1.College of Animal Science,South China Agriculture University,Guangzhou 510642,China;2.Guangdong Dayawan Fishery Development Center,Huizhou 516081,China
Abstract: The fertilized eggs of cuttlefish Sepia pharaonis collected from the South China Sea were artificially incubated indoor at water temperature of 23-25℃,and a salinity of 29.0.The point of no return(PNR)was studied in the newly hatched cuttlefish at constant water temperature of 24,26,28,30,and 32℃.The results showed that the larvae had the upper temperature limit of 30-32℃for survival,and the PNR was 8 days at 24℃,11 days at 26℃,8 days at 28℃and 5-6 days at 30℃.The feeding rhythm observation of 5-day old cuttlefish showed that the feeding peak was observed at dawn and afternoon,higher at night than in the day,though the larvae had constant feeding.The excretion of the 5-day old cuttlefish showed that the excretion peak was found at dawn,and the food was evacuation in 20 hours,though the cuttlefish had constant excretion.