How the Snake Lost Its Legs the butterfly, the snake, and the cheetah. Each consists of three to eight sections named in the style of Rudyard Kipling's "Just So Stories", with titles like "How the butterfly got its spots" or "How the snake elongated its body", though a couple of sections use "Why?" rather than "How?", as in "Why the fly twirls his penis" (it rotates during embryonic development under the control of different genes). In these chapters, Held explains the mechanics of evolutionary developmental biology, complete with accounts of what genes such as hox, hedgehog, and engrailed do to shape bodies. The third part is
Leopard the belly to about . Juveniles have woolly fur, and appear dark due to the densely arranged spots. The leopard is often confused with the cheetah; however, the cheetah is marked with small round spots instead of the larger rosettes. Moreover, the leopard lacks the facial tear streaks characteristic of the cheetah. Other similar species are the clouded leopard and jaguar. The clouded leopard can be told apart by the diffuse "clouds" of spots compared to the smaller and distinct rosettes of the leopard, longer legs and thinner tail. The jaguar has rosettes that typically have spots within them, while