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Plains topminnow

Fundulus sciadicus

What do they look like?

Plains topminnows are dark green with black sides and silvery white on their stomachs. In the breeding season, males turn orange and yellow on their bellies, probably to attract mates. Their fins don't have obvious markings. They have broad, flat heads and their mouths look turned up. Because they are small, they can't swim for long periods of time in fast currents. This makes it difficult for them to colonize new areas after a current, because they would need to swim like that. (Cope, 2009; Pflieger and Smith, 1997; Rahel and Thel, 2004)

  • Sexual Dimorphism
  • female larger
  • sexes colored or patterned differently
  • male more colorful
  • Range length
    36.6 to 52.3 mm
    1.44 to 2.06 in
  • Average length
    42.9 mm
    1.69 in

Where do they live?

Plains topminnows live the some parts of the central United States. They are found along the northern and western edges of the Ozarks, which are the highlands in the center of the country. They live in the Lost and Shoal Creeks in southwestern Missouri and in rivers that drain into the Missouri River. The other places they live are Nebraska, northeastern Colorado, eastern Wyoming, southern South Dakota, northeastern Oklahoma, the Red River in Minnesota, and western Iowa. They area where they live is smaller than any of their closest relatives, because they need a specific kind of habitat. Scientists don't think they live in Missouri any more, and have tried to reintroduce them. (Cope, 2009; Helt, et al., 2003; Koupal and Pasbrig, 2010; Pflieger and Smith, 1997; Rahel and Thel, 2004)

What kind of habitat do they need?

Plains topminnows live in calm, shallow waters sheltered from the wind. They are sometimes found in lakes with gently sloping bottoms. They need sandy bottoms and lots of plants for nesting. Plants living in the water help them to hide from predators and keep their eggs from washing downstream. Plains topminnows live close to the surface of the water where there is more oxygen and they can hide from predators. They can't survive in distilled water. They live in freshwater and slightly salty water, and places where saltwater and freshwater meet. Plains topminnows are specifically adapted to the places where they live and can't move well between different habitats. ("Development, Growth and Reproduction of Plains Topminnow, Fundulus sciadicus, in a Broodstock Pond Located at Sacramento-Wilcox Management Area", 2010; Koupal and Pasbrig, 2010; Rahel and Thel, 2004; SUMNER, 1911; Smith and Hoboken, 1912)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • temporary pools
  • brackish water
  • Average depth
    0.5 m
    1.64 ft

How do they grow?

Female plains topminnows lay many eggs. The eggs have oil inside that gives the minnows nutrients and mucus around the outside so they stick onto plants or rocks. The eggs usually take 8 to 10 days to hatch, and hatch when the water gets to 21 degrees Celsius. Plains topminnows are about 7.6 mm long when they hatch. They begin feeding on the first day after they hatch, and are able to avoid predators within 2 to 4 days. Only 0.42% of the eggs survive to become adults. Plains topminnows keep growing throughout their entire lives. (Glaser, 1912; Kinney and Lynch, 1991; Koupal and Pasbrig, 2010; Pflieger and Smith, 1997; Rahel and Thel, 2004)

How do they reproduce?

Plains topminnows mate in a similar way to their closest relatives. They breed from May to June, once the water temperature reaches 21 degrees Celsius. Males compete for mates and females decide who they mate with. First, two males line up next to each other. They swim in circles until one of them bites the tail of the other. Then, females dig into the sand with the fins on their bellies and make a spot for their eggs. The female releases the eggs and the dominant male releases reproductive cells on top of them. The dominant male fertilizes most of the eggs. Afterwards, other males release their own reproductive cells on top of the same eggs to fertilize any that didn't get fertilized the first time. Males also mate with more than one female. (Kinney and Lynch, 1991; NEWMAN, 1909; Rahel and Thel, 2004)

Plains topminnows breed once a year in early spring and summer. Females lay many eggs with a coating of mucus around them and oil inside. The oil is used as energy and the mucus attaches the eggs onto plants. The colder the water is, the thicker the mucus layer gets. Older mothers also produce more oil and mucus. Plains topminnows lay 200 to 400 eggs. The eggs take 8 to 10 days to hatch, but only about 25 to 50 actually hatch into minnows because the parents don't care for them well. Plains topminnows are about 7.6 mm long when they hatch. They begin to eat the first day after they hatch, and are able to avoid predators 2 to 4 days later. (Glaser, 1912; Kinney and Lynch, 1991; Koupal and Pasbrig, 2010; M.L., et al., 2009; NEWMAN, 1909; Pflieger and Smith, 1997; Rahel and Thel, 2004)

  • How often does reproduction occur?
    Plains topminnows breed once a year.
  • Breeding season
    Plains topminnows breed in late spring and early summer.
  • Range number of offspring
    25 to 50
  • Range time to hatching
    8 to 10 days
  • Average time to independence
    4 days
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Females lay eggs with oil inside them that gives the minnow energy to develop. The eggs also have a mucus coating so they can stick to the ground or on a plant. After the mother lays the eggs, neither of the parents invest any more time or energy in their development. (M.L., et al., 2009; NEWMAN, 1909; Pflieger and Smith, 1997; Rahel and Thel, 2004)

How long do they live?

