Origin, Chapter 6, a whale of a difficulty

Darwin wrote, “It has been asked by the opponents of such views as I hold, how, for instance, a land carnivorous animal could have been converted into one with aquatic habits; for how could the animal in its transitional state have subsisted?”

To address this Darwin cited examples of modern animals that posses transitional habits, like mink, which are at home on land and in water, and examples of animals with present adaptations that are ill suited to their present habitat, like upland geese that rarely or never go near the water, yet have webbed feet.

Again, 150 years of research has borne out Darwin’s hypotheses, and the evolution of the whale is the prime example of a land carnivorous animal that converted to an aquatic habit.

Image of whale evolution from http://darwiniana.org/whale1.gif