Calico cats and tortoiseshell cats, or torties, are often confused; to the untrained eye, they can be difficult to tell apart. Both terms refer to coat colors and patterns -- and have nothing to do with the cat's breed. Domestic shorthair and longhair cats, including several purebred cats, can be calico or tortoiseshell.
Tortoiseshell cats have patches of primarily black and orange fur -- and the orange gene can take on shades of brown, cream, ginger, amber, red and cinnamon. These patches can be in fine speckled patterns, bolder mottled designs or large areas of solid color. A dilute tortie has blue and cream fur instead of black and orange, and a torbie is a patched tabby, or one with brown tabby patterns instead of black fur.
Calico cats are also called tricolor or tortie-and-white. This is because the calico cat has the same black and orange colors as the tortoiseshell, plus white. Even a cat with mottled tortoiseshell patches is considered a calico if she has significant amounts of white in her coloring. A dilute calico has blue patches instead of black, and cream instead of orange.
Tortie and calico cats are nearly always female. About one in 3,000 calicos is male, and is usually infertile -- in fact, only 1 in 10,000 tricolor males is fertile. This is because the O gene that carries the red or orange coloration is carried only in the X chromosome, and males have XY chromosomes. So a male cat with the O gene often ends up an orange tabby. Females get two X chromosomes, and a female with two O genes will also be orange, which is relatively rare. However, an orange gene and a non-orange gene on X chromosomes creates a calico or tortie cat.
What a Tortitude
Tortie and tortie-and-white cats have a unique attitude that cat lovers dub "tortitude." Tortitude manifests as a strong-willed, feisty, possessive and very vocal cat. "Cats like torties, calicos and orange tabbies tend to have a much more distinct personality," cat behaviorist Jackson Galaxy, star of Animal Planet's "My Cat From Hell", told Catster. But he says he tries not to prejudge cats based on his past experiences with tortitude. Next time you interact with a tortie or calico cat, see if you notice this type of personality trait.