230 likes | 394 Views
Chapter 30. MAMMALS. MAMMALS. Existed for 200 million years Therapsids - features of both reptiles & mammals. All mammals have: 1. Hair 2. Mammary glands. Hair: ~ Keratin. CLASS MAMMALIA. Hair: ~ Insulation ~Waterproofing ~Conserve heat. CLASS MAMMALIA.
E N D
Chapter 30 MAMMALS
MAMMALS • Existed for 200 million years • Therapsids - features of both reptiles & mammals
CLASS MAMMALIA • Hair: ~Insulation ~Waterproofing ~Conserve heat
CLASS MAMMALIA • Mammary glands - secrete milk
CLASS MAMMALIA • 4-Chambered Heart • Endotherms • Cooling • Panting or sweat glands
CLASS MAMMALIA • Modified limbs 1. Opposable thumbs 2. Various joint types
CLASS MAMMALIA • Diaphragm • Well-defined teeth 1. Incisors - biting 2. Canines - tearing flesh 3. Molars - chewing
Primates - most intelligent group of animals: - Complex behaviors:- Learning and remembering- Highly developed brains
Three types of mammals: 1. Monotremes 2. Marsupials 3. Placental Mammals
MONOTREMES • Reproduce by laying eggs • Only in Australia, Tasmania, New Guinea • 3 species alive today • Spiny anteaters (echidnas) – 2 species • Duck-billed platypus
MARSUPIALS • Marsupial - short period of development in uterus, second period inside a pouch • Mostly in Australia • One U.S. species
PLACENTAL MAMMALS • Female carries its young inside the uterus until almost completely developed • Gestation - time spent in uterus
Uterus - hollow, muscular organPlacenta - O2, nutrition, wastes VAGINA
COW DIGESTION Cud Chewing - breaking down plant materials (cellulose)