1. Biology of Marine Mammals
Chapter 9 Cont.

2. Swimming and Diving Pinnipeds swim mostly by moving their flippers
Sirenians and cetacean swim by moving their tails and flukes up and down
Remember: Fish swim by moving their tails from side to side.

3. Swimming and Diving INTERESTING FACTS:
Sea Lions have been timed at speeds of 22mph…
Blue and killer whales at 30 mph…
Group of common dolphins at 40 mph!

4. Swimming and Diving There is a wide range in diving ability:
Sea otters can dive for only 4-5 min to depths of 180ft
Pinnipeds normally dive for up to 30 min at maximum depths of ft
Weddell seal has been recorded diving for as long as 1 hr 13 min and as deep as 1,900 ft!
The sperm whale dives for at least an hour to depths of 7,380 ft!

5. Swimming and Diving Adaptations to Increase O2 for Dives:
As much as 90% of the oxygen contained in the lungs is exchanged during each breath (Humans = 20%)
Have relatively more blood than non-diving mammals
Blood contains a higher concentration of red blood cells that carry hemoglobin
Hemoglobin = blood protein that transports oxygen

6. Swimming and Diving Adaptations to Increase O2 for Dives:
Muscles contain more myoglobin
Myoglobin = a muscle protein that stores oxygen

7. Swimming and Diving Adaptations to Reduce O2 Consumption:
Heart rate slows during dives
Blood flow to non-essential parts of the body is reduced

8. Swimming and Diving
Bends = decompression sickness that is caused by nitrogen bubbles forming in the blood after diving
Nitrogen dissolves much better at high pressures, and the blood picks up nitrogen while below the surface
If the pressure is suddenly released, some of the nitrogen will not stay dissolved and forms tiny bubbles in the bloodstream

9. Decompression Sickness

10. Swimming and Diving How Marine Mammals Deal with the Bends:
Collapse lungs during dive
Air gets moved into the central spaces of the lungs where less nitrogen is absorbed
High levels of hemoglobin and myoglobin

11. Echolocation Sensory system based on hearing Nature’s version of sonar
Most (if not all) toothed whales and some pinnipeds are known to echolocate
Some baleen whales may also use echolocation

12. Echolocation
The animal emits burst of sound waves, or clicks, as air is pushed through internal air passages
The melon focuses the clicks into a “beam”
The sound wave “bounces” off of the target and is received by the lower jaw

13. Echolocation
The brain analyzes the echoes…the time it takes the echo to return tells the animal how far away the object is
Low frequency clicks have a high penetrating power and can travel long distances
High frequency clicks are used to discriminate detail and locate nearby prey

14. Behavior…

15. Behavior
Most marine mammals are highly social and live in groups at least part of the time
Sounds, or vocalizations, play a prominent role in communication

16. Behavior
Cetaceans are noted for their play behavior (seemingly pleasurable activities with no serious goal)
Play w/ food or floating objects by throwing them up in the air
Swim on their backs
Dolphins will surf waves and play with rings of bubbles they create

17. Behavior
Breaching = leaping up into the air

18. Behavior Additional evidence of complex behavior of ceteceans:
When one individual is in trouble, others may come to assist

19. Behavior Stranding or beaching: Animals that end up on beaches
Whales die because their internal organs collapse w/o the support of the water
Scientists do not know why beaching occurs, but some have been linked to high-intensity sonar

20. Beaching:

21. Migrations How do whales navigate? Possible answers:
Use memorized landmarks
Use the earth’s magnetic field (possess a type of internal compass to orient themselves)