Download DIVERSITY IN LIVING ORGANISMS

DIVERSITY IN LIVING ORGANISMS
Classification Of Organisms
Different places in different parts of the world are having their
own kind of animals and plants. Every organism of the living
world whether an animal, a plant or a microbe is unique in
itself.
Diversity
Diversity is defined as the existence of millions of life forms.
The diversity in the living organisms is due to the uniqueness
of all individuals whether an animal, a plant or a microbe. The
diversity is boundless because different places have different
living beings. To study diversity effectively, it is necessary to
arrange various kinds of organisms in an orderly manner. This
diversity is originated during the past 3.5 billion years of
organic evolution. In this period many species are lost also.
Classification
The method of arranging organisms into groups or sets on the
basis of similarities and differences is called classification. It
also shows their relationships. By studying just a few
representatives from each group, idea of all members of that
group can be taken. Science of classification is called
Taxonomy.
Importance Of Classification
(i) Classification makes the study of wide variety of
organisms easy.
(ii) It projects a picture of all life forms at a glance
(iii) It helps to understand the interrelationships among the
different groups of organisms.
(iv) It serves as a base for the development of other biological
sciences.
(v) It advances our knowledge for many other branches of
biology.
Protista, kingdom Monera and kingdom Fungi. Then a fivekingdom system of classification formulated, which is having
the following five kingdoms: Five Kingdom System Of Classification
This system of classification was given by Whittaker.
1. Kingdom Monera (Prokaryotic Bacteria And Blue Green
Algae)
2. Kingdom Protista (Unicellular Eukaryotic Organisms –
Protozoans, Fungi And Algae)
3. Kingdom Plantae (Multicellular Green Plants And
Advanced Algae)
4. Kingdom Fungi (Multinucleate Higher Fungi)
5. Kingdom Animalia (Multicellular Animals)
Kingdom Monera
Habitat : Aquatic as well as terrestrial
Features
1. They are the prokaryotic organisms which don’t have a
defined nucleus or organelles.
2. They are unicellular organisms.
3. They may or may not have cell walls.
4. They are either autotrophic or heterotrophic.
Mode Of Nutrition: Autotrophic
Reproduction: Asexual
Examples
Bacteria, blue green algae and mycoplasma.
Classification And Evolution
Most of the life forms that we see today have arisen by an
accumulation of the changes in the body design that allow the
organism possessing them to survive better. This is called
evolution. When we connect this idea of evolution to
classification, we will find two types of organisms, first
primitive or lower organisms which have ancient body designs
that have not changed very much. Secondly the advanced or
higher organisms that have acquired their particular body
design relatively recently. This complexity in design is a result
of evolution and this shows that classification of the life forms
is closely related to their evolution.
Classification Of Plants And Animals
The differences between plants and animals are very clear.
Plants are stationary, trap sun’s energy to make their food and
some plants grow indefinitely. Animals generally move,
depend upon other plants or animals for food, and their bodies
stop growing after attaining a certain size. Because of these
basic differences, plants and animals are put into the two
groups: 1. Plant Kingdom
2. Animal Kingdom
With passage of time it came to know that some organisms
are not strictly under plant or animal kingdom. For those
organisms more kingdoms were introduced like kingdom
Kingdom Protista
Habitat: Aquatic as well as terrestrial
Features
1. They are the eukaryotic organisms which have a defined
nucleus or organelles.
2. They are unicellular organisms.
3. They make use of appendages such as cilia, flagella and
pseudo podia for movement.
4. They are either autotrophic or heterotrophic.
Mode Of Nutrition : Autotrophic
Reproduction : Asexual
Examples
Amoeba, paramecium and euglena etc.
