They have such interesting and unique coats that it's often the first thing people comment on when they see your cat. You might be wondering how they have evolved to have such gorgeous markings.
Much like calico cats , tortoiseshell cats have some pretty interesting genetics, and they've become mainstays in folklore all over the world. Thanks to a number of genetic mutations, their coats develop with almost marbled patterns. Whether you're considering adopting a tortoiseshell or just want to learn more about these fun and frisky cats, these facts and photos are sure to delight. The distinctive feature of a tortoiseshell is the patterned coat—not the breed. A tortoiseshell breed of cat doesn't actually exist.
Several breeds, however, can exhibit tortoiseshell markings, such as American shorthair, British shorthair, Cornish Rex, Persian , and Maine Coons , among others. Although tortoiseshell coats are most commonly a ginger red and black, they can also have hints of cream, orange, or gold.
The colors in their coats are either "bridled" and look like they're woven together, or "patched," which means the colors form in large patches all over the body.
Like calico cats , you'll find most tortoiseshell cats are female. That's because the same chromosomes that determine their sex also determine the colors in their coats. The female sex chromosome X also carries the genetic code for orange or black coat colors; the male sex chromosome Y does not carry information on coat color. Because females have two X chromosomes, they have two sets of genetic information that can determine their coat color.
The embryo shuts off one X chromosome in each cell, resulting in orange and black color variations in their coats. Because a male cat has one X chromosome and one Y chromosome, he'll only be orange or black—not both. In very rare cases—about 1 in 3,—a male tortoiseshell cat can be born with two X chromosomes and one Y chromosome.
Unfortunately, male cats with XXY Syndrome are sterile and often have serious health issues, resulting in significantly shorter lifespans than female torties. Tortoiseshell cats aren't a specific breed, but some believe they have a specific temperament. In a study conducted by UC Davis Veterinary Medical Teaching Hospital, researchers pondered the link between a domestic cat's coat color and its behavior. Tortoiseshell cats along with calicos and "torbies" were the main focus of the study.
After the study was published, word spread that tortoiseshell cats have a distinct, somewhat sassy temperament, which was quickly coined "tortitude. But concluded in the study results, researchers actually didn't find a distinct link between coat color and behavior, temperament, or personality. The majority of torties — The reason for this comes down to chromosomes. Two X chromosomes are required to produce the signature tortoiseshell coat colors and patterns.
Just like humans, female cats have two X chromosomes and males have an X and a Y chromosome. Unfortunately, this chromosome imbalance will also make any male torties sterile. For example, there can be a significant different between an adult Maine Coon and an adult American Shorthair. Adult Maine Coons — which are known to be one of the larger cat breeds — average 15 lbs.
American Shorthair males average 11 lbs. Your veterinarian will be able to determine the breed of your tortoiseshell through a quick exam. Playing with your tortoiseshell and providing them with minimally processed, high-quality cat food is a great weight to make sure they maintain an optimal weight.
Just like weight, the life expectancy of a tortie cat will depend on many factors, including their breed. However, keeping your cat indoors can help them live longer. Fetch by WebMD notes that cats who are kept inside can live to be 17 years or older, while many outdoor cats live an average of two to five years. We have seen that chromosomes contain genes which tell the body to produce certain things. But you can't have two X chromosomes telling the a cell to do the same thing twice, So 'X-inactivation' switches off one chromosome, leaving only one working X set in each cell.
Now this is the critical bit, so pay close attention. X inactivation happens in each cell in the developing fetus, and it happens once. But which X chromosome gets switched off is completely random. So if the cell has the chromosome with the O allele turned off, that cell is going to produce eumelanin, for black fur. But it's a coin toss that means in the cell next door the o-bearing chromosome may be turned off, and the 'O' stays active on the other chromosome, meaning that this cell is going to produce orange fur.
So we end up with cells that have some active O genes and others have active o genes. Once the developing fetus has sorted out which genes will be active in each cell, hair and skin production begins. The alleles in the cells responsible for hair and melanin production melanocytes will create brown, orange or black patches.
The cells with their different active chromosomes intermingle as they are produced deep in the body and travel to the skin. Where these cells end up and start producing their particular shade of melanin determines the colour, shade and position of a Tortie's patches of orange and dark colours. It does not end there - an additional gene is responsible for softening any specific colour; changing orange to cream and black to gray. In Calico cats yet another gene the Spotting Gene produces white unpigmented patches.
There's lots yet to cover in the mystery of cat coat colours, but for now we have the answer to our question. Tortoiseshell cats are female because male cats don't have the chromosomes to produce the right alleles. Simple, really.
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