Tortoise shell (or "torties") are cats with a mixed black
and red fur with some times some white. Some are called "dilute" when the
black and red are replaced by "blue" (light grey) and beige.
Calicos are cats whose fur shows large patches of these three colors.
Tortoise shell color is due to the inactivation of
one of the two X chromosomes in a given region. Hence, you can't have
male tortoise shell cat as he has only one X chromosome. Nevertheless,
one case allows "male" torties is hermaphrodism (XXY). As these cats
bear 3 chromosomes among which are 2 Xs, he can have a tortie fur. This
case is extremely rare and these cats are sterile.
What difference is the between a tortie and a calico ?
The calico cat owns the "tortoise shell" genotype AND an additional
genetic determiner producing white patches .
Against common thoughts, the placement of the patches or colors
doesn't change in time. They will stay in the same place during all the
life of the cat.
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