Biopedia: April 2013

Diversity of organisms

From the dawn of human civilization people must have began to identify plants and animals and named them, because their survival was dependent on the use of plants and animals .

Species were identified separately by their specific characters.

Major groups of plants and animals like grasses , fish , snakes , birds were also identified separately.

The names used were however varies depending on the language of the people and the place . Biological study of organisms need a unified system of classification and nomenclature .

Aristotle was the first person who classified organisms systematically .

Binomial nomenclature

With the advance of science and knowledge of biology different scientists, botanists and zoologists used different methods of naming and classification of organisms.Most often polynomial system was used until eighteenth century .

Carolous Linneus (1707-1778) proposed a binomial system of nomenclature of species which was accepted world wide.According to this name of an organism has two parts .

First is the generic name and the second is specific epithet.

Generic name is usually a noun and specific epithet an adjective describing a particular feature.
Related species have the same generic name with different specific epithets.
Dipterocarpus means fruit with two wings ,
zelanicus means endemic to Sri Lanka.

International codes of binomial nomenclature

Biologists have adopted sets of rules or codes of nomenclature.These codes are slightly different for plants ,animals ,bacteria and viruses.Some of the important rules for naming plants ,fungi and animals are as follows.

The species of organisms cannot have the same name.

Each species has a generic name and a specific name, both together forming the species name or scientific name.

Name should be made up of latinized words written in the Roman nscript.

It should be underlined when hand written and italicized when printed.

The first letter of the generic name must be capitalized and specific epithet must be in simple letters.

A third word can be used to represent a subspecies or a variety.eg:Panthera pardus kotiya -Sri Lankan leopard

In scientific work namr of the author who gave the name is indicated by a capital letter, an abbreviation or full word at the end of the name , which is not latinised.eg; Cocus nucifera L (L for Linnaeus}

Methods of natural and artificial classification

Arrangement of organisms into groups on the basis of the common characteristics is called classification.Taxonomy is the science of classification.This includes placing groups of organisms in a hierarchichal order.

Two methods of classification

Artificial classification

Grouping is based on a few pre selected unifying characters .

The characters are selected first according to convenience and organisms are grouped based on the selected criteria.

Natural relationships are ignored

Only system used before eiteenth centuary.

Easy to used , easy to expand by adding more groups.

Natural Classification

Grouping is based on evolutionary relationships

Represents true natural relationships, based on phylogeny

Systems developed after study of evolution.

Based on many characters.

Characters used can be morphological ,anatomical, cytological or molecullar.

Most resently DNA and RNA sequences are being used .
Eg.Plants can be classified into Bryophyta, Lycophyta, pteridophyta,Coniferophyta, Anthophyta
Arthropods can be classified into Crustacea, Insecta, Chilopoda; Arachnida

Dichotomous key
A written dichotomous key presents the reader with two statements that describe certain characteristics.

The statements should be mutually exclusive for the key to work efficiently. For example, 'it is either or it isn't'.

On selecting one, the reader is presented with the next couplet choice in the key and so on - to eventually arrive at an identification. .

How the key works[edit]

Go to start
Use choices given to arrive at the lowest possible level
Organism is identified as much as possible

Example 1 : Beetle, Honey Bee, Butterfly, Ant

1.Possess wings .....................................2 Do not possess wings .........................Ant

2.Having tranaparent wings...................3       Do not have   tranaparent wings .........Beetle

3.Possess hairs on appendages................Honey Bee
   Do not possess hairs on appendages.....Butterfly

Example2: Snake , Sea Anemone ,Butterfly, Earth worm ,Frog

1.Radially symetrical body ........... Sea Anemone Not having symetrical body..........2

2.Possess legs ................... 3        Donot possess legs................. 4

3.Havings wings...............Butterfly
   Do not have wings...............Frog

4.Body covered by scales...............Snake
Body not covered by scales............Earth worm

Systems of classification

The early classification systems were all artificial systems.

Mostly based on human uses.

Aristotle was the first to classify organisms scientifically.

He divided organisms into

plants

animals

Animals were further classified according to criteria such as

mode of locomotion

reproduction

presence or absence of red blood cells.

