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Tortoiseshell cats are named for their two-tone coat, which resembles a turtle’s shell. Tortoiseshell is not a specific breed, but rather refers to its distinctive patterned coat. Affectionately called “torties,” these colorful kittens, almost exclusively female, are popular pets in many households.
Similar to calico cats, tortoiseshell cats are the result of interesting genetics and they have become a mainstay of folklore around the world. Thanks to several genetic mutations, their fur develops with an almost marbled pattern.
Whether you’re thinking about adopting a tortoiseshell cat or just want to learn more, here are eight interesting facts about tortoiseshell cats.
As with calico cats, you will find that most tortoiseshell cats are female. That’s because the same chromosomes that determine their gender also determine the colors of their fur. The female sex chromosome (X) also carries the genetic code for orange or black coat colors; The male sex chromosome (Y) carries no information about coat color.
Because females have two X chromosomes, they have two sets of genetic information that can determine their coat color. The embryo switches off one X chromosome in each cell, resulting in orange and black color variations in its fur.
In very rare cases – about 1 in 3,000 – a male tortoiseshell cat can be born with two X chromosomes and one Y chromosome.1 In 2014, a Scottish cat rescue welcomed tortoiseshell kitten Harry into the herd – a feat that was so rare that she made the news.
Unfortunately, male cats with XXY syndrome are infertile and often have serious health problems, resulting in a significantly shorter life expectancy than female tortoiseshell cats.2
Although tortoiseshell cats are not a specific breed, some people believe they have a specific temperament.
In a study from the University of California, Davis, Veterinary Medical Teaching Hospital, researchers examined the connection between a domestic cat’s coat color and its behavior. In addition to calico and “torbies,” the focus of the study was tortoiseshell cats.3
After the study was published, speculation spread that tortoiseshell cats had a strong, somewhat cheeky temperament, which was quickly dubbed “tortitude.” Anecdotally, many Tortoiseshell parents agreed that their cats were energetic, cheeky, and even mildly aggressive.
However, the study’s researchers actually found no clear connection between coat color and behavior, temperament, or personality.3
Elizabeth A. Stelow, Melissa J. Bain and Philip H. Kass (2016). The connection between coat color and aggressive behavior in domestic cats. Journal of Applied Animal Welfare Science, 19:1, 1-15, doi:10.1080/10888705.2015.1081820
Perhaps “tortiude” was simply confused with the usual old cases of catitude.
Mixed-breed and pedigree cats can sport the tortoiseshell coat pattern, including:
On the Internet you can find numerous auspicious legends about tortoiseshell cats. They are considered a sign of good luck in several countries, although the backstories are mostly mythical.
In Japan, it is believed that tortoiseshell cats can protect ships from ghosts and shipwrecks.4
According to English folklore, rubbing a wart with the tail of a tortoiseshell cat will cure the condition, although perhaps only in the month of May.4
In the United States, tortoiseshell cats are considered “money cats” that bring good luck to the home.
An extremely rare male tortoiseshell coming to your home? In Scotland and Ireland that means better luck.
Tortoiseshell – from real, live turtles – was used as a material for making high-quality jewelry, eyewear and home accessories before the 1970s. Tortoiseshell cats were named after this material because their fur resembles it in colors and patterns.
With tortoise populations decimated worldwide due to high demand, use of the material was banned by the CITES treaty and synthetic tortoiseshell was developed.
If you cross the color of a tortoiseshell cat with the stripes of a tabby cat, you get a “torbie.” They may also be called “tortoiseshell tabby” or “striped tortoise.” They have beautiful, colorful coats with distinctive stripes and many variations.
President Ronald Reagan and First Lady Nancy Reagan did not keep tortoiseshell cats Cleo and Sara in the White House in the 1980s. Instead, the two kittens stayed at their ranch in California.
Although tortoiseshell coats are most commonly a combination of ginger and black, they can also feature hints of cream, orange, or gold. The colors are either “bridled” (look as if they are woven together) or “patched” (form in large patches all over the body).
Additionally, their coats can be composed of chimeras or mosaics, with mosaics being far more common because chimeras are formed when two embryos fuse in the womb. The chimera pattern features a different color on each side of the face, with the two colors clearly separated along a line. The colors of the mosaic pattern are mixed or swirled throughout the face and body.