A male and female sockeye salmon spawning in the Adams River of British Columbia Canada in October, 2014. This is an example of the physical and colour changes the fish undergo while spawning. They turn from a silver grey to bright red bodies with yellow green heads. The mouth area turns towards black. In an example of sexual dimorphism, the males grow a large hooked beak and hump in the middle of their back. The females outward appearance changes little aside from the colouration.