A comprehensive overview is presented of the literature dealing with the development of sleep-like motility and neuronal activity patterns in non-vertebrate animals. it has been established that spontaneous, periodically modulated, neurogenic bursts of movement appear to be a universal feature of prenatal behavior. New empirical data are presented showing that such ’seismic sleep’ or ’rapid-body-movement’ bursts in cuttlefish persist for some time after birth. Extensive ontogenetic research in both vertebrates and non-vertebrates is thus essential before current hypotheses about the phylogeny of motorically active sleep-like states can be taken seriously. It has been established that spontaneous, periodically modulated, neurogenic bursts of movement appear to be universal features of prenatal behavior. New empirical data are presented that such ’seismic sleep’ or ’rapid-body-movement’ bursts in cuttlefish persist for some time after birth. Extensive onto genetic research in both vertebrates and non-vertebrates is thus essential before current hypotheses about the phylogeny of motorically active sleep-like states can be taken seriously.