Subkingdom Cryptogamae
(Crypto – Hidden, gamous – marriage)
It is further divided into three subdivisions namely
1. Thallophyta
2. Bryophyta
3. Pteridophyta.
These are also known as lower plants, flowerless or seedless
plants. These plants do not have external flowers or seeds that
are why these are considered to have hidden reproductive
organs. It is further divided into three divisions:
Kingdom Fungi
Habitat: Aquatic as well as terrestrial
Features
1. They are eukaryotic organisms.
2. They are multicellulars.
3. Their cell wall is made up of tough complex sugar called
chitin.
4. They are heterotrophic parasites and saprophytes.
Mode Of Nutrition: Heterotrophic
Reproduction: Asexual
Examples
Rhizopus, yeast, agaricus, pencillium,aspergillus.
Division Thallophyta (Thallus– undifferentiated into root
sterns or leaves, phyta – plant)
1. Habitat: Aquatic as well as terrestrial.
2. Features
(i) Most plants are primitive and simple.
(ii) The plant body is not differentiated into stem, root,
and leaves, i.e., it is in the form of an undivided
thallus.
(iii) There is no vascular system i.e., mechanical and
conducting tissues are absent.
3. Reproduction
(i) The reproductive organs are single celled and there is
no embryo formation after fertilization.
(ii) Asexual reproduction generally takes place by spores.
Algae (Sea-weeds)
1. Habitat: Most algae are aquatic both marine and fresh
water, some live on land near moist places.
2. Features
(i) Algae prepare their own food with the help of green
chlorophyll pigment by the process of photosynthesis.
(ii) Some algae have pigments of other colors like red,
blue, yellow.
(iii) They have a cellulose cell wall around their cells.
3. Example: Ulothrix, Chladophora, Ulva.
The Hierarchy Of Classification Groups
Further classification is done by naming the sub groups at
various levels as given below: Kingdom
Phylum (for animals)/ Division (for plants)
Class
Order
Family
Genus
Species
Thus in the hierarchy we finally arrive at the basic unit of
classification called species. A species include all the organisms
that are similar enough to breed and survive.
Plant Kingdom (Kingdom Plantae)
In 1883 Eichler suggested plant kingdom which includes
multicellular green plants and advanced algae and subdivided
it into two subkingdoms.
Plant Kingdom
Cryptogamae
Phanerogamae
Thallophyta Pteridophyta Bryophyta Gymnospermae Angiospermae
2. Division Bryophyta (Bryo-a moss, phyta-plant)
1.
Habitat: These are found in shady damp places.
2.
3.
Features
(i) Bryophyta are the simplest, small, multicellular, green
plants
(ii) Plant body is flat and lack true leaves and roots.
(iii) Reproductive organs are multicellular.
(iv) An embryo is formed upon fertilization.
(v) True vascular system is absent.
Example: Riccia, Marchantia, Funaria.
2.
(ii) The seeds produced by these plants are naked and
are not enclosed within fruits.
Example: Pynes, Cycas, Cedrus.
Division Angiospermae (Case Seed)
1.
Features
They produce seeds which are enclosed within fruits.
Angiosperms are distinguished into two groups on the
basis of cotyledons: (i) Monocotyledons (ii) Dicotyledons
3. Division Pteridophyta
Monocotyledons
The plants with seeds having a single cotyledon are
called monocotyledons or monocots. They have fibrous
roots and generally weak stems. Their leaves show
parallel venation.
Example
Maize, wheat, pulses, rice and grasses etc.
3.
Dicotyledons
The plants with seeds having two cotyledons are called
Dicotyledons or simply dicots. They have tap roots i.e.,
prominent primary roots and woody strong stems. Their
leaves show reticulate venation (network of veins).
Example: Mustard, peas, beans, peanuts and radish etc.
1.
2.
Habitat: Found in mainly shady or damp places.
Features
(i) Plant body is made up to stems, leaves and roots.
(ii) Vascular system is present.
(iii) Reproductive organs are multicellular.
(iv) Fertilized eggs develop into an embryo.
Example: Fern, Azolla, Adiontum.
2.
