Johnny Darter
(Etheostoma nigrum)
Taxonomy
Kingdom Animalia
Phylum Chordata
Class Actinopterygii
Order Perciformes
Family Percidae
Genus Etheostoma
Species nigrum
Etymology - [Etheo = to filter][Stoma = mouth][Nigrum = black]
Identifying Characteristics
The Johnny Darter is a simple yet elegant looking fish with a few unique details to its species. The fishes are small and slender and have scales the color of browns and yellows. The colors are dull and lack brightness and usually look like brown/black markings on a yellow background. The markings themselves consist of an interesting pattern in the shapes of "w" or "x" along their lateral lines. These fish are believed to be able to reach sizes of up to 3 inches with the males being longer and heavier of the two genders. Johnny Darters have two dorsal fins, one which is hard and spinous, and the second made up of soft rays. Their pectoral fins are lower on the fishes body and are exceptionally large for increased maneuverability. Males and females show sexual dimorphism and can be separated by the colors and patterns on their bodies.
Habitat
Johnny Darters habitat is mainly composed of clearer waters that have bottoms containing substrate of sand or gravel. Though they prefer slow-moving water, they oftern can be found in faster flows as well where they might have the ability to catch different prey. Compared to other Darter species, the Johnny is known to be able to handle a much wider range of conditions. It is a mostly benthic fish in terms of feeding and has a subterminal mouth to help it catch its food.
Life History
The Johnny Darter has a complex and intimate pattern of reproduction consisting of a few key components. First, males will migrate to the spawning areas prior to the females in order to create small nests. These nests are then protected as their territory and can consist of a variety of objects all centered around a rock, log or human trash. They will compete and defend the better nesting locations and protect them from other fish who greatly outmatch them in size. Eventually, the females will move into these spawning areas and look for a mate. They will perform a complex dance of moving up and around a specific spawning object while the male prods the female to release her eggs. While the males will stay at their own specific location, females are known to move from nest to nest, depositing eggs in a variety of locations to increase the number and genetic diversity of their progeny. Most females can lay a few hundred eggs and increases with age, and they can begin spawning in their first year of life. These eggs stay attached to objects within the nest and will be maintained and cleaned by the males often.
Geographic Range
The Johnny Darter can be found in a large portion of the Eastern United States and is found in large populations in the states of Minnesota and Ohio. They have been introduced into some Western states and have established small populations but do not seem to be expanding in range across these areas. They are prevalent in a variety of Eastern rivers and drainages including ones belonging to the Mississippi and Tennessee watersheds. |
Diet
The majority of the Jonny Darters diet consists of small insects, crustaceans and a variety of larvae, specifically when they are younger until they reach larger sizes. They are carnivores and eat using a subterminal mouth on the benthic portions of water ways. The predators of the Johnny Darter are many and can include trout species, burbot, smallmouth bass and yellow perch. They can also be attacked by water borne birds such as herons.
The majority of the Jonny Darters diet consists of small insects, crustaceans and a variety of larvae, specifically when they are younger until they reach larger sizes. They are carnivores and eat using a subterminal mouth on the benthic portions of water ways. The predators of the Johnny Darter are many and can include trout species, burbot, smallmouth bass and yellow perch. They can also be attacked by water borne birds such as herons.
Conservation Status
Throughout the majority of their natural range, the Johnny is not considered threatened but is shown to be vulnerable in a few states such as Kentucky, Oklahoma, and Kansas. Though they can withstand high levels of silt and pollution in waters, if exposed to too much, their populations will suffer. They do not provide any negative effects to the ecosystems such as becoming invasive, and in fact play an important role as both a predator of insect populations and a prey of larger species.
Throughout the majority of their natural range, the Johnny is not considered threatened but is shown to be vulnerable in a few states such as Kentucky, Oklahoma, and Kansas. Though they can withstand high levels of silt and pollution in waters, if exposed to too much, their populations will suffer. They do not provide any negative effects to the ecosystems such as becoming invasive, and in fact play an important role as both a predator of insect populations and a prey of larger species.
References:
http://www.fishbase.org/summary/3445
http://wildlife.ohiodnr.gov/species-and-habitats/species-guide-index/fish/johnny-darter
http://www.biokids.umich.edu/critters/Etheostoma_nigrum/
http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=814
http://www.lakesuperiorstreams.org/understanding/johnnydarter.html
http://www.fishbase.org/summary/3445
http://wildlife.ohiodnr.gov/species-and-habitats/species-guide-index/fish/johnny-darter
http://www.biokids.umich.edu/critters/Etheostoma_nigrum/
http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=814
http://www.lakesuperiorstreams.org/understanding/johnnydarter.html