recovery Plan(s)
Date Title Plan Action Status Plan Status
12/03/1990 Louisiana Pearlshell View Implementation Progress Final
Other Recovery Documents
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
  • Notice 5-year Review, Initiation
Five Year Review
Date Title
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.

» Petitions

» Life History

Habitat Requirements

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.

Food Habits

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.

Reproductive Strategy

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 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 is conducting ongoing research to determine various reproductive aspects of the Louisiana pearlshell mussel,including attempts to determine the host fish species via documenting glochidial metamorphosis.

» 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.