MidTerm Answer Key

SIO 133 Mid Term ANSWER KEY (Answers)
Multiple Choice (10 questions – 2 points each)
Please circle the best response
1. Which one of the following is not a characteristic of Class Mammalia?
a. Giving birth to live young (viviparous)
b. Three inner ear ossicles
c. Exothermy
d. Seven cervical vertebrae
2. Which of the following is the best example of Linnean binomial nomenclature?
a. ANCEPS Fuit discipulus
b. Indopacetus pacificus
c. Beaked whale
d. Pinnipedia
3. The study of biological diversity with emphasis on phylogeny is:
a. Systematics
b. Morphology
c. Classification
d. Taxonomy
4. Which of these families is the most speciose?
a. Neobalaenidae
b. Kogiidae
c. Monodontidae
d. Delphinidae
5. Modern cetaceans are considered to be:
a. monophyletic
b. polyphyletic
c. paraphyletic
6. This sub-family contains several species of ice-dependent seals:
Both a and b
No seals are truly ice dependent
7. The recovery of Antarctic Fur Seals following industrial whaling around South Georgia has been
proposed as an example of:
a. prey switching
b. competitive release
c. niche partitioning
d. direct effect
8. What factor is not believed to drive mysticete migrations:
sea ice
rate of upwelling
gradients in salinity
9. The transduction mechanism for mammalian hearing takes place within the:
tensor tympani
10. The marine mammal species best documented to be sensitive to anthropogenic sound is the:
Zalophus californianus
Phoca vitulina
Delphinus delphis
Ziphius cavirostris
Fill-in-the-blank/short & long answers
11. Briefly describe each of the following oceanic processes:
Upwelling: (2 points)
A process driven by wind blowing across the surface of the ocean for long periods of time (e.g.,
weeks, months) that advects typically nutrient-rich water from deep in the ocean to the surface.
Wind-Mixing: (2 points)
A process driven by repeated storms at sea that creates regional scale, deep ocean-mixing, leading
to nutrients being brought up into the photic zone.
12. List one geographical example of an area typically associated with upwelling (1 point)
Equator, California Current, any eastern boundary current, the north Pacific gyre, the Antarctic.
13. The fill in the blanks below to describe the following equation:  =
a. This equation is also known as __________________ (Fick’s Law).

(4 points)
b. The variable “A” refers to ________________________ (Surface area).
c. The thick blubber layers of marine mammals have reduced conductive heat loss by
increasing variable ______ (l) and decreasing variable ______ (∆  ).
14. To what taxonomic family would the drawing of the above whale belong? (2 points)
15. Give the common and scientific name for an example species from the family above. (2 points)
Humpback whale (Megaptera novaeangliae)
Blue whale (Balaenoptera musculus)
Fin whale (Balaenoptera physalus)
Pygmy fin whale (Balaenoptera omurai)
Minke whale (Balaenoptera acutorostrata)
Bryde’s whale (Balaenoptera edeni/brydei)
Sei whale (Balaenoptera borealis)
16. Provide four examples of characteristics that differ between mysticetes and odontocetes:
(4 points)
Example: Migrations
relatively long
relatively short
Feeding morphology: Baleen vs. teeth
Body size: large vs. small
Skull morphology: Symmetrical vs. assymetrical skull
Skull morphology: 2 vs 1 external blowhole
Migration: long seasonal vs. short to- none
echolocation: absent vs. present
17. During the early Eocene, ancestors of modern cetaceans began to adapt to an aquatic lifestyle in
the ______________ (Tethys) Sea. (2 points)
18. There are three major adaptations associated with the evolution from ancient whales to
modern whales that apply to all modern cetaceans. List all three below and provide a sentence or
two for each to explain its adaptive significance.
6 points (1 for feature, 1 for explanation)
Reduction of hind limbs – increased hydrodynamic efficiency
Hyperphalangy – use of forelimbs for locomotion in water
Telescoping of skull – nares on top of head for oxygen
19. Is this a phocid or an otariid? List two characteristics of this animal that helped you decide.
(4 points)
Otariid, it is swimming with its foreflippers, smaller body size, has long neck, or it has external ears.
