The document outlines the principles of animal classification, explaining its importance in understanding biological diversity and identifying organisms based on observable traits and evolutionary relationships. It covers criteria for classification, including germ layers, body plan, symmetry, body cavity, segmentation, and support, while also discussing historical classification methods and the taxonomic hierarchy. Various animal phyla and their characteristics are described, illustrating the complexity and diversity within the animal kingdom.

1. ANIMAL CLASSIFICATION
DR. C. BEULAH JAYARANI
M.Sc., M.A, M.Ed, M.Phil (Edn), M.Phil (ZOO), NET, Ph.D
ASST. PROFESSOR,
LOYOLA COLLEGE OF EDUCATION, CHENNAI - 34

2. ANIMALS Classification
•Animal classification refers to
the arrangement of animals in
taxonomic groups according to
their observed similarities and
evolutionary relationships
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3. WHY classification
• Classification allows us to understand diversity
better.
• It helps in the identification of living
organisms as well as in understanding the
diversity of living organisms.
• Classification helps us to learn about
different kinds of plants and animals, their
features, similarities and differences.
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4. CRITERIA FOR ANIMAL CLASSIFICATION
1. Number of germ layers
2. Animal body plan
3. Body symmetry
4. Body cavity or coelom
5. Body segmentation
6. Body support
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5. 1. Number of germ layers
✓Every multicellular organism begins life as a single cell
called ‘zygote’. The zygote divides many times to form a
mass of cells. These mass of cells get arranged into 2-3
layers called as germinal layers
✓Diploblastic animal: 2 layers, outer ectoderm & inner
endoderm separated by mesoglea. Example: phylum
Cnidaria
✓Triploblastic animal: 3 layers, outer ectoderm, middle
mesoderm & inner endoderm. Example: phylum
Platyhelminthes
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6. CELL AGGREGATE
PLAN
• Includes simplest of
animal types like
sponges
• Animal is made up of
aggregation or
collection of cells
• Tissues & organs are
absent
• There is no nervous
co-ordination
• Example: Phylum
Porifera
BLIND SAC BODY PLAN
• Shown by slightly
complex animals
• Digestive system
having a single opening
which acts as mouth &
anus. Hence ingestion &
egestion is done
through that opening
• Example: Phylum
Cnidaria
2. Animal body plan
6

7. Tube within tube body plan:
• Shown by advanced & evolved animals
• Complete digestive system with 2 separate openings for mouth & anus
• Example: Phylum Annelida
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8. ASYMMETRICAL
• Animals whose
body cannot be
divided into 2
equal parts
through any plane.
• Eg: Some
sponges & snails
BILATERALLY
SYMMETRICAL
• The animal can be divided
into 2 equal halves by
one 1 single median plane
• Example: Fish, frog,
goat
3. Body symmetry
Symmetry means similarity in shape, size & number of parts
on opposite sides of a median line. Median line is the plane
through which animal can be cut into 2 equal halves
▪ Animal whose body can be cut
into 2 similar halves in many
planes
▪ All the cuts pass through the
centre & appear like radii.
• Example: Hydra, starfish
RADIALLY SYMMETRICAL
8

9. ACOELOMATES
✓Animals which do not have
any body cavity
✓The space between body
wall & alimentary canal is
filled with parenchyma
✓Eg: Phylum Platyhelminthes
PSEUDOCOELOMAT
ES
• These animals show a false body
cavity which is lined by patches of
mesodermal cells
• The false cavity is called as
‘pseudocoel’
• Eg: Phylum Aschelminthes
4. Body cavity
Body cavity is the space between the body wall & the alimentary
canal which is produced by the splitting of the mesoderm during
embryonic development
Animals having a true body cavity
• Present in triploblastic animals
• The mesoderm splits into 2 layers
enclosing a body cavity called coelom
• The cavity is filled with ‘coelomic fluid’
COELOMATE
S
9