Aristotle' s pupil Theophrastus

classified plants according to habit

eg: Trees, Shurbs, Herbs and

according to lifespaneg:annuals, biennials, perennials

Upto the time of Linnaeus , scientists used many different methods.

Carolus Linnaeus (1753), Swedish botanist ,

introduced binomial nomenclature and

classified 6000 plants into a hierarchical order of taxa

eg; species

genus

order

class

Classification of flowering plants was based on the

number of stamens and

styles of flowers

He identified two kingdoms of organisms

plants

animals

With the discovery of micro organisms ,

the scientists understood that there were organisms which could not be assigned into either plants or animals.

To get over this difficulty ,

Ernest Haeckel (1866) introduced a third kingdom

Protista

He also introduce the taxon phylum and

classified many organisms

With the discovery of electron microscope,

Biologists identified two cellular organization,

Prokaryotic

Eukaryotic

Five kingdom system of biological classification was introduced by

Robert H.Whittaker-

Monera

Protista

Fungi

Plantae

Animalia

His classification was based on the three criteria

1.cellular organization

2.unicellular or multi cellular nature

3.mode of nutrition

With the acceptance of Darwin's theory on evolution and

unitary origin of life,

Taxonomists began to use of molecular methods in studying evolutionary relationships it became apparent that in the very early evolution, organisms had seperate into three stocks which are now called Domains

Carl Woese (1977)

classified organisms into three domains at a higher level over the kinhdoms

Archaea

Bacteria

Eukarya

Hierarchy of taxa from domain to species

In taxonomy each level of taxonomical hierarchy is called a taxon and each taxon has a rank and a name.

eg: rank name.

class- reptilia

Under the hierarchical system there are levels of taxa.

Each domain divided into kingdoms

Kingdom is divided into phyla

Phylum is divided into classes

Many of these categories may also be sbdivided

eg: sub family. sub species

From domain to species , the number of shared characters among the members in the taxa increases

From species to domain , the number of individuals in the taxon increases

Present system of classification and its basis

With the rapid advance of molecular biology new information on the evolutionary relationships of organisms are being collected rapidly.

The sequance of bases of DNA of important genes

DNA of mitochondria

The base sequance of ribosomal RNA

The sequance of amino acids in common proteins

Molecular structure of cellular components

are used as important taxonomoic criteria in modern systematics.

As a result classification systems are changing rapidly.

The three Domain classification suggested by Woese is adapted here for the convenience.

It is very clear however Kingdom protista is not a natural group.

It is an artificial group including organisms which have different evolutionary origins

Viruses do not have cellular organization , therefore does not belong to any of the kingdoms.

It is also an artificial group considered seperately

Domain- Bacteria
Archaea
Eukarya

Kingdom - Protista
Fungi
Plantae
Animalia

Domain - Bacteria

Cellular organization prokaryotic

Cell wall component peptidoglycan

Lipids in cell membrane are not branched

Sensitive to antibiotics

Protein synthesis begins with formyl methionine

One kind of RNA polymerase enzyme

Lives in many habitats

eg:

Cyanobacteria Purple bacteria Green Sulphur Bacteria

Domain-Archaea

Cellular organization prokaryotic

Cell wall component lacks peptidoglycan, contains proteins and polysaccharides

Lipids in cell membrane have branched and chained structure

Not sensitive to antibiotics kike streptomycin and chloromphenicol

Protein synthesis begins with methinine

Several kinds of RNA ploymerase enzymes

Lives in extreme environmental conditions such as volcanic pits , hot springs,salt marshes,deep sea

Methanococcus

Holobacterium

Thermcoccus

Methanobacterium

Domian - Eukarya

Cellular organization eukaryotic

Cell wall component lacks peptidoglycan, contains polysaccharides

Lipids in cell membrane are not branched

Not sensitive to antibiotics

Protein synthesis begins with methionine

Several kinds of RNA polymerase enzymes

Lives in many different environmental conditions

eg; protists, fungi,plants , animals

Viruses

Viruses are neither prokaryotes nor eukaryotes and donot show any cellular organization

They range in size from 20nm - 300nm and they can be observed only by the use of electron microscope

Viruses are composed of a central core of nucleic acid and surrounded by aprotein coat called the capsid, which is made up of a fixed number of protein molecules called capsomeres

The nucleic acid may be DNA or RNA depending on the type of virus

Most viruses that infect plants have RNA

Very few also have DNA.

