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Johnny darters are eaten by larger, predatory fish, including lake trout, lake whitefish, burbot, smallmouth bass, yellow perch, and others. Because of their shallow water habits, they are also likely prey of wading and diving birds, such as herons, and water snakes. Johnny darters are cryptically colored.
Known Predators:
Anti-predator Adaptations: cryptic
Johnny darters are small, slender fish with brown to yellow ctenoid scales, paler sides, and whitish bellies. The backs and sides are marked with darker "saddle marks" and the sides have distinctive "W" shaped brown spots along the lateral line. There is a dark stripe that extends from the mouth to the eye, the dorsal fins are marked with brown spots, the tail fin has brown stripes, and the pectoral and anal fins are clear. The first dorsal fin has 7 to 9 spines and the second dorsal find has 11 to 14 rays. Males become dusky to black on the head, upper body, and dorsal fins during the breeding season. The ventral portion of the pectoral fins and pelvic rays develop whitish, knobby tips. The average length is 51 mm and the largest recorded individual was 77 mm.
Range length: 77 (high) mm.
Average length: 51 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes colored or patterned differently
Johnny darters live for up to 3 years.
Typical lifespan
Status: wild: 3 (high) years.
Johnny darters are found in shallow water in small to medium sized rivers, creeks, streams, and headwaters. They are found in areas with sandy, muddy, or rocky substrates, but are more common over sandy or gravel substrates in slow-moving water. They are also found along the sandy shores of lakes or large rivers. Johnny darters are generally found in benthic parts of aquatic habitats, at depths of less than 0.5 m, although they have been captured in water as deep as 64 m. Johnny darters are considered pioneer species because they can quickly move in and become established in disturbed habitats.
Range depth: 64 (high) m.
Average depth: 0.5 m.
Habitat Regions: temperate ; freshwater
Aquatic Biomes: benthic ; lakes and ponds; rivers and streams
Johnny darters are found throughout eastern North America, from Wyoming, Colorado, the Dakotas, and Saskatchewan east to the Atlantic seaboard as far south as North Carolina. They are also found south into Alabama and Mississippi. Populations in the Rocky Mountains of Wyoming and Colorado and the Ozark Mountains of Arkansas and Oklahoma are disjunct from other populations. They have been introduced to parts of Utah.
Biogeographic Regions: nearctic (Introduced , Native )
Johnny darters feed on small insect larvae and crustaceans as both adults and young. Young feed on much smaller prey, such as tiny midge larvae and ostracods. Adults eat midge larvae, mayfly nymphs, caddisfly larvae, blackfly larvae, and small crustaceans, such as Hyalella, Cyclops, and Daphnia.
Animal Foods: insects; aquatic crustaceans
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods)
Johnny darters are important members of native aquatic ecosystems, they are important predators of small invertebrates and are prey for larger predatory fish, including game fish, and wading and diving birds.
Johnny darters are important members of native aquatic ecosystems and are some of the first fish to colonize disturbed aquatic habitats. They are important prey for larger game fish.
Johnny darters use their large eyes and keen vision to find prey. They don't respond strongly to olfactory cues. Tactile and visual signals are used in mating communication. They have a complete lateral line.
Communication Channels: visual ; tactile
Perception Channels: visual ; tactile ; vibrations ; chemical
Johnny darters are not considered threatened throughout most of their range. They are considered vulnerable or imperiled in some states, including Arkansas, Kentucky, Oklahoma, Kansas, and Nebraska. Johnny darters are tolerant of high levels of silt and some pollution and are able to colonize disturbed aquatic habitats readily.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Johnny darters spawn in waters from 11.7 to 21.1 degrees Celsius. Temperature influences length of development to hatching, with eggs laid in April (12.8 degrees Celsius) hatching at 16 days and eggs laid in May (20 degrees Celsius) hatching at 10 days. Larvae are 5 mm long at hatching and generally grow to 29 to 54 mm by September.
There are no negative effects of Johnny darters on humans.
Johnny darter males migrate to spawning areas before females and establish small nesting territories in protected, shallow waters. Males select a stationary object of at least 25 cm in diameter, such as a log, rock, or even trash under which spawning occurs. Males compete for nesting territories, with a side-by-side display that helps them to establish dominance. Once one is established as dominant, it drives the other male away. Male Johnny darters aggressively defend their nests, even against fish up to 3 times their size. They attack by butting the threat with their head and biting at the fins of an intruding fish. Johnny darters clean the underside of the chosen spawning object with their anal, pectoral, and tail fins. They also enlarge the nest with movements of their body. Males rarely leave their territory during the day, but territories are not defended at night. Males first swim aggressively towards females that approach their nest, but then begin to swim upside down under their spawning object, which attracts the female. The female swims upside down under the spawning object, alongside the male, who then prods her sides. This stimulates the female to move along the object and deposit eggs. Females place one egg at a time on the object, eventually creating a small, single layer patch of eggs up to 13 cm in diameter. Females mate with 4 to 6 males and males typically mate with more than 1 female.
Mating System: polygynandrous (promiscuous)
Females lay from 30 to 200 eggs at each spawning event, which they will do several times in the nests of different males. Male nests have been recorded with between 30 and 1150 eggs in them. Smaller females have been recorded with from 48 to 299 eggs and larger females with from 86 to 691 eggs. Johnny darters can breed in their first year after hatching.
Breeding interval: Johnny darters breed once yearly.
