I did not mean to imply that Chimerism cannot occur in snakes, other reptiles, etc. I actually have a great uncle who a few years back was diagnosed with testicular cancer. A little while later it was discovered that the "tumor" they had seen wasn't actually cancer, but the remnants of a twin that had been partially absorbed by his body and somehow had remained there throughout his life. Not Chimerism in the sense that he took on the genetic material of a consumed twin, but similar. The brindle color that rarely occurs in horses, mainly in thoroughbred racehorses, is believed to be a form of Chimerism where the offspring inherits both its normal coat color and, in areas, the color from a twin's genetic material. Certainly Chimerism can and does occur in vertebrates. However, the commonly bred snake morphs (albino cornsnakes, pastel ball pythons, etc.) are usually skin pigmentation changes due to genetic mutation. These don't have an effect on internal structure, and are inheritable. The tarantulas discussed in this thread are more than just a tarantula with a different color pattern - they have internal changes, however deep, that somehow also alter their internal structure. Therefore, this isn't just something that can and should be bred as a new "color morph" of P. regalis. If it is a case of Chimerism, it would not be a simple inheritable trait. If it's a mutation or true Chimerism, either way it will be interesting to see how (if) it effects these tarantulas through their life.