Darters are adapted for life in the swift-flowing sections of clear, rocky streams. To keep them from being swept downstream, the gas-filled swim bladder found in most fishes is absent or much reduced in darters. They sink immediately to the bottom when they stop swimming, and the press of the current against their enlarged pectoral fins tends to hold them in place.
Darters remain much of the time beneath or between rocks and are afforded some measure of protection from the direct action of the current.
When moving from place to place, darters proceed by a series of short, quick dashes, and it is this characteristic form of locomotion that has earned them the name “darter.”
Not all darters are found in swift currents. The sand darters (Ammocrypta spp.) inhabit the sandy stretches of sluggish streams. Here they hide much of the time beneath the sand with only their eyes showing. The least darter and its close relative the cypress darter live in quiet pools, where they clamber about over the leaves and stems of submerged plants.
In Ozark streams, darters, along with minnows, are the dominant groups of small fishes. The geographic separation of the various stream systems has led to a great variety of uniquely different species. The common and widespread darters in the Ozarks are the greenside, rainbow, fantail, stippled, orangethroat, and banded darters, and the logperch. The yoke darter is abundant in the White River basin. The bluestripe, Niangua, and Missouri saddled darters are unique to the Ozarks of Missouri.
In the Mississippi Lowlands of Missouri’s Bootheel, darters are well represented but have fewer overall numbers than in the Ozarks. The principal darters in Missouri’s southeastern lowlands are western and scaly sand darters, and the bluntnose, slough, cypress, speckled, blackside, and dusky darters.
In the prairie (dissected till plains) region in the northern half of Missouri, darters are not very diverse. The johnny darter is the only species that is widespread. The logperch and the fantail, orangethroat, and slenderhead darters are common in some streams.
Four species of darters — the logperch, and the slenderhead, river, and western sand darters — are fairly common in the Mississippi River but are rare in the Missouri.