These photos of a mother and young cetacean were taken off Sri Lanka on the usual Blue-Whale-watching boat trip off Mirissa in April 2015. The boatmen said they thought they were Short-finned Pilot Whales. But they appeared to be more-or-less the size of Spinner Dolphins whereas the Pilot Whale is much larger.
I now think they may have been Dwarf Sperm Whales based on the 45°slope of the leading edge of the dorsal fin (unlike the similar-sized Pygmy Killer and Melon-headed Whales) and the peculiar tip of the dorsal fin , as well as the long, straight back in front of the dorsal fin and slight angle between the back and what appears to be the back of the head. This is consistent with their floating with dorsal fin and front part
of back exposed, and having disappeared by sinking into the water.
Would someone with experience in cetacean identification please help me confirm or discard this tentative identification?
Héctor Gómez de Silva