Etheostoma exile
Encyclopedia
The Iowa Darter is a species of freshwater
fish in the perch family (family Percidae) of order Perciformes
. The Iowa darter, along with about seventeen other species of darters, is native to the lakes and streams of Iowa
.
In some parts of its range, the Iowa darter is also known as the weed darter, red-sided darter, or yellowbelly. The Iowa darter, like many other darters, are about 2 inches (51 mm) to 3 inches (76 mm) in length and may be easily confused with other darters that are similar in color.
, east to New York
, south to central Illinois
, and the species is particularly common in the western Great Lakes
drainages and Iowa. Western populations are distributed patchily in Colorado
, Wyoming
, Montana
and Alberta
. They are native in Colorado only in the South Platte River
drainage, but recent research has also placed them in the Yampa River
(Colorado) and the Green River (Utah)
.
, one which is a spinous-rayed fin and another that is a soft-rayed fin. Their caudal fin
is squarish and their pectoral fins
and pelvic fins
are located close to each other behind the gills. They have an anal fin
with two (rarely one) spines and an incomplete lateral line
. The male and female Iowa darter have different color patterns. During breeding males are olivaceous dorsally with darker splotches across the top of their back. Their sides are red with blue rectangular blotches and ventrally they are whitish with a dark wedge shape below the eye. The bottom half of the spiny dorsal fin has blue spots between the spines and above the spots there is a succession of three bands, orange on the bottom, clear in the middle, and then blue on the outside. Females are olive-brown dorsally with darker splotches across the top of their back. Their sides are mottled and fade into a silver-white on their bellies. They also have a dark wedge shape below the eye that is well developed.
, water fleas
, and midge
and mayfly
larvae it finds in underwater vegetation. The Iowa darter has never been found in the stomach of any fish-eating animal because they are too quick to catch.
seems to be their habitat. This may be due to increasing turbidity
limiting their preferred habitat.
mainly in the spring. Found that Iowa darters migrated from deeper regions of lakes and streams to the shallow vegetated reaches for spawning. Males typically migrated before females. Male Iowa darters maintained and defended small territories near undercut banks with rooted vegetation. Smaller males, however, were promiscuous
, did not defend territories, and were mobile, moving from place to place in search of females. When a female entered a male's territory, the male courted the female by swimming around her until she positioned herself near algae
or rooted vegetation. The male mounted the female and positioned himself with his pelvic fins in front of her dorsal fin. The anal and caudal fins of the male were placed on the same side of the female. Most spawning occurred at depths of 10-40 cm on fibrous roots beneath slightly undercut banks, although some eggs were laid directly on sand or on roots or other plant materials on sand. During each spawning act three to seven eggs were deposited. Following the completion of spawning, the eggs received some protection in that by continuing to maintain his territory, the male indirectly guarded the eggs. Females mated with several males, then returned to deeper habitats following spawning.
were between 7.7 and 9.1 mm TL. Much of the lateral line sensory system was formed when the larvae reached approximately 20 mm TL.
word with etheo meaning strain or filter and stoma meaning mouth. The species name, exile, is also Greek and stands for slim or slender.
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
fish in the perch family (family Percidae) of order Perciformes
Perciformes
The Perciformes, also called the Percomorphi or Acanthopteri, is one of the largest orders of vertebrates, containing about 40% of all bony fish. Perciformes means perch-like. They belong to the class of ray-finned fish and comprise over 7,000 species found in almost all aquatic environments...
. The Iowa darter, along with about seventeen other species of darters, is native to the lakes and streams of Iowa
Iowa
Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...
.
In some parts of its range, the Iowa darter is also known as the weed darter, red-sided darter, or yellowbelly. The Iowa darter, like many other darters, are about 2 inches (51 mm) to 3 inches (76 mm) in length and may be easily confused with other darters that are similar in color.
Range
Native distribution of the Iowa darter extends north to central CanadaCanada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, east to New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
, south to central Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
, and the species is particularly common in the western Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
drainages and Iowa. Western populations are distributed patchily in Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
, Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
, Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
and Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
. They are native in Colorado only in the South Platte River
South Platte River
The South Platte River is one of the two principal tributaries of the Platte River and itself a major river of the American Midwest and the American Southwest/Mountain West, located in the U.S. states of Colorado and Nebraska...
drainage, but recent research has also placed them in the Yampa River
Yampa River
The Yampa River is a tributary of the Green River, approximately 250 mi long, in the U.S. state of Colorado. It's located in the Southwestern United States...
(Colorado) and the Green River (Utah)
Green River (Utah)
The Green River, located in the western United States, is the chief tributary of the Colorado River. The watershed of the river, known as the Green River Basin, covers parts of Wyoming, Utah, and Colorado. The Green River is long, beginning in the Wind River Mountains of Wyoming and flowing...
.
