Tortoiseshell cat

[a][6][4] Tortoiseshell cats, or torties, combine two colors other than white, either closely mixed or in larger patches.

[10] Tortoiseshell cats have particolored coats with patches of various shades of orange, red, grey, and black, and sometimes white.

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.

[14] Female cats are homogametic (XX) and undergo the phenomenon of X-inactivation,[15][16] in which one of the X chromosomes is turned off at random in each cell in very early embryonic 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.

This spotting gene produces white, unpigmented patches by delaying the migration of the melanocytes to the skin surface.

In intermediate cases, melanocyte migration is slowed, so that the pigment cells arrive late in development and have less time to intermingle.

[19] The single X chromosome does not undergo X-inactivation, ergo coat color is determined by which O-gene allele is present.

Very rarely (approximately 1 in 3,000[20]) 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.

[23] 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.

[23] Some studies have found that people believe tortoiseshell cats are more likely to be aggressive and have owners report stronger prey interest[25][26] - the slang term "tortitude" was coined in reference to this perceived behavior.

[29] Based on varying study results, assumptions cannot be made between cat coat color and personality.