Mammals

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Mammals

• Chapter 43

Monotreme species Only 5 living duck-billed
platypus 4 species of echidna (spiny
anteaters).
Placental mammals 4000 described species, mostly
rodents and bats
Marsupial mammals
References Holt biology text
materials http//www.ucmp.berkeley.edu/mammal/mamm
al.html
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Objectives for chapter 43

• Describe the major characteristics of mammals.
• Compare the characteristics of early synapsids,
  early therapsids, and modern mammals.
• Explain the advantage of endothermy in mammals.
• Differentiate among the patterns of development
  in monotremes, marsupials, and placental mammals.
• Recognize the various orders of mammals.

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All mammals have the following six major
characteristics

• Mammalian characteristics

• 1. Endothermy
• 2. Hair
• 3. Completely divided heart
• 4. Milk/ mammary glands.
• 5. Single jawbone
• 6. Specialized teeth

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1. Endothermy

• Mammalian characteristics

• All Mammals are endotherms which means they
  conserve and regulate body heat.
• allows mammals to remain active in cold climates.
• enables strenuous activities for extended
  periods.
• Requires eating LOTS of food compared to cold
  blooded animals.

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2. Hair

• Mammalian characteristics

• All mammals have hair- even aquatic ones.
• Insulates against heat loss
• Made of keratin protein filaments
• 4 chambers (2 atria, 2 ventricles)
• Efficient oxygen exchange- no deoxygenated blood
  pumped back into body

3. Completely Divided Heart
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Mammalian characteristics

• 4. Milk/ mammary glands.
• -All mammals produce milk, High in protein
  sugar
• -only Monotremes do not have mammary glands but
  secrete milk like sweat.
• 5. Single jawbone.
• -lower jaw is 1 solid bone (reptiles have
  several bones)
• 6. Specialized teeth
• -teeth modified for different functions

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History of Mammals- Synapsids Therapsids

• Synapsids were animals that were small and
  looked like modern lizards.
• Unlike most other reptiles, which have uniformly
  shaped teeth, these early synapsids had
  specialized teeth.
• Therapsids
• A subset of synapsids, called therapsids, gave
  rise to mammals.
• Therapsids appeared late in the Permian period
  and lived into the Jurassic period.

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• History of Mammals-

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History of Mammals

• Mammals and dinosaurs
• appeared during the Triassic period
• coexisted for more than 150 million years.
• Early mammals
• about the size of mice
• probably insectivores
• active at night.

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Phylogenetic Diagram of Vertebrates

• History of Mammals-

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Mammals have highly developed efficient body
systems

• Circulatory System
• Respiratory System
• Digestive System
• note specialized teeth
• Special Adaptations for Digesting Plants
• Nervous System
• Reproduction

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Circulatory System

• 4 chambered heart
• 2 atria, 2 ventricles
• A septum completely separating the ventricles.
• The complete septum is an adaptation that allows
  mammals bodies to use oxygen more efficiently.

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Respiratory System

• efficient gas exchange.
• larger surface area available for gas exchange
• At rest, mammals breathe mostly with their
  diaphragm.

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Digestive System

• TEETH - size and shape of teeth reflect
  differences in diet in various species.
• Incisors -Chisel-like cut.
• Canines Pointed grip, puncture, and tear.
• Premolars shear, shred, cut, or grind.
• Molars grind, crush, or cut.
• Carnivores have sharp incisors long canines.
• Baleen whales have baleen instead of teeth.

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Types of mammalian teeth
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Special Adaptations for Digesting Plants

• Herbivores have long digestive tracts
• special organs w/ symbiotic microorganisms, which
  can break down cellulose.
• Some have a rumen and are called ruminants.
• Others have a cecum.

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Nervous System

• Big Brains
• A mammals brain is at least 15X heavier than a
  similarly sized fish, amphibian or reptile.
• Humans, other primates, and whales have the
  biggest brains
• due mostly to the size of the cerebrum which is
  folded for max surface area.
• The cerebrum evaluates input from the sense
  organs, controls movement, initiates and
  regulates behavior, and functions in memory and
  learning.
• Senses
• Major senses include vision, hearing, smell,
  touch taste.
• Some animals are more developed in some senses
  example
• Most bats, which are active at night, use
  echolocation to locate prey and other objects.

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There are 3 different kinds of mammals based on
how they give birth

• Monotremes are oviparous, they lay eggs.
• 2. Marsupials are viviparous, they give birth to
  live young that further develop within a pouch on
  the mothers body.
• 3. Placental mammals also viviparous, but the
  fetus typically develops within the mothers
  reproductive system for a longer time receives
  nourishment through blood-rich structure- the
  placenta.

