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th
Class-9
BIOLOGY
STUDY NOTES & WORKSHEET
DIVERSITY IN
LIVING ORGANISMS - II
Fig. 7.26:
Classification of animals
DIVERSITY IN
LIVING ORGANISMS- II
1. DETAILED CLASSIFICATION OF
KINGDOM ANIMALIA
Animals are those organisms which are eukaryotic, multicellular and heterotrophic
in their mode of nutrition. Animal cells do not have cell walls. Except a few, most
animals are mobile. Multicellular animals are often called metazoa which have
been divided into two branches : Parazoa and Eumetazoa.
In Parazoa, the animal body is formed of loosely aggregated cells. These animals
have poorly differentiated tissues and have no organ or digestive cavity. In
Eumetazoa, the cells are properly arranged into tissues and organs. Their
digestive tract is the mouth but with or without an anus.
The Eumetazoa is further classified on the basis of :
(a) the number of germ layers present in the embryo;
(b) the symmetry of the body of the organism; and
(c) mode of origin of mouth.
 Those animals which have two germ layers in the embryo, are called
diploblastic animals and those having three germ layers are called
triploblastic animals.
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In diploblastic animals, the outer cell
layer is called ectoderm, while the inner
layer is termed as endoderm;
Both of the germ layers enclose a noncellular jelly-like layer, the mesoglea.
The triploblastic animals have three germ
layers, namely ectoderm, mesoderm
and endoderm, in their bodies.
(a) Diploblastic
(b) Triploblastic
 The two sides of the body are mirror images of one another. Such body
symmetry type is called a bilateral symmetry. Some animals have radial
body symmetry which can be defined as an arrangement of
usually similar parts in a regular pattern around a central axis.
Bilateral symmetry
Radial symmetry
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 On the basis of mouth origin two types of animals have been recognised.
Protostomia (mouth arising from or near the blastopore of gastrula; gastrula
is an embryonic stage) and Deuterostomia (mouth arising anteriorly at some
distance from the blastoprore).
 Based on the presence or absence of body cavity or coelom.
 The acoelomates do not have a body cavity,
because in them the space between the body
wall and digestive tract is filled with
parenchymatous tissue.
 The pseudocoelomates have a cavity
between the body wall and digestive tract,
but this cavity does not arise from the
mesoderm and is not lined by epithelial cells.
 The coelomates have a true body cavity or
coelom which originates from the mesoderm
and is lined by epithelial cells of mesodermal
origin.
Diagrammatic sectional view of :
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(a) Coelomate (b) Pseudocoelomate (c) Acoelomate
1.1 Phylum Porifera (Organisms with holes, pore bearing)
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Some common features of this phylum are :
1. These are non-motile animals attached to some solid support. They are
commonly called sponges.
2. Simplest multicellular, diploblastic animals.
3. The body design involves minimal differentiation and division into tissues.
4. Asymmetrical or radially symmetrical. Sponges may be vase-like, rounded,
sac-like or branched.
5. Body is perforated with numerous pores. The ostia, that open into a canal
system having canals and chambers lined with collared flagellated cells or
choanocytes. It also has one or more large-sized outlets for water, called
oscula.
6. Mouth, digestive cavity and anus absent.
7. Skeleton is made up of minute calcareous or silicious spicules or spongin
fibre (collagen) or both.
8. Reproduction is both asexual by budding and gemmules and sexual through
fertilization. Possess great power of regeneration.
Phylum Porifera is divided into the following three classes:
Class 1. Calcarea.  Marine.
Examples: Leucosolenia, Sycon (Scypha)
Class 2. Hexactinellida.  Marine
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Example: Euplectella (Venus’s flower basket), Hyalonema (rope sponge)
Class 3. Demospongiae.  Mostly marine and a few fresh water solitary or
colonial form.
Examples: Cliona (boring sponge), Spongilla, Euspongia (bath sponge).
(a) Sycon
(b) Euspongia
(c) Spongilla
1.2 Phylum Cnidaria or Coelenterata
(d) Euplectelea
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Some common features of this phylum are :
1. Aquatic (living in water), mostly marine, a few such as Hydra are fresh water.
Some of these species live in colonies (corals, Physalia), while others live
solitary (Hydra).
