The vertical line marking each dive, on reaching its greatest depth, began to zigzag in the sawtooth pattern characteristic of blue whales when lunge feeding on krill.

• 蓝鲸潜水时总是先直线向下，在到达最深处时，就开始以锯齿状路线行进，这是它们突进捕食磷虾时的行动特征。