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DIVERSITY OF MAMMALS Chapter 30.2 OBJECTIVES : 1. State the various characteristics of mammals in each of three subgroups. 2. Describe various adaptations that contribute to the diversity of mammals. Mammal Classification
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DIVERSITY OF MAMMALS • Chapter 30.2 • OBJECTIVES: • 1. State the various characteristics of mammals in each of three subgroups. • 2. Describe various adaptations that contribute to the diversity of mammals.
Mammal Classification • ● the Class Mammalia is divided into three subgroups based on reproductive methods • 1. Monotremes: mammals that reproduce by laying eggs • (duck-billed platypusand echidna- live only in Australia, Tasmania and New Guinea)
● unique features of monotremes include reptilian bone structure in shoulder area, lower body temp than most mammals, a mix of chromosome size (normal, mammal and reptile-small)
marsupials: pouched animals with a short gestation period • ● immediately following birth, the offspring crawl into a pouch (skin and hair) on the outside of the mother’s body (as early as 8d post fertilization) and continue to develop and be nourished with milk from mammary glands
● marsupials typically live in Australia (and nearby islands) – the opossumis the only marsupial in N America
placental mammals: have a placenta (organ that provides food and oxygen to and removes waste and carbon dioxide from the developing young) - give birth to young that do not require further development in a pouch… • placental mammals are represented by 18 different orders…
Order Insectivora (shrews, hedgehogs, moles) • smallest mammals, pointed snouts, live underground, insect-eaters
Order Chiroptera (bats) • nocturnal, use sonar, adapted for flight, fruit and insect-eaters
Order Primates (monkeys, apes, humans) • binocular vision, large brains, most are tree-dwellers, opposable thumbs
Order Xenarthra (anteaters, sloths, armadillos) • toothless or peg-like teeth, insect-eaters
Order Rodentia (beavers, rats, woodchucks, marmots, squirrels, hamsters and gerbils) • sharp incisor teeth, plant-eaters
Order Logomorpha (rabbits, pikas, hares) • ● back legs are longer than front, adapted to jumping, incisors continuously grow
Order Carnivora (dogs, cats, wolves, bears, seals, walruses, coyotes, skunks, otters, minks, weasles) • ● teeth adapted to tear flesh, meat-eaters
Order Proboscidea (elephants) • ● long trunks, incisors become long tusks, largest land animal
Order Sirenia (manatees and dugongs) • ● slow moving, big heads, no hind limbs
Order Perissodactyla (horses, zebras, rhinoceroses) • ● hoofed, odd number of toes, plant-eaters
Order Artiodactyla (deer, antelope, cattle, sheep, pigs, goats, hippopotamus) • ● hoofed, even number of toes, plant-eaters that chew cud
Order Cetacea (whales, dolphins, porpoises) • ● front limbs that are flippers, no hind limbs, nostril forms a blowhole