Epidermal club cells are not linked with an alarm response in reedfish, Erpetoichthys (= Calamoichthys) calabaricus

Publisher Website
Google Scholar
Abstract
Club cells in the epidermis of reedfish, Erpetoichthys (= Calamoichthys) calabaricus (Pisces, Polypteriformes), are morphologically similar, perhaps homologous, to the "alarm substance cells" found in the skin of cypriniform fishes. Cypriniforms perform a fright reaction when they detect chemicals released from the damaged alarm substance cells of conspecifics. We examined the response of reedfish to conspecific skin extract and checked for a cross reaction to reedfish extract by a cypriniform fish, the zebra danio, Brachydanio rerio. Reedfish responded to conspecific skin extract with an increase in activity but this response did not resemble a fright reaction. Zebra danios responded to reedfish extract with a feeding response. We conclude that reedfish do not show a fright reaction to the skin extract of conspecifics. This suggests that if cypriniform alarm substance cells are homologous to reedfish club cells, their alarm pheromone function is a secondary adaptation.