Chapter 30 – Class: MAMMALIA I. Characteristics of Mammals A. Hair – made of keratin protein; evolved from scales 1. Hair is used for: Insulation – conserves body heat Camouflage Waterproofing Defense Sense changes in environment

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 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 learn 2. use tools 3. are the most intelligent animals

II. Diversity of Mammals – 3 Subclasses, based II. Diversity of Mammals – 3 Subclasses, based on method of reproduction A. Monotremes 1. 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 MAMMALIA Order INSECTIVORA – shrew, mole Order CHIROPTERA – bat Order RODENTIA – rat, squirrel, gopher Order LAGOMORPHA – rabbit, hare Order EDENTATA – armadillo, sloth, giant anteater Order CETACEA – whale, dolphin Order SIRENIA – manatee Order PROBOSCIDEA – elephant Order CARNIVORA – dog, cat, lion, bear, seal, walrus Order ARTIODACTYL – cow, deer (even #) Order PERISSODACTYL – horse (odd #) Order PRIMATES – gorilla, monkey, man