Development of Eggs and Larvae

This chapter summarizes information on the development of fish eggs and larvae, and introduces juvenile development. The chapter focuses on the changes that occur as the eggs develop, hatch into larvae, and finally transform into juveniles (ontogeny). Most fishes have indirect development; that is, as free-living organisms they go through a number of distinct stages or phases of development (egg, larva, juvenile). This is similar to development in amphibians, but opposed to direct development seen in reptiles, birds, and mammals in which all the free-living forms appear similar and development is largely adding size to the organism. The specific topics covered by this chapter include events that take place immediately after spawning (fertilization and activation), the perivitelline space, rate of development and aging of fish eggs, hatching, notochord and stages of larval development and the transformation stage.