BIOLOGY: this implies study of living organisms. This term was coined in 1802 by the

Pioneer scientist LAMARCK, but ARISTOTLE a Greek philosopher was known as the FATHER OF BIOLOGY


HISTORY OF BIOLOGY:

About
12000 years ago in Indian subcontinent started the cultivation of
crops, and then after about 6000 years back Indians developed rice and
were given about 100,000 verities to the world .

We can divide the period of Hindu medicine in two parts

1) Vedic ----- (2500BC to 650BC)

2) Brahmanic ------600 BC to AD1000)

In Vedic period the information source is only what is written in Vedas
 
In Brahmanic age the knowledge was given by Hindu priests’ ideology

Classification of animals:

Majority of animals (99%) are invertebrates means there is no vertebra in them and

Remaining are vertebrates

Animals are classified into two major groups

Nonchordates: animals which do not have notochord in any stage of life

Chordates animals which do not have notochord in any stage of life

Phylum protozoa:      these are unicellular animals; this means only one cell which performs all the vital activities.

They are found everywhere both in water and land   

Sometime these small creatures are surrounded by non- rigid membrane called pellicle

But cellulose is absent in the membrane.

Some protozoan secretes shells which can be of calcium, silica and sand granules.

For locomotion there are different organs which are as follows.

Flagella -----flagellates
 
Pseudopodia------sarcodines

Cilia----------ciliates

But not all the protozoan are locomotory some of them are non- motile example is

SPOROZOA

NUTRITION OF PROTOZOAN

This can be of two types

Holozoic majority of them are holozoic. They feed upon bacteria microscopic algae and sometimes on the protozoan of their own species 
 
Holophytic this means they have chlorophyll and with the help of this pigment they

Prepare their own food by the process known as photosynthesis. Example is EUGLENA

Many
of the protozoan are harmless to man, but some of them are very harmful
to the man are plasmodium, which cause malaria. There are different
species which are vivax plasmodium.

REPRODUCTION IN PROTOZOAN 

These reproduce by both sexual and asexual means

Asexual method is of following types

Binary fission
Budding
Multiple fission
Example is most ciliates, flagellates and sarcodines

Sexual
method: some ciliates follow this method of reproduction in this method
two protozona come in close contact and then they exchange  their
nuclear material this process is known as CONJUGATION.example is euglena
amoeba and  trypanosoma

Phylum protozoa can be divided into 4
groups, the basis for this classification is locomotory organelle, and
the four groups are as follows

1) Mastigophora these have
flagella for locomotion which can vary from one to many example is
trichonympha, giardia, trypanosome, leishmania and trichomonas

2) Sarcodina
it is also known as rhizopoda there locomotory organ is psedopods,
which are protoplasmic outgrowth, but are temporary in nature.
Example is amoeba, entamoeba, and heliozoans


3) Sporozoa
these are parasitic in nature and locomotion is absent in them the mode
of reproduction is sexual and they form Sporozoa so they are called
Sporozoa.
Example is plasmodium, monocystis

 
4) Cilliata: they produce cilia. Which they use for locomotion and for driving food
Example is paramecium, vorticella, and balntidium


                                                     PHYLUM: POROFERA

These are most primitive of multicellular animals and commonly known as SPONGES

They
all are aquatic though they can e fresh water or marine they attach
themselves with rocks ,coral ,shells and other substances
Their subkingdom is PARAZOA, and they are mostly asymmetrical in nature.

At the terminal point of the body there lies a large aperture called OSCULUM.
Digestion is of intracellular variety

Sponges have 4 types of cells

CHOANOCYTES 
POROCYTES
FLAT EPIDERMAL CELLS
AMOEBOCYTES

Mode of reproduction is asexual by fragmentation

One peculiar feature is immense power of regeneration

They are divided into three classes and the basis is skeleton

CALCAREA this exhibit skeleton of calcareous spicules
 
Example is leucosolenia, sycon

HEXACTINELLIDA they have spicules arranged in 6 rays .spicules are made up of silica .example is euplectella, hyalenema (glass rope sponge)

DEMOSPONGIAE their skeleton is made up of sponging fibers of siliceous spicules 

Example is euspongia(bath sponge), spongilla



                                                      PHYLUM CNIDARIA
 

These are simple organisms found in aquatic environment, mostly are marine

They have tissue grade of organization and they have radial symmetry

Their
body is covered by double layer outer one is called ectoderm and the
inner one is called endoderm and the separating layer is called
mesogloea

There is no anus but oral aperture is there which opens
into gastro vascular cavity for this reason these are called
coelenterons.