2. Cnidarians or coelenterates are multicellular, diploblastic animals with tissue
grade of organisation. A gelatinous layer called mesoglea or mesohyl persists
between the ectoderm (epidermis) and endoderm (gastrodermis).
3. Body shows radial symmetry.
4. A central gastrovascular cavity coelenteron is present which lacks anus but has
a mouth which is surrounded with short and slender tentacles.
5. Possess specialized sting cells (cnidoblasts) bearing stinging cell organelles
called nematocysts. Nematocysts serve the functions of paralysing the prey by
injecting poison or holding the prey.
6. Respiratory, circulatory and excretory organs are absent.
7. Nervous system is primitive, has only network of nerve cells.
8. Exhibit the phenomenon of polymorphism (Gr., poly – many; morphe- shape)
which is the specialisation of individuals of colonial species for the division of
labour. For example, hydrozoans have feeding individuals or zooids, the
gastrozooids, protective zooids, the dactylozooids and reproductive zooids,
the gonozooids producing sexual medusae.
9. Body shows two main forms, the polyps and the medusae. The polyp is
diploid, cylindrical and sedentary. It is either solitary or colonial and
reproduces asexually. The medusa is diploid, umbrella-like and free swimming
sexual phase of the animal.
10. Asexual reproduction by budding and sexual reproduction by gametes formed
by medusae.
11. Many forms possess a hard exoskeleton of lime to form corals.
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Phylum Coelenterata is divided into the following three classes.
Class1. Hydrozoa.  Their life history includes both polypoid and
medusoid forms.
Examples: Hydra, Obelia, Millepora (coral)
Class 2. Scyphozoa.  Their life history lacks polypoid phase and has only
medusoid form.
Examples: Aurelia (jelly-fish), Rhizostoma.
Class 3. Anthozoa.  Their life history has only polypoid form, the
medusoid forms are absent.
Example: Pennatula (sea-pen), Tubipora (organ pipe coral), Gorgonia
(sea-fan), Corallium (red coral), Metridium (sea anemone), Fungia
(mushroom coral).
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(a) Aurelia (Medusa)
(b) Adamsia (Polyp)
1.3 Phylum Ctenophora
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Some common features of this phylum are :
1. Transparent body with bilateral symmetry.
Triploblastic.
2. Two tentacles and eight longitudinal rows of
ciliary comb-plates for locomotion are present.
3. Marine, solitary and free-swimming.
4. Nematocysts are absent but colloblasts
(adhesive cells) are present.
5. No polymorphism or dimorphism occurs.
Examples: Pleurobrachia (comb jelly), Cestum
(Venus’s girdle), Ctenoplana, Beroe (sea mitres).
(c) Hydra
(d) Sea anemone
(Pleurobrachia)
1.4 Phylum Platyhelminthes
Some common features of this phylum are :
1. Bilaterally symmetrical (i.e., the left and right halves of the body have the
same design) and dorsoventrally flattended animals.
2. Body thin, soft, leaf-like or ribbon-like.
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3. They are triploblastic animals implying that their tissues differentiate from
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three embryonic germ layers. They are without a body cavity (acoelomate
animals).
Digestive cavity (when present) with a single opening, the mouth (anus is
absent).
Suckers and hooks are usually present.
Circulatory and respiratory systems and skeleton are absent.
Excretory system consists of blind tubules called protonephridia. Blind end
of a tubule bears a tuft of cilia or a flagellum and is called a flame bulb or
flame cell.
Hermaphrodite, i.e., both male and female reproductive organs occur in the
same individual.
The turbellarians are free-living, aquatic, both marine and fresh water and a
few are terrestrial. Trematodes and cestodes are parasitic.
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(a) Planaria
(b) Liver fluke
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(c) Tape worm
Phylum Platyhelminthes includes the following three classes:
Class 1. Turbellaria –Dugesia, Planaria;
Class 2. Trematoda – Fasciola (liver-fluke), Schistosoma (bloodfluke);
Class 3. Cestoda – Taenia solium (pork tape-worm).
1.5 Phylum Nematoda (Aschelminthes)
Some common features of this phylum are :
1. Bilaterally symmetrical, triploblastic, pseudocoelomate and unsegmented
animals.
