Introduction to Mammals

1
Introduction to Mammals

• And Diversity of Mammals

2
Introduction to Mammals

• Endothermic animals (generate their body heat
  internally an example of homeostasis), most
  viviparous (live-bearing, the exception being
  monotremes), all have mammary glands and hair,
  breathe air, and have four-chambered hearts

3
Mammal Evolution and Diversity

• First true mammals appeared about 220 million
  years ago
• 3 major groups of mammals
• Monotremes
• Marsupials
• Placentals

4
Monotremes

• Egg-laying mammals
• Six species found in Australia and New Guinea
  duck-billed platypus, spiny anteaters
• Both the reproductive system and the urinary
  system open into a cloaca that is similar to the
  cloaca of reptiles

5
Marsupials

• Mammals bearing live young that complete their
  development in an external pouch. Once inside
  the marsupium (pouch), the embryo locates a
  nipple, attaches, and spends several months there
• Mostly found in Australia
• Opposum only North American marsupial
• Kangaroo, koala, wallabies

6
Placentals

• Mammals in which egg implants in the uterus
• In placental mammals, nutrients, oxygen, carbon
  dioxide, and wastes are exchanged between the
  embryo and mother through the placenta
• Most widespread dogs, cats, humans

7
Feeding in Mammals

• Teeth tell the tale lots of incisors and
  canines predator, lots of molars herbivore,
  both omnivore (humans, bears)

CARNIVORE
HERBIVORE
Jawjoint
Jaw joint
Horse
Wolf
8
Feeding in Mammals (continued)

• Most consume a lot to maintain metabolism
• Rumen specialized stomach allows some
  herbivores to digest cellulose (cows)
• Cecum large, dead-end sack off intestine acts
  like rumen and in humans is the appendix
• Blood feeders vampire bats
• Filter feeders baleen whales

9
Respiration

• Lungs powered by two sets of muscles chest and
  diaphragm (diaphragm increases volume in chest
  cavity)

10
Circulation in Mammals

• Four chambered heart with double loop system
  lungs and body loops

11
Excretion in Mammals

• Kidneys filter urea from blood and recycle other
  compounds (sugars and salts)
• Best kidney of all animals

12
Response in Mammals

• Most highly developed brain of all animals
• Cerebrum controls thinking and learning large
  in mammals
• Cerebellum coordinates movement
• Medulla regulates body functions
• Well-developed sense of sight, hearing, and smell

13
Movement in Mammals

• Have a variety of adaptations shoulders and
  pelvic girdles
• 4 limbs hooves, hands, wings, flippers

14
Reproduction in Mammals

• Internal fertilization
• Most are viviparous
• Pouch marsupial
• Placenta nutrients, oxygen and wastes exchanged
  through this sac-like organ
• Gestation period length of time spent
  developing in uterus can range from a few weeks
  (mice) to almost two years (elephants) larger
  the young, longer the gestation period

15
Reproduction in Mammals (continued)

• Young spend a long time developing with mother
  after birth important reason for evolutionary
  success
• Advantages?
• More likely to survive and reproduce with great
  success
• Disadvantages?
• Takes a lot of energy and prevents parents from
  reproducing until young are on their own

16
Orders of Mammals

• Insectivora shrews and moles eat insects
• Chiroptera bats eat insects, frogs, fish,
  fruit
• Edentata sloths, anteaters, and armadillos
• Rodentia mice, rats, squirrels, beavers
  incisors constantly grow during entire lifetime
• Lagomorpha rabbits and hares herbivores
• Carnivora cats, dogs, wolves, bears, weasles,
  seals, hyenas
• Cetacea whales, dolphins, porpoises
• Sirenia manatees and sea cows
• Artiodactyla cattle, sheep, goats, hippo,
  giraffe, pigs even number of toes
• Perissodactyla horses, zebras, tapirs, rhinos
  odd number of toes
• Proboscidea elephant (African and Asian)
• Primates humans, monkeys, apes