Human embryos, for instance, develop, then lose, gills, webbed feet and rudimentary tails, reflecting their ancient aquatic life styles.
They contended that land animals that began to adapt to aquatic life would soon be neither fowl nor fish, incapable of surviving in either medium.
Such algae blooms, which can choke other forms of aquatic life, have grown increasingly apparent in lakes and coastal waters recent years as a result of excessive use of agricultural chemicals.
