Would You Believe Me If I Told

You That the US Spends crores of

Dollars on a Project Called SETI

(SEARCH FOR EXTRA

TERRESTRIAL INTELLIGENCE)

Which Searches the Outer Space

for Signs of Life !!!

Do You Believe in Aliens?

YES,THERE MAY BE ALIENS!

The story that I am about to tell you is the

story of how life began.

Scientists think it is likely that somewhere out

in the universe amongst the millions of solar

systems there may be another planet where

this story is just unfolding.

The story of :

HOW LIFE BEGAN ON EARTH

BUT WHAT IS LIFE?WHATEVER

Reproduces

Gets and Uses Energy

Has cellular structure

Responds to stimuli

Excretes waste matter

HAS LIFE

SO HOW DID LIFE BEGIN

ON EARTH ?

4.6 billion years ago the

earth was just

beginning to calm down

after a violent birth. The

atmosphere still had no

oxygen and noxious

fumes of ammonia,

carbon dioxide, sulphur

dioxide enveloped

earth.

Oceans were the cradle of life

The sea was a soup of different

chemicals that came down with the

rain. Lightening fueled some very

interesting reactions and compounds

now only found in living things were

formed inorganically in the sea water.

These chemicals formed

stable colloidal complexes

called COACERVATES

The First Cell Is Born!These inorganically formed coacervates

had to work out a method of reproduction. They needed a genetic material.

The also needed a cell membrane.

Nobody is certain how but they got it.

The first cell fossils are called stromatolites and they are 3.5 billion years old.

Things now begin to get more

complex

The new cell has a virgin environment

before it.

How will it tap all the resources available

to it?

How will it become more efficient?

How will it become a better survivor?

How will it leave behind its genes?

How do we know about this

story?

From Fossils found in rocks

By studying anatomy of closely related animals

By studying animals that have intermediate characteristics between different groups.The missing links

By studying the embryological developmental stages.

Lets look at a fossil of an animal that is

not found today.

This is the fossil of the Archeopteryx.

It is a missing link between birds and reptiles

Protista (Unicellular Eukaryotes)

Photosynthetic

Protista

Decomposer

Protista

Protozoan

Protista

1. Euglenoid

2. Dinoflagellate

3. Diatoms

4. Slime moulds5. Sarcodina

6. Ciliata

7. Mastigophora

8. Sporozoa

Common Features of Protista

1. Eukaryotic cells

2. Photosynthetic or heterotrophic

3. Unicellular e.g. Amoeba, Paramoecium etc.

4. Prototists are thought to have been the

ancestors of animals, plants and fungi, i.e. they

were the unicellular eukaryotic cells..

Amoeba proteus is busy capturing a ciliate by surrounding it with its pseudopodia. The nucleus can be seen just below the pseudopodia. Bottom left is a water expelling vesicle. Amoebaslocomote almost like a fluid. Although amoebas are 'shape-shifters' their shapes limit to a certain range. Each species has its own 'repertoir'

Pseudopodia

Food (bacteria)

Nucleus

Contractile vacuole

(excrete water etc.)

Protozoa: Sarcodina (all have pseudopodia)

Amoeba

Ceratium hirundinella,a dinoflagellate. one of the flagella is just visible. The other runs through the girdle (dark stripes in center image)

2nd Flagella

1st Flagella

Photosynthetic Protista: Dinoflagellata (2 flagella perpendicular to one another):

Noctiluca (Photosynthetic Protista)

Single celled ‘animals’ -

Protozoans

Contractile vacuole

Gullet

Ciliia

Nucleus

Paramoecium

Paramecium bursaria, a green slipper animalcule. It gets its colour by symbiotic algae, Chlorella. They are visible as small round cells.

Paramoecium (Ciliata)

Cilia all ovedr the body

Bell animalcules are common in

fresh water but can also be found in the sea. These colonial Ciliates live attached to a stalk. Find out more about their fresh water relatives on the smallest page on the web

Colonial ciliates

Cilia

Individual Zooids)

Stock

Diatom, Photosynthetic Protista

Diatom

Desmids like this Micrasterias rotata are amongst the most beautiful microscopic organisms. They are conjugating green algae.

Unicellular Plants: Algae

Some are Multicellular

Algae: Volvox Colony

Single celled ‘plants’- algae

Desmid

(Body with pores)

Flat Worms & Round

(Jointed Legs)

(Spine on skin)

Notochord,

Dorsal tubular nerve cord,

Gill slits

Phylum Porifera (Sponges)

1. No distinct tissue layer (although 2 layer of cells)

2. Presence of numerous pores throughout the body

3. Presence of Choanocytes ( collar cells)

4. Spicules mostly made up of calcareous, silicious or spongin fibre.

5. Mostly marine

Porifera: A body full of holes.

