It makes a wonderful link between swimming, as you find it in eels or fish, and quadruped locomotion, as you see in mammals, in cats and humans.
ウナギ、魚類の泳ぎと ウナギ、魚類の泳ぎと ネコやヒトなどの哺乳類に見られる 四足歩行を見事にリンクさせています