DIVERSITY IN LIVING ORGANISMS

 

DIVERSITY IN LIVING ORGANISMS

Classification

Classification of organisms is grouping the organisms with similar characteristics.

This helps in the systematic study of the organisms and diversity in living organisms in the environment.

Concrete examples of characteristics used for hierarchical classification.

1)    Organisms made up of Prokaryote or Eukaryote cell.

2)    Organisms are Unicellular or Multicellular

3)    Organisms can prepare their own food or depend on other for their food.

4)    Level of organisation of body structure of an organism.

 Hierarchy of classification groups

Ernst Haeckel, Robert Whittaker and Carl Woese classified all the living organism in different categories.

Levels of classification

KINGDOM

PHYLUM/DIVISION

CLASS

ORDER

FAMILY

GENUS

SPECIES

Five major KINGDOMS

1)    Monera

2)    Protista

3)    Fungi

4)    Plantae

5)    Animalia

 

1)    Monera

·        Prokaryotic organisms

·        Mode of nutrition – Autotrophic or Heterotrophic

·        Cell wall – present or absent (important feature)

·        Egs. Bacteria, blue green algae (cynobacteria), mycoplasma.

 

2)    Protista

·        Eukaryotic organisms

·        Unicellular

·        Appendages to move around

·        Mode of nutrition – Autotrophic or Heterotrophic

·        Egs. Algae, diatoms, protozoan, Amoeba, Paramecium, Euglena.

 

3)    Fungi

·        Eukaryotic organisms

·        Mode of nutrition- Saprophytic

·        Some of them become multi-cellular at certain stages.

·        Cell wall is made of tough complex sugar called CHITIN.

·        Some of the fungi live in mutually dependent relationship with blue green alga. This is called Symbiotic

·        Egs. Yeast, mushroom

4)    Plantae

·        Eukaryotic

·        Multicellular

·        Cell wall present

·        Mode of nutrition – Autotrophic – perform photosynthesis with the help of chlorophyll.

·        Egs. All plants

 

5)    Animalia

·        Eukaryotic

·        Multicellular

·        Mode of nutrition – Heterotrophic

·        Egs. All animals

 

PLANTAE

Further classification is based on

a.     Differentiation of plant body

b.     Special tissues for transport of water and other substances in plant body

c.      Presence of seeds

d.     Seeds enclosed within fruit or open

 I] THALLOPHYTA

§  Body is not differentiated

§  Aquatic plants

§  Algae

§  Egs. Spirogyra, ulothrix, cladophora, chara

 

II] BRYOPYTA

§  Plant body is differentiated into stem and leaf like structures

§  Amphibian plants

§  No specialised tissues for conducting water and other substances

§  Egs. Moss, marchantia

 

III] PTERIDOPHYTA

§  Plant body is differentiated into roots, stem and leaves.

§  Conducting tissues to conduct water and other substances are present.

§  Egs. Marsilea, fern, horse tails.

 Notes :

Thallophytes, bryophytes and pteridophytes have naked embryos called “spores”.

These groups are “Cryptogamae” – inconspicuous reproductive organs.

Phanerogams – well differentiated reproductive tissues.

 

IV] GYMNOSPERMS

§  Plants bear naked seeds

§  Evergreen, perennial and woody plants.

§  Egs. Pines, deodar.

 

V] ANGIOSPERMS

§  Plants bear covered seeds.

§  Seeds are enclosed in fruit

§  Flowering plants

§  Structure in embryo is called “Cotyledon”

§  Monocotyledons – seeds with one cotyledon (Monocots)

§  Egs. paphiopedilum

§  Dicotyledons – seeds with two cotyledons (Dicots)

§  Egs. Ipomea

 

ANIMALIA

       i.            Eukaryotic

     ii.            Multicellular

  iii.            Heterotrophic

  iv.            Cell wall is absent

 

1)    Porifera

·        Pores are present all over the body.

·        Animals are attached to the support.

·        Canal system is present which circulates water throughout the body.

·        Commonly called as “Sponges”

·        Egs. Sycon, Euplectela, Spongilla.

 

2)    Coelenterata

·        Aquatic organisms

·        Diploblastic body (body made up of 2 layers cells)

·        Living style – free or in colonies

·        Egs. Corals, hydra, jellyfish, sea anemone

 

3)    Platyhelminthes

·        Flat worms

·        Body is bilaterally symmetrical

·        Body is triploblastic

·        Some degree of tissue formation

·        Living – Free living or parasitic

·        Egs, Planaria (Free living), Liver fluke (Parasitic)

 

4)    Nematoda (Aschelminthes)

·        Round worms

·        Bilaterally symmetrical and triploblastic body

·        Presence of tissues but no organ formation

·        Parasitic worms which causes diseases

·        Egs.   Filarial worm – Elephantiasis

Round/pin worms – intestinal worms

 

5)    Annelida

·        Segmented body

·        Bilaterally symmetrical and triploblastic

·        Organ differentiation occurs

·        Habitat – fresh water, marine, moist soil

·        Egs. Earthworm, Litches

 

 

 

6)    Arthropoda

·        Largest group of animals

·        Open circulatory system

·        No well defined blood vessels

·        Joint legs – so called Arthropods

·        Egs. Scorpions, spiders, housefly, crabs, cockroach

 

7)    Mollusca

·        Segmented body

·        Open circulatory system

·        Kidney like organ for excretion

·        Foot like organ for locomotion is present

·        Egs. Snails, Mussels

 

8)    Echinodermata

·        Spiny skinned organisms

·        Free living and marine

·        Water driven tubular system

·        Skeleton made up of calcium carbonate is present

·        Egs. Starfish, Sea urchins

 

9)    Protochordata

·        Bilaterally symmetrical and triploblastic body

·        Marine animals

·        Presence of Notochord – rod like support which runs along the back separating nervous system.

·        Provides place for attachment of muscles

·        Egs. Balanoglossus

 

Ø VERTEBRATA

·        True vertebral column

·        Internal skeletal system

Special features

i)                   Have notochord

ii)                Dorsal nerve chord

iii)              Triploplastic

iv)              Paired gill pouches

v)                Coelomate

 

Five classes

1)    PISCES

§  All fishes

§  Aquatic organisms

§  Skin is covered with scales/plates

§  Streamlined body with muscular tail

§  Respires through gills using dissolved oxygen

§  Cold blooded animals

§  Two chambered heart

§  Lay eggs

 AMPHIBIA

§  Lives on land as well as in water

§  Scales are absent

§  Moist skin with mucus glands

§  Three chambered heart

§  Respires through gills or lungs

§  Lay eggs

§  Egs. Frog, toads, salamanders

 

3)    REPTILIA

§  Cold blooded animals

§  Skin is covered with scales

§  Respires through lungs

§  Three chambered heart (Four chambered heart in Crocodile)

§  Lay eggs

§  Egs. Snakes, turtles, lizards, crocodiles

 

4)    AVES

§  All Birds

§  Warm blooded animals

§  Body is covered with feathers

§  Two fore limbs modified to wings for flight

§  Breath through lungs

§  Four chambered heart

§  Lay eggs

5)    MAMMALIA

§  Warm blooded animals

§  Four chambered heart

§  Mammary glands for production of milk

§  Hairy skin

§  Give birth to young ones

§  Platypus and Echidna lay eggs

§  Kangaroo gives birth to very poorly developed young ones

 (Vrushali N.)

(Vrushuraj Classes)