They also secrete digestive enzymes and the digestion is of extracellular type undigested food is ejected through mouth

Though there is no brain but there are nerve nets which are about 2 in numbers

They exhibit two body types

Polyp

Medusa

Polyp can be sessile or pedunculated they can e solitary or colonial
Medusa is always solitary and is free swimming its shape resembles that of umbrella

Mode
of reproduction can be vegetative budding or sexual .polyps usually
reproduces by budding and medusa reproduces by sexual mode. Some
specific characteristics are polymorphism, metagenesis.  

Following fertilization, the zygote forms a ciliated larva called planula

They are divided into three classes

Hydrozoa either only polyp or polyp and medusa are present

Example hydra, obelia, physalia

Scphozoa polyp is either absent or inconspicuous example is Aurelia

Anthozoa in this medusa form is absent
Example is gorgonia, (sea-fan) fungia (mushroom coral), corallium (red coral)


                                               PHYLUM-CTENOPHORA

They are marine animals and they have flat or oval body surface
They are also known as comb –jellies, goose berries

They
possess specialized cells to capture their prey called colloblasts, for
movement they have cilia which join together and form comb plates

They
have gastro vascular cavity which is branched and opens to the exterior
by stomodaeum, they also have double layer of membrane.

The characteristic of this phylum is the presence of special sence organ which is present at the opposite end of the mouth.

The method of reproduction is sexual only.
 
Example is clenoplan, hormiphora

  


                                           PHYLUM-PLATYHELMINTHES (FLATWORMS)

It
contains animals such as flatworms, tapeworms and flukes, many of these
are aquatic and parasitic in nature on humans and on animals

They are bilaterally symmetrical and triploblastic

They have organ system organization
Alimentary
canal is incomplete they have mouth but anus is absent .their body
surface is adapted to absorb nutrient because they lack alimentary canal
.and respiration and circulation also takes place through body surface .

Their nervous system comprises of single brain called brain ganglia

The outer surface has hooks and suckers
Flatworms have special cells called flame cells for excretion and osmoregulation.and they are ammonotelic

Regarding
reproduction they reproduce both sexually and asexually and the system
is hermaphroditic (it means each individual produce both sperms and egg)

These have great power of regeneration.

This phylum is classified into three classes
   
Turbellaria they are acquatic and their surface is covered with cilia
They are scavengers and carnivores
Example: dugesia

Trematoda these have    oval body which is not segmented like flatworms.

They are parasites flukes are included in this class. They exhibit suckers on their surface for attachment to the host.

Example is blood fluke (Schistomata)
                  Liver fluke (Fasciola)

Cestoda they are mostly found in the intestine of vertebrates thus they are mainly endoparasites.

Their body is divided into many proglottids, but there are no cilia

Example is taenia (tapeworm)
Echinococcus (dog tapeworm)




                                                          PHYLUM-NEMATHELMINTHES


They are also known as nematodes. The body is cylindrical in shape

They are also known as roundworms because if seen in cross section they appear round
These are non –segmented and bilaterally symmetrical in shape.

They
have reached to a organ type of grade and the specific point about them
is that they exhibit   : tube within a tube body plan, which is very
specific for them.

Their digestive tract is divided into
mouth, pharynx, intestine and anus .they also have peristalsis movement
in the pharynx which allows them to suck the blood from the host

Their body movements are very flexible in nature
They have very co-coordinated movements, which are due to the presence of a nerve ganglion around the pharynx.

There excretion is by the excretory tubes which remove the waste from the body

Reproduction they are typically unisexual and show sexual dimorphism. Females are longer than their male’s counterpart.

Examples are Ascaris, Wuchereia, Anchylostoma, and Enterobius



                                                            PHYLUM-ANNELIDA


First class having true coelom.

They are bilaterally symmetrical and have organ grade og organization

Their bodies are divided into true parts, and these segments are added throughout life

They have the outer most layers called ectoderm

They have both longitudinal and circular muscles

They have bristles or chaetae on the lower side of the body which helps during locomotion

Their coelom is also called hydrostatic skeleton as it is important for transport of body fluids and discharge of gametes

This phylum is also divided into 3 classes on the basis of setae or bristles

1) Polychaeta

They have well developed parapodia
Example is Nereis
                Aphrodite

2) Oligochatea

Their body has few setae. There is no metamorphosis

Example is Pheretima (Indian earthworm)
                 Lumbricus

3) Hirudinea
they are ectoparasites leeches. They have very peculiar connective
tissue beneath the muscular layer of body wall around the alimentary
canal botryoidal tissue 

Examples are hirudinaria
Acanthobdella




                                                     PHYLUM-MOLLUSCA

They have very soft bodies .they are triploblastic and have bilateral symmetry.
They have shells to protect their soft bodies which are made up of various shapes

They have non-segmented body which can be divided into head, foot, and dorsal hump

They have soft skin .the hump contains circulatory and digestive system

Respiratory and excretory functions is done by gills

Nervous system they have paired ganglia .they have sensory tentacles also

Mouth has rasping organ called radula

They are basically oviparous

They are classified into 6 classes

Class 1) Monoplacophora they have characters of two phylum, both annelida and mollusca

Like Annelida they have internal segmentation and presence of nephredia.

