Ellipsaria lineolata

Geographic Range

Ellipsaria lineolata, the butterfly mussel, is native to the United States and Canada. In the United States, it is found from the midwestern states to the east coast, and south to the Gulf of Mexico. Specifically, it has been recorded in Minnesota, Wisconsin, Iowa, Missouri, Illinois, Indiana, Ohio, Louisiana, Alabama, Mississippi, Georgia, Tennessee, Kentucky, West Virginia and Pennsylvania. It is considered widespread but only locally abundant. ("Butterfly mussel", 2008; "Butterfly- Ellipsaria lineolata", 2013; Minnesota Department of Natural Resources, 2013; "Ellipsaria lineolata", 2010; Suber, 1913; "Ellipsaria lineolata (Rafinesque, 1820)", 2013)


The butterfly mussel usually inhabits large rivers with swift currents and gravel or sand substrates. It has been found to adapt to life in reservoirs in the southern United States where it can be found in depths up to 6 m or 20 ft. (Minnesota Department of Natural Resources, 2013)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • temporary pools
  • Range depth
    6 (high) m
    19.69 (high) ft

Physical Description

The shell of the butterfly mussel is somewhat triangular with rounded ventral, dorsal and anterior margins. The exterior of the shell has numerous rays and is generally yellowish in color, but older specimens can be brown. The hinge may have a green tint and the interior of the shell is white. The male mussels have a compressed body shape while the females are slightly inflated. The shell of both sexes is thick and females generally measure less than 7 cm while males can reach up to 12.7 cm in length. The beak is turned forward and the beak sculpture consists of a few fine, double-looped lines. This species also has fully developed pseudocardinal and lateral teeth. ("Butterfly mussel", 2008; Minnesota Department of Natural Resources, 2013)

  • Sexual Dimorphism
  • male larger
  • sexes shaped differently
  • Range length
    5 to 12.5 cm
    1.97 to 4.92 in


Males release sperm into the water, and the sperm is drawn into the female by the incurrent siphon. Once the eggs are fertilized, the eggs hatch into larvae called glochidia. They remain in the female for about 11 months until the following summer, when they are released and attach to a fish where they develop into juvenile mussels. Known fish hosts for the glochidia of the butterfly mussel include sunfish (Lepomis spp.), sauger (Sander canadensis), and drum (Aplodinotus grunnieus). While encysted in the fish tissue, they develop into juvenile mussels. Once they have reached this stage, they release from the fish and fall to the riverbed as free-living mussels. (Minnesota Department of Natural Resources, 2013)


In late summer, Ellipsaria lineolata males release sperm into the water. The sperm is carried by the current to nearby females, which draw in the sperm through the incurrent siphon. (Coker, et al., 1921; Minnesota Department of Natural Resources, 2013)

Once the eggs are fertilized, they are brooded in the gills of the female. They then develop into larvae called glochidia. Females brood their young long-term (bradytictic) from August to July before releasing them as glochidia. These glochidia then live as parasites by attaching themselves to a fish's gills or fins using their valves. They remain attached until they turn into juvenile mussels at which time they detach from the fish and fall to the riverbed as free-living mussels. (Coker, et al., 1921; Minnesota Department of Natural Resources, 2013)

  • Breeding interval
    Ellipsaria lineolata reproduces once a year.
  • Breeding season
    Spawning takes place in late summer.

Females retain the fertilized eggs and then later the glochidia in a brood pouch for 11 months, from August until July of the following summer. They release the glochidia when a host fish is close, so that the larvae will have a host fish to attach to. Once the glochidia are released, they are independent of the female parent and receive no more care. (Minnesota Department of Natural Resources, 2013)

  • Parental Investment
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female


While the specific lifespan for Ellipsaria lineolata is unknown, other freshwater mussel species are known to live for many decades and in some cases up to 100 years. (Minnesota Department of Natural Resources, 2013)


Mussels are typically sessile adults unless there is a negative change in the environment causing them to relocate. Juveniles are typically more mobile than adults, using their muscular foot. Freshwater mussels often live in groups with other species of mussels in mussel beds, but they are not social animals and do not interact with each other. (Minnesota Department of Natural Resources, 2013)

Communication and Perception

There is little information available about the communication and perception of Ellipsaria lineolata. Like many freshwater mussels, they likely take cues from their environment, such as water temperature, to initiate spawning and other actions. They can also likely detect changes in light, vibrations, and physical touch. Individuals do not typically communicate to each other. (Minnesota Department of Natural Resources, 2013)

