Notes on NCERT Chapter = 7 (DIVERSITY IN LIVING ORGANISMS) Part 3 => 9th class

This is Online Notes on NCERT Chapter =   7 (DIVERSITY IN LIVING ORGANISMS) Part 3 of 9th class for preparation of CBSE BOARD Examination, NTSE etc.




Five Kingdom Classification R. H. Whittaker taxonomist was the first one to propose five kingdom classification. 

Kingdom V : ANIMALIA

Basis of classification of Animalia kingdom :

(i) Symmetry :

(a) Bilateral symmetry : It is when an organism can be divided into right and left halves, identical but mirror images, by a single vertical plane.

(b) Radial symmetry : It is when an organism is equally spaced around a central point, like spokes on a bicycle wheel.

(ii) Germ layers : In embryonic stages there are different layers of cells called germ cells. The three different types of germ cells are :

• Ectoderm : It is the outermost layer which forms nail, hair,

epidermis, etc.

• Endoderm : It is the innermost layer which forms stomach, colon, urinary, bladder, etc.

• Mesoderm : It is the middle layer between ectoderm and endoderm which forms bones, cartilage, etc. 

So, according to the number of germ layers present in embryonic stage, animal could be :

• Diploblastic : Organisms which are derived from two embryonic

germ layers (ecto and endo).

• Triploblastic : Organisms which are derived from all the three

embryonic germ layers.

(iii) Coelom : Body cavity or coelom is important for proper functioning of various organs. 

For example, heart which has to contract and expand needs some cavity or empty space, which is provided by the coelom.

On the basis of presence or absence of coelom, organisms are divided into :

• Acoelomates : These are the simple organisms having no body

cavity.

• Coelomates : These are complex organisms having true cavity lined by mesoderm from all sides. 

These are further sub-divided into schizocoelomates or protostomes (coelom formed due to splitting or mesoderm) and enterocoelomates or dueterostomes (coelom formed from pouches pinched off from endoderm).

• Pseudo coelamate : These are organisms having false coelom. They have pouches of mesoderm scattered between endoderm and ectoderm.

(iv) Notochord : It is a long rod like structure, which runs along the body between nervous tissues and gut and provides place muscle to attach for ease of movement.

Organisms could be :

• without notochord

• with notochord

• with notochord in initial embryonic stages and vertebral column in adult phase

Phylum 1 : Porifera or Sponges

(i) Cellular level of organization

(ii) Non-motile animals

(iii) Holes on body which led to a canal system for circulation of water and food

(iv) Hard outside layer called as skeletons

(v) Examples : Sycon, spongilla, euplectelia

Phylum 2 : Coelenterata

(i) Tissue level of organization

(ii) No coelom

(iii) Radial symmetry, diploblastic

(iv) Hollow gut

(v) Can move from one place to another

(vi) Examples : Hydra, sea anemone, jelly fish (solitary), corals (colonies)

Phylum 3 : Platyhelminthes:

(i) Also called flat worms

(ii) No coelom present

(iii) Bilateral symmetry, triploblastic

(iv) Free living or parasite

(v) Digestive cavity has one opening for both ingestion and egestion

(vi) Examples : Planaria (free living), liver fluke (parasitic)

Phylum 4 : Mollusca

(i) Coelom present

(ii) Triploblastic, bilateral symmetry

(iii) Soft bodies sometimes covered with shell

(iv) Generally not segmented

(v) No appendages present

(vi) Muscular foot for movement

(vii) Shell is present

(viii) Kidney like organ for excretion

(ix) Examples : Chiton, octopus, pila, unio

Phylum 5 : Annelida

(i) Second largest phylum

(ii) Coelom present

(iii) Bilateral, triploblastic

(iv) Segmented (segments specialized for different functions)

(v) Water or land

(vi) Extensive organ differentiation

(vii) Examples : Earthworm, leech, nereis.

Phylum 6 : Arthropoda

(i) Largest phylum (consist of 80% of species)

(ii) Generally known as insects

(iii) Coelom present

(iv) Bilateral, triploblastic

(v) Segmented, sometimes fused

(vi) Tough exo-skeleton of chitin

(vii) Joing appendages like feet, antenna

(viii) Examples : Prawn, scorpio, cockroach, housefly, butterfly, spider

Phylum 7 : Echinodermata

(i) Spiny skin, marine

(ii) No notochord

(iii) Coelom present, bilateral symmetry, triploblastic

(iv) Endoskeleton of calcium carbonate

(v) Water vascular system for locomotion

(vi) Bilateral symmetry before birth and radial symmetry after birth

(vii) Examples : Antedon, sea cucumber, star fish, echinus

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