Like mollusca they have mantle, shell and foot

Example is neopilina


Class 2) Amphineura
Shells are sometimes absent also

Example is chiton

Class 3) Scaphopoda

They have conical foot which is mainly used for digging

Example is dentalium (elephant tusk shell)      

Class 4) Gastropoda they have shell made of one piece only.body in later stages is asymmetrical

Example is Pila
                 Limax
                 Patella
 
Class 5) Pelecypoda

Their body is enclosed in a bivalve shell; they also use their foot for digging.

Example is unio
Solen, pectin


Class 6) Cephalopoda they have well developed large head with eight tentacles, hence name is cephalopod or head foot

Their eyes can form image and similar to ours

Some of them are largest invertebrates

Example is octopus sepia(cuttle fish)

   

                                                PHYLUM ORTHROPODA

They form the largest group of animals

They can be found anywhere

They are triploblastic, coelomate, and bilaterally symmetrical

The body is covered by chitinous cuticle

 They have segmented body

They have variety of respiratory organs

Marine forms have gills
Terrestrial forms have book lungs or air tubes


They have open type of circulatory system

They have Malpighian type of excretory system

They have specialized type of sense organs

                                         Antennae   -- as tactile organ
                                        Eyes -----as photoreceptors
                                        Taste receptors
                                       Pheromones which help in communication

They can have simple or compound eyes

They are unisexual they have two types of reproduction external and internal

They are oviparous.
In some arthropods like scorpion they give birth to young one

Classification (5 classes)

Class 1) Crustacea they have hard shells

Their body can be divided into two parts

                   1) Cephalothorax
                    2) Abdomen 

There are two pairs of antennae and one pair of compound eyes

These animals have 5 pair of appendages which are modified for swimming, respiration and reproduction.

 Examples are cancer, Lucifer, lepas


Class 2) Chilopoda

Their body has many segments and is divided into head and trunk. They have legs in each segment
They have a single pair of antennae and there are legs in each segment and first pair of legs is called poison claws.


Class 3) Diplopoda

There is single pair of antennae and there body is divided into head, thorax, and abdomen


Example is julus (millipede)


Class 4) Insecta 

The body is typically divided into head thorax and legs.
They have a pair of compound eyes and antennae.

Thorax has three segments with three pair of legs and two pairs of wings
There are 11 segments in the thorax.  .

Examples are lepisma (silver fish), gryllus, periplaneta (cockroach), termite, butterflies.


Class 5) Arachnida
 
 The body is divisible into cephalothorax and abdomen they do not have any antennae

Respiratory organs are book lungs, or trachea or both.

Examples are palamnaeus, lycosa (spider), ixodes, and mite



                                                         PHYLUM –ECHINODERMATA

As the name suggests these include spiny animals, which is there ectoderm has many spines so as the name.

Their
inhabitat is marine, thay are tripoblastic, and coelomate.they has anus
on the upper side and mouth on the lower side          

 They have a very unique feature WATER VASCULAR SYSTEM, which is a part of coelom.

They have many radiating appendages called tube feet.

This system performs many important functions such as locomotion, respiration feeding etc.

There is no circulatory system in them

Respiration is performed by tube feet which are equivalent to gills.

Excretion is through body surface only.

They have the power to regenerate.

They have separate sexes there are 5 pairs of sex organs, fertilization occurs in open water.


This phylum is divisible into 5 classes


Class 1) Asteroidea

Example is asterias, pentaceros


Class 2) Ophiuroidea

Example is ophiothrix

Class 3) Echinoidea

Example is echinocardium


Class 4) Holohuroidea

Example is holothuria


Class 5) Crinoidea

Example is antedom




                                                          PHYLUM-CHORDATA


These have notochord in any stage of their life either early embryonic or later in life

All of them are triploblastic, coelomate, and bilaterally symmetrical

They have closed vascular system

They have dorsal hollow nerve cord,

Phylum chordate has 4 sub-phylum’s which are as follows


HEMICHORDATA
UROCHORDATA
CEPHALOCHORDATA
VERTEBRATA


Characteristic of each sub phylum are as below


HEMICHORDATA

No notochord
Gills are present
Example is Balanoglossus



UROCHORDATA

There is notochord only in larval form
Example is ciona, salpa



CEPHALOCHORDATA

There is notochord from head to tail

Example is branchiostoma



 
VERTEBRATA

There is notochord in embryonic period and replaced by vertebral Colum in adult life

All vertebrates are chordates but all chordates are not vertebrates.