Animal viruses include DNA - Herpes simplex or RNA - influensa

rabies virus

retro virus - HIV

Bacterial virus either include DNA or RNA

Protein coats of the viruses give them a characteristic symmetry.

Onthis basis two morphological types are recognized

They are Icosa hedral and
Helical

Some viruses have pollyphospholipid coats

eg: Retro virus

Viruse' s posses an enzyme called reverse transcriptase which transcribes their RNA to DNA eg; HIV

Many viruses cntain within the capsid one or more enzymes that are released into the host cell after the virus is uncoated

The most common enzymes are polymerases and they help in the replication of nucleic acids of viruses

A wide variety of of lipid components have also been found in viruses
eg: phospholipids , glycolipids and fatty acids

Some viral envelopes contain with spikes made up of glycoprotein

Nature of viruses

Viruses are obligate parasites

They can live and reproduce only wth in a metabolizing host cell using protein synthesizing and energy generating system of the cell

Viruses are widely distributed in nature and also they can infect other micro organisms

Since viruses are obligate parasites , cultivation of viruses requires living cells eg; chick embryo

Sruses have complex structures

eg: bacterio phage

Reproduction of virus

The life cycle of bacterio phage

The life cycle of plant viruses or animal viruses are similar

Plant viruses enter plant cells through surface wounds or insects feeding on plant sap

Characteristic features of bacteria

Prokaryotic organisms

Photoautotrophic, Chemoautotrophic or heterotrophic

Motile or non motile

Uni cellular or colony forming

Cell division is by transverse binary fission

Plasma membranes are made of different kinds of lipids

The cell walls are composed of peptidoglycan (carbohydrate + protein complex)

