The blue crab Callinectes sapidus Rathbun has been the subject of scientific investigation for more than 100 years. The crab is a key predator in shallow estuarine and coastal environments, and supports a large commercial fishery along the Atlantic and Gulf Coasts of the United States. Much of the initial research on C. sapidus was purely descriptive and provided only a patchwork perspective on the natural history of the crab. This is in contrast to more modern work that has defined a clear, interrelated series of processes that underlie the early life history of the species. The intent of the present review was to discuss contemporary understanding of the early life history of blue crabs in the context of a coherent time line of development. The review begins with a short section on general aspects of the life history, which provides a background for the overall discussion. This is followed by a segment on courtship and mating, with particular emphasis on chemical communication between mating pairs. Three subsequent sections then deal, respectively, with spawning migrations within the estuary, larval release in the adjacent coastal ocean, and transport of larvae on the inner continental shelf. A following segment, describes settlement of the larvae in the lower estuary and eventual transport of early juvenile stages to estuarine nursery areas. The final section provides a summary and conclusions. Points of emphasis in the review include the following: (1) the role of pheromones in courtship and mating; (2) the discovery of two distinct phases in the spawning migration; (3) the importance of chemical cues in assuring synchronized hatching of eggs; (4) the predominant effect of wind- and buoyancy-driven processes in controlling larval transport in the coastal ocean; (5) the development of mathematical models that allow critical analysis of transport processes; and (6) the combined physical and behavioral processes that facilitate transport of megalopa larvae from the estuarine mouth to nursery habitat in the lower estuary.
