How the Snake Lost Its Legs fly embryo. His books on evolutionary developmental biology (evo-devo) include "Imaginal Discs: The Genetic and Cellular Logic of Pattern Formation" (2002), "Quirks of Human Anatomy: An Evo-Devo Look at the Human Body" (2009), and "Deep Homology? Uncanny Similarities of Humans and Flies Uncovered by Evo-Devo" (2017). In Held's view, "Quirks", "Snake", and "Deep Homology" form a trilogy on evo-devo. "How the Snake Lost Its Legs" is ostensibly organised into six chapters, but in effect into three parts. The first chapter serves as an introduction and overview. The next four chapters provide what Held calls "the meatier aspects of evo-devo" with
Viceroy (butterfly) not be a good model-mimic pair for Batesian mimicry. Experimental evidence has shown that avian predators express aversion to the queen butterfly after being exposed to viceroys. That the avian predators avoided the queen butterfly implies that the queen does not serve as a model and the viceroy as a parasitic mimic; rather, they may be Müllerian co-mimics. When avian predators were exposed to butterfly abdomens without the wings, many avian predators rejected the viceroy after a single peck. Furthermore, they exhibited distress behavior similar to that displayed when eating other, known, unpalatable species. When palatability was measured by looking