L7 Bevan - Cetacean and Pinniped Diversity and Adaptions

Question 1

What are the 3 families of seal?

Answer 1

Otariidae = sea lions and fur seals

Phocidae = ‘true seal’ - crabeater, leopard, weddell, harbour/common, grey

Odobenidae: walrus

Question 2

What order are each in?

a) polar bears
b) otters
c) dugongs and manatees

Answer 2

a) Polar bear - Ursidae
b) Mustelidae - otters
c) dugongs and manatees - Sirenia

Question 3

What adaptions to cetaceans have for thermoregulation?

Answer 3

1. Blubber - also doubles as an energy store
2. Circulatory adjustments - counter current heat exchangers (also used for heat radiation, which is dangerous for beached whales)

Question 4

What other adaptions apart from for thermoregulation do cetaceans have?

Answer 4

Osmoregulation - it takes in salt water

Sensory adaptions - echolocation (only in odontocetes)

Question 5

Cetaceans are long lived but have low recruitment, what is meant by this?

Answer 5

They breed every 1-4 years

Only produce 1 calf each time

Late sexual maturity

Question 6

What 2 ways can you determine a whales age?

Answer 6

1. tooth aging - GLGs (growth layer groups)
2. Ear plugs - these sit i the channels from exterior to inner ear of whales, as whales grow so do these

1 GLG = 1 year

Question 7

What family do dolphins belong to?

Answer 7

Delphinidae

Question 8

What family do porpoises belong to?

Answer 8

phocoenidae

Question 9

What kind of system is the cetacean mating system?

Answer 9

They are either polygynous (1 male many females) or promiscuous (not attached)

Question 10

What grouping do whales form?

Answer 10

Baleen whales usually don’t form groups, if they do they are small
Humpback whales are an exception - group foraging

Odontocetes are different and do form groups - killer whales hunt in groups

Question 11

Describe the reproductive biology of Humpback Whales

Answer 11

• they have low latitude winter breeding grounds
• small groups of females are escorted by males
• competitive group of males competing for a single female during breeding season
• females reproduce every 2-4 years

Question 12

How do whales bubble net feed?

Answer 12

1. a dozen whales work together
2. 1 leader
3. once a shoal of fish is found the leader blows a net of bubbles that completely encircles the shoal
4. another whale calls to synchronise the group and to scare the fish
5. The fish panic with the sound, and wont cross the bubble net - whales catch them
6. Only occurs in Alaska

Question 13

What are the 3 types of grouping in Killer Whales?

Answer 13

1. Resident - complex and stable social grouping system
2. Transient - Transient pods are smaller than resident pods, typically consisting of an adult female and one or two of her offspring
3. Pelagic

Question 14

What is the social structure of pilot whales

Answer 14

• Matrilineal pods
• post reproductive females maintained - odd in a nature as they have a loss of purpose - can provide a stability to the group, and roles such as:
  - protection
  - knowledge
  - surrogate mothers

Question 15

What kind of groups do Sperm Whales form?

Answer 15

• groups of females and immatures for units of 5-15 whales (similar to killer whales) found at lower lats
• males age 4-5 leave the group and move to a higher latitude

Question 16

What kind of group does each form:

a) bottle nosed dolphins
b) spinner dolphins
c) harbour porpoise

Answer 16

a) fission-fusion structure - small groups of 2-10 animals with females and their offspring. Mature males for pairs or triplets that are stable for years
b) large groups 100-1000, sub groups of 12-15. These show leaping and spinning - sexual display?
c) small groups 1-3 animals, usually mature at 3-4 years

Question 17

What are the advantages of group living?

Answer 17

• Protection against predators
• easy to find mates
• co-operative foraging

Question 18

What are the disadvantages of group living?

Answer 18

• competition for prey
• risk of inbreeding - genetically isolated pods
• risk of extirpation (eradication) if subjected to a large scale mortality event