Ribosomal proteins and RNA polymerase are different from those of eukaryotes

eg Coccus, Bacillus

Characteristic features of Cyanobacteria

Prokaryotic organisms

Photosynthetic

Most are unicellular. But some are linked to form filaments ,sheathed in mucous

Photosynthetic pigments are chlorophyll a, phycocyanin, Blue green in colour

Some have the ability of fixing nitrogen

eg: Lyngbia

http://botit.botany.wisc.edu/botany_130/Laboratory.html

Main characteristic features of kingdom protista

Eukaryotic

Unicellular or multi cellular or colonial form

Photoautotrophic or heterotrophic

If cell wall is present it is made up of cellulose

Flagella, cilia or pseudopodia may be present

Phyla of kingdom protista

Ciliophora
Rhizopoda
Chrysophyta
Phaephyta
Rhodophyta
Chlorophyta

Characteristic features of phyla of kingdom protista

Ciliophora

Unicellular

Heterotrophic

Cilia as the locomotory organ

No cell wall

Paramecium

Rhizopoda

Uni cellular

Heterotrophic

Pseudopodia for the locomotion

No cell wall

Amoeba

Chrysophyta

Uni cellular

Photoautotrophic.Ch a, Carotine, Fucoxanthin are the photosynthetic pigments

Reproductive cells have single flagella

Cell wall is made up of cellulose, pectin, mainly silica

Storage is chrysolaminarin Diotoms

Phaeophyta

Multi cellular

Photoautotrophic.Ch. a,c, carotine, Fucoxanthin as photosynthetic pigments

Reproductive cells have flagella

Ceii wall is made up of cellulose. alginic acid

Storage food is lamnarin and manitol
Sargasum

Rhodophyta

Multi cellular

Photoautotrophic.Ch.a,d,Phycocyanin, Phycoerithrin as photosynthetic pigments

No flagella

Cell wall is made up of cellulose and agar

Storage is floridian starch Gelidium

Chlorophyta

Uni or multi cellular

Photoautotrophic

Vegetative cells and reproductive cells posses flagella

Cell wall is made up of cellulose and pectin

Storage food is starch

Chlamidomonas

Kingdom - Fungi

Eukaryotic

Unicellular or not

Truly multi cellular which form pypae

Saprophtic or parasitic or symbiotic

Cell wall is made up of chitin

Storage food is gycogen

A few are flagellated

Phyla of kingdom fungi

Chytridiomycota
Zygomycota
Ascomycota
Basidiomycota

Characteristic features of phyla of kingdom fungi

Chytridiomycota

Aquatic

Flagellated fungi, dichotomously branched hypae

Asexual reptoduction by zoospores

Sexual reproduction by motile male and female gametes
eg: Allomyces

Zygomycota

Branched, multinucleated and aseptate mycelium

Asexual reproduction by spores within sporangium

Zygosporangium is produced in sexual reproduction

eg:Mucor

Ascomycota

Branched, multinucleated and septate mycelium

Asexual reproduction by conidia , cut off by conidispores

Sexual reproduction by ascospores

eg:Aspergillus

Basidiomycota

Branched, monokaryotic or dikaryotic and septate mycelium

No. of sexual reproduction

Sexual reproduction by basidiospores

eg:Agaricus

Characteristic features of kingdom plantae

Eukaryotic

Multicellular

Photoautotrophic

Cell wall is mainly composed of cellulose

Main storage food is staech

Locomotory organ s absent but cilia or flagella may be found in gamates

Phyla of kingdom plantae

Bryophyta

Lycophyta

pterophyta

Cycadophyta

Coniferophyta

Anthophyta

Main characteristics of the phyla of kingdom plantae

Bryophyta

Especially common in moist places

No vascular tissue

Gametophytes are dominant and photosynthetic

Homosporous

External water is necessary forfertilization

Seed plants

eg; Marchantia
Mosses- Pogonatum

Lycophyta

Common in moist places

Sporophytesare dominant and gametophytes partially depend on sporophytes

Homosporous or heterosporous

External water is necessary for fertilization

Seed less plants

eg:Sellaginella

pterophyta

Terrestrial life adaptations are found

Vascular tissues are present

Sporophytes are dominant and photpsynthetic

Gametophytes depend on sporophytes

Heterosporous

External water is not necessary for fertilization

Seed bearing plants

Naked seed plants

eg; Nephrolepis
Cycadophyta

eg : Pinus
Anthophyta

Seeds in fruits

Bear flowers as sexual reproducing unit

eg: Flowering plants

Classes of phylum anthophyta

Monocotyledoneae
The embryo have only one cotyledonae

Fibrous root system

Parallel veins in leaves

Flower parts are trimerous

Perianth present in flowers( no distinct calyx/sepals and corolla/petals)

Number of xylem and phloem groups generally 12-20

Vacular bundles in the stem do not have cambia and are scattered
eg: grasses, coconut, paddy

Dicotyledonae

Embryo have two dicotyledonae

Tap root system

Reticulate veins in leaves

Flowers are pentamerous or tetramerous

Distinct calyx and corolla present in flowers

Number of xylem and phloem groups 5-6

Vascular bundles in the stem have cambia and arranged in a ring

eg: Rose, shoe flower

Characteristic features of kingdom Animalia

Eukaryotic

Multicellular

Heterotrophic

Cell wall absent

Special locomotory organs present such as cilia, flagella and contractile fibrils

