Biogeography of Hemisquilla ensigera californiensis (Crustacea: Stomatopoda) with Emphasis on Southern California Bight Populations

Abstract. - The mantis shrimp Hemisquilla ensigera californiensis (Crustacea: Stomatopoda) ranges from south of Point Conception in southern California to the Golfo de Chiriqui, Panama. Hemisquilla populations occur off four of the eight California Islands: Santa Cruz, Anacapa, Santa Catalina and San Clemente, as well as numerous islands off Baja California and mainland Mexico. Insular and continental populations occur in habitats usually characterized by: 1) generally stable, low physical disturbance regimes; 2) silty sand sediments with a high organic content; 3) abundant food resources; 4) variable predation pressure and 5) fluctuating light regimes. Mechanisms that may influence the observed patterns of distribution and abundance include: 1) ocean currents favorable for dispersal of planktonic larval stages; 2) habitat suitable for successful recruitment; 3) sufficient food resources and 4) low levels of predation pressure and physical disturbance.