Development

Abstract

AbstractMost developmental biologists implicitly understand the focus of their research as the processes extending from a zygote to an adult condition, which include embryonic and larval development. Data are available from not only living species but also the fossil record (especially from the Cambrian Orsten faunas). Although the nauplius often occurs as the initial larval stage, an intimal nauplius is not universal, and several distinct nauplii are recognizable. One must distinguish between an orthonauplius and various types of metanauplii, as well as germ bands and egg nauplii. Ontogeny is a sequence of independent stages in which no one stage can predict what the next stage will look like, let alone what the final stage will look like. Each stage is autonomous. Care must be exercised in analyzing and interpreting biohistorical events.