Invertebrate phyla of kingdom animalia

Coelenterata

Platyhelminthes

Nematoda

Annelida

Mollusca

Arthropoda

Echnodermata

Main characteristics of the invertebrate phyla of kingdom animalia

Coelenterata

1.Marine and fresh water

2.Radial symetry

3.Diploblastic

4.Mesoglia present

5.Two types of body form

Tube like polyps and

Umbrella shaped medusa

6.No segmentation

7.Cephalization absent

8.Nematocyst present in cell layer,
No cuticle

9.Only corals posses exoskeleton, limy or horny

10.Incomplete alimentary canal, only mouth,
no anus
11.No circulatory system

12.No respiratory system

13.No excretory system

14.Nerve net

15.Some with eyespots or statocyst as sensory organs

16.Simple reproductive system and no ducts

17.Asexual reproduction by budding or
regeneration

18.Unisexual/bisexual

19.External fertilization

20.Planula larvae can be seen in the life cycle

Platyhelminthes

Free living forms inhabit warer or moist soil.Prasites live inside the host body

Bilateral symetry

Triptoblastic

No body cavity

Dorsoventrally flattened body

No segmentation

Shows a degree of cephalization

Epidermis soft and ciliated or covered by cuticle and with external suckers or hooks or both

Incomplete alimentary canal, only mouth, no anus

No circulatory system

No respiratory system

Flame cells and ducts with excretory system

prence of a pair of anterior ganglia and longitudinal nerve cords (1-3)

Free living forms have eye spots /eyes

Some have chemoreceptors in head as sensory receptors

Reproductive system with ducts and aditional organs

Asexual reproduction in some forms by fragmentation

Usually bisexual

Internal fertilization

Many larval stages in parasitic forms .No larval stages in free living forms
in the life cycle

Nematoda

Found everywhere in soil, water and as parasites

Bilateral symetry

Triploblastic

Pseudocoelomate

Slender, Cylindrical tapered end body.No segmentation

Shows a degree of cephalization

Extra cellular tough cuticle is present

Hydrostatic skeleton of pseudocoelomic fluid

Lack cilia at any stage

Complete alimentary canal. Only mouth , no anus.

No circulatory system

No respiratory organs

Prence of simple excretory system with ducts

Prence of paired anterior ganglia and a pair of lateral longitudinal nerve cords

mainly papillae as sensory organs

A few have paired reproductive system

No asexual reproduction or regeneration

Unisexual

Internal fertilization

Larval parasites, larval stages in free living forms in the life cycle

Annelida

Found in world wide- marine, fresh water or on/in soil

Bi lateral symmetry

Triloblastic

Well developed coelom

Cylindrical worm like body, internal and external segmentation

Advanced cephalization

Definite cuticle and chetae of chitin, arranged segmentally

Hydrostatic skeleton of coelomic fluid

Complete alimentary having mouth and anus

Closed circulatory system with lateral hearts

Some have external gills

Excretory structures are nephridia

One pair of cerebral ganglia and double, solid ventral nerve cord

Simple forms of eye

Asexual reproduction in some by budding or regeneration

Reproductive system with sexual organs and ducts

Unisexual or bisexual

External fertilization

Trochophore larvae can be seen in the life cycle

Mollusca

Mostly marine or fresh water, some are terrestrial

Bilateral symmetry

Triploblastic

Haemocoel

A little trace of segmentation

Show a clear cephalization ,body is divided into head, muscular foot, visceral mass

Body covering is soft and it forms a mantle

Many have exo skeleton.In some have endoskeleton

Complete alimentary canal having mouth and anus

Radulla in mouthOpen circulatory system with dorsal heart

Gills or ctenidia in the mantle cavity for respiration

Excretory structures are nephridia

Nerve ring with ganglia and two pairs of nerve cords

Sensory organs are eyes , tentacles, some have eye spots or statocysts

Reproductive organs with ducts

Usually unisexual

External or internal fertilization

Trochophore or veliger larvae can be seen in the life cycle

Arthropoda

Lives in terretrial or aquatic environments

Bilateral symmetry

Triploblastic

Coelom greatly reduced and presence of haemocoel

Externally jointed, segmented body.Each segment typically bears a pair of jointed appendages.

Distinct cephalization can be seen.Parts of body are head, thorax and abdomen.