2. Body is worm-like (i.e., round, slender and tapering at the two ends),
cylindrical or flattened.
3. Body is covered with a tough, resistant cuticle; cilia absent.
4. Alimentary canal straight and complete with mouth and anus; pharynx
muscular.
5. Sexes are separate.
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6. Most forms are parasitic but some are free-living
in soil or water.
7. Parasitic nematodes are pathogenic, meaning they
produce diseases in the hosts. For example:
elephantiasis.
Examples: Ascaris (round-worm),
Ancylostoma (hook-worm), Wuchereria
bancrofti (filarial worm), Enterobius
(pinworm of human).
Ascaris
Wuchereria
Differences between Platyhelminthes and Nemathelminthes (= Nematoda)
Platyhelminthes
1. They are flatworms.
2. They are acoelomate.
3. They have an incomplete digestive system.
4. They are hermaphrodites (i.e., an
individual has both types of sex organs).
Examples: Liver fluke, pork, tape-worm.
Nemathelminthes
1. They are cylindrical in form and are
called roundworms.
2. They are pseudocoelomate.
3. They have a complete digestive system.
4. They are unisexual (i.e., males and
females are present).
Examples: Ascaris.
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1.6 Phylum Annelida (Segmented worms)
Some common features of this phylum are :
1. Body triploblastic, bilaterally symmetrical, soft, elongated, vermiform and
cylindrical or dorsoventrally flattened.
2. Body is metamerically segmented externally by transverse grooves and
internally by septa.
3. Exoskeleton absent; body is covered by a thin cuticle.
4. Locomotory organs are segmentally arranged paired lateral appendages,
parapodia or chitinous setae or chaete.
5. Alimentary canal is tube-like, complete and extends straight from mouth to
anus.
6. True coelomate animals with closed blood vascular system.
7. Excretion by paired segmental nephridia which removes wastes from coelom
and blood stream directly to the exterior.
8. The nervous system consists of a dorsal “brain” and a ventral nerve cord
having ganglia and lateral nerves in each body segment.
9. Reproduction is by sexual means. Sexes may be united (hermaphroditic) or
separate.
10. They live in a variety of habitats. Mostly aquatic, marine or fresh water; some
are terrestrial (in moist soil), burrowing in tubes, some free-living forms.
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(a) Nereis
(b) Earthworm
(c) Leech
(d) Hirudinaria
Phylum Annelida includes the following three classes:
Class 1. Polychaeta  Locomotion by segmetally arranged
parapodia having numerous setae.
Examples: Nereis (clam worm or sand worm),Aphrodite (sea
mouse).
Class 2. Oligochaeta.  Body without distinct head and lack eyes,
tentacles and parapodia.
Examples: pheretima (earth worm), Eutypheus.
Class 3. Hirudinea.  Body with anterior and posterior suckers.
 Parapodia and setae are absent.
Examples: Hirudinaria (Indian cattle leech).
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1.7 Phylum Arthropoda (jointed foot animals)
Some common features of this phylum are :
1. Triploblastic, bilaterally symmetrical and metamerically segmented animals.
2. Body segments are grouped into two regions- cephalothorax (head and thorax
together) and abdomen, or three regions- head, thorax and abdomen. Anterior
part of body forms a distinct head, bearing sense organs and brain.
3. Exoskeleton of cuticle, containing protein, lipid, chitin, and often calcium
carbonate is secreted by underlying epidermis and shed (moulted) at
intervals.
4. They have complex muscular system, with exoskeleton for attachment,
striated muscles for rapid actions and smooth muscles for visceral organs.
Cilia are absent.
5. Each body segment (somite) usually bears paired lateral and jointed legs or
appendages.
6. Body cavity is haemocoel (i.e., filled with blood). The coeloms are reduced to
the spaces of the genital and excretory organs.
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7. Alimentary canal is complete; mouth and anus lie at opposite ends of the
body.
8. Respiration through general body surface, by gills, air tubes (tracheae) or
book-lungs.
9. Circulatory system is open with dorsal heart, arteries and haemocoel (blood
sinues) but without capillaries and veins. It means that blood does not flow in
well-defined blood vessels.
10. True nephridia absent. Excretion by coelomoducts, malpighian tubules or
green or coxal glands.
