Annual shes are a fascinating group of freshwater shes due to their particular developmental, ecological, physiological, and evolutionary adaptations. They possess an uncharacteristically short life cycle among vertebrates, that is, less than a year long. This unique life cycle is correlated to the seasonal pools of water they inhabit both in the African and Neotropical realms (Figure 1.1). The term “annual shes” was coined by Myers (1952) to specically refer to these short-lived vertebrates. Recent papers have reviewed the distinct developmental and growth pathways (Berois et al. 2012; Blažek et al. 2013) and overall biology (Berois et al. 2014) of annual shes. This chapter will review hypothesized phylogenetic relationships from higher taxa to genus levels.