1. Charismatic Megafauna (Marine Mammals)
- Classification of Marine Mammals
- Whales and Whaling
- Review for Exam 3
Reading:
4th Ed, Ch 15 Secs 35-39, Ch 6 Secs 21-22, Ch 17 Sec 19
5th Ed, Ch 15 Secs 35-38, Ch 6 Secs 24-25, Ch 17 Sec 21
Graphic: Humback whale breaching. Cmmdr. J. Bortniak, NOAA Corps, photographer.
Courtesy of NOAA.
2. Classification of Marine Mammals
Cetaceans: Porpoises, Dolphins, Whales
Carnivora (Pinnipedia): Seals, Seal lions, Walruses
Sirenia: Manatees, Dugongs
Graphic: (top) Manatee. National Marine Fisheries Service Historical Collection.
Courtesy of NOAA, (bottom) 38 Ma, Dorudon atrox skeleton at the Univ. of
Michigan.
3. Traits Common to All Marine Mammals
- Streamlined body shape
- Generate internal body heat
- Modified respiratory system
- Adaptations to salt water environment
Graphic: Dolphins in bow wake. Cmmdr. G. Tuell, NOAA Corps. Courtesy of NOAA.
4. Adaptations Common to Many Marine Mammals
Large body size
- reduces heat loss
Blubber/fat layer
- insulates against cold
- stores food reserves
- aids in floatation
- improves streamlining
Graphic: Walrus contemplating the photographer. Capt. B.Christman, photographer
(NOAA Corps). Courtesy of NOAA Photo Gallery.
5. The Diving Reflex
Per kg of mass, marine mammals store more oxygen than humans
- most oxygen is stored in body tissues, not the lungs
Oxygen in 30kg seal
70 kg human
Lungs
55 ml
720 ml
Blood
1125 ml
1000 ml
Muscle and 370 ml
440 ml
tissue water
Total
1550 ml
2160 ml
Oxygen per kg 52ml/kg
31ml/kg
Graphic: Humpback whale's tails have distinctive markings which identify each
individual. Cpt. B.Christman (NOAA Corps), photographer, courtesy of NOAA.
6. Seals and Sea Lions - What's the Difference?
Seals:
- smooth heads
- use webbed hind feet spread vertically like the back fin of fishes
Sea Lions:
- protruding ears
- front flippers as paddles
- hind limbs have greater range of motion
Both leave the ocean to mate and raise young
Graphic: Top: Monk seal. Dr. J.P. McVey, NOAA Sea Grant. Courtesy of NOAA.
Bottom: Stellar sea lion. Capt. B. Christman, NOAA Corps. Courtesy of NOAA.
7. Whale Migrations and Navigation
Whales can migrate 1000's of kilometers
Many whales move between
-warm water wintering grounds
-cold water feeding grounds
Navigation
- based on sensing Earth's magnetic field
- fluctuations in the magnetic field may explain mass strandings of whales
Graphics: Garrison, 4th Ed., Box 15.2b (top) and 15.2a (bottom), pg 407. Note
error in Box 15.2, Fig. b (summer feeding areas are in polar zones, winter
breeding areas are in tropical zones).
8. Migrations, Whale Songs and Identification
During migrations, whales vocalize ("sing") to stay in contact
This is particularly important for young whales, who must remain near their
mothers
A whale's song is as distinctive as its markings
Graphic: Humback whales. R. Wicklund, OAR/National Undersea Research Program and
Univ. of N. Carolina at Wilmington. Courtesy of NOAA.
9. Breaching and Spyhopping
Whales exhibit many complex behaviors
Breaching may help establish dominance
Spyhopping in coastal waters may help whales get their bearings
Graphics: Whale behavoir (top) humpback breaching, (bottom) orca spyhopping,
both courtesy of NOAA.
10. Giant Size from Tiny Food!
Baleen whales are the largest known animals
A diet abundant in plankton provides the energy that these giants need to
survive
Graphic: Humpback whales feeding on krill, courtesy of NOAA.
11. Baleen Whales
Baleen:
-sheets of closely-spaced parallel plates
- used to strain food
Feeding strategies:
- sieve while moving forward
- lunging into schools of prey
- scooping mud from the bottom
Each feeding strategy corresponds to different body types
Graphic: Garrison, 4th Ed., Fig. 15.41a, pg 408, 5th Ed., Fig. 15.41a, pg 384.
12. Baleen Whale Species
Sieving (right, bowhead)
- large mouths
- long baleen fringes
Lunging (minke, blue, humpback, fin, sei)
- smaller mouths (that open wide)
- pleats or furrows in throat
Bottom feeders (grey)
- adapted for scooping sediment
Graphic: Garrison, 4th Ed., Fig. 15.39a, pg 404, 5th Ed, Fig. 15.39, pg 404.
13. Toothed Whales
Toothed whales hunt using echolocation (biological equivalent of sonar)
Modifications of head and respiratory systems allow
- sending and receiving sounds over a wide range of frequencies
- focusing the direction of the sound they emit
Graphic: Garrison, 4th Ed., Fig. 15.40, pg 406, 5th Ed., Fig. 15.40, pg 384.
14. Toothed Whale Species
Large brains for advanced sound processing
Prey depends on size
Small (porpoises,dolphins)
- small squids and fish
Larger (killer)
- fish, penguins, seals, sea lions, porpoises
Very large (sperm)
- giant squid
Graphic: Garrison, 4th Ed., Fig. 15.39b, pg 405, 5th Ed., Fig. 15.39, pg 405.
15. A Timeline of the Whaling Industry
1600s First major commercial whaling
1868 Invention of explosive harpoon gun
1900s Use of motorized ships and "factory" ships
1930s Blue whales reduced to 4% of original numbers
1946 Formation of International Whaling Commission (IWC)
Graphic: Whale fishery. From a painting by J.S. Ryder. NOAA Historic National
Marine Fishery Service Collection.
16. A Timeline of the Whaling Industry
1979 IWC moratorium on whaling (Indian Ocean) outlaws use of factory ships
1985 Start of global commercial whaling moratorium
1994 Establishment of whale sanctuary (Antarctic waters)
1994 Grey whale is 1st marine mammal removed from US endangered species list
Commercially extinct whales: fin, sperm, sei, blue, humpback
Graphic: Whaling vessels, New Bedford MA, 1901. C. Stevenson, 1902.
17. The Marine Mammal Protection Act (1972)
Bans:
(1) Taking of marine mammals in US territorial waters
(2) Imports of marine mammal products
(3) Taking of marine mammals on the high seas by persons or vessels subject to
US jurisdiction
Significantly reduced the dolphin "bykill" from the tuna industry
Graphic: Humback whales. R. Wicklund, OAR/National Undersea Research Program and
Univ. of N. Carolina at Wilmington. Courtesy of NOAA.
18. Midterm 3 - Overview
Tuesday, Apr 10, Lectures 14-20 (inclusive), Waves through Mammals
Each midterm worth 26% of your total grade; your lowest midterm is dropped
~60 questions, multiple choice with diagrams and maps
Bring a pencil (or two) and an eraser – be on time
Content: Waves, Tides, Coastlines and Beaches, Challenges of the Marine
Environment, Marine Plants, Marine Invertebrates and Fish, Marine Mammals