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Mammalian orders

• Mammals are commonly classified into
• a single (1) order of Monotremes
• 7 orders of Marsupials
• about 18 orders of Placental mammals

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Phylogenetic Diagram of Mammals
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Monotremes

• Lay incubate large eggs
• Mom protects feeds newborns until able to
  survive on their own.
• The order Monotremata, (monotremes) is the only
  order in the subclass Prototheria.
• Just 3 species exist today
• The duckbill platypus is adapted to life around
  rivers or streams in Australia.
• Two echidna species live in dry woodlands or
  deserts in Australia and New Guinea.

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Marsupials

• Embryo develops in the uterus, but when born,
  crawls into the mothers pouch, attaches to a
  nipple to feed develops in the pouch for several
  months.
• Previously 1 order, but are now divided into at
  least 7 orders in the super order Marsupialia.
• Most of 280 species live in Australia,
• Virginia opossum is only marsupial native to USA
• Theory marsupials began to evolve in isolation
  when Australia drifted away from the other
  continents more than 40 million years ago.

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Placental Mammals

• Placental mammals give birth to well-developed
  young after a long period of development inside
  the uterus.
• During this period, the placenta provides
  nourishment and oxygen to developing offspring

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Your assignment

• Read pages 868 to 874 in the textbook.
• Write down the following orders give the main
  characteristics of each Plus at least 2 example
  organisms
• Monotremes
• Superorder marsupialia
• Placental mammals in super order Eutheria
• Xenarthra
• Lagomorpha
• Rodentia
• Primate
• Chiroptera
• Insectivora
• Carnivora
• Artiodactyla
• Perissodactyla
• Cetacea
• Sirenia
• Probscidea
• Also the 5 orders in the table 43-1
• Then- Answer questions 1-5 on page 874

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18 orders of Placental Mammals

• Order Xenarthra
• The order Xenarthra includes about 30 living
  species of anteaters, armadillos, and sloths
  living in the Americas.
• Order Lagomorpha
• The order Lagomorpha, the lagomorphs, includes
  about 70 species of rabbits, hares, and pikas.

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18 orders of Placental Mammals

• Order Rodentia
• The order Rodentia, the rodents, is the largest
  mammalian order, which includes more than 1,800
  species.
• Rodents are adapted to a wide range of habitats
  worldwide.
• Squirrels, marmots, porcupines, chipmunks,
  gophers, muskrats, mice, and rats are rodents.
• Order Primates
• The order Primates is made up of 235 living
  species, including lemurs, tarsiers, lorises,
  monkeys, gibbons, apes, and humans.
• They live in a variety of terrains most are
  omnivores with complex behaviors.

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18 orders of Placental Mammals

• Order Chiroptera
• Chiroptera, the bats, are the only mammals that
  truly fly.
• More than 900 species live throughout the world,
  except in polar environments.
• Order Insectivora
• The order Insectivora includes about 390 species
  of shrews, hedgehogs, and moles.
• Most members of this order are insectivores, but
  not all insectivores are members of the order
  Insectivora.

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18 orders of Placental Mammals

• Order Carnivora
• The 274 living species of the order Carnivora are
  distributed worldwide.
• Dogs, cats, raccoons, bears, hyenas, otters,
  seals, and sea lions are some well-known
  carnivores.
• Most members of this order eat meat. Most are
  skilled hunters.
• Aquatic carnivores, known as pinnipeds, include
  the sea lions, seals, and walruses.

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Hoofed Mammals

• Hoofed mammals are ungulates.
• Most are herbivores that run quickly.
• The two main groups of ungulates are
  characterized by their foot structure and by the
  presence of either a rumen or a cecum.
• Order Artiodactyla
• Ungulates with an even number of toes are
  artiodactyls, in the order Artiodactyla.
• Most artiodactyls are ruminants, or animals that
  have a rumen.
• This order includes about 210 species of deer,
  cattle, giraffes, pigs, and camels.
• Order Perissodactyla
• Ungulates with an odd number of toes are
  perissodactyls, in the order Perissodactyla.
• Perissodactyls have a cecum.
• This order includes about 17 living species, such
  as horses, zebras, rhinoceroses, and tapirs.

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Some Aquatic Mammals

• Order Cetacea
• Closely related to Artiodactyla is the order
  Cetacea, the cetaceans.
• Cetaceans include about 90 species of whales,
  dolphins, and porpoises worldwide.
• Cetaceans are totally aquatic but evolved from
  land-dwelling mammals.
• Order Sirenia
• Four species of manatees and dugongs make up the
  order Sirenia, the sirenians.
• These herbivores live in tropical seas,
  estuaries, and rivers.
• The similarities between whales and sirenians
  came about through convergent evolution.

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• More mammals

• Order Probscidea
• Members of the order Proboscidea have a nose that
  is modified into a long, boneless trunk, or
  proboscis.
• The only living species of this order are the
  Asian elephant and the African elephant, which is
  the largest living land mammal.
• Mammoths and mastodons are extinct members of
  this order.
• Elephants have long gestation periods, and can
  live to be 80 years old.

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And other orders making up less than 1 of mammals