2. Adaptation of an animal

This is a picture of a Rainbow Darter (Etheostoma caeruleum). The Rainbow darter is an example of an adaptation of an animal. An adaptation is where a trait is modified to better suit an animal or plant's living conditions. Percid fish typically have a swim bladder to help them maintain their position in the water column. The Rainbow Darter, though a percid, has done away with its swim bladder so that it can live in riffles.