Breeding season: Spawning occurs in the spring, usually in April or May.
Range number of offspring: 48 to 691.
Range gestation period: 10 to 16 days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
Johnny darter eggs are attached to the underside of rocks and guarded by males until they hatch. Males rub the eggs with their fins to clean them from 13 to 16 times an hour. They also fan the eggs with their pectoral fins. When an eggs becomes covered with fungus, the male will eat it. Males aggressively defend their eggs against fish that might want to eat them.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male)
Etheostoma nigrum és una espècie de peix de la família dels pèrcids i de l'ordre dels perciformes.
Els mascles poden assolir els 7,2 cm de longitud total.[2]
Es troba a Nord-amèrica.[2]
Rhywogaeth o wibiwr yw'r gwibiwr du[1] (Etheostoma nigrum) sy'n byw yn nyfroedd dwyrain Gogledd America.
Rhywogaeth o wibiwr yw'r gwibiwr du (Etheostoma nigrum) sy'n byw yn nyfroedd dwyrain Gogledd America.
The johnny darter (Etheostoma nigrum) is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is native to shallow waters throughout North America east of the Rocky Mountains.
The johnny darter's Latin name comes from the Greek root words etheo, meaning to filter, stoma, meaning mouth, and nigrum, meaning black.[2]
The johnny darter is found from Saskatchewan and Colorado to the Atlantic seaboard and from Hudson Bay south to the Gulf Coast drainage systems.[3] They are the most common darter in Minnesota[2] and Ohio.[4]
The johnny darter can reach a length of 7.2 centimetres (2.8 in) TL though most only reach about 3.9 centimetres (1.5 in).[3] Males weigh a little over 2.0 grams, and the females weigh about 1.6 grams.[2] These small, slender fish have brown to yellow scales, paler sides, and whitish bellies.[5] They have no bright colors and generally just have brown or black markings on a lighter tan background. These markings are usually a series of black "w" or "x" shapes along their sides running along their lateral lines.[4] On the fish, the opercles (or bony areas forming the gill covers) have scales, whereas the preopercles (bone at the start of the cheek), napes, and breasts are scaleless. The johnny darter has two dorsal fins, the first has hard (spinous) rays, while the second is soft-rayed (flexible). The pectoral and pelvic fins are close to each other behind the gills. The pectorals are large and fan-like and are situated on the lower sides of the fish. The pelvic fins are small and round and situated in the ventral side of the fish.[6] They have a rounded tail fin on the ventral side, as well.
Johnny darters prefer clear water with sandy and gravelly bottoms. They like slow-moving water, but can be found in moderately cloudy, moving water, as well.[2] They are bottom dwellers and stay on rocks at the bottoms of small ponds and streams with their heads facing into the current.[4] Of all the darter species, the johnny darter is the most tolerant of diverse conditions.[7] Since this darter is a benthic,[5] its mouth is a subterminal where the nose is only slightly beyond the mouth and is situated in an inferior position that makes it easy for it to eat and catch food. Its diet is varied, but as young fish, it tends to eat copepods, small crustaceans, and waterfleas. As it grows, the fish start eating larger waterfleas, different types of larvae, including midges, mayflies, and caddisflies, and the occasional sideswimmer.[2] These darters are generally eaten by larger predatory fish, such as burbots, lake trout, smallmouth bass, walleyes, and yellow perch.[2]
The spawning season is May and most of June, when the water temperatures are between 12 and 24 °C. Males arrive first to establish territories throughout the pond, lake, or stream. Spawning occurs in the shallow water, pools and slow runs, with large rocks, logs, cans, shells, or other debris. When a female approaches the nest, the male darts at her and chases her out of the territory. However, when she approaches the nest upside down and tries to enter, the male will accept her. They then both turn upside down and the female will lay between 30 and 200 eggs on the underside of the debris. Johnny darters are not monogamous and the female and male will spawn with other fish. A single nest may hold up to 1000 developing eggs. The male will guard the nest and keep them oxygenated and will eat the ones that develop fungus until the embryos hatch, which is after about six to 10 days.[5]
These fish are not considered threatened throughout most of their range. They are considered vulnerable only in Arkansas, Kentucky, Oklahoma, Kansas, and Nebraska.[5] In Minnesota, they have no special conservation status, but are protected by state law.[2]
The johnny darter (Etheostoma nigrum) is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is native to shallow waters throughout North America east of the Rocky Mountains.
Etheostoma nigrum es una especie de peces de la familia Percidae en el orden de los Perciformes.
Los machos pueden llegar alcanzar los 7,2 cm de longitud total.[1]
Se encuentran en Norteamérica.
Etheostoma nigrum Etheostoma generoko animalia da. Arrainen barruko Percidae familian sailkatzen da.
Etheostoma nigrum Etheostoma generoko animalia da. Arrainen barruko Percidae familian sailkatzen da.
Etheostoma nigrum is een straalvinnige vissensoort uit de familie van de echte baarzen (Percidae).[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1820 door Rafinesque.
Bronnen, noten en/of referenties
黑鏢鱸為輻鰭魚綱鱸形目鱸亞目河鱸科的其中一種，分布於加拿大、美國聖羅倫斯河、五大湖、密西西比河等流域，體長可達7.2公分，棲息在沙泥底質的水塘、溪流，屬肉食性，以水生昆蟲為食，雄魚具有護卵的行為。
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