11. Sexes are usually separate; sexual dimorphism is well marked in several
forms.
12. Fertilization is usually internal, oviparous or viviparous and often with
metamorphosis.
13. Terrestrial or aquatic (fresh water and marine), free-living, commensal or
parasitic (on other animals and plants) forms.
14. Arthropoda forms the largest phylum of Animal kingdom. About 900,000
species are known.
Phylum Arthropoda is divided into the following five classes:
Class 1. Onychophora.  Body is elongated, segmented and is
covered with thin cuticle.
Example: Peripatus.
Class 2. Crutacea.  Head and Thorax are fused together to form
cephalothorax.  Respiration by gills.
Examples: Palaemon (prawn), Daphnia (water flea), Cyclops (oneeyed gian), Cancer (True crab).
Class 3. Myriapoda.  Body is elongated, metamerically
segmented with each segment having one or two pairs of legs.
 Respiration by tracheae.
Examples: Scolopendra (centipede), Julus (millipede).
Class 4. Insecta.  Body is divisible into distinct head, thorax and
abdomen.  Abdomen lacks appendages, head has a pair of
antennae and mouth parts and thorax has three pairs of legs and two
pairs of wings.  Respiration by tracheae.
Examples: Lepisma (silver fish), Melanopus (grasshopper), Gryllus
(house cricket), Periplaneta (cockroach), Musca (house fly), Apis
(honey bee), Anopheles (mosquito), pieries (butterfly), cimex (bed
bug).
Class 5. Arachnida.  Body divisible into cephalothorax and
abdomen.  Antennae and true jaws are absent.
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 Respiration by tracheae, book-lungs or book-gills.
Examples: Limulus (king-crab), Palamnaeus (scorpion); Sarcoptes
(itch-mites), Aranea (spider) , Argus (tick).
(a) Locust
(b) Butterfly
(c) Scorpion
(d) Prawn
Differences between annelids and arthropods
Annelids
1. Their appendages are unjointed.
2. They have a closed circulatory
system, i.e., their blood flows inside
blood vessels.
3. They have a well developed true
coelom.
6. Their sensory system is less
developed.
7. Their locomotory organs include
parapodia and chaetae.
Examples. Earthworm, Nerreis.
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1. Their appendages are jointed.
2. They have a open circulatory system,
i.e., their blood flows through large
sinuses or spaces.
3. They have a small coelom. Instead
they have blood filled body cavities
called haemocoel.
4. A chitinous exoskeleton is present in
them.
5. Their excretory organs are green
glands and malpighian tubules.
6. Their sensory system is well
developed.
7. Their locomotory organs are legs and
wings.
Examples. Centipede, crab, cockroach.
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4. A chitinous exoskeleton is absent in
them.
5. Their excretory organs are nephridia.
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Arthropods
1.8 Phylum Mollusca (molluscus-soft)
Some common features of this phylum are :
1. Body is soft, bilaterally symmetrical, with little segmentation and without
appendages.
2. Body is divisible into an anterior head, a ventral muscular foot, a hard dorsal
visceral mass. The entire body is covered by a fold of thin skin, called mantle
which secretes a hard calcareous shell.
3. Body cavity is haemocoel.
4. Digestive tract has a simple structure.
5. Respiration through gills (called ctenidia), mantle or a “lung” of the mantle.
6. Circulatory system is open except in cephalopods.
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7.
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Excretion by a pair of metanephridia or kidneys.
Sexes are usually separate.
Sensory organs of touch, smell, taste, equilibrium and vision.
Aquatic, mostly marine, few fresh water and some terrestrial forms.
Osmoregulatory organs are closed at the inner end, they are called
protonephridia, but when they open into a coelomic space at their inner
end, they are called metanephridia.
(a) Chiton
(b) Octopus
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(c) Pila
(d) Unio
The phylum Mollusca is divided into the following five main classes:
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Class 1. Polyplacophora.  Shell composed of eight calcareous pieces.
Example: Chiton
Class 2. Gastropoda.  Univalve shell and visceral mass are spirally coiled
(torsion).
Examples: pila (apple snail), Aplysia (sea hare), Helix (garden
snail), Limax (gray slug).
