Taxonomy Chapter 22 Kingdom Animalia Phylum Chordata Class Mammalia Mammals Characteristics Evolution of Mammals Have hair and First appear in the mammary glands Breathe air, 4chambered heart, endotherms fossil record 220 million years ago About 60 million years ago was the mammal explosion Monotremes, marsupials, and placental mammals survive today A. Body Temperature Control Form and Function in Mammals Endothermic High Rate of Metabolism External body hair Subcutaneous layer of fat Layer of fat under the skin Sweat glands to help cool the body 1
B. Feeding Jaws and Teeth of Mammals Form and function of jaws and teeth is adapted to the foods they eat Herbivores Carnivores Omnivores Canines Jaw joint Incisors Jaw joint Molars and premolars The size of the digestive tract depends on the type of food it eats Carnivores = short intestine because enzymes quickly digest meat. Herbivores = have a longer intestine because plant tissues take longer to digest. Ungulates have a stomach chamber called the rumen, in which swallowed plant food is stored and processed. It contains bacteria that digest the cellulose of plant tissues. The food is then regurgitated chewed again and sent to the actual stomach C. Respiration Use lungs Have a diaphragm 2
D. Circulation Two loops and a four-chambered heart Right side receives oxygen-poor blood from the body and pumps it to the lungs. Left side receives oxygen-rich blood from the lungs and pumps it to the rest of the body. Right atrium Right ventricle Left atrium Left ventricle Complete division E. Excretion F. Response Kidneys extract wastes from the blood in the form of urea. Urea, other wastes, and water combine to form urine. From the kidneys, urine flows to a urinary bladder, where it is stored until it is eliminated. The kidneys control the amount of water in the body Well-developed brains with three main parts: cerebrum controls thinking and learning cerebellum controls muscular coordination medulla oblongata regulates involuntary body functions Outer layer of the cerebrum is called the cerebral cortex which is the center of thinking and other complex behaviors. Reading is possible only with the human cerebral cortex Highly developed senses to detect and respond to stimuli from their external environment Ears have the same basic parts, but differ in ability to detect sound. Dogs, bats, and dolphins detect sounds at higher frequencies than humans can. Elephants detect sounds at much lower frequencies. The ability to distinguish colors varies among species. Color vision is most useful to diurnal animals. 3
G. Movement H. Reproduction Mammals have backbones that flex Mammals reproduce by internal vertically and side to side. Shoulder and pelvic girdles are streamlined and flexible, permitting both front and hind limbs to move in many ways. Variations in limb bones and muscles permit a variety of movements. Diversity of Mammals fertilization. All newborn mammals feed on their mother s milk. Parental care ensures that young will survive and reproduce. The duration and intensity of parental care varies among different species. The three groups of living mammals are: monotremes marsupials placentals A. Monotremes Monotremes lay eggs. Monotremes share 2 characteristics with Milk is produced from pores on the abdomen The digestive, reproductive, and urinary 3 species exist today: duckbill platypus 2 species of spiny anteaters, or echidnas. Females lay soft-shelled eggs that incubate Found in Australia and New Guinea. reptiles: systems all open into a cloaca. outside the body. 4
B. Marsupials C. Placentals Pouch animals, bear In placental mammals, nutrients, oxygen, live young Young are born very underdeveloped and take about 9 months to complete development in the pouch carbon dioxide, and wastes are exchanged efficiently between embryo and mother through the placenta. The placenta allows the embryo to develop for a longer time inside the mother. 12 Orders of Placental Mammals Insectivores (insect eaters with long, narrow snouts and sharp claws) Sirenians (large, slow moving mammals that live in aquatic environments) Cetaceans (aquatic mammals that must come to the surface to breathe) Rodents (have a single pair of long, curved incisor teeth) Perissodactyls (hoofed mammals with an odd number of toes on each foot) Artiodactyls (hoofed mammals with an even number of toes on each foot) Lagomorphs (herbivores with two pairs of incisors and hind legs adapted for jumping) Carnivores (have sharp claws and teeth that they use to catch, kill, and eat prey) 5
Chiropterans (winged mammals) Xenarthrans (simple teeth without enamel, or no teeth) Primates (highly developed cerebrum and complex behaviors) Proboscideans (mammals with trunks) 6