Animal Kingdom - Notes | Class 11 | Part 14: Chordata (Tetrapoda)

Superclass Tetrapoda

Class Amphibia

  • They live in aquatic & terrestrial habitats and need water for breeding.
  • Body has head & trunk. Some have tail.
  • Moist skin without scales. Most have 2 pairs of limbs.
  • Tympanum represents ear.
  • 3-chambered heart (2 auricles + 1 ventricle).
  • Poikilotherms (Cold-blooded animals): Animals that lack the capacity to regulate their body temperature.
  • Alimentary canal, urinary & reproductive tracts open into a Cloaca which opens to exterior.
  • Respiration is by gills (in larva), lungs & skin.
  • Sexes are separate. External fertilisation. Oviparous.
  • Development is indirect.
  • Examples:
    • Bufo (Toad)
    • Rana (Frog)
    • Hyla (Tree frog)
    • Salamandra (Salamander)
    • Ichthyophis (Limbless amphibia)
Amphibia Example

Class Reptilia

  • Dry & cornified skin, epidermal scales or scutes.
  • Snakes and lizards shed their scales as skin cast.
  • Limbs - 2 pairs (if present).
  • Crawling mode of locomotion.
  • Tympanum represents ear.
  • 3-chambered heart (4-chambered in crocodiles).
  • Poikilotherms.
  • Well-developed alimentary canal.
  • Respiration by lungs.
  • Internal fertilisation. Oviparous.
  • Development is direct.
  • Examples:
    • Chelone (Turtle)
    • Testudo (Tortoise)
    • Chameleon (Tree lizard)
    • Calotes (Garden lizard)
    • Crocodilus (Crocodile)
    • Alligator
    • Hemidactylus (Wall lizard)
    • Poisonous snakes: Naja (Cobra), Bangarus (Krait), Vipera (Viper) etc.
    • Non-poisonous snakes: Python etc.
Reptilia Example 1 Reptilia Example 2

Class Aves (Birds)

  • Presence of feathers and beak. Forelimbs are modified into wings.
  • Dry skin without glands except the oil gland at the base of tail.
  • Hind limbs have scales and are modified for walking, swimming or clasping tree branches.
  • Hollow & pneumatic long bones.
  • Tympanum represents ear.
  • 4-chambered heart.
  • Homoiotherms (warm-blooded animals): Animals having ability to maintain a constant body temperature.
  • Digestive tract has additional chambers, the crop & gizzard.
  • Double respiration.
  • Air sacs connected to lungs.
  • Internal fertilisation.
  • Oviparous.
  • Development is direct.
  • Examples:
    • Corvus (Crow)
    • Columba (Pigeon)
    • Psittacula (Parrot)
    • Struthio (Ostrich)
    • Pavo (Peacock)
    • Aptenodytes (Penguin)
    • Neophron (Vulture) etc.
Aves Example 1
Aves Example 2

Class Mammalia

  • Presence of mammary glands (milk producing glands).
  • Skin with hair.
  • 2 pairs of limbs for walking, running, climbing, burrowing, swimming or flying.
  • External ear (Pinnae).
  • 4-chambered heart.
  • Homoiotherms.
  • Well-developed alimentary canal.
  • Dentition is Heterodont, thecodont & diphyodont.
  • Respiration by lungs.
  • Sexes are separate.
  • Internal fertilisation.
  • Viviparous (except Echidna and Platypus).
  • Development is direct.
  • Examples:
    • Ornithorhynchus (Platypus)
    • Macropus (Kangaroo)
    • Pteropus (Flying fox)
    • Camelus (Camel)
    • Macaca (Monkey)
    • Rattus (Rat)
    • Canis (Dog)
    • Felis (Cat)
    • Elephas (Elephant)
    • Equus (Horse)
    • Delphinus (Common dolphin)
    • Balaenoptera (Blue whale)
    • Panthera tigris (Tiger)
    • Panthera leo (Lion)
Mammalia Example

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