xviii
Introduction
weaned, fasting elephant seal pup on a California beach are not the same as those facing
a whale on a long migration, yet they approach it in a remarkably consistent fashion. The
hydrodynamic design of a swimming walrus is not very similar to that of a high-speed
dolphin, but they are both constrained by the forces of drag, lift, and buoyancy. Each chapter has a “Toolbox” section where the authors discuss many of the newest methods for
working on the physiology of marine mammals.
In short, we are asking you to consider the following questions: If 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 and dark? These
questions and more are throughout this book. As with all research, we expect that for
every question answered, you will ask several more.
I.2 What are the requisites for ocean living?
Our chapter topics are grouped into major themes: diving and locomotion, nutrition and
energetics, reproduction, sensory systems, and environmental interactions.
We begin with one of the most fundamental aspects of these species, diving and locomotion. Marine mammals need to be able to swim and dive and to do it very well. Humans
can swim and dive too, but it is clear that we cannot hold our breath for over an hour, or
dive to a 600 m depth. This group of four chapters (Section I) begins with an analysis of
marine mammal hydrodynamics by Jeremy A. Goldbogen, Frank E. Fish, and Jean Potvin
(Chapter 1). They explore many of the complications of moving a body through water that
must be resolved, including larger questions of drag, swimming at various depths, and
more unique aspects such as what happens when a whale swimming at high speeds opens
its mouth to catch krill on its baleen.
A marine mammal must be able to hold its breath for a very long time to be able to dive
and swim. As mammals, they do not have gills or specialized organs to extract oxygen
from the seawater. Where do they carry the oxygen they need, how do they utilize that
oxygen, and what happens if they stay underwater for longer than the amount of oxygen
they have available? Paul J. Ponganis and Cassondra L. Williams (Chapter 2) discuss how
these species can remain underwater for so much longer than terrestrial mammals.
Next, Terrie M. Williams and Jennifer L. Maresh (Chapter 3) discuss the energetic costs
of swimming and exercise. Even the most hydrodynamic body shapes incur energy costs
to move through the water. How does this efficiency vary among the wide range of marine
mammals? Does it cost the same to move a large whale through the water as it does to
move a small porpoise? What is the optimal speed to swim? How would you even begin
to consider effective measurements of the cost of swimming?
Finally, if the animals dive deeply, how do they withstand the tremendous pressures
at depth? Why do they not get “the bends?” What are the physiological and biochemical
adaptations that allow their tissues and cells to survive such an insult? There are many
marine mammal species that collapse their lungs dozens of times a day, yet this is a critical injury in a human. Sascha K. Hooker and Andreas Falhman (Chapter 4) explore those
adaptations that allow marine mammals to dive far deeper than freely diving humans
have ever even approached.
The next set of five chapters (Section II) examines how marine mammals are able to
feed, obtain energy, fast for very long periods of time, live without freshwater, and manage
to maintain their body temperatures in extreme environments.
Introduction
weaned, fasting elephant seal pup on a California beach are not the same as those facing
a whale on a long migration, yet they approach it in a remarkably consistent fashion. The
hydrodynamic design of a swimming walrus is not very similar to that of a high-speed
dolphin, but they are both constrained by the forces of drag, lift, and buoyancy. Each chapter has a “Toolbox” section where the authors discuss many of the newest methods for
working on the physiology of marine mammals.
In short, we are asking you to consider the following questions: If 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 and dark? These
questions and more are throughout this book. As with all research, we expect that for
every question answered, you will ask several more.
I.2 What are the requisites for ocean living?
Our chapter topics are grouped into major themes: diving and locomotion, nutrition and
energetics, reproduction, sensory systems, and environmental interactions.
We begin with one of the most fundamental aspects of these species, diving and locomotion. Marine mammals need to be able to swim and dive and to do it very well. Humans
can swim and dive too, but it is clear that we cannot hold our breath for over an hour, or
dive to a 600 m depth. This group of four chapters (Section I) begins with an analysis of
marine mammal hydrodynamics by Jeremy A. Goldbogen, Frank E. Fish, and Jean Potvin
(Chapter 1). They explore many of the complications of moving a body through water that
must be resolved, including larger questions of drag, swimming at various depths, and
more unique aspects such as what happens when a whale swimming at high speeds opens
its mouth to catch krill on its baleen.
A marine mammal must be able to hold its breath for a very long time to be able to dive
and swim. As mammals, they do not have gills or specialized organs to extract oxygen
from the seawater. Where do they carry the oxygen they need, how do they utilize that
oxygen, and what happens if they stay underwater for longer than the amount of oxygen
they have available? Paul J. Ponganis and Cassondra L. Williams (Chapter 2) discuss how
these species can remain underwater for so much longer than terrestrial mammals.
Next, Terrie M. Williams and Jennifer L. Maresh (Chapter 3) discuss the energetic costs
of swimming and exercise. Even the most hydrodynamic body shapes incur energy costs
to move through the water. How does this efficiency vary among the wide range of marine
mammals? Does it cost the same to move a large whale through the water as it does to
move a small porpoise? What is the optimal speed to swim? How would you even begin
to consider effective measurements of the cost of swimming?
Finally, if the animals dive deeply, how do they withstand the tremendous pressures
at depth? Why do they not get “the bends?” What are the physiological and biochemical
adaptations that allow their tissues and cells to survive such an insult? There are many
marine mammal species that collapse their lungs dozens of times a day, yet this is a critical injury in a human. Sascha K. Hooker and Andreas Falhman (Chapter 4) explore those
adaptations that allow marine mammals to dive far deeper than freely diving humans
have ever even approached.
The next set of five chapters (Section II) examines how marine mammals are able to
feed, obtain energy, fast for very long periods of time, live without freshwater, and manage
to maintain their body temperatures in extreme environments.