Body covered with tiny pores

No tissue organisation

Sessile, filter feeder

Spicules present

Choanocyte cell and extensive canal

system present.

Sponge (Porifera)

Porifera

Osculum)

Spicules

Ostia

Phylum Cnidaria

1. Body with distinct tissue system: 2 layers:

Ectoderm & Endoderm

2. Presence of nematocyst cells

3. One gastrovascular cavity (Coelenteron)

4. Can be polyp, medusoid or both form

PolypMedusa

Coelenteron

Tentacle(with nematocyst)

Cnidaria (Coelenterata)

Presence of nematocyst

Bag like body with one opening guarded by finger-like tentacles.

Radial Symmetry

Two layer of cells (diploblastic).Network of nerve cells present.

Polyp form Medusa form

Ectoderm

Endoderm

Tentacles

The Hydra is a fresh-water polyp that can extend its

flexible body to an extreme and reach a length of 2 centimeters. The tentacles bear tiny harpoon-like organs called nematocysts. These are used for capturing waterfleas and other small crustaceans. It can turn itself inside out and has amazing capabilities of regeneration!…

Tentacle with

Nematocyst

Mouth

Foot

Phylum: Cnidaria ( 2 layer of

Tissue: Ectoderm & Endoderm)

Obelia Medusa ( Cnidaria )

Obelia medusa

Tentacles with nematocyst

Manubrium (Mouth)

Gonads

Jelly fish

Ctenophora

Ctenophora

Platyhelminthes

Bilateral Symmetry

Three tissue layers

Dorsoventrally flattened

Acoelomate solid body

Well developed tissues like nerves etc

but no blood vascular system.

Incomplete digestive system or absent

Flatworms are multicellular organisms. They posses simple eyes and a simple nervous system. The mouth can be found underneath in the center. The flatworm body is covered with tiny cilia used for locomotion.

1. Body dorsoventrally flattened

2. Solid with distict 3 tissue layer

3. Acoelomate

The Flatworm (Planaria)

Eye spot

Ciliated body surface

Tape worm as parasite inside the Dog

bakerinstitute.vet.cornell.edu

Tape wormTaenia solium

www.medicalook.com

Liver Fluke

www.student.loretto.org

With courtesy from:-

Website:sph.bu.edu

Platyhelminthes

Aschelminthes: Round Worms

Mouth and Anus present

Body round in cross-section

Pseudocoelomate body

Sexes separate

Round worm (Pseudo coelomate body, round in cross section

& distinct mouth and anus)

Ascaris lumbricoides

Hookworm – Anchylostoma

With courtesy from:-

Website:sph.bu.edu

Annelida: The segmented

worm

Body metamerically segmented

Blood vascular system present

Setae present for locomotion

Nerve ring present

Nephridia for excretion

Hermaphrodite has both male and

female reproductive organ

Earthworm Pheretima posthuma

Photocredit:- www.flickr.com -

Polychaeta worm: Nereis

LeechHirudinaria granulosa

Anterior

sucker

Posterior

sucker

Arthropoda (Chitinous exoskeleton & jointed legs)

Arthros = Jointed

Podos = Legs

Arthropoda: Largest group of

living organism

Presence of hard exoskeleton

Presence of jointed legs

Open circulation

_________________________________

Velvet worm (Peripatus)

Photocredit::www.fs.usda.gov

Peripetus

www.teara.govt.nz

Myriapoda

Centipede Scutegera

www.swellvoyage.comsuperscientastic.blogspot.com

Fly with compound Eye

Hermit Crab

www.montereybayaquarium.org

Barnacle (closed)

Barnacle (Open)

Crab (Crustacea)

Spider (Arachnida)

Wolf Spider (Arachnida)

Spider (Arachnida)

www.enchantedlearning.com www.medtogo.com

Scorpion

Mollusca (Muscular foot and mantle usually

which secrete shell

Periwinkle, Gastropoda very common in sea-shore, eat dead animals.

Mollusca: They have soft body

Soft unsegmented body

Presence of mantle covering the body

which usual secretes shell

Cone Shell

Slug

Gastropod snail

Bivalve

Mytilus(with mysis- the thread for attachment)

One valve (shell) of Bivalvia

Top - Shell

OCTOPUS

SQUID

NAUTILUS

www.fantasticforwards.com

Nautilus Shell (showing gas-chamber)

Echinodermata: Spiny skin

Calcareous spines on the skin

Water vascular system with tube feet.

