Mammals come in a bewildering variety of shapes and sizes and yet all of the 4700 or so species have some characteristics in common, which justifies the inclusion of diverse types within a single group. Although mammals evolved on land, a number of species have become adapted to spending part or all of their lives in water and it is these mammals that you are going to concentrate on in this course. You will meet some aquatic mammals, find out how we can study them, consider their evolutionary history and read about human impacts on one iconic group.

After studying this course, you should be able to:

• contrast the physical properties of air and water and describe implications of such differences for aquatic mammals
• give examples of the adaptations displayed by aquatic mammals that enable them to hold their breath while submerged for relatively long periods
• describe some of the biological differences between pinnipeds, sirenians and cetaceans
• discuss the importance of communication by sound in aquatic mammals, describe the role of blubber and explain countercurrent heat exchange
• explain the diving response and its significance in natural dives.