The larvae of many marine invertebrates start their development in the pelagic zone where it proceeds until metamorphosis marks the transition to a benthic environment. Larval recruitment to adult populations depends on successful completion of pelagic development. Larval survival and growth vary with food quality and quantity. Mariculture generated many studies on the nutritional value of different algal species and diets. Gross composition of algae includes protein, carbohydrate, lipids, minerals, and nucleic acids. Information on nutritional requirements comes mostly from nutritional studies on commercial species of crustaceans and molluscs. Food quality influences the duration of larval development in crustaceans, echinoderms, and molluscs. The diversity of marine invertebrate larval diets manifests itself through two modes of nutrition: the direct mode performed by the feeding organs and the indirect mode or the uptake of dissolved nutrients. Larvae feed on an extensive array of particle sizes as well as food kinds.