Class Mammalia is characterized by having mammary glands, hair, a diaphragm, and three middle ear ossicles. Mammals also have a heterodont dentition, sweat, sebaceous, and scent glands, a four chambered heart, and a large cerebral cortex. There are three main types of mammals: monotremes like the platypus and echidna, marsupials which have a pouch like kangaroos, and placental mammals which give birth to young that develop fully inside the mother like humans. Gestation periods vary greatly among mammals from 16 days in mice to 640 days in African elephants. Mammals can decrease their metabolic rates through torpor,

1. Class Mammalia

2. Characteristics
•Mammary glands
•Hair
•Diaphragm
•Three middle ear ossicles

3. Characteristics
•Heterodont dentition
•Sweat, sebaceous, scent glands
•Four chambered heart
•Large cerebral cortext

4. Mammary Glands

5. Hair
•Regulate body temperature
•Protection

6. Ossicles

7. Dentition

8. Heterodont Dentition

9. Human teeth

10. Large Cerebral Cortex

11. Types of Mammals
•Monotremes
•Marsupials
•Placental

12. Monotremes
Duck-billed Platypus
Echidna (Spiny Anteater)

15. Marsupials
• Pouched
• Not
mammals
well develop young

17. Placental Mammals
• Gives
birth to young that remain
inside the mother’s body until their
body system are able to function
independently.

18. Gestation Period
• The
time the young spend inside
the mother’s uterus.

20. Animal
Camel
Cat
Cow
Chimpanzee
Dog
Dolphin
Elephant, African
Ferret
Fox
Giraffe
Goat
Guinea pig
Hamster
Hedgehog
Horse
Human
Gestation Period
(days)
406
62
280
237
62
276
640
42
52
395-425
151
68
16
35-40
337
266
Animal
Hyena
Kangaroo
Lion
Mink
Monkey, rhesus
Mouse
Opposum
Orangutan
Pig
Rabbit
Rat
Reindeer
Seal, northern fur
Sheep
Skunk
Squirrel, grey
Gestation Period
(days)
110
40
108
50
164
21
13
245-275
113
32
21
215-245
350
148
62
44

21. Decrease of Metabolic Rates
•
Torpor-time of decreased metabolism and lowered body
temperature that occurs daily in bats, humming birds and
some other small birds and mammals.
•
Hibernation-decrease metabolism and lowered body
temperature that may last for weeks or months.
•
Winter Sleep-occurs in some large mammals. Sustain
mammals through periods of winter inactivity no dropping of
temp. substancially.
•
Aestivation-period of inactivity in some animals that must
withstand extended periods of drying. Common in
invertebrates, reptiles, and amphibians.