Larva bilateral but adult radial symmetry

Echinodermata

Characters:

1. Presence of echinus, calcareous spicules

2. Body divided into oral and aboral side

3. Presence of water vascular system & tube feet

4. Exclusively marine

5. Larval stage motile with bilateral symmetry but

in adult radial symmetry

wiki.hicksvilleschools.org

Brittle Star

Feather- star

Balanoglossus : Hemichordate

• Stomochord instead of Notochord

• Gill slits

• Nerve-cord not dorsal

ChordataNotochord present

Dorsal,tubular nerve cord

Pharyngeal gill slits

Post anal tail

Closed Vascular system

A generalized chordate showing fundamental

chordate characters

engage.intel.com/.../phylum%20chordata%20and%20protochordates.ppt

Ideal Chordate Structure

Notochord

Nerve cord

Gill SlitsPost-anal tail

Sub Phylum: Urochordata

Bag-like,sessile,marine organism

Adult body covered by tunic

Notochord present in larva only in tail

Nerve cord present in larva but

degenerates in adult

Pharyngeal gill slits

Ex: Doliolum sp. Salpa sp. (Ascidians)

forum-psicologos.blogspot.com -

Ascidia (Urochordata) Larva

commons.wikimedia.org

Sub Phylum: Cephalochordata

Notochord present throughout the life

Dorsal,tubular nerve cord extended up

to head

Pharyngeal gill slits distinct

Amphioxus ( Cephalochordates)

Sub Phylum: Vertebrata

Presence of skull (Craniata)

Notochord modified into bony vertebra

in adultVertebra

Nerve chordsSkull (Cranium) covering brain

Super Class: Agnatha

Class: Cyclostomata

No jaws

Pharyngeal gill slits with pouches

Mouth circular

Body cartilagenous

All marine

Unpaired fins (no paired appendages)

Example: Lamprey(Petromyzon sp.) Hagfish

(Myxine sp.)

PETROMYZON

CYCLOSTOMATA

Sub Phylum : Gnathostomata

Presence of jaws

Presence of paired appendages

Upper jaw

Lower jaw

Paired Appendages

Class: Chondrichthyes (Cartilagenous fish)

Endoskeleton made up of cartilage

Gills without operculum

Paired and unpaired fins without fin-rays

Mouth ventral

Tail or caudal fin heterocercal

Heart 2 chambered

Example: Sting-ray(Trygon sp.) Shark, Electric

–ray (Torpedo sp.)

Class: Osteichthyes

Bony endoskeleton

Gill-slits covered by operculum

Fins with fin-rays

Tail fin homocircal

Presence of swim-bladder

Heart 2 chambered

Ex: Gold fish, Eel, Sea-horse, Flying fish

Osteichthyes (Bony fish)

Eel

Glass fish

Class: Amphibia

Tadpole larva grows in water and adult is terrestrial (i.e. two stages in the life cycle-aquatic and terrestrial)

Moist skin

Two pairs of pentadactyl limbs

3 chambered heart

Respire through gills(in larva), lungs and moist skin (in adult)

Ex: Caecilian(Icthyophis sp.), Salamander (Salamandra sp.), Toad (Bufo melanostictus), Frog (Rana tigrina)

Class: Reptilia

Terrestrial organisms with pentadactyle

clawed digits and four limbs (Tetrapods)

Respiration only by lungs

Body covered with dry scales

Heart 3 ½ chambered ( except

crocodiles were it is 4 chambered)

Ex: Tortoise, Crocodile, Lizard, Snake,

Chameleon

Reptilia

Class: Aves (Birds)

Presence of feather

Beak without teeth

Forelimbs modified into wings

Hollow bones

Homeotherm (Warm blooded)

4-chambered heart

Ex: Peacock (Pavo cristatus), Ostrich (Struthio

sp.) Albatross, Purple sun-bird

Class: Mammalia

Presence of mammary gland

Hairs all over the body

Give birth to young ones (except Platypus and Echidna)

External ear (Pinna) present

Placenta present in most

Diaphragm present

4 chamberd heart

Ex: Whale, Seal, Elephant, Bat, Man,Kangaroo, Platypus

The African Elephant

Class Mammalia

Sub-Class: Prototheria

(Egg-laying mammal)

Lays reptile-like egg

No external ear

No placenta

Body not properly homeotherm

Mammary gland without niples

Example: Platypus(Ornithorhynchus sp.)

Echidna ( Tachyglossus sp.)

Sub Class: Marsupiala

Placenta yolk-sac type

Presence of marsupium (Pouch)

Immature babies born inside marsupium

Ex Kangaroo(Macropus),Wombat,

Koala, Opossum

Sub Class Eutheria

(Placantal mammal)

Presence of true placenta(allanto-

chorionic)

Urino-genital apparatus and anus

separate

Placental mammal

Order Insectovora-shrew

Order Rodentia-rat,squirrel

Order Primate.Ex Monkey,Gorrila,Man

Order Chiroptera-bat(Pteropus sp.)

Order Cetacea-dolphin,whale.

Order Carnivora-tiger,dog,cat

Order Artiodactyla-deer,giraffe,cow

The Polar Bear

Compiled by:-

Jyoti Parruck

jparruck@gmail.com

9312690129

(taken help from CD and NET)