Animal Kingdom (Kingdom Animalia)
Subkingdom Phanerogame (Spermatophyte)
(spermato – seeds).
1. Habitat: These grow in soil in the presence of sunlight.
2. Features
(i) These are called seed plants. Body is differentiated
into true stem, leaves and root.
(ii) Vascular system (xylem, Phloem) is well developed.
(iii) Reproductive organs are multicellular.
(iv) An embryo develops from fertilized egg.
There are two subdivisions of this kingdom on the basis of
presence or absence of fruit.
1. Gymnospermae
2. Angiospermae
Division Gymnospermae (Naked Seed)
1.
Features
(i) They are most primitive and simple seep plant.
Animals are divided into several phyla mainly on the basis of
their cell organization, symmetry, presence or absence of
notochord and body cavity. In the two-kingdom system
animals are arranged progressively from simple single-celled
protozoans to highly complex animals. You will study the
evolution of this gradual complexity in animals in more details
in higher classes. Here only some of the distinctive characters
of each phylum have been given.
Phylum Porifera (Includes Sponges).
1. Habitat: Aquatic (mostly marine but a few fresh water).
2. Features
(i) These are multicellular where cells are loosely held
together and do not form tissues.
(ii) Organisms are sessile and attached to the rock layer.
(iii) Body is having many pores called ostia all over it
from where water can move in and out. This is called
canal system.
(iv) A large sized water outlet osculum is there at the top.
Water brings food and oxygen.
3.
4.
5.
(v) Body is asymmetrical or radially symmetrical.
Sponges may be vase-like, rounded or sac like.
(vi) Skeleton is made up of calcareous or siliceous
spicules or sponging fibres.
Nutrition: Nutrition is mostly heterotrophic.
Reproduction : Reproduction is both asexual by budding
and sexual through fertilization.
Example: Sycon, Euplectella, Spongilla.
Phylum Cnidaria (Coelenterata)
1.
2.
3.
4.
5.
Habitat: It includes aquatic (both fresh water and
marine), solitary or colonial forms.
Features
(i) Multicellular organisms.
(ii) Show radial symmetry.
(iii) Tentacles are present and body is supplied with
special stinging cells, called cnidoblasts.
(iv) Respiratory, Circulatory and Excretory organs absent.
(v) Animals in this group exist in two types of individuals
or forms called zooids – polyps and medusae.
(vi) Polyps lead solitary or colonial life but are always
fixed at their places (sedentary). They are diploid
cylindrical. They reproduce asexually.
(vii) Medusae are free swimming. They are diploid
umbrella like. They reproduce sexually.
(viii) A cavity in the centre of the body called gastro
vascular cavity or coelenterons is present.
(ix) Many cnidaria forms a hard skeleton made of lime.
These are corals.
Nutrition: Nutrition is heterotrophic.
Reproduction : Asexual (budding) in polyp form and
sexual in medusa form.
Example: Hydra, Obelia, Sea anemone, Aurelia.
4.
5.
Reproduction: They are mostly hermaphrodite which
means male and female sex organ are present in the
same animal.
Example: Dugesia (planaria), Fasciola (liverfluke),
Schistosoma (blood fluke), Taenia solium (tape worm).
Phylum Aschelminthes (Nematoda: -round or
thread worms)
1. Habitat : They are mostly parasitic some are free-living
in soil and water.
2. Features
(i) Body size varies from microscopic to several
centimeters in length.
(ii) They are triploblastic, unsegmented and show
bilateral symmetry.
(iii) Body is cylindrical or flattened covered with tough
resistant cuticle (waxy coating).
(iv) Body cavity is not a true coelem.
(v) Alimentary canal is complete.
3. Nutrition: Nutrition is heterotrophic.
4. Reproduction: Sexes are separate. Reproduces sexually
through fertilization.
5. Example: Ascaris (Round worm), Enterobius (Pin worm),
Wuchereria (filarial worm).
