The North American channel catfish is an ostariophysan, or a bony fish occupying a freshwater habitat. These fishes are known to produce club cells and alarm substances for communication purposes. Both the fish's habitat and the presence of chemosensory cells covering the body are presumably the results of favored selection for this method of communication. Catfishes are capable of producing and recognizing individual specific pheromones. Through these pheromones, a catfish can identify not only the species and sex of a conspecific, but also its age, size, reproductive state, or hierarchical social status.