Class 3. Scaphopoda.  Tusk-like tubular shell opens at both ends.
Examples: Dentalium (tusk shell)
Class 4. Pelecypoda (Bivalvia).  Shell consists of two lateral valves
hinged together mid-dorsally.
Examples: Unio (fresh water mussel), Mytilus (sea mussel); Pinctada
(Indian pearl oyster), Teredo (ship worm).
Class 5. Cephalopoda.  Shell external, internal or absent.
 Foot altered into a series of sucker-bearing arms or tentacles.
 Eyes are highly developed.
Examples: Nautilus, Loligo (squid), Sepia (cuttle-fish), Octopus (devil-fish)
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1.9 Phylum Echinodermata (spiny skin)
Some common features of this phylum are :
1. Simple animals may be star-like, spherical or elongate.
2. Body triploblastic, coelomate, unsegmented (nonmetameric) and radially
symmetrical (larva bilaterally symmetrical). i.e., pentamerous symmetry in
adults.
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3. Body lacks head, but has oral and aboral surfaces. Oral surface of body has
five radial areas called ambulacra.
4. Body wall is covered with spiny hard calcareous (calcium carbonate) plates
(ossicles) that forms a rigid or flexible endoskeleton.
5. Body cavity is modified into a unique water vascular system which moves
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respiratory and locomotary organs, the tube feet or podia.
Digestive system is usually complete. Anus is absent in ophiuroids.
Excretory organs absent.
Reproduction sexual, asexual or by regeneration. Sexes are separate.
Exclusively marine, free-living and gregarious (live in groups) animals.
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(a) Antedon
(b) Holothuria
(c) Echinus
(feather star)
(sea cucumber)
(sea urchin)
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(d) Asterias
(star fish)
Phylum Echinodermata includes the following five classes:
Class 1. Crinoidea.  The oral surface is directed upward.
Example: Antedon (feather star)
Class 2. Holothuroidea.  Worm-like body without arms and spines.
 Mouth surrounded by tentacles.
Example: Holothuria, Cucumaria (sea cucumber)
Class 3. Echinoidea.  Spherical or discoidal body lacking arms.
 Body enclosed in an endoskeletal shell.
Examples: Echinus (sea urchin)
Class 4. Asteroidea.  Flattened, pentagonal or star-shaped body with
flexible endoskeleton.
Examples:Pentaceros (sea pentagon), Asterias (star fish or sea star)
Class 5. Ophiuroidea.  Asteroids-like body is flat and composed of long
arms and a central disc.
Examples: Ophioderma (brittle star), Ophiura (brittle star).
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1.10 Phylum Hemichordata (hemi = half)
Some common features of this phylum are :
1. Body is soft, unsegmented worm-like and bilaterally symmetrical. These
animals possess a combination of invertebrate (nonchordate) and chordate
characters.
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2. Body
is divided into proboscis, collar
(collarette) and trunk.
3. These animals resemble chordates only in
having pharyngeal gill-clefts or gill slits. Gill
slits form the respiratory system and connects
the pharynx with outside.
4. ‘Buccal diverticulum’, earlier regarded as
“notochord” is present in proboscis.
5. No nephridia. Single glomerulus connected
to blood vessels has a excretory function.
6. Exclusively marine, solitary or colonial,
mostly tubicolous and detritus feeders like the
earthworms.
Balanoglossus
Examples: Balanoglossus (acorn worm or tongue worm;), Cephalodiscus.
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Differences between non-chordates and chordates
Nonchordates
1. Notochord is absent in them.
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solid and ventral.
Heart, if present in them, is dorsal in
position.
Their circulatory system is of open
or closed type.
Respiratory pigment, the
haemoglobin, if present, is dissolved
in plasma of blood.
Pharyngeal gill slits are absent in
them.
They contain anus at posterior end
of body, so post-anal tail is not
present.
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2. Their central nervous system is
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Chordates
Notochord is present in them at
some of their developmental stage.
Their central nervous system is
hollow and dorsal.
Heart is always present and it is
ventral in position.
Their circulatory system is of
closed type.
Haemoglobin is present in their red
blood cells or corpuscles.
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6. Pharyngeal gill-slits are present in
them.
7. Their anus is not located at
posterior tip of body, so contain a
post-anal tail.
