''Lampsilis higginsii'' is a rare species of

freshwater mussel Freshwater bivalves are molluscs of the order Bivalvia that inhabit freshwater ecosystems. They are one of the two main groups of freshwater molluscs, along with freshwater snails. The majority of bivalve molluscs are saltwater species that l ...

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

endemic Endemism is the state of a species being found only 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 foun ...

to the United States, where it occurs in the upper

Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...

and the drainages of some of its

tributaries A tributary, or an ''affluent'', is a stream or river that flows into a larger stream ('' 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 into which the ...

. It is threatened by the introduced

zebra mussel The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel, an Aquatic animal, aquatic bivalve mollusk in the family Dreissenidae. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally Intro ...

(''Dreissena polymorpha''). ''Lampsilis higginsii'' is a federally listed

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

Description

This

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

is in the family

Unionidae The Unionidae are a Family (biology), 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 a ...

, 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 Nacre ( , ), also known as mother-of-pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer. It is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is ...

is white, sometimes tinged pink and partly

iridescent Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear gradually to change colour as the angle of view or the angle of illumination changes. Iridescence is caused by wave interference of light in microstruc ...

.''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, United States, at the confluence of the St. Croix River (Wisconsin-Minnesota), St. Croix River and Mississippi River. Prescott is at the edge of the Minneapolis–St. Paul metropolitan area. The pop ...

, to Louisiana, Missouri, as well as nine tributaries of the Mississippi. Today it can be found in the Mississippi from

La Crosse, Wisconsin La Crosse ( ) is a city in La Crosse County, Wisconsin, United States, and its county seat. Positioned alongside the Mississippi River, La Crosse is the largest city on Wisconsin's western border. La Crosse's population was 52,680 as of the 202 ...

, to

Muscatine, Iowa Muscatine ( ) is a city in and the county seat of Muscatine County, Iowa, United States. The population was 23,797 at the time of the 2020 United States census, 2020 census, an increase from 22,697 in 2000 United States Census, 2000. It is loca ...

, and two tributaries, the St. Croix and

Wisconsin River The Wisconsin River is the longest river in the U.S. state of Wisconsin, at approximately 430 miles (692 km) long. As a tributary of the Mississippi River, it is part of the Mississippi River System. The river's name was first recorded in 1673 b ...

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 harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...

. The mussel is now

extirpated Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions. Local extinctions mark a chan ...

from the

Illinois River The Illinois River () is a principal tributary of the Mississippi River at approximately in length. Located in the U.S. state of Illinois, the river has a drainage basin of . The Illinois River begins with the confluence of the Des Plaines ...

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, aqua ...

s and locks.

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 th ...

may also have negatively affected the mussel.USFWS
''Lampsilis higginsii'' Five-year Review.
May 2006.

Overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing Fish stocks, fish stock), resu ...

may have reduced the population, as well. Today the worst threat to the species is the

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

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 aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a spe ...

. 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 (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e and sperm, preventing reproduction. Deposits of waste products degrade the habitat. Other invasive species include the Asian clam (''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, 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 nigricans'') is a carnivorous, freshwater fish, freshwater, ray-finned fish in the Centrarchidae (sunfish) family, native to the eastern United States, eastern and central United States, southeastern Canada an ...

(''Micropterus salmoides''),

smallmouth bass The smallmouth bass (''Micropterus dolomieu'') is a species of freshwater fish in the Centrarchidae, sunfish family (biology), family (Centrarchidae) of the order (biology), order Centrarchiformes. It is the type species of its genus ''Micropterus ...

(''M. dolomieu''),

walleye The walleye (''Sander vitreus'', Synonym (taxonomy), synonym ''Stizostedion vitreum''), also called the walleyed pike, yellow pike, yellow pikeperch or yellow pickerel, is a freshwater perciform fish native to most of Canada and to the Northern ...

(''Sander vitreus''), and

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

(''Perca flavescens'').

References

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