Tortoiseshell and calico cats have a great deal in common. They both have the genes that create the distinctive tortoiseshell coat pattern with blotches of red fur mingled with black.
Where calico and tortoiseshell cats differ, is that calico cats have an additional gene we call the spotting gene. And the spotting gene breaks up the tortoiseshell pattern and intersperses it with patches of white fur. In some parts of the world calicos are referred to as tri-colored cats.
Tortoiseshell Vs Calico similarities
Coat color genes in animals are fascinating. And the tortoiseshell and calico patterns have some unusual features.
Calico cats and tortoiseshells, also known as torties, are usually female. And the rare males that do occur are usually infertile.
This is because the genes that causes the tortoiseshell and calico patterns are carried on the x chromosome. Females have two x chromosomes but males have only one, and so rarely have the pairs of tortoiseshell genes required for the pattern to be expressed.
How The Tortoiseshell Vs Calico Pattern Is Created
There are specific genes for the base colors of your cat’s fur. Then there are genes that determine whether that base color is solid, or broken up with white patches. And other genes that decide how those colors are arranged.
Like most mammals, cats actually have only two basic pigments for their genes to work with, black and red. Yet the different combinations of genes a cat inherits are responsible for a myriad of different color effects and patterns.
In some types of fur the black and red colors are distributed together along each hair shaft in bands. But in a tortoiseshell or calico, the colors are distributed in little blocks or patches of either one color or the other.
How The Spotting Gene Works
The spotting genes found in the tri-colored calico cat ensures that the main coat pattern or color is broken up with white patches. And it is these genes that separate the calico cat from the tortoiseshell.
The spotting gene cleverly slows down the movement of pigment and the rate at which it does this varies depending on the combination of genes inherited by the cat. This is why calico cats vary in the amount of white fur that is generated.
Dilute Vs Dense
Genes also decide whether or not a cat’s colors are expressed at maximum intensity like a full saturation color photo, or ‘washed out’ to a paler version in the dilute tortie, by the dilute gene.
Torties and calicos are no exception and come in both dilute and full color varieties. In dilutes, black fur become a blue grey, chocolate becomes lilac, and red fur becomes fawn or cream
Calico Vs Tortie Types
The tortoiseshell coat variation is not breed specific. A tortie is a cat with a very specific coat, but it isn’t a specific breed.
There are a number of different pedigree cat breeds, the American Shorthair for example, where the tortoiseshell variety (with or without white patches) is recognized. And other breeds, such as the Burmese, where it is not.
There are also different types of tortoiseshell in that some torties have tabby markings in their black patches of fur. These cats are sometimes referred to as torbies. And calico cats can also have torby patches in their fur
Tortoiseshell Vs Calico Cat Personality
Many tortoiseshell and calico cat owners are convinced that torties and calicos have higher levels of aggression and general feistiness than cats with different coat patterns. There is even a term ‘tortitude’ to describe this trait!
And while not all the available research supports their view, some serious studies have come to the same conclusion.
The reason that there can sometimes be a link between a cat’s temperament or health and its appearance is to do with the way that genes are passed on. Genes that are located close together on a chromosome are more likely to be passed on together. We often refer to these ‘appearance’ genes as markers. And one of those markers is white fur, so we’ll look at that next.
Tortie Vs Calico Health
There do not seem to be any particular health issues associated with tortoiseshell fur. But you may be aware that there is a link between white fur and deafness.
Deafness is more common in white cats and dogs than in colored ones. And around 70% of pure white cats are deaf. And in dogs we tend to see deafness associated with white patches over their ears.
However, there does not seem to be any evidence for deafness associated with the white spotting gene in cats. So hopefully, your calico cat will have just as good hearing as their tortoiseshell relatives.
Are Calicos and Torties Rare?
As only females can express these two beautiful coat variations, there are fewer calico and tortoiseshell cats than cats with other coat variations.
So while they are not truly rare, they are certainly less common than tabby cats or black and white cats, for example.
The dilute versions are even more unusual as the dilute gene is recessive and requires copies from both parents in order for the dilution to be expressed.
Tortoiseshell and Calico Origins
These pretty cats can be found all over the world, and no-one really knows where they came from.
What we do know is that the original wild cats from which our pets descend all carried the genes necessary to express the huge range of colors we see in our cats today.
These colors start to appear when we domesticate wild mammals, and they no longer need the protection of a camouflaged coat.
Wherever they came from, tortoiseshells and calicos are here to stay, and to be loved and much admired by their human friends.