Lab 9. Mammalia

Question 1

Unique characteristics

Answer 1

• hair
• mammary glands
• sweat, oil and scent glands
• 1 lower jaw bone (dentary)
• heterodont dentition
• 3 middle ear bones (ossicles)
• anucleate red blood cells
• diaphragm
• advanced cerebral cortex

Question 2

2 subclasses

Answer 2

Prototheria (oviparous)

Theria

Question 3

Prototheria infraclass

Answer 3

ornithodelphia (monotremes)

Question 4

2 subclass theria infraclasses

Answer 4

1. Metatheria

2. Eutheria

Question 5

Infraclass metathereia

Answer 5

viviparous, primitive placenta, marsupial pouch (marsupials)

Question 6

Infraclass eutheria

Answer 6

viviparous, complex placenta (placentals)

Question 7

Integument

Answer 7

• keratinized epideremis to protect from dehydration
• dermis = thick with many blood vessels for temp regulation
• sebaceous glands (lubricate and waterproof skin and hair)
• sudoriferous (sweat) glands for temp regulation

Question 8

Hair

Answer 8

• found on all mammals

- arrector pili muscle associated with each hair

Question 9

2 types of hair

Answer 9

1. guard hair

2. undercoat

Question 10

guard hair

Answer 10

long, coarse, weatherproofing when coated with thin layer of oil

Question 11

vibrissae/whiskers

Answer 11

modified guard hair for sensory role

Question 12

undercoat

Answer 12

short, fine hair for insulation

Question 13

Locomotion

Answer 13

• 7 neck vertebrae (elongated or compressed)
• trunk = thoracic (articulated for flexibility) and lumbar regions (interlocking processes, support at cost of flexibility)
• sacral vertebrae and other bones in pelvic girdle often fused (good for locomotion, sucky for birth, but joint between pelvis halves loosens a bit before birth)
• last vertebrae are caudal: tail! good for locomotion, thermoregulation, balance. sometimes just coccyx
• appendicular skeleton rotated under body so faster movement

Question 14

Food acquisition and digestion

Answer 14

• lower jaw is single bone (dentary/mandible)
• 2 sets of teeth during lifetime (milk/primary/deciduous and permanent)
• Heterodont
• some are homodont like dolphins
• some like anteaters have no teeth

Question 15

4 different types of teeth

Answer 15

• incisors
• canines
• premolars
• molars

Question 16

incisors

Answer 16

chisel-shaped. nipping/gnawing

Question 17

canines

Answer 17

long, pointed in carnivores and reduces in herbivores. catching prey/tearing flesh

Question 18

premolars

Answer 18

truncated surfaces for chewing

Question 19

molars

Answer 19

broad surfaces for chewing

Question 20

1/2 human jaw numbers

Answer 20

2.1.2.3

2 incisors
1 canine
2 premolars
3 molars

Question 21

gas exchange

Answer 21

• lots of alveoli

- makes up for inefficiencies associated with bidirectional flow of air

Question 22

Sensory abiliites

Answer 22

most complex brain
vision, hearing, smell and touch are sensory modes
unique in every mammal

Question 23

reproduction

Answer 23

only at specific time in year due to climate and resources
humans can control their environment so this doesn’t apply
large difference in gestation period
some are altricial and some are precocial
variable parental strategies

Question 24

altricial

Answer 24

helpless at birth

Question 25

pecocial

Answer 25

mature and mobile at birth