The oldest plains topminnows identified in the wild were 4 years old. (Rahel and Thel, 2004)

  • Range lifespan
    Status: wild
    4 to 4 years
  • Average lifespan
    Status: wild
    4 years

How do they behave?

Adult plains topminnows probably don't compete with each other for resources very often, because there are not very many of them. They are usually more active in warmer water. ("Development, Growth and Reproduction of Plains Topminnow, Fundulus sciadicus, in a Broodstock Pond Located at Sacramento-Wilcox Management Area", 2010; Koupal and Pasbrig, 2010; Pflieger and Smith, 1997; Rahel and Thel, 2004)

Home Range

Scientists don't know the size of the territories of plains topminnows. (Cope, 2009; Koupal and Pasbrig, 2010; Rahel and Thel, 2004; SUMNER, 1911)

How do they communicate with each other?

Plains topminnows don't group together in schools like many others of their closest relatives. Like all fish, they get information about water currents and vibrations from their lateral line, which runs from their head to their tail. ("Development, Growth and Reproduction of Plains Topminnow, Fundulus sciadicus, in a Broodstock Pond Located at Sacramento-Wilcox Management Area", 2010; Rahel and Thel, 2004)

What do they eat?

Scientists don't know exactly what plains topminnows eat in the wild. They probably eat fly larvae like nonbiting midges and black flies, as well as plankton on the surface, crustaceans, and some kinds of bladder snails. These assumptions are based on their habitat and the shape of their jaw, which is adapted for feeding at the surface of the water. In captivity, plains topminnows eat insects. ("Development, Growth and Reproduction of Plains Topminnow, Fundulus sciadicus, in a Broodstock Pond Located at Sacramento-Wilcox Management Area", 2010; Pflieger and Smith, 1997; Rahel and Thel, 2004)

  • Animal Foods
  • insects
  • mollusks
  • aquatic or marine worms
  • aquatic crustaceans
  • other marine invertebrates
  • zooplankton

What eats them and how do they avoid being eaten?

Plains topminnows are probably eaten by green sunfish, creek chubs, birds, and black bullheads. These species of fish live in the same habitat as them and eat other similar species. (Rahel and Thel, 2004)

What roles do they have in the ecosystem?

Plains topminnows are both predators and prey, but scientists don't know exactly what animals are their predators or prey. The number of plains topminnows decreased after western mosquitofish were introduced. Western mosquitofish were introduced into their habitat to try to limit the number of mosquitoes. In laboratories, western mosquitofish can be very aggressive against plains topminnows. (Pflieger and Smith, 1997; Rahel and Thel, 2004)

Plains topminnows get two kind of parasites that only live on plains topminnows. They get one kind of flatworm as they take in oxygen. Their bladder and the tubes that connect to them get another kind of flatoworm, which is probably from eating clams. Neither one of these parasites kills plains topminnows. (Ferdig, et al., 1991; Helt, et al., 2003; Rahel and Thel, 2004)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • gill flatworms (Salsuginus yutanensis)
  • trematodes (Phyllodistomium funduli)

Do they cause problems?

Plains topminnows compete for resources with western mosquitofish, which help control the number of mosquitoes. (Rahel and Thel, 2004)

How do they interact with us?

Plains topminnows are used in aquariums and as bait fish. They are aggressive against other fish, but survive well in aquariums. They are also used as bait by fishermen, but this is illegal in some states like Colorado because they are not very many of them. (Pflieger and Smith, 1997; Rahel and Thel, 2004)

Are they endangered?

Plains topminnows are not endangered according to the United States government, but their numbers are decreasing and they are considered rare in South Dakota. In Nebraska, they only live in one quarter of the places they used to. Plains topminnows have a limited habitat and their numbers are declining slowly. They are impacted by digging ditches, changing the flow of water to water crops, and competition with western mosquitofish. They are also affected by sediments getting into the water and pollution. In Colorado, scientists have tried to reintroduce them into places they used to live. (Cope, 2009; Koupal and Pasbrig, 2010; M.L., et al., 2009; Rahel and Thel, 2004)

Some more information...

