Tortoiseshell cats, often called "torties," are cats with a coat coloring that resembles the shells of tortoises. Their fur is a mix of two colors other than white, typically red (which can appear as orange, yellow, or cream) and black (which can be black, chocolate, gray, tabby, or blue). The tortoiseshell pattern can be seen in different breeds and non-purebred cats, frequently with small or no white markings. When white patches are present along with the tortoiseshell colors, they are often called calico or tortoiseshell-and-white cats. Almost all tortoiseshell cats are female due to the genetic mechanism behind their color. Female cats have two X chromosomes and the tortoiseshell coloring arises because one of the X chromosomes is randomly inactivated in different cells, creating patches of two colors. Male tortoiseshell cats are rare and usually have an extra X chromosome (XXY), known as Klinefelter syndrome, often making them sterile. Tortoiseshell cats come in various patterns and shades, with some having tabby stripes called "torbies." Their fur can be mixed closely or show large color patches. These cats are popular in several cultures and often considered good luck. Regarding behavior, tortoiseshell cats have a reputation for being temperamental ("tortitude"), but scientific evidence linking their coat color and personality is limited, and individual temperament varies widely. In summary, "tortoiseshell cat" refers to a coat pattern characterized by a mix of orange and black colors, mostly in females, with unique genetic and cultural significance across many cat breeds.