Exoskeleton of chitin secreted by epidermis

Exoskeleton

Lacks cilia in any stage

Complete alimentory canal having mouth and anus

Mouth parts in mouth

Open circulatory system with dorsal heart

Gills or book lungs or trachea as respiratory structures

Green glands or malphigian tubules can be seen as excretory structures

Paired dorsal central ganglia and double solid ventral nerve cord

Sensory organs are antennae,statocyst, sensory hairs, simple/ compound eyes

Reproductive system with reproductive organs and ducts

Asexual reproduction take place by parthenogenesis in some insects and crustaceans

Uni sexual

Mostly internal fertilization can be seen

One or more larval stages can be seen in the life cycle

Echinodermata

Exclusively marine

Adults are penta radial symmetry and larvae are bilateral symetry

Large coelom .It is developed as a water vascular system with associated tube feet

Cylindrical, star or flower form.No segmentation

No cephalization .Body is arranged in oral and aboral axis

Body covered by delicate epidermis often with spines

Prence of endoskeleton

Complete alimentary tract in some , some lack anus

Reduced circulatory system

Respiration by skin gills or papillae or tube feet or cloacal respiratory tree.

No excretory system

Radial nervous system present

Most donot have sensory organs.Some have tube feet for touch or sensivity. Some have eye spots or sensory tentacles as sensory organs

Have large reproductive organs.

Uni sexual

External fertilization can be seen

Bipinnaria or dipleurula larvae can be seen in the life cycle.

Vertebrates

Chordata

A rod like dorsal notochord present some developmental stge at least during part of the life cycle.
A single, dorsal hollow nverve cord present some developmental stage at least during part of the life cycle
Pharyn gill slits are present at some developmental stage
Poat anal tail is present at least during the embryonic developmental stage
Closed circulatory system with a ventral heart.
Coelom well developed.
Sleleton if present, as an endoskeleton formed by mesoderm.
Sexes usually seperate , oviporous or viviporous

External features of organisms to identify their classes

Classes of phylum Coelenterata

Hydrozoa

Dominant stage polyp which is solitary or colonial
Medusa is small and free swimming

Radial symmetry

A circle of tentacles around mouth

eg:Hydra

Obelia

Soft coral

http://www.google.lk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&docid=LbBU2OOCiF4TtM&tbnid=wJ5tOvxTZJY0YM:&ved=0CAQQjB0&url=http%3A%2F%2Fwww.noaanews.noaa.gov%2Fstories2006%2Fs2652.htm&ei=qH41UuGeJIn7rAfU54CoDg&bvm=bv.52164340,d.bmk&psig=AFQjCNF1wPlZQFKvvi1kg9GrYN4EMsMDtg&ust=1379323130207017

Scyphozoa

Dominant stage medusa which is free swimming ,

polyp stage is minute or lacking.

Radadial symmetry

Four oral arms around mouth and tentacles like gastric filaments on the edge

eg: Aurelia

Anthozoa

Poplp stage only, which is solitary or colonial and no medusa.

Biradial symetry

Many tentacles around mouth in many rings

eg: Sea anemone

True coral

http://www.okc.cc.ok.us/biologylabs/Documents/Porifera_Cnidaria/Cnidaria.htm

Classes of phylum platihelminthes

Turbellaria

Free living

Leaf like body with head

Ventral mouth with reversible pharynx, no suckers

Ciliated epithelium with mucous glands

eg:Planaria,

Dipalium

Trematoda

Endoparasite

Leaf like body without head

Ventral suckers on ventral side and anterior sucker surrounds mouth

Cuticle with spines

eg: Fasciola - liver flukes

Cestoda

Endoparasite

Slender, elongated, flat body divided into scolex and proglotids

Suckers and hooks on scolex

No mouth

Cuticle with microvilli

eg:Taenia - tape worm

Classes of phylum annelida

http://bio.rutgers.edu/~gb102/lab_2/301am-platyhel.html

Polychaeta
Distinct head with eyes and tentacles
Presence of parapodia
Numerous setae

No clitellum

eg:Nereis

Oligochaeta

No distinct head
No parapodia
Fewer numbr of setae
Clitellium present

eg: earth worm

Hirudinea
No distinct head having anterior and posteriot suckersNo parapodia
No setae

No clitelum

eg:Leech

Classes of phylum Mollusca

http://www.okc.cc.ok.us/biologylabs/Documents/Porifera_Cnidaria/Cnidaria.htm

Polyplachophora

Dorsal shell formed by 8 overlapping plates

Radula present

Large flat foot

Head is present without eyes or tentacles

Eye spots in some

eg:Chiton

Bivalvia

Shell of two lateral valves

No radula

Hatcher shaped foot

No head

No eyes

No tentacles

eg:Mussels

Oyster

Gastropoda

Univalved shell usually coiled.Sometimes shells are reduced.