Contributors

Jonathan Zwart (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Catherine Kent (editor), Special Projects.

References

Game and Parks Commission. Development, Growth and Reproduction of Plains Topminnow, Fundulus sciadicus, in a Broodstock Pond Located at Sacramento-Wilcox Management Area. T-57. Lincoln, NE 68508: Nebraska Publications Clearinghouse. 2010. Accessed March 19, 2012 at http://nlc1.nlc.state.ne.us/epubs/G1000/B145-2010.pdf.

Cope, 2009. "Fundulus sciadicus" (On-line). Natureserve Explorer. Accessed March 24, 2012 at http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Fundulus%20sciadicus.

Ferdig, M., M. McDowell, J. Janovy, Jr.. 1991. SALSUGINUS YUTANENSIS N. SP. (MONOGENEA: ANCYROCEPHALIDAE) FROM FUNDULUS SCIADICUS IN CLEAR CREEK OF EASTERN NEBRASKA. American Society of Parasitologists, 77(1): 58-61. Accessed February 08, 2012 at http://www.jstor.org/stable/pdfplus/3282556.pdf?acceptTC=true.

Glaser, O. 1912. CHANGES IN CHEMICAL ENERGY DURING THE DEVELOPMENT OF FUNDULUS HETEROCLITUS. Science, 35/892: 189-191. Accessed February 08, 2012 at http://www.sciencemag.org/content/35/892/189.1.full.pdf?sid=b15e27d5-cd78-4751-ab8c-93281cca8845.

Helt, J., J. Janovy, J. Ubelaker. 2003. Phyllodistomum funduli n. sp. (Trematoda: Gorgoderidae) from Fundulus sciadicus Cope from Cedar Creek in Western Nebraska. The Journal of Parasitology, 89(2): 346-350. Accessed February 08, 2012 at http://www.jstor.org/stable/pdfplus/3285959.pdf?acceptTC=true.

Kinney, T., J. Lynch. 1991. The fecundity and reproductive seasons of Fundulud sciadicus. Transactions of the Nebraska Academy of Sciences, XVIII: 104-104.

Koupal, K., C. Pasbrig. 2010. Development, Growth and Reproduction of Plains Topminnow, Fundulus sciadicus, in a Broodstock Pond Located at Sacramento-Wilcox Management Area. Project No. T-57: 1-20. Accessed March 22, 2012 at http://nlc1.nlc.state.ne.us/epubs/G1000/B145-2010.pdf.

Li, C., M. Bessert, G. Orti. 2009. Low Variation but strong population structure in mitochondrial control region of the plains top minnow, Fundulus sciadicus. Journal of Fish Biology, 74: 1037-1048. Accessed March 21, 2012 at http://golab.unl.edu/publications/Li_et_al_2009.pdf.

M.L., B., M. J., O. G.. 2009. Low variation but strong population structure in mitochondrial control regions of the plains topminnow, Fundulusus sciadicus. Journal of Fish Biology, 74: 1037-1048.

NEWMAN, H. 1909. THE QUESTION OF VIVIPARITY IN FUNDULUS MAJALIS. Science, VOL. XXX. No. 778: 769-771. Accessed February 08, 2012 at http://www.sciencemag.org/content/30/778/769.full.pdf?sid=b15e27d5-cd78-4751-ab8c-93281cca8845.

O’Hare, J. 1985. Morphological and biochemical variation of disjunct populations of plains topminnow, Fundulus sciadicus. Omaha, NE: MSc Thesis, University of Nebraska.

Pflieger, W., P. Smith. 1997. The fishes of Missouri. Jefferson City: Missouri Dept. of Conservation.

Rahel, F., L. Thel. 2004. Plains Topminnow (Fundulus sciadicus): A Technical Conservation Assessment. USDA Forest Service, Roky Mountain Region, Species Conservation Project: 1-45. Accessed March 21, 2012 at http://www.fs.fed.us/r2/projects/scp/assessments/plainstopminnow.pdf.

SUMNER, F. 1911. FUNDULUS AND FRESH WATER. Science, VOL. XXXIV. No. 887: 928-931. Accessed February 08, 2012 at http://www.sciencemag.org/content/34/887/928.full.pdf?sid=b15e27d5-cd78-4751-ab8c-93281cca8845.

Smith, E., N. Hoboken. 1912. Fundulus and fresh water. Science, XXXV No. 891: 144-145. Accessed March 20, 2012 at http://www.sciencemag.org/content/35/891/144.1.full.pdf.

 
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Zwart, J. 2013. "Fundulus sciadicus" (On-line), Animal Diversity Web. Accessed July 24, 2014 at http://www.biokids.umich.edu/accounts/Fundulus_sciadicus/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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