20. What order contains the pinnipeds, sea otters and polar bears? (2 points)
21. Complete the following table with the missing information: (12 points)
Example Common Name
Example Species (Latin
sperm whale
leopard seal
Hydrurga leptonyx
22. Place these in order from oldest to youngest: Sea Otters/Cetaceans/Phocids/Sirenians/Otariids
(5 points)
Oldest  ________, _________, _________, __________, __________  Youngest
Cetaceans, Sirenians, Phocids, Otariids, Sea Otters
23. Are marine carnivores a monophyletic group? (2 points)
24. List 2 aspects of fur seal biology which make them vulnerable to over-exploitation (4 points)
Harem reproduction strategy of the animals makes them easy targets
80% of breeding population for Northern fur seal uses Pribilof Islands
Pup mortality is naturally high
25. Due to climate change, there may be reduced sea ice habitat for krill resulting in a decline in
krill populations. Whale populations that are dependent on krill may suffer as a result. Is this an
example of a bottom up or top down process? (2 points)
Bottom up
26. Please name and describe the hypothesis that Springer et al 2003 present to explain the curves
in the figure above. (4 points)
Sequential Megafaunal Collapse Hypothesis: After great whales were commercially huntend in the
North Pacific, killer whales that had previously preyed on them were forced to switch to prey on
pinnipeds and eventually otters which lead to the sequential collapse of each population.
27. List 3 lines of evidence that are used to support this hypothesis: (6 points)
● -Stellar sea lion adults and pups had good body condition, reduced foraging effort and relatively
low field metabolic rates, not supporting the nutrient-limitation explanation for their low
● -Abundant SSL prey was incongruent with nutrient limitation hypothesis
● -Seabird populations feeding on same type of prey as SSL were stable or increasing over the
same period
● -killer whales attack and consume all species of great whale
● -Scars from KW teeth on great whales indicate attacks are common
- migration of baleen whales had been proposed as evolutionary response to KW predation
● -failure of bowhead whales in arctic to recover from commercial whaling was also proposed as
a result of KW predation
28. Provide at least one piece of evidence that disputes the SMC hypothesis: (2 points)
● peak of whale biomass removal differs from what is claimed (large baleen whale biomass in
Bering Sea, Gulf of Alaska, and West Coast of N. America all much greater than pinniped biomass
during the time period)
● whale biomass trends were increasing in that time period (humpback, blue, gray, fin – in the
different regions)
● known KW predation patterns differ from what is claimed (no large population of KWs that
primarily ate whales)
● minke whales and small cetaceans have always been available as prey for killer whales
● it is widely considered to be rare and maladaptive for killer whales to unidirectionally switch
prey for extended time
● decline of pinnipeds and sea otters was not statistically sequential
29. Shade in the area of this globe that represents the antitropical region. (2 points)
30. Draw a feedback loop that describes an interaction between climate change and rising
temperatures in the ocean. (2 points)
Increased atmospheric CO2  Increased temperature/oceanic stratification  decreased
Decreased ice cover  decreased reflectance of solar radiation  increased temperature
31. Explain how each of the following aspects of climate change will affect marine mammals, and
provide one example. (4 points)
a. Warming oceanic temperatures
Warming waters are latitudinally changing the distribution of some marine mammals. This is
especially threatening for species that cannot shift due to geographical barriers. Examples include
all polar species, or the Vaquita.
b. Loss of sea ice
● Reduction of habitat for ice seals – examples are beach crowding for walruses or reduction of
the ring seal population.
● Reduction in production and availability of krill to seals and whales.
● Longer migration routes for migrating whales – example is the gray whale.
● Loss of temporal alignment for migrations with prey – example beluga whales showing up
before salmon.
32. List four adaptions that have improved underwater vision for marine mammals . (4 points)
Large eyes
Increased photoreceptor density
Increased % of rods vs. cones
Shifted pigments to detect blue/green light
Tapetum lucidum
Rapid dark-adaption rates