The life-history of the sand crab Hippa cubensis saussure living on a small island

The closely related sand crabs Hippa and Emerita both inhabit the intertidal zone of tropical sandy beaches but Emerita is absent from many oceanic islands while Hippa is absent from most mainland coasts. The distribution patterns are explained by comparing the life-history of H. cubensis, living in the West Indies, with published information on Emerita species. Size distributions and beach habits of the 2 genera were similar and differences in egg production and larval development times are considered to be temperature-dependent and not generic differences. A preference of Hippa for coarse sand beaches, found mainly on islands, partly accounts for the distribution of this genus. The preference is accounted for by the absence of an effective respiratory tube and behavioral adaptations traced to feeding habits. Hippa appears to be relatively stenothermal, which would account for its absence from warm temperate areas occupied by Emerita. The distribution patterns of Emerita are not readily explained. The possibilities of predation of Emerita on extremely light or dark sand, as found on islands or predation of young Emerita by Hippa are considered.Science, Faculty ofZoology, Department ofGraduat