''Lampsilis higginsii'' is a rare species of

freshwater mussel Freshwater bivalves are one kind of freshwater mollusc, along with freshwater snails. They are bivalves that live in fresh water as opposed to salt water, which is the main habitat type for bivalves. The majority of species of bivalve molluscs ...

known as Higgins' eye pearly mussel or simply Higgins' eye. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the United States, where it occurs in the upper

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it fl ...

and the drainages of some of its

tributaries A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainag ...

. It is threatened by the introduced

zebra mussel The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally introduced to numerous other areas and has become an invasive species in ma ...

(''Dreissena polymorpha''). ''Lapsilis higginsii'' is a federally listed endangered species.

Description

This bivalve mollusc is in the family

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

, the river mussels. It is oval in shape with a thick, heavy shell which is yellowish or brown, sometimes with greenish rays.''Lampsilis higginsii''.
The Nature Conservancy. It reaches up to 10.2 centimeters in length (between 4-5 inches).Miller, A. C. and B. S. Payne. (2007)
A re-examination of the endangered Higgins eye pearlymussel ''Lampsilis higginsii'' in the upper Mississippi River, USA.
''Endanger Species Res'' 3 229-37. The nacre is white, sometimes tinged pink and partly iridescent.''Lampsilis higginsii''.
Illinois Natural History Survey.

Conservation

The historical range of this species stretched along 850 kilometers (about 520 miles) of the Mississippi River from

Prescott, Wisconsin Prescott is a city in Pierce County, Wisconsin at the confluence of the St. Croix River and Mississippi River. The population was 4,258 at the 2010 census, making it the second-largest city in the county after River Falls, and the largest entir ...

, to

Louisiana, Missouri Louisiana is a city in Pike County, Missouri, United States. The population was 3,364 at the 2010 census. Louisiana is located in northeast Missouri, on the Mississippi River, south of Hannibal. Louisiana is located at the junction of State Rout ...

, as well as nine tributaries of the Mississippi. Today it can be found in the Mississippi from La Crosse, Wisconsin, to

Muscatine, Iowa Muscatine ( ) is a city in Muscatine County, Iowa, United States. The population was 23,797 at the time of the 2020 census, an increase from 22,697 in 2000. The county seat of Muscatine County, it is located along the Mississippi River. The lo ...

, and two tributaries, the

St. Croix Saint Croix; nl, Sint-Kruis; french: link=no, Sainte-Croix; Danish and no, Sankt Croix, Taino: ''Ay Ay'' ( ) is an island in the Caribbean Sea, and a county and constituent district of the United States Virgin Islands (USVI), an unincor ...

and

Wisconsin River The Wisconsin River is a tributary of the Mississippi River in the U.S. state of Wisconsin. At approximately 430 miles (692 km) long, it is the state's longest river. The river's name, first recorded in 1673 by Jacques Marquette as "Meskous ...

s. It has always been rare, but it experienced a large reduction in population after 1965, when it began to lose the northernmost and southernmost reaches of its distribution, a total of over 50% of its range. One cause of the drop in population was

pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

. The mussel is now

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

from the Illinois River because of pollution. The habitat has been altered by impoundments, including

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...

s and

locks Lock(s) may refer to: Common meanings *Lock and key, a mechanical device used to secure items of importance *Lock (water navigation), a device for boats to transit between different levels of water, as in a canal Arts and entertainment * ''Lock ...

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

may also have negatively affected the mussel.USFWS
''Lampsilis higginsii'' Five-year Review.
May 2006. Overfishing may have reduced the population, as well. Today the worst threat to the species is the invasive species invasion of the zebra mussel. Zebra mussels attach to the shells of this and other native mussels, deforming them, preventing them from moving, and preventing their

filter feeding Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

. The zebra mussels can use up all the food in the vicinity and deplete the oxygen, and may also consume the native mussels'

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e and sperm, preventing reproduction. Deposits of waste products degrade the habitat. Other invasive species include the

Asian clam ''Corbicula fluminea'' is a species of freshwater clam native to eastern Asia which has become a successful invasive species throughout North America, South America, and Europe. ''Corbicula fluminea'' is commonly known in the west as the Asian cl ...

(''Corbicula fluminea''), which competes with the native mussel and consumes its sperm, larvae, and juveniles. Some introduced species of fish may eat juvenile mussels. This mussel has been propagated in captivity and released into appropriate habitat in areas where it has been extirpated.

Biology

During breeding, the male releases sperm and the female siphons it and keeps the fertilized eggs in her gills until they hatch. The

glochidia The glochidium (plural glochidia) is a microscopic larval stage of some freshwater mussels, aquatic bivalve mollusks in the families Unionidae and Margaritiferidae, the river mussels and European freshwater pearl mussels. These larvae are t ...

, or mussel larvae, are released and enter the bodies of host organisms, which are fish.USFWS
''Lampsilis higginsii'' Life History.
/ref> Some fish hosts for the mussel are

largemouth bass The largemouth bass (''Micropterus salmoides'') is a carnivorous freshwater gamefish in the Centrarchidae ( sunfish) family, a species of black bass native to the eastern and central United States, southeastern Canada and northern Mexico, bu ...

(''Micropterus salmoides''), smallmouth bass (''M. dolomieu''),

walleye The walleye (''Sander vitreus'', synonym ''Stizostedion vitreum''), also called the yellow pike or yellow pickerel, is a freshwater perciform fish native to most of Canada and to the Northern United States. It is a North American close relat ...

(''Sander vitreus''), and

yellow perch The yellow perch (''Perca flavescens''), commonly referred to as perch, striped perch, American perch, American river perch or preacher is a freshwater perciform fish native to much of North America. The yellow perch was described in 1814 by Sam ...

(''Perca flavescens'').

References

{{Taxonbar, from=Q3014997 higginsii Molluscs of the United States Bivalves described in 1857 ESA endangered species Taxonomy articles created by Polbot