Rolf Hicker Nature Photography
Humpback Whale, Megaptera novaeangliae at MarineBio.org
) to expand during feeding. The baleen plates are broad and short, and the left and right rows are continuous anteriorly. The dorsal fin is
falcate
(curved).
Whale Evolution
All members of the
Order Cetacea
(includes all whales, toothed and those using baleen) are believed to have evolved from terrestrial hoofed mammals like cows, camels, and sheep some 45 million years ago - that's about 40 million years before man! Recent comparisons of some milk protein genes (beta-casein and kappa-casein) have confirmed this relationship and have suggested that the closest land-bound living relative of whales may be the hippopotamus. Throughout their evolution, cetaceans have become perfectly suited to an aquatic environment, and are virtually incapable of leaving it. Cetaceans illustrate an example of
|
