[Truncated abstract] In this thesis I investigated the ingestive and digestive morphology and digestive physiology during development of phyllosomata of the ornate spiny lobster, Panulirus ornatus. This knowledge was applied to develop a suitable formulated diet to be fed in combination with Artemia or used as a supplement to reduce production costs. The major impediment to closure of the life cycle of spiny lobsters has been an inadequate dietary regime, stemming from a lack of information on their feeding biology and ingestive and digestive capabilities. Of all spiny lobster species, P. ornatus is the best candidate for aquaculture in Australia having the shortest larval development phase (46 months) and fast growth rate, attaining 1 kg within 2 years of hatch. Currently, Artemia and fresh feeds such as mussel are used routinely as hatchery feeds. However, the development of a formulated diet that is palatable and delivers the correct balance of nutrients is seen as a highly attractive and cost effective alternative. An appropriate formulated diet for aquaculture of phyllosomata of spiny lobsters can be developed more effectively when the ingestive and digestive morphology, physiology and feeding behaviour are fully understood. ... Partial replacement trials revealed that P. ornatus phyllosoma are stimulated to feed by visual cues. Furthermore, 75% of the entire Artemia ration can be replaced with a formulated diet without having any adverse effects on survival and growth of early-stage phyllosomata. Weaning P. ornatus phyllosomata onto 100% formulated diet during stages II-III resulted in reduced survival but demonstrated that diets containing 44-50% crude protein with a diverse range of marine protein sources provides optimum survival and growth. This thesis has identified both physical and nutritional components that will contribute to the successful development of formulated diets for aquaculture of this species. Ultimately, although formulated diets are ingested and provide more than adequate survival when fed in combination with Artemia during early ontogeny, greater success and the possibility of totally replacing Artemia may occur after day 32 (stage IV) due to an increased efficiency to capture and manipulate larger sized particles externally and a greater capacity to triturate prey and sort and filter particles internally. Furthermore, a general increase in specific activity of digestive enzymes at stage IV suggests the possibility of a greater capacity to digest and assimilate nutrients.