chapter 30 – class: mammalia i.characteristics of mammals a.hair – made of keratin protein;...
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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.)
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
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