2.3. Statistical analysis
Data analyses were performed with SPSS 19.0 for Windows statistical package. Prior to analysis, raw data were diagnosed for normality of distribution and homogeneity of variance using Kolmogorov–Smirnov test and Levene test respectively. The tentacle insertion rate, IR and FPR were subjected to one-way analysis of variance (ANOVA). The differences between day and night of IR and FPR were compared using independent sample T-test. A two-way followed by Tukey's multiple range tests for post-hoc pairwise comparisons to test the feeding proportion and three digestive enzymes activities between different times and sea cucumber size groups. Differences were considered significant at P b 0.05, and all data were presented as means ± standard deviation.