1.11 Phylum Chordata (chorda = string)
Some common features of this phylum are :
1. Chordates are characterized by the following three features: (a) a dorsal,
hollow, tubular nerve cord; (b) a pliable rod called notochord that occurs
ventral to nerve cord and is replaced by a bone or cartilage to form a vertebral
column in vertebrates; and (c) paired gill-slits in the pharynx.
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2.
3.
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7.
The notochord is a long rod-like support structure that runs along the back
of an animal and separates the nervous tissue from the gut.
Notochord is a primitive type of endoskeleton which is characteristic
among all chordates, at some stage of life cycle. The notochord provides
longitudinal stiffening of the main body axis, a base for trunk muscles and
an axis around which the vertebral column develops.
Body bilaterally symmetrically, metamerically segmented, triploblastic and
coelomate.
A post-anal tail present at some stage of life.
Segmental muscles in an unsegmented trunk.
Ventral heart, with dorsal and ventral blood vessels and closed blood vascular
system.
Complete digestive system.
A cartilaginous or bony endoskeleton present in majority of members
(Vertebrates).
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Chordata characteristics
 Chordata is the most advanced group of animals. Phylum Chordata is
divided into two groups: Protochordata (Acrania) and Vertebrata
(Craniata).
 Protochordata includes two subphyla, Urochordata and Cephalochordata.
 Group Vertebrata is divided into two subphyla, Agnatha and
Gnathostomata.
 Agnatha includes a single class Cyclostomata.
 Gnathostomata is divided into six classes: Chondrichthyes, Osteichthyes,
Amphibia, Reptilia, Aves and Mammalia. Chondrichthyes and
Osteichthyes, both are commonly known as (fishes).
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A. Protochordata
Subphylum 1. Urochordata (Gr., oura-tail), or Tunicata.
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They are bag-like, sessile, soft-bodied, non-metameric animals.
Adult body is covered with a tunic or test containing cellulose.
Notochord is present only in the tail of free-living tadpole-like
larva. Sessile adult has no notochord.
Dorsal tubular nerve cord is present in the larval form and it
degenerates in the form of small ganglion in the adult.
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The only chordate character present in the adult animal is the
presence of numerous gill-slits in the pharynx.
Hermaphrodites.
Exclusively marine, solitary and colonial.
Examples: Oikopleura, Herdmania, Pyrosoma, Doliolum, Salpa.
Subphylum 2. Cephalochordata
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Fish-like, metamerically segmented, headless coelomate animals
which retain notochord, dorsal tubular nerve cord and pharyngeal
gill-slits throughout life.
Notochord and nerve cord extend throughout the entire length of
body.
Exoskeleton, head, jaws and paired fins are absent.
Pharynx large and perforated by numerous gill-slits.
Sexes separate.
Marine, burrow in the sand of shallow sea water.
Examples: Amphioxus or Branchiostoma (lancelet).
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B. Vertebrata
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Subphylum 1. Agnatha (Gr., a – without; gnathos – jaws).
 Animals have vertebral column and cranium.
 Without true jaws; but possess a suctorial mouth.
 Without paired appendages or fins.
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Agnatha includes the following single class:
Class – Cyclostomata (circular mouth)
 Body is long, elongated and eel-like.
 Skin is soft, slimy, smooth and scaleless.
 Mouth is round, suctorial and without jaws. They are ectoparasites
and use their mouth to stick to the back of other fishes.
 Single and median nostril is present.
 Respiration is through gills contained in pouches.
 Endoskeleton is cartilaginous and the notochord is in the form of
cylindrical rod and persists throughout life.
 Heart is two chambered.
 Gonad is single and fertilization is external. Development is direct
or indirect. Petromyzon has ammocoete larva in its life cycle.
 Aquatic, marine and fresh water.
 Free-living and ectoparasites of fishes.
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Examples: Petromyzon (lamprey), Myxine (hagfish), Bdellostoma
(hagfish)
Subphylum 2. Gnathostomata (jaws and mouth): Vertebrates with jaws
and paired appendages. This subphylum is divided into the following six
classes:
Class 1 and Class 2 (Chondrichthyes and Osteichthyes)
are combined to form super class - Pisces
Class 1. Chondrichthyes (Cartilaginous fish)
 Marine fishes with completely cartilaginous endoskeleton. They are generally
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large in size (up to 10 – 20 metres long).
