The vast diversity of animal life on Earth comprises more than 1.5 million described species. This diversity is confusing and incomprehensible for beginners. Since the animals (Metazoa) can be traced back to a last common ancestor, studying their evolutionary history or phylogeny is one key to breaking down this diversity. Although, with the invention of phylogenomic analyses, significant progress has been made in unraveling metazoan phylogeny, open and controversial questions still exist. Nevertheless, the evolutionary history of Metazoa is reflected by comparative morphology, among other things. But what are the reasons for the evolutionary and biological success of Metazoa? This goes back to a few key events in evolution, such as the origin of multicellularity, which was accompanied by the specialization of cells to certain specific functions. After separating into generative and vegetative cells, the latter have been further diversified from less than ten in Placozoa to about 200 in vertebrates. Another key invention was the evolution of true epithelia, sealing the inside from the external environment, a prerequisite for the evolution and function of sensory, nerve, and muscle cells, or nephridia. Several of these innovations have made it into the names of higher taxa, such as Bilateria, Nephrozoa, and Chordata. This practical book focuses on the morphology and the evolutionary context of the major animal lineages. We present the ground patterns and specific morphological adaptations of various animal groups in photos and make them understandable for students in introductory zoological dissection courses.