Cetacea

Question 1

What are the 2 suborders in Cetacea?

Answer 1

• Mysticeti (toothless whales)

- Odontoceti (toothed whales)

Question 2

Suborder: Mysticeti

Answer 2

• Skull symetrical
• Paired external snares
• Do not echolocate
• Sternum consists of one bone

Question 3

Suborder: Odontoceti

Answer 3

• Single external snare
• Teeth usually homodont, monophyodont
• Echolocate
• Sternum consists of three or more bones
• Skull generally asymetrical

Question 4

Fossil Record

Answer 4

• All morphologicals are secondarily derived, whales evolved from terrestrial mammals
• Share common ancestor w/ archaic ungulate
• Common ancestor for both orders was order Condylarthra in the Paleocene

Question 5

Skull Morphology

Answer 5

• Unusually long rostrum
• Nares migrated back
• Bones in skull are telescoped

Question 6

Tail and Limb Morphology

Answer 6

• Tails flattened dorsal-ventrally into flukes
• Forelimbs are modified flippers
• Vestigial hind limbs
• Dorsal fin in most species

Question 7

General Morphology

Answer 7

• Fusi-form shaped body
• Blubber
• No sebaceous glands
• Hairless
• Specialized muscles to control blow hole
• Neck short and cervical vertebrae fused

Question 8

Sensory Abilities

Answer 8

• Large brains
• Use auditory communication
• Some species echolocate
• Dolphins can see just as well above and below the surface of the water

Question 9

Respiratory Adaptions

Answer 9

• Extra capillaries in lungs
• Use 3x as much oxygen from air as terrestrial mammals
• Can force almost all air from lungs when exhaling
• High tolerance to carbon dioxide

Question 10

Circulatory Adaptions

Answer 10

• Twice as high concentration of red blood cells
• 2-9 times as much myoglobin in muscle tissue
• Heart rate drops half of normal during long dives
• During dives, blood is redistributed
• High tolerance to lactic acid

Question 11

Swimming Adaptions

Answer 11

• Lack of hair except few vibrissae
• Few external appendages
• Parabolic body form

Question 12

When were the first baleen whales seen?

Answer 12

In the late Oligocene

Question 13

What is the ancestor of baleen whales?

Answer 13

• Aetiocetus cotylalveus

- Baleen whales used to posses teeth

Question 14

Use of Echolocation

Answer 14

• Production of clicks
• Focusing of clicks thru melon
• Reception by lower jaw and middle ear

Question 15

How is respiratory canal and food passages separated?

Answer 15

Thru specializations in the glottis and larynx