The area on the DNA where this gene (and genes governing other physical features such as muzzle length, coat characteristics,
relative leg length, body proportion and ear floppiness) is found is very prone to mutations, and dogs have many more of these mutations than other species.
They differ most obviously from their spider and scorpion
relatives in three ways: their massive two - segmented jaws, which can be up to one - third of their body
length and are armed with teeth and spine - like and horn - like processes of various sizes; the flagellum, found on the jaws of adult males in most species and thought to play a major role in reproduction; and the malleoli, racquet - shaped sensory organs on the underside of the first segment of the last pair of
legs.