Wednesday, July 29, 2020

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

4. ANIMAL KINGDOM


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).

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 (but a septum partially separates ventricle). Heart is 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.

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.

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).

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