Tail flukes.

Humpback whale diving, Antarctica.

A Humpback whale displays its tail flukes as it dives to feed. Antarctica. The markings on the underside of the humpback’s tail are as individual as human fingerprints and provide a means for researchers to catalogue the movements of specific whales.

Humpback whale diving, Antarctica.
A Humpback whale displays its tail flukes as it dives to feed. Antarctica.

Part of the Antarctica image gallery. ~KD.