Diversity in living organisms

DIVERSITY IN LIVING ORGANISMS

CLASSIFICATION : Science of arranging organisms in series of groups and

subgroups on the basis of their similarities and dissimilarities.

Aristotle classified organisms on the basis of their habitat means the place where they live , in water , in air and on land.

Basic characteristics of classification

Nature of cells : prokaryotic or eukaryotic

Cellularity : unicellular or multicellular

Level of organisation : cellular ,tissue ,organ and

organ systemMode of nutrition :

autotrophic and heterotrophic

Classification and evolutionTime is the key factor which helps in development of complex organisms

from the simple ones.Charles Darwin firstly gave the idea of evolution in 1859 in his famous

book ‘the origin of species’.Those organisms which have ancient body design and not

changed much are called primitive organisms.

Those who acquired certain special characters during the time period are known as advanced or higher

organisms

BiodiversityBiodiversity is the term

used for the various forms of life found in a

given area.These life forms depend

on each other and on the environment and

results in a stable community.

Human also is the part of this biodiversity.It is estimated that

there is about 10,000,000 species on this planet , we know only about 20,00,000

species.

Hierarchy of classificationErnst Haeckel , Robert Whittaker , carl woese have tried to classify all living

organisms into broad categories. R.Whittaker proposed five kingdom system

which is widely used .This kingdom includes monera , protista ,

fungi , plantae and animalia.Carl woese divided monera into archaebacteria and eubacteria.

Further classificationFurther classification is

done by naming the sub groups at various levels

as given :Kingdom-phyllum\

division-class-order-family-genus-species

Kingdom moneraKingdom protista

Kingdom fungiKingdom plantaeKingdom animalia

Kingdom : moneraUnicellular organismsNucleus and cell organelles are absent May or may not have cell wallAutotrophic or heterotrophicAble of nitrogen fixation Reproduce by asexual methodsBacteria , cyanobacteria and mycoplasma.

Kingdom : Protista

Unicellular organisms.A well defined nucleus and cell organelles arepresent . They may be autotrophic or Heterotrophic. Some of these organisms have appendages like cilia and flagella for movement.They reproduce by both sexual and asexual methods.Diatoms , protozoan's arefew examples.

Kingdom : fungiHeterotrophic eukaryotic

organismsSaprophytes

Cell wall made of chitinSome of them live in close

relationship with certain algae and plants forming lichens and mycorrhizaeSome of them have the

ability of being multicellularYeast ,mushroom and

rhizopus.

Kingdom : plantae They are

multicellular eukaryotic organisms.

This kingdom includes all the plant species.

They are autotrophic and

prepare their own food.

They are further classified into five major divisions.

Division : ThallophytaBody of the organisms is not differentiated into organs .Mainly aquatic found in marine and fresh water.Tissue for conduction of material and for mechanical strength is absent.They are covered by mucilage.Reproduce by vegetative , asexual and sexual reproduction.Algae is example of this division.

Division : BryophytaPlant body is differentiated

into leaf , root and stem like structures.

Special conducting tissues are not present.

These are known as amphibians of plant

kingdom.Reproduce by vegetative ,

asexual and sexual reproduction.

Funaria , anthoceros and marchantia are few

examples.

Division : PteridophytaPlant body is differentiated into leaf , stem and roots.

They also have conductive tissues.

All the above discussed plant types doesn't bear seeds instead they bear

spores. They are also known as cryptogams.

They require water for the purpose of reproduction.

Fern , adiantum and selaginella are few

examples.

Division : GymnospermsThese plants bear naked seeds means seeds which are not enclosed in fruits.These are perennial , evergreen trees having woody trunk.They bear cones in which seeds are placed.Sequoia sempervirens is the largest tree found on earth [125 meters] is an example. Other examples are pinus and cycas.

Division : AngiospermsBear seeds covered by special organs known as fruits.They bear flowers as their reproductive organs.Embryo in seed has special structure called cotyledons which act as seed leaves at the time of germination.They are divided into two groups : monocots and dicots.Wheat , rice , rose and tomato are examples of this division.

Kingdom : AnimaliaMain characteristics of this kingdom are as follows :These are eukaryotic organisms of heterotrophic nature.These are multicellular organisms.Their cells do not bear cell walls and chloroplasts.They are further subdivided into following categories:

Phylum : PoriferaThese animals bear small holes on their

body surface.They are aquatic and sedentary means non

motile.They have cellular level

of body design.They bear hard external

skeleton and have a canal system for the

distribution of food and gases.

Spongilla and sycon are the examples.

