DIVERSITY OF MAMMALS

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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.

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• Mammal Classification
• ? the Class Mammalia is divided into three
  subgroups based on reproductive methods
• 1. Monotremes mammals that reproduce by laying
  eggs
• (duck-billed platypus and echidna - live only in
  Australia, Tasmania and New Guinea)

3

• ? 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)

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• 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 mothers body (as early as 8d post
  fertilization) and continue to develop and be
  nourished with milk from mammary glands

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• ? marsupials typically live in Australia (and
  nearby islands) the opossum is the only
  marsupial in N America

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• 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

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• Order Insectivora (shrews, hedgehogs, moles)
• ? smallest mammals, pointed snouts, live
  underground, insect-eaters

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• Order Chiroptera (bats)
• ? nocturnal, use sonar, adapted for flight, fruit
  and insect-eaters

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• Order Primates (monkeys, apes, humans)
• ? binocular vision, large brains, most are
  tree-dwellers, opposable thumbs

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• Order Xenarthra (anteaters, sloths, armadillos)
• ? toothless or peg-like teeth, insect-eaters

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• Order Rodentia (beavers, rats, woodchucks,
  marmots, squirrels, hamsters and gerbils)
• ? sharp incisor teeth, plant-eaters

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• Order Logomorpha (rabbits, pikas, hares)
• ? back legs are longer than front, adapted to
  jumping, incisors continuously grow

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• Order Carnivora (dogs, cats, wolves, bears,
  seals, walruses, coyotes, skunks, otters, minks,
  weasles)
• ? teeth adapted to tear flesh, meat-eaters

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• Order Proboscidea (elephants)
• ? long trunks, incisors become long tusks,
  largest land animal

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• Order Sirenia (manatees and dugongs)
• ? slow moving, big heads, no hind limbs

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• Order Perissodactyla (horses, zebras,
  rhinoceroses)
• ? hoofed, odd number of toes, plant-eaters

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• Order Artiodactyla (deer, antelope, cattle,
  sheep, pigs, goats, hippopotamus)
• ? hoofed, even number of toes, plant-eaters that
  chew cud

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• Order Cetacea (whales, dolphins, porpoises)
• ? front limbs that are flippers, no hind limbs,
  nostril forms a blowhole