Northern water snake (Nerodia sipedon) with crusty and thickened scales overlaying raised blisters as a result of a fungal skin infection.

Northern water snake (Nerodia sipedon) with crusty and thickened scales overlaying raised blisters as a result of a fungal skin infection.

Northern water snake (Nerodia sipedon) with crusty and thickened scales overlaying raised blisters as a result of a fungal skin infection.
Northern water snake (Nerodia sipedon) with crusty and thickened scales overlaying raised blisters as a result of a fungal skin infection.
Photograph by D.E. Green, USGS National Wildlife Health Center