Obviously we are looking at the dorsal surface of a large cetacean such as a whale. The skin is dark blue-black with various nicks and scratches. Northern Right Whale, Southern Right Whale and Bowhead Whale lack a dorsal fin and can be eliminated.
The shape of the dorsal fin is the key. It emerges from the back with a gentle if irregular slope and is thus not 'shark-like'. This shape rules out Fin Whale, Sei Whale, Bryde's Whale, Minke Whale and the various beaked Whales - all of which have a more erect dorsal fin with a concave trailing edge.
The dorsal fin of Sperm Whale is reduced to rather triangular hump that is followed by a ridge of smaller bumps along the lower back. The skin is also characteristically wrinkled (prune-like) and is not smooth like the mystery mammal. This leaves Humpback Whale and Blue Whale. The dorsal fins of both species are rather variable in shape. The skin color seems too dark for Blue Whale and lacks the characteristic faint pale splotches. There is pronounced hump just in front of the fin. This is the feature that gives the Humpback Whale its name.
These Humpback Whales (Megaptera novaeangliae) including the 'mystery mammal' were all photographed on Monterey Bay California in July 1998.
Copyright © 1998 All rights reserved.Angus WilsonBack to the Index Page