Food Habits

Butterfly mussels feed by drawing water in through their incurrent siphon. They then filter the food (bacteria, protozoans, algae, and other organic matter) out of the water. The food particles are then carried into the mouth by cilia that are located on the gills and the remaining water is expelled from the mussel through the excurrent siphon. (Minnesota Department of Natural Resources, 2013; Suber, 1913)


Predators of butterfly mussels are mammals such as raccoons, muskrats, and otters. The only protection and defense against predators for Ellipsaria lineolata is its hard shell which protects its soft body. These mussels are also known to burrow into the sediment of the river bottom. ("Butterfly- Ellipsaria lineolata", 2013; Minnesota Department of Natural Resources, 2013)

Ecosystem Roles

Butterfly mussels, along with many other species of mussels, filter the water in which they live. This removes many particles from the environment, creating a cleaner system. However, if the water is too polluted, it is unhealthy for the mussels and they are not able to survive in that location. Ellipsaria lineolata serves as prey to a variety of mammals. Larvae are parasites on several fish species, including sunfish (Lepomis spp.), drum (Aplodinotus grunnieus), and sauger (Sander canadensis). (Minnesota Department of Natural Resources, 2013)

Species Used as Host

Economic Importance for Humans: Positive

Mussels are a sign of a healthy water source. The health of a Ellipsaria lineolata population, as well as examination of individual mussels can provide significant information on the status of an ecosystem. Butterfly mussels are also filter feeders that help purify the water in which they live. (Minnesota Department of Natural Resources, 2013)

  • Positive Impacts
  • research and education

Economic Importance for Humans: Negative

There are no known adverse effects of Ellipsaria lineolata on humans.

Conservation Status

Though the IUCN Red List describes Ellipsaria lineolata as being near threatened, it was last changed in 1996 and states that it is in need of updating. Threats to this species are water pollution, industrial discharge, residential discharge, siltation, herbicide and fertilizer run-off, changes to the natural flow of rivers, increased water temperatures, dredging, and invasive species such as zebra mussels. Though the butterfly mussel has not been given an official federal listing, many of the states in its geographic distribution consider it threatened. Due to decreases in populations, it is considered endangered in Ohio and Wisconsin, threatened in Iowa, and a species of special concern in Illinois. ("Ellipsaria lineolata", 1996; "Butterfly- Ellipsaria lineolata", 2013; "Ellipsaria lineolata (Rafinesque, 1820)", 2013)


Leslie Schroeder (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Angela Miner (editor), Animal Diversity Web Staff.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.


an animal that mainly eats decomposed plants and/or animals


particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

female parental care

parental care is carried out by females


union of egg and spermatozoan


a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.


mainly lives in water that is not salty.


An animal that eats mainly plants or parts of plants.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death


photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season


remains in the same area


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


uses sound above the range of human hearing for either navigation or communication or both


uses sight to communicate


Georgia Museum of Natural History. 2008. "Butterfly mussel" (On-line). Accessed March 24, 2013 at http://naturalhistory.uga.edu/~gmnh/gawildlife/index.php?page=speciespages/ai_species_page&key=elineolata.

Iowa Department of Natural Resources. 2013. "Butterfly- Ellipsaria lineolata" (On-line). Accessed March 24, 2013 at http://www.iowadnr.gov/portals/idnr/uploads/education/Species/mussel/butterfly.pdf.

University of Illinois Board of Trustees. 2013. "Ellipsaria lineolata (Rafinesque, 1820)" (On-line). Accessed March 24, 2013 at http://wwx.inhs.illinois.edu/collections/mollusk/publications/guide/index/106.

IUCN Red List of Threatened Species. 1996. "Ellipsaria lineolata" (On-line). Accessed March 24, 2013 at http://www.iucnredlist.org/details/summary/7629/0.

NaturServe. 2010. "Ellipsaria lineolata" (On-line). Accessed March 26, 2013 at http://www.edulifedesks.org/groups/activity/images?page=4.

Coker, R., A. Shira, H. Clark, A. Howard. 1921. Natural history and propagation of fresh-water mussels. Bulletin of the Bureau of Fisheries, 37: 75-181.

Minnesota Department of Natural Resources, 2013. "Species Profile: Ellipsaria lineolata" (On-line). Accessed February 27, 2013 at http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=IMBIV13010.

Suber, T. 1913. Notes on the natural hosts of fresh-water mussels. Bulletin of the Bureau of Fisheries, 32: 101-116.