''Epioblasma obliquata'', commonly called the catspaw, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 ...

. It is native to eastern North America, where it is classified as endangered under the

Endangered Species Act The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting and conserving imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of e ...

. There are two subspecies, each with distinct morphology. Due to species rarity, the behavior of this organism is unknown beyond general freshwater mussel behavior.

Natural history and conservation

This species was historically widespread in the

Ohio River The Ohio River () is a river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing in a southwesterly direction from Pittsburgh, Pennsylvania, to its river mouth, mouth on the Mississippi Riv ...

and

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...

drainage basin A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

s. Like many other North American freshwater mussels, it relies on a habitat of shallow, gravelly riffle zones in larger rivers. This oxygen-rich habitat has largely been destroyed over the past 200 years by dam construction and dredging, which caused a massive population decline.NatureServe
/ref> Freshwater mussels also face the major threats of water temperature, water velocity, and

turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of both water clarity and wa ...

changes. These factors add great stress on the survival of these mussels in their respective environments. They change the

ecophysiology Ecophysiology (from Greek , ''oikos'', "house(hold)"; , ''physis'', "nature, origin"; and , '' -logia''), environmental physiology or physiological ecology is a biological discipline that studies the response of an organism's physiology to envir ...

of the organisms and change the way they are able to interact with their resources and surroundings. Both subspecies, the white catspaw and the purple catspaw, are critically endangered. By the time ''E. obliquata obliquata'', the purple catspaw, was listed in 1990 under the Endangered Species Act, no surviving breeding populations were known. This changed in 1994 when a few young individuals were found in

Killbuck Creek Killbuck Creek is a tributary of the Walhonding River, 81.7 mi (131.5 km) long,Ohio Department of Natural Resources''A Guide to Ohio Streams.''Ohio Ohio ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Erie to the north, Pennsylvania to the east, West Virginia to the southeast, Kentucky to the southwest, Indiana to the ...

, indicating a small breeding population. An attempt to collect young individuals was made in order to start a captive breeding program. However, to the researchers disappointment, surveys from 2006–2007 recorded a population of only 12 males and zero females. It wasn't until 2012 that researchers were able to find their first female individuals that could be used for captive breeding programs, which are now underway. Epioblasma_obliquata_Purple_Catspaw

The status of subspecies ''E. obliquata perobliqua'', the white catspaw, is more dire. Only a single population has persisted into the modern day, found in Fish Creek, a tributary of the St. Joseph River in

Indiana Indiana ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Michigan to the northwest, Michigan to the north and northeast, Ohio to the east, the Ohio River and Kentucky to the s ...

. At this location, only five living individuals were documented during surveys from 1975 to 1999, with the last living female recorded in 1975. Since then, surveys of Fish Creek have failed to find any living white catspaw mussels.

Taxonomy

This species exhibits variable shell characteristics, which have been taxonomically treated as either subspecies or separate species. Citing phylogeny, shell characteristics and allopatry, the Fish and Wildlife Service, supported by Williams et al. (2017), has separated the purple and white catspaws into distinct species, each protected by the Endangered Species Act as an endangered species. * Purple catspaw (''Epioblasma obliquata obliquata''), now protected federally as ''Epioblasma obliquata'' * White catspaw (''Epioblasma obliquata perobliqua''), now protected federally as ''Epioblasma perobliqua'' (Conrad, 1836)

Organism Description

One of the subspecies, the white catspaw, exhibits morphological differences between the sexes. The males have shells that are more oval-like and the grooves are deeper than those of the female. The shell of the females appear to resemble more of a rectangle than the oval. The outer layer of the shell is a tannish color while the iridescent interior is a pearly white. Overall, the mussel is around 2 inches. The purple catspaw has a yellow/green/brownish shell surface with a deep purple iridescent interior. This subspecies demonstrates different sex morphologies as well with the male shell narrower than the wider shell of the female. Males can be up to 70mm.

Behavior

Due to the rarity of both subspecies, reproduction timing is unknown. Maturation, developmental

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

, and lifespan have not been observed. These muscles are

filter feeder 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 s ...

s through and consuming what food available floating through the water. Basic organismal research needs to be done on the catspaw mussel if there is any hope of reintroduction to its historical ranges.

References

{{Taxonbar, from=Q3790538 obliquata ESA endangered species Taxa named by Constantine Samuel Rafinesque