Phylum Annelida (segmented worms)
1.
2.
Phylum Platyhelminthes (Flatworms)
1.
2.
3.
Habitat: Aquatic both marine and fresh water and a few
are terrestrial.
Features
(i) Their body is dorsoventrally (relating to back) flat and
leaf-like or ribbon-like (platy means flat).
(ii) Body is bilaterally symmetrical.
(iii) They are the first triploblastic animals (which means
their tissues differentiate from three embryonic germ
layers) but without a body cavity.
(iv) Circulatory, respiratory system and skeleton are
absent.
Nutrition: Nutrition is hetrotrophic.
3.
4.
5.
Habitat: Mostly aquatic (marine or fresh water). Some
are terrestrial (in moist soil), Some are free living.
Features
(i) They are elongated, with segmented body and
bilateral symmetry.
(ii) First animals with true body cavity (coelom)
containing digestive tract.
(iii) Some of the anterior body segments concentrate to
form head.
(iv) Body bears lateral appendages (attachments) for
locomotion in the form of chitinous setae or chaete.
Nutrition: Nutrition is heterotrophic.
Reproduction: Reproduce by sexual means
Example: Nereis (sand worm) Aphrodite (sea mouse),
Pheretima (earthworm), Hirudinaria (cattle leech).
Phylum Arthropoda (The largest phylum, animals with
jointed feet)
1. Habitat: They are found everywhere, on land, in soil, in
fresh and marine water and as parasites on other animals
and plants.
2. Features
(i) They possess jointed legs (arthros = jointed) and are
biletrally symmetrical.
(ii) The body is segmented and segments are grouped
into two regions – cephalothorax (head and thorax
together) and abdomen, or three regions – head,
thorax and abdomen. III) Anterior part of body forms
a distinct head, bearing sense organs and brain.
(iii) Exoskeleton is chitinous (made of a hard substance
called chitin) and jointed.
(iv) Body cavity is reduced and filled with blood (called
haemocoel).
(v) Respiration is by gill, tracheae, booklung, etc.
3. Nutrition: Nutrition is heterotrophoc.
4. Reproduction: Sexes are separate. Reproduce sexually.
5. Example: Scolopendra (centipede). Palaemon (prawn),
Periplaneta (cockroach), Musca (housefly), Anopheles
(mosquito), Apis (honeybee), scorpion, spider.
3.
4.
5.
(iv) These are unsegmented. Excretory organs absent.
(v) Body cavity is modified into a water-vascular system
with tube like outward extension for locomotion,
called tube feet.
(vi) Body wall is covered by spiny calcareous plates
forming a rigid and flexible endoskeleton.
Nutrition: Nutrition is heterotrophic.
Reproduction: Reproduce sexually through fertilization.
Example: Asterias (star fish), Echinus (sea urchin),
Holothuria (sea cucumber), Antedon (feather star).
Phylum Mollusca (mollusca-soft)
1.
2.
3.
4.
5.
Habitat: Aquatic, mostly marine, few fresh water and
some terrestrial forms.
Features
(i) They are soft having unsegmented body. Body is
bilaterally symmetrical
(ii) Body is divided into three regions: (head, dorsal
visceral mass and ventral foot).
(iii) Body is covered with thin skin called mantle.
(iv) Body cavity is filled with blood.
(v) The size varies from a microscopic to a giant forms
like Octopus of size up to 50 feet.
(vi) Respiration is by gills called ctenidia.
Nutrition: Nutrition is heterotrophic.
Reproduction: Reproduce sexually
Example: Chiton, Pila (snail), Unio, Octopus.
Phylum Protochordata
1.
2.
3.
4.
5.
Habitat: These animals are exclusively marine.
Features
(i) They are bilaterally symmetrical..
(ii) They are triploblastic and have a coelom.
(iii) They have a notochord at least at some stages during
their lives.
