Burrowing behavior of penaeid shrimps

Brown shrimp, Farfantepenaeus aztecus, and white shrimp, Litopenaeus setiferus, were held were held under natural light conditions before experiments. Experiments were conducted in twelve rectangular tanks (58 cm x 149 cm) under fluorescent lighting (7-10 microEinsteins/sec/sq m). Shrimp were placed in randomly-assigned tanks the day before observations were initiated at 0730 h, the lights were turned on, and observations of thepercentage of shrimp burrowed ( 1/2 of their body beneath the substrate) were recorded hourly (starting at 0830 h) throughout the daylight hours. For both species, burrowing rates decreased significantly as the substrate became courser. Brown shrimp burrowing was marginally affected by salinity with the lowest burrowing rates at 5 ppt white shrimp burrowing was not significantly affected by salinity. Large brown shrimp burrowed more than small and medium sized shrimp, but size did not significantly affect burrowing of white shrimp. The presence of a fish predator in the tanks did not affect burrowing of either species, but hunger level significantly affected burrowing for both species.