Penaeid shrimp are highly valued by people and other animals as a marine food source. In the last decade, there has been a formidable rise in aquaculture production of shrimp: the quantity of shrimp grown in captivity has more than doubled from 1994 to 2003, rising from 882,000 mt to more than 1,800,000 mt in 2003 (FAO, 2006), the latter weight being valued at US$9.3 billion. This is partly due to the tremendous amount of research that has been carried out on penaeid shrimp biology, most of which has focused on the genus Penaeus, which includes the largest and the most economically important species. According to the most recent taxonomy, however, all the former sub-genus taxa within Penaeus have been raised to genus level (Perez-Farfante and Kensley, 1997). Both the old and new species names are now used in the literature. In this chapter, the term “shrimp” is synonymous with “penaeid shrimp” and the new species names will be used even when referring to older literature.