Most people, when asked to name ten mammals off the top of their head, are likely to list only terrestrial mammals and don’t think to include marine mammals. It seems that we humans have an unconscious bias toward thinking of mammals as being terrestrial rather than maritime, perhaps because we ourselves are mammals, the dominant terrestrial mammals, and the other terrestrial mammals seem more like us than do the marine mammals. This is a book about all the marine mammals, and is divided by chapters into the four commonly recognized sub-groups: cetaceans (whales, dolphins, porpoises), sirenians (manatees, dugongs), pinnipeds (seals, sea lions, walruses), and fissipeds (polar bears, sea otters).