10. 5. Body segmentation
➢It is also called as ‘metamerism’ (true
segmentation)
➢It is a series of segments arranged along
the body of the animal
➢When the external segmentation matches
with the internal segmentation, such
animals are called as ‘metamerically
segmented animals’. Eg: Earthworm
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11. 6. Body Support
• The internal or external framework which
provides support to the body is called as
skeleton
• It is of 2 types. Exoskeleton (outside) &
endoskeleton (inside)
• Lower animals have only exoskeleton for
protection. Eg: cockroach
• Higher developed animals have both
exoskeleton & endoskeleton for their
protection. Eg: fish, cobra, parrot, man,
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12. TAXONOMY
• Classification is the
arrangement of organisms into
orderly groups based on their
similarities
• Classification is also known as
taxonomy. “Taxonomy – the
study of biological
classification.”
• Taxonomists are scientists that
identify & name organisms
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13. • There are 13 billion known
species of organisms
• This is only 5% of all
organisms that ever lived!!!!!
• New organisms are still being
found and identified
Species of Organisms
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15. • Accurately & uniformly
names organisms
• Prevents misnomers such
as starfish & jellyfish that
aren't really fish
• Uses same language
(Latin or some Greek) for
all names
Latin Names are Understood
by all Taxonomists
Benefits of Classifying
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16. •Binomial nomenclature used
•Genus species
•Latin or Greek
•Italicized in print
•Capitalize genus, but NOT
species
•Underline when writing
Standardized Naming
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17. • The International Code for
Binomial Nomenclature
contains the rules for
naming organisms
• All names must be
approved by International
Naming Congresses
(International Zoological
Congress)
• This prevents duplicated
names
Rules for Naming Organisms
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18. • Taxon ( taxa-plural) is a
category into which related
organisms are placed
• There is a hierarchy of groups
(taxa) from broadest to most
specific
• Domain, Kingdom, Phylum,
Class, Order, Family, Genus,
species
Classification Groups
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19. Hierarchy-Taxonomic Groups
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
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20. Dumb
King
Phillip
Came
Over
For
Gooseberry
Soup!
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21. CLASSIFICATION OF HUMAN
CLASSIFICATION
CATEGORY
• Domain Eukarya
• Kingdom Animalia
• Phylum Chordata
• Class Mammalia
• Order Primates
• Family Hominidae
• Genus Homo
• Species Homo sapiens
CHARACTERISTICS
• Cells with Nuclei
• Multicellular, motile, ingestion of food
• Dorsal supporting rod & nerve cod
• Hair, mammary gland
• Adapted to climb trees
• Adapted to walk erect
• Large Brain
• Body proportions of Modern human
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22. Early systems
Aristotle – Plants / Animals
Animals split into groups:
• Live and move in the water
• Live and move on land
• Move through the air
Linnaeus and other
scientists
Observable
features
Use of
microscopes
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23. principles of classification
• Classification –the grouping of organisms often on
the basis of simple observable features
1.Artificial classification
Divides organisms by what is useful at the time
e.g. Colour, size, no of legs (analogous features)
2.Natural classification
Based on the evolutionary relationships between
organisms and their evolutionary descent e.g.
Shared features and derived from ancestors
(homologous characteristics)
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24. Classification of animals
NON-CHORDATES
• Absence of notochord
• Pharynx not perforated by
gill-slits
• Nerve chord, if present,
double, ventral and solid
• Heart, if present, dorsal in
position
CHORDATES
• Presence of notochord at
some stage of development
• Pharyngeal gill-slits present
at some stage of life
• Single, dorsal and hollow
nerve chord
• Heart – Ventral in position.
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25. ANIMAL CLASSIFICATION
NON-CHORDATES CHORDATE
S
CLASS:
PISCES
CLASS:AMPHIBIA
CLASS: REPTILIA
CLASS: AVES
CLASS: MAMMALIA
PORIFERA - sponge
PLATYHELMINTHES -
Planaria
ANNELIDA - Earthworm
MOLLUSCA - Pila
HEMICHORDATA - Balanoglossus
PROTOZOA-Amoeba
COELENTERATA- Hydra
NEMATHELMINTHES-
Ascaries
ARTHROPODA - Crab
ECHINODERMATA - Starfish
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26. Phylum - Protozoa
➢Unicellular, Microscopic
➢Free-living, symbiotic or parasitic
➢Free-living forms are mostly aquatic or
terrestrial
➢Locomotion by pseudopodia, cilia, flagella
➢Ingestion of food by phagocytosis or
pinocytosis
➢Asexual reproduction by binary/multiple
fission and sexual by conjugation
➢E.g. Amoeba, Entamoeba, Plasmodium,
Paramoecium, Euglena
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27. Phylum - Porifera
✓Simplest animals having pores called ostia
✓Aquatic. Mostly marine
✓Sessile ,i.e., not locomotive
✓Body is supported by spicules
✓Feed on small organisms or nutrients
✓Ingestion by ostia or large openings – oscula
✓Asexual reproduction by budding
✓Have a great power of regeneration
✓E.g. Sycon, Euspongia, Hyalomena
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28. Phylum - Coelenterata
❑Cylindrical (polyp) or umbrella (medusa) like
animals
❑Radially symmetrical and diploblastic body
❑Solitary or colonial and sessile or free-swimming
❑Mouth is surrounded by tentacles having
cnidocytes
❑Tentacles – food capturing
❑Stinging cells – offence, defence organs
❑Asexual reproduction by budding
❑Have a great power of regeneration
❑E.g. Hydra, Sea anemone, physalis, Aurelia
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29. Phylum - Platyhelminthes
❑Dorsoventrally flattened thin body
❑Mostly endoparasites or free- living
❑Triploblastic body
❑They are hermaphrodite
❑E.g. Planaria, Liver fluke, Tapeworm
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30. Phylum - Nemithelminthes
✓Long, slender, cylindrical worms
(round worms)
✓Free-living or endoparasites
✓Triploblastic body covered by a thick
cuticle
✓Unisexual organisms
✓E.g. Ascaris, Filaria, Hook worm.
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31. Phylum - Annelida
oElongated, cylindrical, metameric
segmented animals
oFree living/ ectoparasitic
oMarine / terrestrial
oTriploblastic, bilaterally symmetrical
coelomates
oLocomotive organs : setae,
parapodia, suckers
oHermaphrodite or separate sexes
oE.g. Earthworm, Leech, Nereis.
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32. Phylum - ArthRopoda
➢Most successful, largest animal group
➢Found in all habitats
➢Triploblastic, coelomate and bilaterally
symmetrical segmented animals with
heads
➢Have paired jointed appendages for
locomotion
➢Chitinous exoskeleton covering the body
➢Separate sexes
➢E.g. Crab, Spider, Millipede, Cockroach. 32

