Section Objectives: Objective 1: Describe the evolutionary origin of modern mammals Objective 2: Describe basic characteristics of modern mammals Objective 3: Explain the characteristics and classification of Cetaceans Objective 4: Explain the characteristics and classification of Chiropterans Objective 5: Explain the characteristics and classification of Primates Objective 6: Explain the characteristics and classification of Ungulates Objective 7: Explain the characteristics and classification of Carnivores Objective 8: Explain the characteristics and classification of Monotremes and Marsupials

Section 32.1 Summary – pages 841 – 847 What is a mammal? Mammals, like birds, are endotherms. Section 32.1 Summary – pages 841 – 847

Section 32.1 Summary – pages 841 - 847 What is a mammal? They have hair and produce milk to nurse their young. Mammals also have diaphragms, four-chambered hearts, specialized teeth, modified limbs, and highly developed brains. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals have hair Like feathers, mammalian hair, made out of the protein keratin, is also thought to have evolved from scales. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals have hair The arrangement of hair provides insulation and waterproofing and thereby conserves body heat. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals have hair Mammals also have internal feedback mechanisms that signal the body to cool off when it gets too warm. Mammals cool off by panting and through the action of sweat glands. Panting releases water from the nose and mouth, which results in a loss of body heat. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals have hair Sweat glands help regulate body temperature by secreting moisture onto the surface of the skin. As the moisture evaporates, it transfers heat from the body to the surrounding air. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals nurse their young Mammals have several types of glands, which are a group of cells that secrete fluids. They include glands that produce saliva, sweat, oil, digestive enzymes, hormones, milk, and scent. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals nurse their young Mammals also feed their young from mammary glands, possibly modified sweat glands, which produce and secrete milk, a liquid that is rich in fats, sugars, proteins, minerals, and vitamins. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals nurse their young Mammals nurse their young until they are able to digest and absorb nutrients from solid foods. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 – 847 Respiration and circulation in mammals The mammals’ diaphragm helps expand the chest cavity to aid the flow of oxygen into their lungs. Position of ribs when exhaling Position of ribs when inhaling Lungs when exhaling Lungs when inhaling Position of diaphragm when inhaling Position of diaphragm when exhaling Section 32.1 Summary – pages 841 – 847

Section 32.1 Summary – pages 841 - 847 Respiration and circulation in mammals A diaphragm is the sheet of muscle located beneath the lungs that separates the chest cavity from the abdominal cavity, where other organs are located. Position of diaphragm when inhaling Position of diaphragm when exhaling Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Respiration and circulation in mammals Mammals have four-chambered hearts in which oxygenated blood is kept entirely separate from deoxygenated blood. Left atrium Right atrium Right ventricle Left ventricle Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Respiration and circulation in mammals Circulation also removes waste products from cells and helps regulate body temperature. Blood helps keep a constant cellular environment, which maintains homeostasis. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Most mammals have specialized teeth Mammals with teeth have different kinds that are adapted to the type of food the animal eats. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Most mammals have specialized teeth The pointed incisors of moles grasp and hold small prey. The chisel-like incisors of beavers are modified for gnawing. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Most mammals have specialized teeth A lion’s canines puncture and tear the flesh of its prey. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Most mammals have specialized teeth Premolars and molars are used for slicing or shearing, crushing, and grinding. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Most mammals have specialized teeth Many hoofed mammals have an adaptation called cud chewing that enables the cellulose in plant cell walls to be broken down into nutrients they can absorb and use. When plant material is swallowed, it moves into the first two of four pouches in the stomach where cellulose in the cell walls is broken down by bacteria. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Most mammals have specialized teeth The partially digested food, called cud, is repeatedly brought back up into the mouth. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Most mammals have specialized teeth After more chewing, the cud is swallowed again and when the food particles are small enough they are passed to the other stomach areas, where digestion continues. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals have modified limbs Mammal limbs are adapted for a variety of methods of food gathering. Primates, for example, use their opposable thumb to grasp objects—including fruits and other foods. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals can learn Mammals can accomplish complex behaviors, such as learning and remembering what they have learned. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals can learn Primates, including humans, are perhaps the most intelligent animals. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals can learn Chimpanzees, for example, can use tools, work machines, and use sign language to communicate with humans. Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 Mammals can learn Cerebrum Motor area Sensory area Speech area Language area Vision area Taste area General interpretation area Intellect, learning, and personality Balance area Hearing area Brain stem Cerebellum Section 32.1 Summary – pages 841 - 847

Section 32.1 Summary – pages 841 - 847 A Mammal Heart Diaphragm Glands Teeth Mammary glands Hair Section 32.1 Summary – pages 841 - 847