Tortoiseshell cat

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Two-color coat coloring in cats

title: "Tortoiseshell cat" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["cat-coat-types"] description: "Two-color coat coloring in cats" topic_path: "general/cat-coat-types" source: "https://en.wikipedia.org/wiki/Tortoiseshell_cat" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Two-color coat coloring in cats ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/c/c5/Short-haired_tortoiseshell_cat.jpg" caption="A short-haired black tortoiseshell cat"] ::

Tortoiseshell is a cat coat coloring named for its similarity to tortoiseshell pattern. Like tortoiseshell-and-white or calico cats, tortoiseshell cats are almost exclusively female. Male tortoiseshells are rare and are usually sterile.

Tortoiseshell cats, or torties, combine two colors other than white, either closely mixed or in larger patches.

"Tortoiseshell" is typically reserved for multicolored cats with relatively small or no white markings. Those that are predominantly white with tortoiseshell patches are described as tricolor, tortoiseshell-and-white, or calico.

Tortoiseshell markings appear in many different breeds, as well as in non-purebred domestic cats. and exists in the Cornish Rex group.

Patterns

::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/8e/Dilute_tortoiseshell_feline.jpg" caption="Cat with a blue ("dilute") tortoiseshell coat"] ::

Tortoiseshell cats have particolored coats with patches of various shades of orange, red, grey, and black, and sometimes white. The size of the patches can vary from a fine speckled pattern to large areas of color. Typically, the more white a cat has, the more solid the patches of color are. Dilution genes may modify the coloring, lightening the fur to a mix of cream and blue, lilac or fawn; the markings on tortoiseshell cats are usually asymmetrical.

Occasionally tabby patterns of black and brown (eumelanistic) and red (phaeomelanistic) colors are also seen. These patched tabbies are often called a tortie-tabby, a torbie or, with large white areas, a caliby. Tortoiseshell coloring can also be expressed in the point pattern, referred to as a tortie point.

Genetics

Main article: Cat coat genetics

Leonard Doncaster was the first to prove that tortoiseshell is the female heterozygote of orange and black, the corresponding male being orange. In the course of his studies he discovered that the rare tortoiseshell male is often sterile.

Tortoiseshell and calico coats result from an interaction between genetic and developmental factors. The primary gene for coat color (B), for the colors brown, chocolate, cinnamon, etc., can be masked by the co-dominant gene for the orange color (O), which is on the X chromosome and has two alleles: orange (XO) and not-orange (Xo) that produce orange phaeomelanin and black eumelanin pigments, respectively. Typically, the alleles are notated as an uppercase O for orange, or a lowercase o for not-orange. Tortoiseshell and calico cats are labeled XOXo, indicating O-gene heterozygosity. The (B) and (O) genes can be further modified by a recessive dilute gene (dd) which softens the colors. Orange becomes cream, black becomes gray, etc. Various terms are used for specific colors, for example, gray is also called blue, orange is also called ginger. Therefore, a tortoiseshell cat may be a chocolate tortoiseshell or a blue/cream tortoiseshell or the like, based on the alleles for the (B) and (D) genes.

Female cats are homogametic (XX) and undergo the phenomenon of X-inactivation, in which one of the X chromosomes is turned off at random in each cell in very early embryonic development. The inactivated X becomes a Barr body. Cells in which the chromosome carrying the orange (O) allele is inactivated express the alternative non-orange (o) allele, determined by the (B) gene. Cells in which the non-orange (o) allele is inactivated express the orange (O) allele. Pigment genes are expressed in melanocytes that migrate to the skin surface later in development. In bi-colored tortoiseshell cats, the melanocytes arrive relatively early, and the two cell types become intermingled; this produces the characteristic brindled appearance consisting of an intimate mixture of orange and black cells, with occasional small diffuse spots of orange and black.

In tri-colored calico cats, a separate gene interacts developmentally with the coat color gene. This spotting gene produces white, unpigmented patches by delaying the migration of the melanocytes to the skin surface. There are a number of alleles of this gene that produce greater or lesser delays. The amount of white is artificially divided into mitted, bicolor, harlequin, and van, going from almost no white to almost completely white. In the extreme case, no melanocytes make it to the skin and the cat is entirely white (but not an albino). In intermediate cases, melanocyte migration is slowed, so that the pigment cells arrive late in development and have less time to intermingle. Observation of tri-color cats will show that, with a little white color, the orange and black patches become more defined, and with still more white, the patches become completely distinct. Each patch represents a clone of cells derived from one original cell in the early embryo.

Male cats, like males of other therian mammals, are heterogametic (XY). The single X chromosome does not undergo X-inactivation, ergo coat color is determined by which O-gene allele is present. Accordingly, the cat's coat will be either entirely orange or melanistic (respectively XOY or XoY). Very rarely (approximately 1 in 3,000) a male tortoiseshell or calico is born; these typically have an extra X chromosome (XXY), a condition known in humans as Klinefelter syndrome, and their cells undergo an X-inactivation process like in females. As in humans, these cats often are sterile because of the imbalance in sex chromosomes. Some male calico or tortoiseshell cats may be chimeras, which result from fusion in early development of two (fraternal twin) embryos with different color genotypes; these torties can pass only one color to their offspring, not both, according to which of the two original embryos its testes are descended from. Others are mosaics, in which the XXY condition arises after conception and the cat is a mixture of cells with different numbers of X chromosomes.

