Placental Mammals

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Placental Mammals

• Classification

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Order Rodentia Gnawing Mammals

• Largest mammalian order
• 1800 species
• Mice, squirrels, porcupines, beavers
• Every continent except Antarctica
• Large incisors in upper and lower jaw that grow
  throughout their life

Capybara
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Order Rodentia

• Basically defenseless verse predators
• Their reproduction habits allow them to survive
• Reach sexual maturity quickly
• Have short gestation period give birth to
  altricial young
• Produce large litters
• Can reproduce frequently

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Order Rodentia

• Field mice
• Weaned at three weeks
• Independent at four weeks
• Capable of bearing litters at six weeks
• Capable of producing up to seventeen litters in a
  single year
• A single individual could produce around 75
  offspring in one year

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Order Lagomorphs

• Rabbits, hares, pikas
• 80 species
• Herbivores
• Fast moving
• Reproductive habits similar to rodents
• Also have a pair of always growing incisor teeth
  like rodents
• Have an additional pair of chisel-shaped teeth
  outside the other pair

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Order Carnivora Meat-Eating Mammals

• Most of the meat-eating mammals
• Enlarged canine fangs and sharp molars for
  tearing flesh

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Order Carnivora

• Family Felidae- cats, lions, tigers, cheetahs
• Family Ursidae- bears
• Family Canidae- dogs, wolves, foxes, coyotes
• Three Pinniped Families- live in marine
  environments, spend most of their time in water,
  but come ashore to sleep, mate, and give birth,
  large bodies are not a problem in water, blubber
  keeps them warm in cold water, awkward movement
  on land
• Phocidae- true seals, no visible ear flaps
• Otariidae- eared seals including the sea lion
• Odobenidae- walrus
• Other families include mongooses, meerkats,
  hyenas, weasels, wolverines, skunks, raccoons

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Order Cetacea Aquatic Mammals

• Do not come ashore
• Still must surface to breath
• Whales, dolphins, porpoises
• 90 species

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Order Cetacea

• Whales are divided into two groups toothed
  whales and baleen whales
• Toothed whales and dolphins use echolocation
• Baleen whales filter invertebrates from the water
  with a net of baleen in their mouth
• Largest creature on Earth, the great blue whale,
  is a baleen whale

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Order Cetacea

• Movement
• Pair of pectoral flippers supported by bones
• Pair of boneless tail flukes
• Flukes move up and down rather than side to side
  like the caudal fin in fish

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Order Sirenia

• Manatees, dugongs, sea cows
• 4 species
• Herbivores feeding on underwater and floating
  foliage
• Breathe through nostrils rather than blowholes
  like whales

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Order Primates Erect Mammals

• Great apes, monkeys, lemurs
• Freely moving arms and legs with large hands and
  feet
• Opposable thumbs for grasping items
• Nails on most fingers and toes
• Forward facing eyes, permitting binocular vision
  with depth perception
• Poor sense of smell
• Ability to walk erect when on land, though most
  of their time is spent in trees
• A strong tendency to be social, often living in
  large groups
• Less specialized teeth than those of most other
  mammals
• A mostly vegetarian diet, possibly supplemented
  with eggs, insects, and occasionally other small
  animals

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Order Primates

• Chimpanzees are a type of ape, possibly the most
  intelligent animal
• Some use tools and weapons
• Some have been taught to communicate using sign
  language
• Some show the ability to reason in order to solve
  problems

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Order Artiodactyla Even-Toed Ungulates

• Pigs, hippos, camel, giraffes, cows, deer, sheep,
  goats
• Includes the ruminant suborder that chews the cud
• Long legs with 2 or 4 functional hoofed toes
• 210 species

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Order Perissodactyla Odd-Toed Ungulates

• Horse, donkey, zebra, rhinoceros
• Herbivores
• Rely on cecum rather than multichambered stomach
  to digest plant material hindgut fermenters

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Order Edentata Toothless Mammals

• Anteaters, armadillos, sloths
• Anteaters are truly toothless
• Others have peglike teeth, but lack enamel

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Order Insectivora Insect-Eating Mammals

• Hedgehogs, moles, shrews
• 400 species
• One of the least studies orders of mammals
• Sharp conical cusps
• Pointy flexible noses are common
• Acute sense of smell

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Order Proboscidea Trunked Mammals

• Two species remain the African and Asian
  elephant
• Mammoths and mastodons are extinct
• Flexible and useful trunk, essentially an
  elongation of the nose and upper lip
• Ivory tusks are the two upper incisors that
  continually grow
• Other teeth are 4 brick-sized molars
• African elephant is the largest terrestrial
  (land) animal

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Order Chiroptera Flying Mammals

• Only mammals capable of true flight
• 900 species of bats
• Megachiropterans in tropics and subtropics of
  Africa, Asia, and Australia can grow up to 5.6
  feet. They navigate by sight rather than sound
  and feed mainly on fruit and nectar
• Microbats navigate using echolocation and feed on
  insects, fruit, nectar, sometimes fish and
  amphibians. The vampire bats in Central and South
  America do feed solely on blood