(iv) They have unsegmented, worm like body.
Nutrition: Nutrition is heterotrophic.
Reproduction: Reproduce sexually.
Example: Balanoglossus, amphioxus, herdmania.
Phylum Echinodermata (spiny skinned animals)
1.
2.
Habitat: They are exclusively marine, gregarious (live in
groups and free-living animals).
Features
(i) Shape may be star-like, spherical or elongate.
(ii) Body surface is covered all over by calcareous spines.
(iii) Symmetry is radial in adults but bilateral in larvae.
Phylum Vertebrata
1.
Habitat: These animals are terrestrial and can adapt
themselves to any environment.
2.
3.
4.
Features
(i) Head is well differentiated.
(ii) Nervous system and endoskeleton are highly
developed.
(iii) Notochord is replaced by a jointed vertebral column.
(iv) There are two pairs of appendages (mostly hemi
dactyl).
(v) Respiration is by gills in aquatic animals and by lungs
in land animals.
(vi) They are triploblastic, coelomic and bilaterally
symmetrical.
Nutrition: Nutrition is heterotrophic.
Reproduction: Sexes are separate. Reproduce sexually.
Vertebrata Is Divided Into Five Classes
Class Pisces (Fishes)
1.
2.
Class Aves (Birds)
Features
(i) Their skin is covered with scales/plates.
(ii) They respirate by gills.
(iii) The body is streamlined in shape.
(iv) They have a muscular tail for moving.
(v) They are cold blooded.
(vi) Their heart is two chambered.
(vii) They lay eggs.
(viii) Some have bony skeleton and some have
cartilaginous.
Example: Rohu, Seahorse, flying fish, lion fish, torpedo,
sting ray.
2.
Class Amphibia (Vertebrates Leading Two Lives)
It includes frogs, toads newts and salamanders.
1. Features
(i) They live in fresh water and moist ground.
(ii) Body varies in form and is without scales.
(iii) There are mostly two pairs of pentadactyl (five digits)
limbs, which may be absent in some cases.
(iv) Respiration is by gills, lungs or skin.
(v) Heart is 3- chambered.
2. Example: Rana (frog), Bufo (toad), Hyla (tree from),
Necturus.
1.
2.
1.
Class Reptilia (Creeping Vertebrates)
Features
(i) Mostly terrestrial and live in warmer regions.
(ii) Body varies in form and is covered by scales. Animals
are cold blooded.
(iii) They have two pairs of pent dactyl (five digits) limbs,
which are absent in snakes and some lizards.
(iv) Respiration is by lungs only.
Features
(i) Warm blooded vertebrates with various flight
adaptations.
(ii) Fore limbs are modified into wings.
(iii) Body is divisible into head, neck, trunk and tail.
(iv) Body is covered with feathers.
(v) Skeleton is light.
(vi) A beak modified for different purposes surrounds
mouth.
(vii) Respiration is by lungs only.
(viii) Heart is 4 – chambered.
Example: Columba (pigeon), Pavo (peafowl) Passer
(sparrow), Struthio (ostrich).
Class Mammalia (Mammals)
2.
1.
(v) Heart is generally 3- chambered.
Example
Hemidactylus (wall lizard), Chameleon, Draco (flying
lizard)
Features
(i) Body is of varied shapes, covered with hair.
(ii) They have two pairs of pentadactyl limbs modified for
various purposes.
(iii) Respiration is by lungs only.
(iv) Females have milk producing mammary glands which
secrete milk for the nourishment of the young.
(v) Heart is 4 – chambered.
(vi) Have a developed nervous system.
(vii) Have a post anal tail.
(viii) Primarily terrestrial and occupy all sorts of habitats.
Example
Macropus (kangaroo), Rattus (rat), Balaenoptera (whale),
Panthera (lion, tiger), Elephas (elephant), Macaca (Rhesus
monkey), Pan (chimpanzee), Homo (man), bat.