Kidneys are the main excretory organs

They have closed circulatory system

They follow sexual mode of reproduction

Sub-phylum vertebrata has two sub-groups

                     SUPERCLASS AGNATHA

                    SUPERCLASS GNATHOSTOMATA


  SUPERCLASS AGNATHA (jawless vertebrates)

Class cyclostomata
There are about 12 pairs of gill slits in the gill pouch for respiration
No scales over the body
Functional penial eye is present
Example is petromyzon and myxine




SUPERCLASS GNATHOSTOMATA has 6 classes
 

CHONDRICHTHYES

OSTEICHTHYES

AMPHIBIA

REPTELIA
 
AVES

MAMMALS



CLASS CHONDRICHTHYES

This includes all marine cartilaginous fishes
Body is covered with epidermal PLACOID (tooth like scales)
Example is sharks, skates, rays


CLASS- OSTEICHTHYES

These fishes have bony endoskeleton
Gills are covered by operculum
They have pectoral, pelvic, dorsal and caudal fins for swimming.
Fertilization occurs outside the female body
Males have brood pouch in sea horse
Mostly these are fishes used to eat
Common Indian fishes which are used as food are rohu, mrigal, kalbasu pomfret, Bombay duck.



                
CLASS- AMPHIBIA

As the name suggest they have two phases in their life

They use skin for gas exchange

They live in moist inhabitat
 
They have two pair of limb, which has 4 digits on forelimbs and 5 digits on hind limbs

They is no neck, body has only head and trunk

They have eyelids on the eyes

They also have tympanum. In place of external ear 

Alimentary canal, urinary system and reproductive tract open into common chamber CLOACA

The heart is three chambered

They are cold blooded animals

They have ten pair of cranial nerves

They produce larva, tadpoles which have external gills

They are divided into three orders.




CLASS -REPTELIA

These are first terrestrial animals

Body is covered with dry cornified skin

They do not have external ear openings

They have two pairs of limbs with 5 digits each

They are cold blooded animals with single occipital condyle

They have three chambered heart

Anal aperture is transverse
 
They are carnivores, except few tortoises are herbivores

They shed their skin as cast

 
They have internal fertilization (very peculiar feature)

They have special membrane called amnion around developing embryo

They have four orders

ORDER-CHELONIA
ORDER-SQUAMATA
ORDER-RHYNCHOCEPHALIA
ORDER-CROCODILIA



CLASS-AVES


The characteristic feature is the ability to fly and presence of feathers

Their eggs have calcareous shells outside their eggs

Their forelimbs are modified to wings

Forelimbs has 3 clawless digits and hind limbs have 4 digits with claws

They have hollow bones which help in flying

They have 12 pairs of cranial nerves

They are warm blooded animals

They have 4 chambered hearts

Respiration is through lungs

They do not have teeth

Birds have acute vision and excellent muscle reflexes

Coordination and balance is very well developed

They have only left sided ovary and oviduct

They are oviparous

They have following orders

ORDER –RATITAE
ORDER-CARINATAE




                                CLASS-MAMMALIA


They have unique milk producing glands

They have unique features of having hair on the skin

External ears are present which are not found in other classes

Four chambered hearty is specific

Lungs are well developed and oxygenate the blood

Teeth are present in sockets thus they are called thecodont

These are homoeothermic and endothermic also
 
They have following classes


SUBCLASS-PROTOTHERIA (EGG LAYING MAMMALS)

SUB-CLASS-METATHERIA (POUCHED MAMMALS)

SUB-CLASS EUTHERIA (PLACENTAL MAMMALS)



SUBCLASS-PROTOTHERIA (EGG LAYING MAMMALS)

Mammary glands without nipples
Cloaca present into which rectum and urogenital sinus is present
Example is ornithorhynchus


SUB-CLASS-METATHERIA (POUCHED MAMMALS)
 
Mammary glands with nipples
Females have marsupian ouch of skin fold upon their abdomen
Ear pinna and teeth are present
Testes is extra abdominal and penis is bifid and they have two vaginal sacs
True placenta is absent


SUB-CLASS EUTHERIA (PLACENTAL MAMMALS)

Mammary gland and their teats are well developed
Perfectly warm blooded
Uterus and vagina are unpaired
Eggs are small
This subclass has following orders
ORDER INSECTIVORE

ORDER DERMOPTERA

ORDER CHIROPTERA

ORDER EDENTATE

ORDER PHOLIDOTA

ORDER RODENTIA

ORDER LAGOMORPHS

ORDER CARNIVORA

ORDER CETACEA

ORDER SIRENIA

ORDER PROBOSCIDIA

ORDER PERISSODACTYLA

ORDER ARIODACTYLA

ORDER PRIMATES

You might also like following articles