Types of feeding in the ontogeny of fishes and the life-history model

Abstract

SynopsisDifferent types of ontogenies in fishes —indirect and direct — are correlated with different nutrient availability and feeding during early life history. A comprehensive life-history model, developed earlier, facilitates the understanding of decisive events in the life of an organism. Embryos with insufficient endogenous food supply (yolk) to build a definitive phenotype directly need the transient form of a nutrient-gathering larva. They represent an indirect development. In contrast, a large endogenous supply of nutrients enables the definitive adult phenotype to develop directly, avoiding an intervening larva and the cost of metamorphosis. The larger and more advanced an individual at the onset of exogenous feeding, the better are its chances to survive. This can be achieved by heterochronies related to feeding. Different types of feeding during the early ontogeny of fishes — endogenous, exogenous, absorptive, and a combination of all (mixed) — are demonstrated and integrated into the life-history model.