Radula present.

Largely developed foot

Gead is present with tentacles and eyes .

Eyes onone pair of tentacles.

eg: Slug

snail

Cephalopoda

External or internal shell present or none

Radula present

foot is modofied into arms and siphon

Head is present conpicuous

Eyes and 8-10 arms or many tentecles and siphon are present.

eg: squid

octopus

Classes of phylum Arthropoda

Crustacea

Body is divided into cephalothorax and abdomen

One pair of appendages

Two pairs of antenna

eg:

prawn

crab

Insecta

Head thorax and abdomen distinct

Three pairs of legs on thorax and two pairs of wings

One pair of antenna

eg:cockroach , any insect

Chilopoda

Head followed by numerous segments of body

One pair of legs per somite

One pair of antenna

eg: Centiped

Diplopoda

Head , short thorax and abdomen

Two pairs of legs per somite

One pair of antenna

eg: Millipeds

Arachnida

Prosoma -cephalothorax and abdomen - ophisthosoma

Four pairs of legs on cephalothorax

No antennae

eg:Scorpion, Spider,Ticks ,Mites

Classes of phylum Echinodermata

Asteroidea

Consists of acentral disc and five tapering arms or ends

On the upper surface there are many blunt calcareous spines and pedicellaria

Mouth is locate in the lower surface- oral surface and arms are in the upper surface - aboral surface

eg:Star fish

Ophiuroidea

Small rounded disc wth five distinct arms which are long and fragile

Long arms are jointed .

No pedicellaria.

Spines in lateral side of arm

Mouth is centered Mouth is centered.orally and no anus

Tube feet in two rows and no suckers

eg: Britle star

Echinoidea

No anus. Rounded or flat body

Skeleton eith movable spines and pedicellaria present

Mouth or anus either central or lateral

Slender tube feet with suckers

eg: sea urchin, sand dollar

Holpthuroidea

Elongated slender body

No spines or pedicellaria

Mouth anterior

Anus posterior

Tube feet usually present

eg: sea cucumber

Crinoidea

Bodi is a small cup shaped calyx of limy plates to which are attached five flexible arms.Some have stalks

Bearing many slender lateral pinnules

No spines

Mouth and anus on oral surface

Tentacles like tube feet

eg: Sea Lily

Classes of phylum chordata

Chondrichthyes

http://www.marinebiodiversity.ca/skatesandrays/external%20anatomy.htm

1.Spindle shaped body divided into head, trunk and tail

2.Skin with placoid scales

3.Paired pectoral and pelvic fins.Heterocercal caudal fin

4.Ventral mouth with emamelcapped teeth

5.Inner ear only,no middle or external ear

6.Cartilaginous skeleton

7.Eyes ususlly well develloped without lids

8.Two chambered heart

9.Respiration by gills,several gill slits ,no opperculum

10.Excretion by metanephric kidney.

11.Major nitrogenous waste is urea

12.Body temperature ectothermal

13.Brain with ten pairs of cranial nerves

14.No larval stage,eggs produced, ovoparou or oviviviporous

15.Internal fertilization

eg:shark,skate

http://visual.merriam-webster.com/animal-kingdom/fishes/cartilaginous-fish.php

Osteichthyes

1.Spindle shaped body divided into head , trunk and tail

2.Skin eith cycloid or ctenoid scales

3.Paired pectoral pelvic fin

4.Homocercal caudal fin

5.Usually terminal mouth with teeth which are bony

6.Inner ear only. no middle or external ear

7.Bony skeleton

8.Eyes normally well developed without lids

9.Two chambered heart

10.Four paired gill openings covered with opperculum

11.Major nitrogenous waste is ammonia

12.Body temperature ectothermal

13.Brain with ten pairs of cranial nerves

14.Larval stage may be present.Eggs produced usually oviporous

eg:

Mullet

Carangids

Tuna

1.Body comprises head ,trunk and tail.

