There are three known genera of darters: Percina, which contains about 40 species: Etheostoma, which contains about 112 species, and Ammocrypta, which contains 7 species. The genus Percina contains the largest darters. Most are rather dull and cryptic in colouration, although the males of some species show impressive colouration during spawning. The genus Etheostoma is diverse in shape and colouration. The bodies and fins of many of these darters are coloured in shades of red, blue, yellow, green and orange with black spots. Members of the genus Ammocrypta are dull and sandy in colour. This camouflages them from predators in the large rivers with sandy bottoms where they live. Darters can reach up to 12 inches in length (Percina lenticula), although most are only a few inches long, even as adults. The smallest is the fountain darter (Etheostoma fonticola), which grows to just 11 × 2 inches as an adult. The darter has two dorsal fins, the anterior with hard spines and the posterior with soft rays. The tail fin is usually rounded or convex. Many darters are sexually dimorphic, with males usually being larger and more brightly coloured. Males also develop thickened body tissues, fleshy tubercles on the dorsal fin rays and spines, and nest tubercles during spawning. The spectacular appearance of the males during spawning is thought to attract females and explains the great interest in fishing for this group.
Darters are found from northern Mexico to Canada and from the eastern coastal plains west to the continental divide. Only one species, the Mexican darter (Etheostoma pottsi), occurs west of the continental divide in northern Mexico. Darters are most diverse in the southern Appalachians of Tennessee and Virginia and on the Ozark Plateau of northern Arkansas. The johnny darter (Etheostoma nigrum) is the most common, followed by the orangethroat darter (Etheostoma spectabile) and possibly the logperch darter (Percina caprodes).
Darters are found in all types of freshwater habitats. They can inhabit small streams, large rivers, spring reservoirs, ponds, lakes or reservoirs. They are most commonly found in fast moving water.
Life history and Behavior
As a group, darters are well adapted to life in swift water and at the bottom of streams. Their rounded bodies and slightly flattened heads are particularly hydrodynamic. In addition, most members of the group have no or poorly developed swim bladders. They use their enlarged pectoral fins to land on rocks, allowing them to stay on the bottom of the stream, out of the current. Their body shape matches the unique swimming style for which the group as a whole is named. Darters do not swim like most fish. They jump from place to place in short jumps or 'darts'. Darters show great variability in their reproductive strategies. Most produce few, relatively large eggs and provide some parental care. Most members of the genus Etheostoma spawn in burrows, laying sticky eggs on the underside of medium-sized rocks, usually in swift water. Males of this genus are often brightly coloured to attract females to the nesting sites they have prepared. Members of the genera Percina and Ammocrypta breed in a simpler way. Two or more individuals gather in areas of swift water on the sand between larger stones. The males and females line up their bodies side by side, then simultaneously release sperm and eggs into the substrate and bury them. This protects the eggs from predators and flooding. Most throwers spawn in spring and early summer. Some species are thought to spawn several times a year. Throwers are not a long-lived group. Most species live less than 5 years. Sexual maturity is usually reached between 1 and 3 years of age.
Food and feeding habits
Darters feed mainly on benthic organisms, small insects, worms and snails. As a group, however, they display a diversity of feeding strategies that is consistent with morphological differences. Larger darters feed on insects on rocks or fork them out of sand and gravel. Shorter and more flexible darters often feed on clinging insects between and under rocks. As a result of these different feeding strategies, several species of darter can coexist in the same area of a stream.
|Conservation status||Least Concern|
|Life span, years||5|
|Maximum body weight, kg||0.002|
|Maximum length, cm||7.2|
|Sailing speed, m/s||No information|
|Threat to people||No information|
|Way of eating||Bentophage|
Darters: Johnny Darter
Tags: Darters: Johnny Darter