Class 9 Diversity in Living Organisms Notes

Notes Important Questions

Diversity in Living Organisms Notes

The hierarchy of classification groups:-

  • Kingdom
    Phylum (for animals) / Division (for plants)
    • Class
      • Order
        • Family
          • Genus
            • Species

There are five types of kingdoms:-


  • They are unicellular prokaryotes.
  • Some of them have cell wall while some do not.
  • The mode of nutrition in some of them is autotrophic and in some of them heterotrophic.
  • For example:- Bacteria, blue green algae (cyanobacteria) and mycoplasma etc.


  • These are unicellular eukaryotes.
  • Some of them have hair like cilia or whip like flagella for moving around.
  • They can be heterotrophic or autotrophic.
  • For example:- Unicellular algae, diatoms and Protozoans (paramecium, amoeba, euglena).


  • These are heterotrophic eukaryotes.
  • They obtain food from dead or decaying organic material. So, they are called saprophytes
  • They have cell wall made of a tough complex sugar called chitin.
  • For example:- Yeast and mushroom etc.
  • Symbiotic relationship:- The permanent mutually dependent relationship between two organism is called symbiotic relationship. Ex:- Lichen, which is a symbiotic relationship between cyanobacteria and fungi.


  • These are multicellular eukaryotes with cell wall.
  • These are autotrophs.
  • They have chlorophyll for photosynthesis.


  • These are multicellular eukaryotes without cell wall.
  • These are heterotrophs.



  • They do not have well differentiated body design.
  • The plants in this group are commonly called algae.
  • These plants are predominantly aquatic.
  • Ex:- Spirogyra, Ulothrix, Cladophora and Chara.


  • These are called the amphibians of the plant kingdom.
  • The plant body is commonly differentiated to form stem and leaf like structure.
  • They have no specialised tissue for conduction of water and other substances.
  • Ex:- Moss (Funaria) and Marchantia etc.


  • The plant body is differentiated into roots, stems and leaves.
  • They have specialised tissue for the conduction of water and other substances.
  • Ex:- Marsilea, ferns and horse-tails.
  • Cryptogamae:-
    • They have naked embryos that are called spores.
    • They have hidden reproductive organs.
    • The thallophytes, the bryophytes and the pteridophytes fall in this group.
  • Phanerogams:-
    • They have well-differentiated reproductive tissues.
    • They produce seeds.
    • Seeds consist of embryos along with stored food.
    • This group is further classified, based on whether the seeds are naked or enclosed in fruits, into two groups: gymnosperms and angiosperms.


  • They have naked seeds.
  • They are usually perennial ,evergreen and woody.
  • Ex:-Pine, Deodar etc.


  • They are flowering plants.
  • The seeds are enclosed in fruits.
  • The angiosperms are divided into two groups on the basis of the number of cotyledons:
    • Monocotyledonous/Monocots:- Plants with seeds having a single cotyledon are called monocots. Ex:- Paphiopedilum.
    • Dicotyledonous/Dicots:- Plants with seeds having two cotyledons are called diocots. Ex:- Ipomoea.



  • These are non motile animals.
  • There are holes or ‘pores’, all over the body.
  • These animals are covered with a hard outside layer or skeleton.
  • They have very minimal differentiation.
  • They are mainly found in marine habitats.
  • They are commonly called sponges.
  • Ex:- Sycon, Spongilla, Euplectelia, etc.


  • These animals live in water.
  • They show more body design differentiation.
  • They have cavity in the body.
  • The body is made of two layers of cells.
  • Some of these species live in colonies (corals), while others have a solitary like–span (Hydra).
  • Ex:-Jellyfish, Hydra, Sea anemones etc.


  • The body is bilaterally symmetrical.
  • The body is triploblastic.
  • There is no true internal cavity or coelom.
  • The body is flattened so they are called flatworms.
  • They are either free living or parasitic.
  • Ex:- Planareia, Liverfluke, Tape worm etc.


  • The body is bilaterally symmetrical and triploblastic.
  • The body is cylindrical.
  • They have a sort of body cavity or pseudocoelom.
  • These are parasitic worms causing diseases like filarial worms causing elephantiasis or the worms in the intestine (roundworms or pinworms)
    Ex:-Ascaris, Wuchereria.


  • These are bilaterally symmetrical and triploblastic.
  • They have a true body cavity.
  • They are founded in marine waters , fresh water as well as on land
    Ex:-Earthworm, Nereis, Leech.


  • It is the largest group of animals.
  • These are bilaterally symmetrical and segmented .
  • They have open circulatory system .
  • The coelomic cavity filled blood .
  • They have jointed legs .
  • Ex:-Mosquito, Housefly, Butterfly, Spider.


  • These animals are bilaterally symmetrical .
  • The coelomic cavity is reduced.
  • They have an open circulatory system.
  • They have kidney-like organs for excretion.
  • They have a foot for moving around.
  • Ex:-Chiton , pila , octopus.


  • These are free living marine animals.
  • These are spiny skinned organisms.
  • They are triploblastic.
  • They have a coelomic cavity.
  • They have skeleton made of hard calcium carbonate.
  • Ex:- Starfish, sea urchins.


  • These are bilaterally symmetrical and triploblastic.
  • They have a coelom.
  • They have a notochord which is shown at least at some stages of their lives.
  • These are marine animals.
  • Ex:- Balanoglossus, Herdemania and Amphioxus.


  • They have a true vertebral column and internal skeleton.
  • They are bilaterally symmetrical, triploblastic and segmented.
  • They are coelomate.
  • They show complete body differentiation.

Vertebrates are grouped into five classes:-


  • These are fish.
  • They are aquatic animals.
  • Their skin is covered with scales/plates.
  • They have gills.
  • They are cold blooded.
  • They have two chambered heart.
  • They lay eggs.
  • The body is streamlined.
  • Some of them have skeletons made entirely of cartilage, such as sharks, and some have a skeleton made of both bone and cartilage, such as tuna or rohu.


  • They have lack of scales.
  • They have three chambered heart.
  • They have mucus glands in skin.
  • They lay eggs.
  • Respiration is through either gills or lungs.
  • They are found both in land and in water.
  • Ex:- Salamanders, Toads, Frogs etc.


  • These animals are cold blooded.
  • They have scales.
  • They breathe through lungs.
  • Most of them have a three chambered heart, but crocodiles have four chambered heart.
  • They lay eggs on land.
  • Ex:- Turtle, Chameleon, King Cobra, Flying lizard (Draco), House wall Lizard (Hemidactylus) etc.


  • They are warm blooded animals.
  • They have four chambered heart.
  • They lay eggs.
  • They have a outside covering of feathers.
  • They breathe through lungs.
  • The two forelimbs are modified for flight.
  • All birds fall in this category.
  • Ex:- Ostrich (Struthio camelus), Duck , Pigeon, Sparrow, Crow etc.


  • They are warm blooded.
  • They have four chambered heart.
  • They have mammary glands for production of milk.
  • There skin has hairs as well as sweat and oil glands.
  • Most of them produce live young ones.
  • Some of them like platypus and echidna lay eggs.
  • Ex:- Cat, Human, Rat, Bat, etc,


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