Randall S. Wells’s research while affiliated with Chicago Zoological Society and other places

Bottlenose dolphins (. Tursiops truncatus) are the best known of all cetaceans. Variation in size, coloration, and cranial characteristics associated with feeding led to descriptions of at least 20 nominal species of Tursiops. Recognition of the polymorphic nature of Tursiops and the existence of clinal variation had led to general agreement for many years that Tursiops was a single-species genus. However, recent genetic, morphologic, and physiologic studies suggest that revision of the genus may be necessary to acknowledge significant differences between forms from different oceans, as well as differences between forms in inshore versus offshore habitats within ocean basins. Common bottlenose dolphins are found in temperate and tropical marine waters around the world, with an estimated 600,000 animals world-wide. In the North Pacific, they are commonly found as far north as the southern Okhotsk Sea, the Kuril Islands, and central California. In the North Atlantic, they are seen inshore during the summer months off New England and offshore as far north as Nova Scotia, and they have been recorded off Norway and the Lofoten Islands.