Classification and characteristics of Superclass: Tetrapoda

  • Tetra-four, podos-feet
  • Primarily terrestrial, some are secondarily aquatic in.
  • Two pairs of pentadactyl limbs.
  • Body covered by an exoskeleton of epidermal hair, feathers or scales.
  • Lungs are main respiratory organs. Amphibian may respire by gills, skin or lungs.
  • 3 or 4 chambered heart present.
  • They are divided into 4 classes:

Class 2: Amphibia

  • Amphi-dual; bios-life.
  • Dual mode of life, can live in water or on land.
  • First chordates to live out of water.
  • Occupy intermediate space between the fish and reptiles.
  • Cold blooded vertebrates with two pairs of limbs, fore limbs are smaller than hind limbs.
  • Have smooth and moist skin with many glands, scales absent.
  • Two nostrils connected with the buccal cavity.
  • Heart is three chambered with two auricles and one ventricle.
  • RBCs are oval, biconvex and nucleated.
  • Breathe by buccal cavity, lungs and skin. The tadpole larva respire by gills.
  • Head and trunk are body parts.
  • Show hibernation (winter sleep) and aestivation (summer sleep).
  • Moveable eyelids are present in the eyes. Tympanic membrane is found in some cases.
  • Endoskeleton is large and bony.
  • Ten pairs of cranial nerves present in the brain.
  • Metamorphosis is present which includes tadpole stage.

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Examples: Rana (frog), Bufo (toad), Hyla, etc.

 Class 3: Reptilia

  • rept- creeping.
  • Dry, horny scaly skin.
  • Show creeping movement.
  • Cold blooded animals, terrestrial or aquatic.
  • Two pairs of pentadactyl limbs. In snakes and some lizards lmbs are secondarily lost.
  • Heart is imperfectly four or completely four chambered.
  • Respiration always by lungs.
  • Twelve pairs of cranial nerves present.
  • RBC is oval, biconvex and nucleated.
  • Fertilization is internal. Sexes are separate and shows sexual dimorphism.
  • Eggs are large with much yolk in leathery or limy shells.
  • There is no metamorphosis.

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Examples: cobra, krait, crocodiles.

Class 4: Aves (birds)

  • Streamlined body present to reduce the resistance during flight.
  • Body is covered with feathers.
  • Forelimbs modified to wings, covered with feathers.
  • Hind-limbs are suited for walking and perching.
  • Show better flight adaptation.
  • Bones are pneumatic i.e. bones are light, porous with air cavities to reduce the body weight.
  • Heart is four chambered. RBC is oval, biconvex and nucleated.
  • Air sacs are present.
  • Warm blooded animals.
  • Twelve pairs of cranial nerves present.
  • Have large eyes and a strong sense of light.
  • Lungs are compact, attached to ribs.
  • Lungs have air sacs which help in double respiration.
  • Oviparous, eggs have large yolk covered with hard horny shell.
  • Right ovary and right oviducts are disappeared reducing the body weight.
  • Sexes are separate.
  • Fertilization is internal.

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Examples: Crow, Pigeon, Parrot, etc.

Class 5: Mammalia (mammals)

  • Highly developed animals with a much advance brain.
  • Body usually covered with hairs.
  • Mammary glands are present so called mammals.
  • Includes diverse group of animals from tiny mice to huge whale.
  • Viviparous in nature i.e. give birth to young ones except class Prototheria (platypus, spiny ant eater).
  • Senses of sight, hearing and smell are well developed.
  • Fore limbs and hind limbs are usually present except cetaceans and sirenians.
  • Various types of teeth present for cutting, tearing or grinding.
  • Mammal’s skull is unique, brain is more complex.
  • The parental care is much highly developed and maximum in human.
  • Feet with five toes for various purposes.
  • Can fly, glide, jump, swim, burrow and dive.
  • Respiration takes place by lungs.
  • Heart is four chambered: two auricles and two ventricles.
  • External ear or pinnae is present.
  • Red blood cells are small, biconvex and nonnucleated except camel.
  • Muscular diaphragm separates the thoracic cavity with the abdominal cavity.
  • Twelve pairs of cranial nerves present.
  • Warm blooded animals.
  • Sexes are separate, fertilization is internal.
  • More successful and more dominant animals of today.

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Examples: man, monkey, lion, whale, etc.

Classification and characteristics of Superclass: Tetrapoda

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