ABSTRACT
This chapter focuses on the concept that deep diving marine mammals and birds are adapted to withstand both the rapid and extreme pressure changes that are associated with diving. Even though they are air-breathing endotherms like humans, marine mammals and diving birds exploit the deep marine environment freely and with very few negative repercussions. There are three groups of marine mammals that include the cetaceans, pinnipeds and sirenians. From first principles, one might expect that the ability to tolerate pressure collapse of internal air spaces, the ability to rapidly ascend and descend without suffering from the ‘Bends’ and the time necessary to swim to great depth would be important limiting factors for these mammals and birds. In some of the very first studies of diving depth and duration under natural conditions, G. L. Kooyman demonstrated that the longest dives of Weddell seals were usually ‘shallow’.
