Chapter 30 – Class: MAMMALIA

I. Characteristics of MammalsA. Hair – made of keratin protein;

evolved from scales1. Hair is used for:

Insulation – conserves body heat

Camouflage

Defense

Sense changes in environment

Waterproofing

2. Cooling Off Panting: releases water from nose

& mouth, causing loss of body heat Sweat glands: moisture is secreted onto skin’s surface; as moisture evaporates, heat from body is transferred to air

B. Mammary Glands - produce & secrete milk that is rich in nutrients

C. Diaphragm – sheet of muscle that expands chest cavity to get O2 into

lungs

D. 4-chambered heart – fully separates O2-rich blood from O2-poor blood, delivering the

maximum amount of O2 to the body

E. Special Teeth – based on diet

1. Incisors – chiseled flat for biting & cutting

2. Canines – sharp for stabbing & tearing

3. Premolars & Molars –

flat for

grinding & crushing

F. Endothermic

G. Internal Fertilization

H. 2 pairs of limbs in most species – for food gathering (opposable thumbs, wings, etc.)

I. Highly developed brains - mammals:

1.can learn2. use tools

3. are the most intelligent animals

II. Diversity of Mammals – 3 Subclasses, based on method of reproduction

A. Monotremes1. Lay amniotic eggs 2. platypus, spiny

anteater/echidna

3. Found only in Australia, Tasmania, & New Guinea – evolved after Pangaea split up

B. Marsupials

1. Young develop incomplete inside mother, then in pouch made of skin & hair – are blind & hairless

2. koala, kangaroo, opossum

3. Found mainly in Australia – evolved before

Gondwana split up

C. Placental Mammals (90% of all mammals)

1. Young develop inside mother’s muscular uterus until

body systems are fully functional & can live independently of mother’s body

2. Placenta – organ that provides nutrients to offspring

3. Gestation varies by body size, but these mammals are better protected 4. Human, dog, horse, lion, seal, whale

5. Found Worldwide – evolved before Pangaea split up

III. Orders of the class MAMMALIAOrder INSECTIVORA – shrew, moleOrder CHIROPTERA – batOrder RODENTIA – rat, squirrel, gopherOrder LAGOMORPHA – rabbit, hareOrder EDENTATA – armadillo, sloth,

giant anteaterOrder CETACEA – whale, dolphinOrder SIRENIA – manateeOrder PROBOSCIDEA – elephantOrder CARNIVORA – dog, cat, lion,

bear, seal, walrus

Order ARTIODACTYL – cow, deer (even #)

Order PERISSODACTYL – horse (odd #)Order PRIMATES – gorilla, monkey,

man