Gallery

File:Tortoiseshellshorthair (2013 photo; cropped 2022).JPG|Black tortoiseshell ("tortie") short-haired cat File:Blu-tortie-point-masch.jpg|Blue tortoiseshell Birman cat File:British shorthair with calico coat (2).jpg|Black tortoiseshell-and-white tricolor ("calico") cat File:Stray calico cat near Sagami River-01.jpg|Black tortoiseshell tabby-and-white tricolor ("caliby") cat File:Tortie-point.jpg|Black colourpoint tortoiseshell ("tortie point") cat File:A tortoiseshell cat's speckled paw-pads.jpg|Black and red mottling on the paw-pads of a tortoiseshell cat File:White colour progression in Tri-colour calico cat.jpg|An extreme case of slow melanocyte migration from the skin and fur of a tri-color calico cat File:BabyRagdoll2.jpg|A 16-year-old female tortoiseshell Ragdoll cat. While tortoiseshell Ragdolls are actually colourpoint tortoiseshell-and-white (calico) in color, the nomenclature is different in this breed's descriptions of colors and patterns. File:Chat EcailleTortue Calico Angora.jpg|Long-haired tortoiseshell calico cat

Folklore

In the folklore of several cultures, cats with tortoiseshell coloration are believed to bring good luck. In Ireland, tortoiseshell cats are considered to bring good luck to their owners. In the United States, tortoiseshells are sometimes referred to as money cats. In Japan, tortoiseshell cats are considered to bring good luck against shipwrecks. There are some additional interpretations of the luck of tortoiseshell cats, such as the one in England that describes an announcement of misfortune when a strange tortoiseshell cat enters a house. In England, if a woman dreams of a tortoiseshell cat, it can be interpreted as a warning that she should take care of her so-called friends.

Behavior

Some studies have found that people believe tortoiseshell cats are more likely to be aggressive and have owners report stronger prey interest - the slang term "tortitude" was coined in reference to this perceived behavior. There is, however, little existing scientific evidence on the matter. One study found that there was not a relationship between coat color and tameness. Based on various study results, assumptions cannot be made between cat coat color and personality.

Notes

References

  • Atkins, Carla. Cats: An Owner's Guide (2003). San Diego, California: Thunder Bay Press.

References

  1. (1975). "An animal model for the XXY Klinefelter's syndrome in man: Tortoiseshell and calico male cats". American Journal of Veterinary Research.
  2. (1973). "Male Tortoiseshell and Calico (T-C) Cats: Animal models of sex chromosome mosaics, aneuploids, polyploids, and chimerics". Journal of Heredity.
  3. Atkins (2003), p. 61
  4. (2020). "Feline Dermatology". Springer.
  5. Carver, Leslie. "Characteristics of Tortoiseshell Cats". The Nest.
  6. Atkins (2003), p.105
  7. (25 April 2021). "Torbie Cat Breed Facts and Information".
  8. "Breed Profile: Japanese Bobtail". Cat Fancier's Association.
  9. Atkins (2003), p. 90
  10. "Cat Colors FAQ: Common Colors". Fanciers.com.
  11. Bateson, W.. (10 June 1920). "Prof. L. Doncaster, F.R.S.". [[Nature (journal).
  12. Crosta, Maria Cristina. (2020). "Coat Color Genetics". Springer International Publishing.
  13. (1984). "Fertile male tortoiseshell cats". Journal of Heredity.
  14. "X Chromosome: X Inactivation". Nature Education.
  15. "X-chromosome inactivation". Federal Government.
  16. Lyon, Mary F.. (22 April 1961). "Gene action in the X-chromosome of the mouse (''Mus musculus L.'')". [[Nature (journal).
  17. Robinson, Roy. (1991). "Genetics for Cat Breeders and Veterinarians". Butterworth-Heinemann Medical.
  18. Gould, Laura. (1996). "Cats Are Not Peas". Springer.
  19. Spadafori, Gina. "Feline Fallacies". VeterinaryPartner.com.
  20. Foster, Robert A. (2022). "Disorders of sexual development in the cat: Current state of knowledge and diagnostic approach". Journal of Feline Medicine and Surgery.
  21. "Tortie Ragdolls". FloppyCats.
  22. Bonnerjea, Biren. (21 September 1935). "Cats in Folklore and Belief". Notes and Queries.
  23. (2004). "Language in the USA: Themes for the Twenty-first Century". [[Cambridge University Press]].
  24. (2016). "Behavioral associations with breed, coat type, and eye color in single-breed cats". Journal of Veterinary Behavior.
  25. (2 January 2016). "The Relationship Between Coat Color and Aggressive Behaviors in the Domestic Cat". Journal of Applied Animal Welfare Science.
  26. (2012). "Human Perceptions of Coat Color as an Indicator of Domestic Cat Personality". Anthrozoös.
  27. Zielinski, Sarah. "Judging a Cat (Wrongly) by the Color of its Coat". [[Smithsonian (magazine).
  28. Umbelino, M. T. L. P.. (2014). "Evaluation of the relation between tameness and coat color in cats". [[University of Évora]].
  29. (26 July 2017). "Personality in Nonhuman Animals". Springer.

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