Tortoiseshell cat
Encyclopedia
Tortoiseshell describes a coat coloring
found mostly in female cats. Cats of this color are mottled, with patches of orange or cream and chocolate, black or blue. They are sometimes called torties. A cat with this coloring, but also with the tabby
pattern, is a torbie.
"Tortoiseshell" is typically reserved for cats with brindle
d coats with relatively few or no white markings.
Those that are largely white with red and brown patches (rather than a brindled aspect) are described as tortoiseshell-and-white (in the United Kingdom
) or calico (in Canada
and the United States
). Tortoiseshells and calicos are not specific breeds of cat. The tortoiseshell markings appear in many different breeds as well as in non-purebred domestic cats. This pattern is especially preferred in the Japanese Bobtail breed.
patterns of eumelanistic and pheomelanistic colors are also seen (these are often then called "tortie-tabby", "torbie" or, with white, "caliby"). Tortoiseshell also can be expressed in the point
pattern.
and has two alleles, The Orange (XO) and not-Orange(Xo), that produce orange phaeomelanin and black eumelanin pigments, respectively. (NOTE: Typically, the X for the chromosome is assumed from context and the alleles are referred to by just the uppercase O for the orange, or lower case o for the not-orange.) The Tortoiseshell and Calico cats are indicated: Oo to indicate they are heterozygous on the O gene. 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.
The cells of female cats, which like other mammalian females have two X Chromosome
(XX), undergo the phenomenon of X-inactivation
, in which one or the other of the X-chromosomes is turned off at random in each cell in very early 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, producing 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 other mammalian males, have only a single X chromosome (XY) that does not undergo X-inactivation: coat color is determined by which allele is present on the X, and they will be either entirely black or orange. Very rarely (approximately 1 in 3,000) a male tortoiseshell or calico is born. These animals typically have an extra X chromosome (XXY), a condition known in humans as Klinefelter syndrome, and undergo an inactivation process like that in females. As in humans, these cats are sometimes sterile because of the imbalance in sex chromosomes. Some male calico or tortoiseshell cats may be chimeras
, which result from the fusion in early development of two embryos with different color genotypes. 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.
Simply said they are melanistic calicos meaning saturation of color.
in the folklore of many cultures. In the United States
, these are sometimes referred to as money cats. The Japanese Maneki Neko
figurine is almost always a calico cat.
Animal colouration
Animal coloration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. The mechanisms for colour production in animals include pigments, chromatophores, structural coloration, and bioluminescence....
found mostly in female cats. Cats of this color are mottled, with patches of orange or cream and chocolate, black or blue. They are sometimes called torties. A cat with this coloring, but also with the tabby
Tabby cat
A tabby is any cat that has a distinctive coat that features stripes, dots, lines or swirling patterns, usually together with an "M" mark on its forehead. Tabbies are sometimes erroneously assumed to be a cat breed. In fact, the tabby pattern is found in many breeds of cat, as well as among the...
pattern, is a torbie.
"Tortoiseshell" is typically reserved for cats with brindle
Brindle
Brindle is a coat coloring pattern in animals, particularly dogs, cats, cattle, guinea pigs, crested geckos and, rarely, horses. It is sometimes described as "tiger striped", although the brindle pattern is more subtle than that of a tiger's coat...
d coats with relatively few or no white markings.
Those that are largely white with red and brown patches (rather than a brindled aspect) are described as tortoiseshell-and-white (in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
) or calico (in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
). Tortoiseshells and calicos are not specific breeds of cat. The tortoiseshell markings appear in many different breeds as well as in non-purebred domestic cats. This pattern is especially preferred in the Japanese Bobtail breed.
Patterns
Tortoiseshell cats have coats with patches of red, brown or black, chocolate, cream, or cinnamon. 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. 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 tabbyTabby cat
A tabby is any cat that has a distinctive coat that features stripes, dots, lines or swirling patterns, usually together with an "M" mark on its forehead. Tabbies are sometimes erroneously assumed to be a cat breed. In fact, the tabby pattern is found in many breeds of cat, as well as among the...
patterns of eumelanistic and pheomelanistic colors are also seen (these are often then called "tortie-tabby", "torbie" or, with white, "caliby"). Tortoiseshell also can be expressed in the point
Point (coat color)
Point coloration refers to animal coat coloration with a pale body and relatively darker extremities, i.e. the face, ears, feet, tail, and scrotum...
pattern.
