Cephalopod ontogeny and life cycle patterns

Abstract

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

Ontogeny of predatory capacity and prey choice during early life of the holobenthic octopus Amphioctopus fangsiao (d’Orbigny, 1841): switching prey-choice strategy

“…This is likely to be true of octopuses, which are well-known predators in marine benthic communities. Adult octopuses living in shallow waters can consume various animals such as crabs, shrimps, lobsters, gastropods, bivalves, polychaetes, and teleost shes (Ambrose 1984;Iribarne et al 1991;Vincent et al 1998 Among benthic octopus species, there are two types of life cycle strategy: one is the merobenthic type having planktonic paralarval phase before taking up the benthic life, and the other is the holobenthic type that commences benthic life immediately after hatching (Villanueva and Norman 2008;Vidal and Shea 2023). Although the hatchlings of both reproductive types are miniatures of the adult form showing typical carnivorous behavior, the hatchlings of holobenthic octopuses possess relatively well-developed morphological traits such as longer arms with dozens of suckers and more chromatophores compared with those of merobenthic species.…”

Early Transport Patterns and Influencing Factors of Different Stocks of Uroteuthis edulis in the East China Sea

“…During the life cycle of marine organisms, individuals undergo a transition from the passive drifting of paralarva to the active long-distance migration of adults between feeding and spawning grounds [ 1 ]. The environment of spawning grounds and paralarva transport routes regulate the reproductive success of adults, which determines the dynamic growth, migration, and recruitment mechanisms of the organisms [ 2 , 3 ]. Therefore, understanding the early transport process of marine organisms can help to understand the population dynamics and habitat requirements at key life history stages [ 4 ].…”