Thursday, July 08, 2010

Calico capers

kw: photographs, animals

We recently got a calico kitten who is now 15 weeks old. I'd come to understand a long time ago that the calico coat was four colors, but all the recent material I have read says that a calico is a three-color piebald, the piebald meaning the white background. But I am not clear whether "three-color" means in addition to the white or not.

The tiger striping on the head, neck and side show that she has a tabby parent. If I count the gray tabby stripes, she really does have four colors: white, brown, near-black and gray. I guess a non-tabby calico is white, brown and black only. In the Wikipedia articles Tortoiseshell Cat and Calico Cats, the brown color is called either gold or ginger. The first article states that calico cats are tortoiseshell cats with a lot of white (piebald), while the latter article states that they are not tortoiseshells, but are a distinct variety with slightly different genetics.

The genes for piebalding apparently do not reside on X chromosomes, because both male and female cats can be piebald; that is how you get black-and-white or brown-and-white cats of either sex. The extra X chromosome in females can carry a different color than the other. The mosaic X-inactivation pattern determines which portions of the coat will be either black or brown, and the piebalding gene(s) determine how much white there is. See the next pic:

This shot, while she was playing with a piece of packing foam, shows the entirely white belly and inside the legs. I have looked at a lot of pictures of calico cats, and I have yet to see one with much color on the belly. That indicates to me that piebalding is a bottom-to-top phenomenon, but I have not read anything about this.

As interesting as the coat color is, I am more continually enthralled by the playfulness of this kitten. She has long legs and big eyes, so I expect a rather large adult cat in a few months. My wife would prefer a smaller cat; our last cat never weighed more than five pounds (2.2 kg). This kitty already weighs four pounds (1.8 kg). Large or small, we're glad that so far, she is an affectionate cat. I take my blood pressure at home from time to time, and since we got her, it has dropped by about 15 points.

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