Feeding and Nutrition of Crustacean Larvae

Among the Crustacea, there is an enormous diversity of species, range of sizes and body morphologies, habitats, lifestyles, and life cycles, which include a remarkable range of larval development pathways. Despite this divergence, there are commonalities in their larval nutrition. The majority of crustaceans have free-living larvae that will feed on live prey. Their feeding is typically opportunistic, with their behavior often directed toward ensuring they encounter suitable prey. Larval prey are usually proportionally smaller than their body size, with some notable exceptions. Consequently, modes of feeding in larval crustaceans include bacterivory, detritivory, herbivory of unicellular phytoplankton, the omnivory of a mix of phytoplankton and metazoan prey, and carnivory. Frequently, the diet of crustacean larvae changes markedly through their developmental stages as the size and feeding capabilities of the larvae increase. The articulated appendages and alimentary tracts of crustacean larvae show a remarkable range of morphologies, enabling the capture and processing of different food sources. A wide range of digestive enzymes are typically used to break down ingested food because of the limited capacity of the gut for physical processing, which is common among many larvae. The absorption of a wide range of nutrients makes use of the metabolic flexibility of crustaceans for using a variety of nutritional substrates and for converting biomolecules, as well as storing and redeploying nutritional resources. Regardless, some dietary nutrients, such as sterols, long-chain polyunsaturated fatty acids, and some minerals are essential dietary requirements. Much of our in-depth knowledge of larval nutrition in crustaceans comes from larger and commercially important crustaceans, especially crab, lobster, and shrimp species. A better understanding of the diversity of larval feeding and nutrition among crustaceans is required among a wider range of species, especially for those crustaceans that play major roles in many of our marine ecosystems.