ABSTRACT
The major function of the digestive system is to supply dietary nutrients to the body tissues. The efficiency of this process is one of the key factors that determine the supply of substrates to the rapidly growing larval tissues, particularly during the first critical stages when the larvae start exogenous feeding. This chapter deals mainly with teleosts. The ontogeny of the digestive system varies between species. Goblet cells can be identified in all intestinal regions, while the distribution of the enteroendocrine cells varies between larval types. Pyloric caeca develop during the transition from larvae to juveniles and originate in the anterior part of the intestine. The midgut plays a key role in the digestion and absorption of ingested feeds in larval fish. The pancreas serves important exocrine as well as endocrine functions in the digestion and post-prandial metabolism of ingested feeds.
