Michael A. Castellini & Jo-Ann (North Pacific Research Board, USA) Mellish 
Marine Mammal Physiology 
Requisites for Ocean Living

Suppose you were designing a marine mammal. What would you need to think about to allow it to live in the ocean? How would you keep it warm? What would you design to allow it to dive for very long periods to extreme depths? Where would it find water to drink? How would you minimize the cost of swimming, and how would it find its prey in the deep an