A cheetah and a rare king cheetah with darker spots and lines running down her back. King cheetahs are the product of a recessive gene that causes a rare fur pattern mutation. - photo by Alison Lee Rubie, via save.big.cats, on Instagram; These are mother and daughter from Taronga Western Plains Zoo. The mother is the King cheetah. Original photo at https://www.facebook.com/alisonleerubiephotography/photos/a.1110152629004022.1073741828.1110150429004242/1110757402276878/?type=3&theater
The silver fox is a melanistic form of red fox. Melanism is when the animal's coloring is much darker than normal. Interestingly, fox squirrels, who have brownish body fur and reddish tummy fur also have a melanistic form that resembles this. I had a "black" fox squirrel that I hand raised. He lived to be 12 years old, a full ten years longer than he would have in the wild.
18 Rare Cat Breeds From Around The World You've Never Heard Of