Critter Catalog

What do they look like?

The shell of the butterfly mussel is triangular in shape with rounded edges. The outerside of the shell is yellowish in color, though older mussels can be brown. The hinge connecting the two shells may be greenish, and the inside of the shell is white. Male mussels are flatter than females. 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. ("Butterfly mussel", 2008; Minnesota Department of Natural Resources, 2013)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes shaped differently

• Range length

  5 to 12.5 cm

  1.97 to 4.92 in

Where do they live?

Ellipsaria lineolata, the butterfly mussel, lives in 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. ("Butterfly mussel", 2008; "Butterfly- Ellipsaria lineolata", 2013; Minnesota Department of Natural Resources, 2013; "Ellipsaria lineolata", 2010; Suber, 1913; "Ellipsaria lineolata (Rafinesque, 1820)", 2013)

• Biogeographic Regions
• nearctic
  • native

What kind of habitat do they need?

The butterfly mussel usually lives in large rivers with fast flowing waters and gravel or sand on the river bottom. In the southern United States, it also lives in reservoirs as deep as 6 meters. (Minnesota Department of Natural Resources, 2013)

• These animals are found in the following types of habitat
• temperate
• freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• temporary pools

• Range depth

  6 (high) m

  19.69 (high) ft

How do they grow?

Males release sperm into the water, and the sperm is drawn into the body of females. When the eggs are fertilized, the eggs stay in a pouch in the female and hatch into larvae called glochidia. The glochidia stay in the female for 11 months until the following summer. Glochidia are parasites and need to attach to a fish to finish development. The female parent releases the glochidia and they attach to a nearby fish, such as sunfish (Lepomis spp.), sauger (Sander canadensis), and drum (Aplodinotus grunnieus). While attached to the fish, the glochida develop into juvenile mussels, and they drop off the fish and fall to the river bottom, where they will develop into adults. (Minnesota Department of Natural Resources, 2013)

• Development - Life Cycle
• metamorphosis

How do they reproduce?

In late summer, butterfly mussel males release sperm into the water. The sperm is carried by the water to female mussels. The sperm enters the female body through a tube called the incurrent siphon. (Coker, et al., 1921; Minnesota Department of Natural Resources, 2013)

• Mating System
• polygynandrous (promiscuous)

Once the eggs are fertilized, they remain in a special pouch in the gills of the female. They then hatch into larvae called glochidia. Females keep the glochidia inside them for 11 months, from August until July of the next summer. The females then release the glochidia, which live as parasites on fish. (Coker, et al., 1921; Minnesota Department of Natural Resources, 2013)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• broadcast (group) spawning

• How often does reproduction occur?

  Ellipsaria lineolata reproduces once a year.

• Breeding season

  Spawning takes place in late summer.

Female butterfly mussels provide significant parental care. They keep the fertilized eggs, and then later the hatched larvae inside of them for almost a year. They release the larvae when a fish is close, so that the larvae will have a place to attach to and develop. Once the larvae are released, they are independent and the mother provides 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

How long do they live?

It is not known for sure how long butterfly mussels live, but other related species of freshwater mussels live for many decades, and in some cases up to 100 years. (Minnesota Department of Natural Resources, 2013)

How do they behave?

Buttefly mussels spend much of their time in one spot, only moving if their environment changes. Juvenile mussels move around more than adults. To move, mussels use a muscular body part called the foot. They stick the foot out between their shells and use it to pull themselves along. Butterfly mussels often live in groups with other species of mussels. This is called a mussel bed. But mussels do not really interact with each other, even though many of them may live together. (Minnesota Department of Natural Resources, 2013)

• Key Behaviors
• parasite
• motile
• sedentary
• colonial

How do they communicate with each other?

Mussels do not really communicate with each other. Mussels can detect water temperature, touch, vibrations, and likely can sense changes in light. (Minnesota Department of Natural Resources, 2013)

• Perception Channels
• visual
• tactile
• ultrasound

What do they eat?

Butterfly mussels feed on tiny particles of food in the water. These particles are usually bacteria, protozoans, algae, and other organic matter. Mussels draw water and the particles in the water into their bodies through a tube called the incurrent siphon. They filter the food particles out from the water, and they are carried into the mouth by little hair-like projections called cilia. The leftover water then leaves the body through another tube called the excurrent siphon. (Minnesota Department of Natural Resources, 2013; Suber, 1913)

• Primary Diet
• herbivore
  • algivore
• detritivore

• Plant Foods
• algae
• phytoplankton

• Other Foods
• detritus
• microbes

• Foraging Behavior
• filter-feeding

What eats them and how do they avoid being eaten?

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

• Known Predators

  • raccoons, Procyon lotor
  • river otters, Lontra canadensis
  • muskrats, Ondatra zibethicus

What roles do they have in the ecosystem?

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. Butterfly mussels are eaten by many mammals. Their larvae are parasites on several fish species, including sunfish (Lepomis spp.), drum (Aplodinotus grunnieus), and sauger (Sander canadensis). (Minnesota Department of Natural Resources, 2013; Minnesota Department of Natural Resources, 2013)

• Ecosystem Impact
• parasite

Do they cause problems?

Butterfly mussels do not cause any problems for humans.

How do they interact with us?

Mussels need good, clean water to survive, so if there are mussels in a body of water, it is a good sign that the habitat is healthy. Scientists can look at populations of butterfly mussels and can get information about their habitat. (Minnesota Department of Natural Resources, 2013)

• Ways that people benefit from these animals:
• research and education

Are they endangered?

Butterfly mussels are considered to be near threatened. This means that their populations are decreasing, and if these mussels continue to disappear, they will become endangered. One of the main reasons butterfly mussel numbers are decreasing is water pollution. Many states are trying to prevent these mussels from becoming endangered. ("Ellipsaria lineolata", 1996; "Butterfly- Ellipsaria lineolata", 2013; "Ellipsaria lineolata (Rafinesque, 1820)", 2013)

• IUCN Red List

  Near Threatened

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Contributors

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

References

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.