Twisted Sisters: Amazing Tortoiseshell Cats & Kittens

Blessed with beautifully mottled black & orange coats and a personality so pronounced it’s acquired a distinct name, Tortoiseshell Cats are rapidly emerging as one of the most popular cats around. Have you got the fortitude to own a cat with “tortitude”?

Swirled Famous

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You may have seen them in your neighborhood, at a pet store, on cat-themed calendars or even on TV: sweetly serene cats whose coats reflect a swirling whirlpool of black, gold and orange. They’re Tortoiseshell Cats and if you think you’ve seen them more often lately, you’re not imagining it – the more people see so-called “Torties”, the more they want one of their very own.

(images via: Science Photo Library, Science Notes and Volker’s Blurb)

While cats can have fur of almost any earth-tone color from black to white expressed in any number of patterns, true Tortoiseshell Cats are restricted to a mix dominated by black and orange. The name derives from actual tortoiseshell, a natural material made from polished shells of the endangered Hawksbill or Loggerhead sea turtle. Though processing and purchasing items made from tortoiseshell is at least frowned-upon, at most illegal, owning a Tortoiseshell Cat is completely guilt-free.

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Their coats may exhibit undertones of rust, cinnamon and even red and the pattern may be expressed in patches, stripes, swirls or an overall brindle effect that seems to shimmer as the cat stretches, walks and runs.

(images via: Inspiration Line, Animal Photography and PBase/Louise Simard)

Tortoiseshell Cats have been confused with exotic cat breeds such as Bengal Cats by virtue of their mottled coloring and “jungle-like” patterned coats. In addition, the oft-fearless and pugnacious attitude expressed by many Tortoiseshell Cats leads some onlookers to believe the “breed” is wilder than the average domestic cat.

Ladies Only?

(images via: Pet Care Tips and

Tortoiseshell Cats and their kissin’ cousins, Calico Cats, are not formal breeds like Persians (above), Manx or American Shorthair cats. Indeed, almost any breed of cat can be a Tortoiseshell Cat, a factor that contributes even further to the exceptional variety encompassed by the type.

(image via: Associated Newspapers Ltd.)

Even more unusual is the fact that the vast majority of Tortoiseshell Cats are female. Male Torties exist but they’re an exception to the rule and their appearance is a result of different genetic factors coming into play. Britain’s Rarest Cat, shown above, is very rare indeed: a 1 in 400,000 shot! Non-mutational male Tortoiseshell Cats, if we can use such a term, are either all black or are ginger Tabby cats.

(images via: and Great Pictures of Cats)

Speaking of genetics, let’s get the chalkboard out and go over the X’s and Y’s. The cells of female cats have two X-chromosomes while those of males are XY. The co-dominant gene for orange fur color only appears on the X-chromosome and is itself comprised of the alleles (genes or group of genes) for Orange and not-Orange – the former turns on orange pigment production while the latter expresses black pigment.

(images via: Sodahead, BBC and Olegvolk)

Early in the development of a female cat embryo, the cat’s cells undergo a process of “X-inactivation” via which one of the X-chromosomes is turned off. The remaining chromosome may carry either the Orange or not-Orange allele. Since the X-inactivation process works randomly and pigment cells migrate to the embryo’s skin at an early stage of development, the cells are intermingled and the characteristic brindled pattern emerges with the growth of fur.


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