Phylum : CoelentrataThey are aquatic

animals and have tissue level of body

design.They have a body

cavity called coelom so named coelentrata.

They may be solitary or colonial.

They have special stinging cells called cnidoblasts so also known as cnideria.Hydra , obelia and

physalia are few examples.

Phylum : Platyhelminthes Show bilateral symmetry and are triploblastic means have three germ layers.They are dorsoventrally flattened so also called flatworms.They are either free living or parasitic.They have tissue level of body design.They do not have any body cavity.Planarian and liver flukes are examples.

Phylum : NematodaThese animals show

bilateral symmetry and are triploblastic means have

three germ layers.They are cylindrical in

shape.They have pseudocoelom.

They have tissue level of body design.

They are mainly parasitic in nutrition.

Ascaris and wuchuraria are examples.

Phylum : AnnelidaShow bilateral symmetry and are triploblastic.They are cylindrical in shape and have a true body cavity.Organ system level of body design is found.Body is divided into small segments called annuli so phylum is also known as annelida.They are found on both land and water.Earthworm and leech are examples.

Phylum : ArthropodaThese animals show

bilateral symmetry and are triploblastic means

have three germ layers.They have a true body

cavity which is blood filled.

Organ system level of body design is found.

Open circulatory system is found in these animals.Largest group of animals.

They have jointed legs.Cockroach , housefly ,

butterfly are examples.

Phylum : MolluscaBody cavity is highly

reduced.These animals show

bilateral symmetry and are triploblastic means

have three germ layers.They also have open

circulatory system.They have kidney like

structure for excretion.A highly muscular foot is

used for movement.Pila and chiton are

examples.

Phylum : EchinodermataThese are spiny skin organisms.They are free living animals found only in marine water.They are triploblastic and have true body cavity.They have a tube system for the purpose of movement.They show high power of regeneration.Starfish and sea urchin are examples.

Phylum : Protochordata

These animals show bilateral symmetry and are triploblastic

means they have three germ layers.They are cylindrical in shape and have a

true body cavity.They also have a notochord at any stage of life which provide surface for the attachment of

muscles and to provide support.

Amphioxus , balanoglossus are

examples.

Phylum : VertebrataThey have

notochord at any stage of life.

They have a dorsal nerve chord.

They are triploblastic.

They have paired gill pouches.

They have true body cavity.

It includes classes : pisces , amphibia , reptilia, aves and

mammalia.

Class : PiscesThey are aquatic

animals found in fresh and marine water.Skin is covered by

scales or plates and have gills for

respiration.Body is streamlined and

has a tail.They have two

chambered heart and are cold blooded.

Skeleton is made up of either cartilage or bone.

Scoliodon and labeo rohita are some

examples.

Class : AmphibiaThey are animals with uncovered skin which help in gas exchange.They have three chambered heart and are cold blooded.They are found in both water and on lad.They lay eggs without any hard shell.Frog and salamanders.

Class : ReptiliaThey are terrestrial as

well as aquatic.Skin is covered by

scales.They are cold blooded

animals mostly having three

chambered heart except crocodile.

Their eggs are covered by a hard

shell.They breathe through

lungs.Examples are snakes

and tortoise.

Class : AvesThey have four

chambered heart and are warm blooded.

They breathe through lungs.

They lay eggs covered by hard shells.

Their body is covered by feathers and are very

good fliers.They do not have teeth

and bear beak and claws.All the birds are

examples.

Class : MammaliaThey have four chambered heart and are

warm blooded.They breathe through lungs.

They have mammary glands for the production of milk.

They have hairs and nails as well as sweat and oil glands.

They give birth to young ones except platypus and echidna.

All the milk producing animals including humans.

All the milk producing

Need for Nomenclature :To solve the problem of many

names for any organism in different areas. Such as Lady

Finger (Abelmoschus esculentus) is known by Bhindi , Gumbo in

different countries.To solve out the confusion

occurred by the common names of some organisms.

Such as Silver fish , Cuttle fish are example of arthropods and molluscs respectively , but the name produce confusion that they belong to class Pisces.

How to write scientific namesCarlous Linnaeus introduced the

system of providing unique names to each organism.

Few rules are proposed for naming that are following :

1.Name should be given in Latin language.

2. Name of Genus begins with capital letter.

3.Name of the species begins with small letter.

4.The scientific name should be written in italics when printed and should be underlined separately

when hand written.Such as the name for Humans is

Homo sapiens for Lion is Panthera Leo.

Made ByPratima Lakshmi

9th ADLSK