Genetics
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 located on the X ChromosomeX chromosome
The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals and is common in both males and females. It is a part of the XY sex-determination system and X0 sex-determination system...
and has two alleles, The Orange (XO) and not-Orange(Xo), that produce orange phaeomelanin and black eumelanin pigments, respectively. (NOTE: Typically, the X for the chromosome is assumed from context and the alleles are referred to by just the uppercase O for the orange, or lower case o for the not-orange.) The Tortoiseshell and Calico cats are indicated: Oo to indicate they are heterozygous on the O gene. 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.
The cells of female cats, which like other mammalian females have two X Chromosome
X chromosome
The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals and is common in both males and females. It is a part of the XY sex-determination system and X0 sex-determination system...
(XX), undergo the phenomenon of X-inactivation
X-inactivation
X-inactivation is a process by which one of the two copies of the X chromosome present in female mammals is inactivated. The inactive X chromosome is silenced by packaging into transcriptionally inactive heterochromatin...
, in which one or the other of the X-chromosomes is turned off at random in each cell in very early development. The inactivated X becomes a Barr body
Barr body
A Barr body is the inactive X chromosome in a female somatic cell, rendered inactive in a process called lyonization, in those species in which sex is determined by the presence of the Y or W chromosome rather than the diploidy of the X or Z...
. 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, producing 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
Cat coat genetics
The genetics of cat coat coloration, pattern, length, and texture is a complex subject, and many different genes are involved.- Genes involved in albinism, dominant white, and white spotting :...
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
Bicolor cat
A bicolor cat has white fur combined with fur of some other color, for example black or tabby. There are various patterns of bicolor cat. These range from Van pattern through to solid color with a throat locket...
, harlequin, and van
Turkish Van
The Turkish Van is a recognized cat breed that is known for its unusual love of water and swimming. They were created from the cats native to the Lake Van area of Turkey. The cats of this type are named in Turkish Van Kedisi , in Armenian vana katou or vana gadou and in Kurdish...
, 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
Melanocyte
-External links: - "Eye: fovea, RPE" - "Integument: pigmented skin"...
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 other mammalian males, have only a single X chromosome (XY) that does not undergo X-inactivation: coat color is determined by which allele is present on the X, and they will be either entirely black or orange. Very rarely (approximately 1 in 3,000) a male tortoiseshell or calico is born. These animals typically have an extra X chromosome (XXY), a condition known in humans as Klinefelter syndrome, and undergo an inactivation process like that in females. As in humans, these cats are sometimes sterile because of the imbalance in sex chromosomes. Some male calico or tortoiseshell cats may be chimeras
Chimera (genetics)
A chimera or chimaera is a single organism that is composed of two or more different populations of genetically distinct cells that originated from different zygotes involved in sexual reproduction. If the different cells have emerged from the same zygote, the organism is called a mosaic...
, which result from the fusion in early development of two embryos with different color genotypes. Others are mosaics
Mosaic (genetics)
In genetic medicine, a mosaic or mosaicism denotes the presence of two populations of cells with different genotypes in one individual who has developed from a single fertilized egg...
, in which the XXY condition arises after conception and the cat is a mixture of cells with different numbers of X chromosomes.
Simply said they are melanistic calicos meaning saturation of color.
Folklore
Cats of this coloration are believed to bring good luckLuck
Luck or fortuity is good fortune which occurs beyond one's control, without regard to one's will, intention, or desired result. There are at least two senses people usually mean when they use the term, the prescriptive sense and the descriptive sense...
in the folklore of many cultures. In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, these are sometimes referred to as money cats. The Japanese Maneki Neko
Maneki Neko
The is a common Japanese sculpture, often made of ceramic, which is believed to bring good luck to the owner. The sculpture depicts a cat beckoning with an upright paw, and is usually displayed—many times at the entrance—in shops, restaurants, pachinko parlors, and other businesses...
figurine is almost always a calico cat.
Gallery
Photo Gallery |
|---|
| Gallery of the various types |
Tortoiseshell Tortoiseshell and white Calico Dilute tortoiseshell Torbie/caliby Tortoiseshell point |
External links
- Tortoiseshell and tri-color cats
- Calico cat
- tortiecats.free.fr : website showing the diversity of tortie and calico coats