highly significantP < 0.004
The Mann-Whitney U test for two independent-samples showed that there was a highly significant difference in the mean CSA (P < 0.004) and lesser diameter (P < 0.001) of the type I fibres of the adult and senile dolphins, i.e., the hypothesis of the homogeneity of the mean values for the adult and senile groups can be rejected at the 0.1% significance level.