33. Phylum - Mollusca
✓Aquatic or terrestrial
✓Triploblastic, coelomate and
unsegmented soft- bodied animals
✓A large muscular foot modified for
creeping, burrowing, swimming
✓Body enclosed in membranous
structure (mantle) secreting
calcareous protective shell
✓Separate sexes
✓E.g. Pila, Bivalve, Snail, Octopus.
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34. Phylum - Echinodermata
✓Exclusively marine animals
✓Triploblastic, coelomate
✓Pentaradial symmetry in adults
✓Bilateral symmetry in larvae
✓Move by tube feet also for grasping the food
✓Few are sessile
✓Skeleton of calcareous plates or spines
✓Separate sexes
✓E.g. Starfish, Sea urchin, Brittle star, Sea
cucumbar
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35. Phylum - Hemichordata
➢Acorn worms
➢Marine animals living in burrows
➢Divisible in 3 regions : proboscis,
collar, trunk
➢May have one to several gill – slits
➢Sexes are separate
➢May be hermaphrodite
➢E.g. Balanoglossus, Saccoglossus.
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36. Chordates
❑Presence of notochord at some
stage of development
❑Presence of pharyngeal gill-slits
❑Presence of single, dorsal,
tubular, hollow nerve chord
❑Heart in ventral position.
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37. Sub- Phylum - Urochordata
✓Marine animals
✓Body surrounded by leathery covering
(tunic / test)
✓Larvae are free swimming &
notochord is only in tail in larvae
✓After settling on seashore, they get
transformed into sessile adults
✓Generally hermaphrodite
✓E.g. Ascidians, Doliolum, Oikopleura
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38. Sub-phylum - Cephalochordata
❑Small fish-like marine animals
❑Notochord extends along the
entire body
❑Pharynx is large with
numerous gill- slits
❑Sexes are separate
❑E.g. Amhioxus.
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39. Sub-phylum -
Vertebrata
✓The notochord is replaced by a
vertebral column
✓The head is well developed
✓Brain is protected in a cranium
✓Endoskeleton may be cartilaginous
or bony
✓They may be jaw-less (Agnatha),
with jaws (Ganathostomata).
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40. Class Cyclostomata
➢They have suctorial mouths without
jaws
➢Skin is soft and devoid of scales
➢Absence of paired appendages
➢Cartilaginous endoskeleton
➢Mostly ectoparasites
➢E.g. Petromyzon, Myxine.
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41. Class Pisces (Fishes)
➢Cold blooded, aquatic
➢Stream-lined body
➢Fins – Swimming Tail-fin – Direction changing
➢Exoskeleton is the form of scales
➢Endoskeleton may be cartilaginous or bony
➢Respiration by gills
➢Eyes without eye-lids
➢E.g. Dogfish, Rohu
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42. Class Amphibia
➢Cold-blooded and freshwater or terrestrial
➢Limbs are two pairs
➢Digits are without claws
➢Absence of exoskeleton
➢Smooth, moist skin for respiration
➢Presence of ear drum
➢Eyes are protruding &provided with eyelids
➢E.g. Frog, Toad, Salamander
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43. Class Reptilia
❑Cold-blooded animals
❑Crawl on the ground
❑Their dry skin bears scales or
bony plates
❑Presence of neck
❑Absence of external ear
❑Digits are provided with claws
❑E.g. Tortoise, Wall lizard, Snake
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44. Class Aves (Birds)
✓Warm-blooded animals
✓Stream lined body for lower air
resistance during flight
✓Fore-limbs are modified into wings.
Digits are clawed and covered with
scales
✓Exoskeleton is in the form of feathers
✓Neck, beck are present
✓E.g. Parrot, Pigeon, Duck.
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45. Class Mammalia
➢Presence of mammary glands
➢Warm-blooded animals
➢Body is divisible into Head-Neck-Trunk-Tail
➢Digits are provided with nails, claws,
hooves
➢Exoskeleton is in the form of hairs or fur
➢External ear is absent
➢E.g. Bat, Squirrel, Rat, Lion, Monkey, Man.
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46. REFERENCES
“SCIENCE READER”
➢Tamil Nadu text books
➢NCERT Books
➢Google Images
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