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Compare-Contrast-Connect: The Deep Divers

NGSS Crosscutting Concepts
NGSS Disciplinary Core Ideas


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

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.


SF Table 9.1. A table showing several marine organisms, the maximum depth and pressure they can achieve, and the relative size of their lungs when at depth.

Dives to depth




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
  1. Calculate the pressure (atm) at the maximum diving depth for each of the organisms in SF Table 9.1.
  2. What is the relationship between maximum diving depth and the volume of lungs at depth compared to the surface?
  3. Consider the conditions in the deep ocean. What other adaptations would an organism need to survive in deep waters?
Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.