Physical Description
The Iowa darter has a very slim, small body. Their common length is around 5.5cm and their max. age is 3 years. They have a small mouth and snout with scaled opercles and cheeks. they have two dorsal finsFish anatomy
Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does.- Body :...
, one which is a spinous-rayed fin and another that is a soft-rayed fin. Their caudal fin
Fish anatomy
Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does.- Body :...
is squarish and their pectoral fins
Fish anatomy
Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does.- Body :...
and pelvic fins
Fish anatomy
Fish anatomy is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does.- Body :...
are located close to each other behind the gills. They have an anal fin
Flipper (anatomy)
A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins , cetaceans A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins (also called...
with two (rarely one) spines and an incomplete lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
. The male and female Iowa darter have different color patterns. During breeding males are olivaceous dorsally with darker splotches across the top of their back. Their sides are red with blue rectangular blotches and ventrally they are whitish with a dark wedge shape below the eye. The bottom half of the spiny dorsal fin has blue spots between the spines and above the spots there is a succession of three bands, orange on the bottom, clear in the middle, and then blue on the outside. Females are olive-brown dorsally with darker splotches across the top of their back. Their sides are mottled and fade into a silver-white on their bellies. They also have a dark wedge shape below the eye that is well developed.
Habitat and habits
Iowa darters prefer cool, clear water over a sand or organic matter substrate. Iowa darters lack a swim bladder and because of this, the Iowa darter sinks to the stream or lake bottom. To move around, it makes short dashes of astonishing speed (hence the name), often faster than the human eye can follow. The darter can zip along stream and lake substrate looking for food using less energy than other fish, which would keep floating up off the bottom.Diet
The Iowa darter eats copepodsCopepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
, water fleas
Cladocera
Cladocera is an order of small crustaceans commonly called water fleas. Around 620 species have been recognised so far, with many more undescribed. They are ubiquitous in inland aquatic habitats, but rare in the oceans. Most are long, with a down-turned head, and a carapace covering the apparently...
, and midge
Midge
A midge is a very small, two-winged flying insect. "Midge" may also refer to:-Real:* Midge Costanza , American politician* Mildred Gillars , aka "Midge", American broadcaster of Nazi propaganda during World War II...
and mayfly
Mayfly
Mayflies are insects which belong to the Order Ephemeroptera . They have been placed into an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies...
larvae it finds in underwater vegetation. The Iowa darter has never been found in the stomach of any fish-eating animal because they are too quick to catch.
Conservation status
Iowa darters are considered vulnerable due to decreasing abundance and distribution. They appear to be decreasing in distribution over the last decade and the limiting factorLimiting factor
A limiting factor or limiting resource is a factor that controls a process, such as organism growth or species population, size, or distribution. The availability of food, predation pressure, or availability of shelter are examples of factors that could be limiting for an organism...
seems to be their habitat. This may be due to increasing turbidity
Turbidity
Turbidity is the cloudiness or haziness of a fluid caused by individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality....
limiting their preferred habitat.
Reproduction
Iowa darters spawnSpawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
mainly in the spring. Found that Iowa darters migrated from deeper regions of lakes and streams to the shallow vegetated reaches for spawning. Males typically migrated before females. Male Iowa darters maintained and defended small territories near undercut banks with rooted vegetation. Smaller males, however, were promiscuous
Promiscuity
In humans, promiscuity refers to less discriminating casual sex with many sexual partners. The term carries a moral or religious judgement and is viewed in the context of the mainstream social ideal for sexual activity to take place within exclusive committed relationships...
, did not defend territories, and were mobile, moving from place to place in search of females. When a female entered a male's territory, the male courted the female by swimming around her until she positioned herself near algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
or rooted vegetation. The male mounted the female and positioned himself with his pelvic fins in front of her dorsal fin. The anal and caudal fins of the male were placed on the same side of the female. Most spawning occurred at depths of 10-40 cm on fibrous roots beneath slightly undercut banks, although some eggs were laid directly on sand or on roots or other plant materials on sand. During each spawning act three to seven eggs were deposited. Following the completion of spawning, the eggs received some protection in that by continuing to maintain his territory, the male indirectly guarded the eggs. Females mated with several males, then returned to deeper habitats following spawning.
Life cycle
The spawned eggs of the Iowa darter average around a 1.1 mm diameter. The developmental time of Iowa darter eggs is around 18-26 days at 13-16°C and the newly hatched darters are around 3.4 mm SL. The hatching size are around 3.6 mm TL and most major structural features, including the pectoral fin, first dorsal fin, second dorsal fin, and the branchiostegal rays were formed when the larvaeLarva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
were between 7.7 and 9.1 mm TL. Much of the lateral line sensory system was formed when the larvae reached approximately 20 mm TL.
Etymology
The genus name, Etheostoma, is a GreekGreek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
word with etheo meaning strain or filter and stoma meaning mouth. The species name, exile, is also Greek and stands for slim or slender.