Cephalopod ontogeny and life cycle patterns

Life cycle definitions provide the background for conceptualizing meaningful questions to address mechanisms that generate different life patterns. This review provides explicit and explanations of steps in a cephalopod cycle, from fertilization death. Each large step, or phase, is characterized by particular developmental process morphology. phase composed smaller developmentally distinct steps, stages. The comprised all some following phases: Embryonic, Paralarval, Juvenile, Subadult, Adult Senescent, each taxon-specific. All cephalopods have direct development maintain consistent body plan throughout ontogeny (i.e., no true larval metamorphosis). Most marked long early short adult followed senescence. Cephalopods two modes: they produce either small planktonic hatchlings as paralarvae, juveniles. go through Hatchling stage soon after eclosion during which rely on modes nutrition: endogenous (yolk) exogenous (prey). Many with paralarvae will become benthic their Settlement remain pelagic Metapelagic stage. Juvenile growth fast ontogenetic changes (outside gonadal maturation) generally cease at end phase. Subadult begins when definitive morphology (except size proportions) acquired (e.g., full complement photophores). Sexual organs undergo most starts spawning competency concludes gonads are spent. Senescent spent ends Using this new terminology, we examine patterns cycles find there four main based presence Paralarval habitat occupied phase: Holopelagic (all phases pelagic), Holobenthic benthic), Merobenthic Meropelagic (phases alternate between environments). In these last patterns, difference species. terminology proposed here unifying framework future ecological, evolutionary research cephalopods.