SF Fig. 9.3. Diving depth and duration records for human, walrus, bottlenose dolphin, sperm whale, and Cuvier’s beaked whale (Adapted from J. Cousteau, The Ocean World, 1979.)
Image by Byron Inouye
Title
Compare-Contrast-Connect: The Deep Divers
NGSS Crosscutting Concepts
NGSS Disciplinary Core Ideas
Table of Contents
For each 10 m of depth, the pressure on an object or organism increases by 1 atm. The relationship between pressure and volume is directly inverse. For each increase in pressure, there is a corresponding decrease in volume—this has profound implications for deep diving organisms with lungs (SF Fig. 9.3).
SF Table 9.1 shows the pressure that selected marine organisms can withstand at their maximum depths. For many of these organisms, it is not possible to maintain surface lung capacity at depth. They have special adaptations to survive their deep dives. The sperm whale, which holds the record for the deepest dives by a surface-dwelling animal, has a host of specializations that allow it to dive to amazing depths. The rib cage and lungs of the whale are actually adapted to collapse under pressure, squeezing all the air the lungs contain into a small space. When the sperm whale dives, the concentration of oxygen containing molecules in the blood and muscles—hemoglobin and myoglobin—are increased to hold more oxygen in the tissues. The whale experiences a reflexive response to the cold temperatures of the deep waters called bradycardia. Bradycardia is a slowing of the heart rate, which means that all physiological processes slow down and the whale consumes less oxygen.
| Organism |
Dives to depth (m) |
Pressure (atm) |
Percent volume of lungs at depth compared to surface |
|---|---|---|---|
| hawksbill turtle | 20 | 3 | 1/3 = 33% |
| human | 214 | 22 | 1/22 = 4.5% |
| Weddell seal | 741 | 74.5 | 1/74.5 = 1.3% |
| sperm whale | 2250 | 224 | 1/224 = 0,45% |
| Cuvier's beaked whale | 2992 | 298 | 1/298 = 0.34% |
Question Set
- Calculate the pressure (atm) at the maximum diving depth for each of the organisms in SF Table 9.1.
- What is the relationship between maximum diving depth and the volume of lungs at depth compared to the surface?
- Consider the conditions in the deep ocean. What other adaptations would an organism need to survive in deep waters?
