Chapter 30MAMMALS

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

• 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

•Parental care - Guard young and teach them

Three types of mammals:

1. Monotremes 2. Marsupials3. 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

VAGINA

Uterus - hollow, muscular organPlacenta - O2, nutrition, wastes

COWDIGESTIONCud Chewing -

breaking down plant materials (cellulose)

Only in

India!