2.Soft skin with gland.

3.Paired pentadactyl limbs.

4.Some adults have tail.All larval forms have tails.

5.Ventral mouth.If teeth are present they are fasterned to the surface of bones.

6.Inner and middle ear only. No external ear.

7.Largely bony skeleton.

8.Eyes oftenly with movable lids and nictitating membrane.

9.Three chambered heart.

10.Respiration by gills, lungs and skin or mouth lining.

11.Excretion by metanephric kidney.Major nitrogenous waste is urea.

12.Body temperature ectothermal.

13.Brain with ten pairs of cranial nerves.

14.Larval stage usually present.Eggs produced.( oviparous).

15.External or Internal fertilization.

eg: Toad, Frog,Salamander, Ichthyopus

Reptelia

1.Body is composed of head , neck trunk and tail

2.Skin dry with horny scales and horny plates.

3.Paired pentadactyl limbs.

4.Post anal tail covered with scales.

5.Long mouth margined with teeth in sockets in some reptiles.

6.No external ear. Inner and middle ear only.

7.Well ossified skeleton.

8.Large lateral eyes with eye lids and with nictitating membrane.

9.Four chambered heart.

10.Respiration by lungs.

11.Excretion by metanephric kidney.

12.Excretion by metanephric kidney.Major nitrogenous waste is urea or uric acid.

13.Body temperature ectothermal.

14.Brain with 12 pairs of cranial nerves.

15. No larval tage . Oviparous or ovoviviparous. Yolky eggs in shells.

16.Internal fertilization.

eg: lizard

cobra

crocodile

Aves

1. Stream lined body divided into head, neck trunk and tail.

2.Skin bears feathers .Legs have scales

3.Paired pentadactyl limbs.

4.Ventral mouth with teeth in sockets.

5.Absence of external ear,Presence of middle and internal ear.

6.Endo skeleton light,strong,fully ossified with air cavities.

7.Large and lateral eyes with eye lids and nictitating membrane.

8.Four chambered heart.

9.Respiration by lungs.

10.Excretion by metanephric kidnry,major nitrogenous waste is urea or uric acid.

11.Body temperature endothermal.

12.Brain with12 pairs of cranial nerves.

13.No larval stage.Yolky eggs in calcareous shells oviparous.

14.Internal fertilization.

eg:parrot, crow

Mammalia

1.Body with head,neck, trunk and tail. Differ in forms.

2.Skin bears hairs and glands.

3.Paired pentadactyl limbs.

4.Tails are of diverse forms.

5.Ventral mouth with teeth in sockets.

6.Presence of external, middle and inner ear.Presence of pinna.

7.Skeleton largely of bone with cartilage over surfaces of joints.

8.Eyes with movable lids.Some have nictitating membrane.

9.Four chambered heart.

10.Respiration by lungs

11.Excretion by metanephric kidney.Major nitrogenous waste is urea or uric acid.

12.Body temperature endothermal.

13.Brain with 12 pairs of cranial nerves.

14.No larnal stage.Eggs develop within mother.(viviparous or oviparous.

15.Internal fertilization.

eg:Rat.Man

quagga

Echidna.

long-beaked echidnas (short-beaked echidna)

Echidna

duck-billed platypus

spiny anteater

pouched-mammals

Koala.

Thylacinus, an extinct marsupial wolf.

The bat

http://visual.merriam-webster.com/animal-kingdom/insectivorous-mammals.php

Biopedia

Pages

Friday, April 19, 2013

Unit-3

International codes of binomial nomenclature

Methods of natural and artificial classification

How the key works[edit]

Hierarchy of taxa from domain to species

Present system of classification and its basis

Nature of viruses

Characteristic features of Cyanobacteria

Ciliophora

Rhizopoda

Phaeophyta

Rhodophyta

Chlorophyta

Characteristic features of phyla of kingdom fungi

Chytridiomycota

Aquatic

No vascular tissue

Vertebrates