Streamlined body is either laterally compressed and spindle-shaped or
dorsoventrally flattened and disc shaped.
Mouth is ventral in position.
Skin is tough and covered with minute placoid scales.
Respiration through gills. The gill-slits are not covered by gill-cover or
operculum.
They have fins for locomotion (swimming) and balance. Fins may be paired
(pectoral fins, pelvic fins) or median (dorsal fin, caudal fin and anal fin).
Tail or caudal fin is heterocercal. Muscular tail is used for movement.
Heart is two chambered.
Digestive system has a J-shaped stomach.
Sense of smell, vibration reception and electro-reception developed.
Alimentary canal and urinogenital ducts open into a common aperture, called
cloaca.
Excrete urea (ureotelic animals).
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Synchiropus splendidus Caulophyryne jordani Pterois volitans
(Mandarin fish)
Sting ray
(Angler fish)
Scoliodon (Dog fish)
(Lion fish)
Electric ray
(Torpedo)
Pristis
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Examples: Scoliodon (dog-fish, Indian shark), Sphyrna
(hammer-headed shark), Torpedo (electric ray), Trygon
(sting ray), Pristis (saw-fish).
Class 2. Osteichthyes (Bony fishes)
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Marine and fresh-water fishes with partly or whole bony endoskeleton.
Size varies from 10 mm to 4 metres.
Body is generally spindle-shaped.
Skin is either naked or covered with cycloid or ctenoid scales.
Mouth is usually terminal (anterior) in position.
Four pairs of gills are present and they are covered by operculum. Gills
are filamentous. Fish obtain oxygen dissolved in water by using gills.
Tail or caudal fin is homocercal.
Cloaca is absent. Anus and urinogenital apertures are distinct.
Excrete ammonia (ammonotelic animals).
Heart is two chambered containing one auricle and one ventricle.
They are cold-blooded (ecothermic) animals.
They lay eggs and fertilization is external.
Examples: Labeo (rohu, carp), Pterois volitans (lion fish),
Hippocampus (sea horse), Anabas(climbing perch).
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Labeo rohita
Male Hippocampus
Exocoetus
Anabas
(Rohu)
(Sea horse)
(Flying fish)
(Climbing perch)
Differences between bony fishes and cartilaginous fishes
Bony fishes
1. They have a bony endoskeleton.
2. They contain four pairs of gill slits.
3. Their gill slits are covered with an
operculum.
4. Their mouth is terminal in position.
5. Their caudal fin is homocercal.
6. Air bladder is usually present in them.
Example. Carp, sea horse, etc.
Cartilaginous fishes
1. They have a cartilaginous
endoskeleton.
2. They contain 5-7 pairs of gill slits.
3. An operculum is absent in them.
4. Their mouth is ventral in position.
5. Their caudal fin is heterocercal.
6. Swim bladder is absent in them.
Example. Indian shark, electric ray, etc.
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Class 3. Amphibia. It includes frogs, toads, newts and salamanders.
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In evolutionary terms, amphibians form the first group among the
chordates to live outside water.
These animals live partly in fresh water and partly on land (moist
places).
Skin is smooth or rough, moist, slimy, glandular and mostly
without scales. Skin has mucus glands.
Body has a distinct head and trunk and has no neck. Mouth is
usually large.
Two pairs of pentadactyl (five digit) limbs are present. Digits or
toes are without claws. Limbs may be absent in some cases.
Three-chambered heart has two auricles and one ventricle. Double
circulation through the heart.
Respiration either by gills, lungs, skin or the mouth lining.
Excrete either ammonia (tadpole larva) or urea.
Oviparous, lay yolk-laden eggs with gelatinous covering usually in
water. Fertilization is external in frogs and toads, but internal in
salamanders and apoda. Metamorphosis is present.
Ectothermal (= cold blooded animals).
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Toad
Rana tigrina
Hyla
(Common frog)
(Tree frog)
Examples: 1. Apoda: Ichthyophis; 2. Urodela: Amphiuma,
Salamandra, Ambystoma, Necturus; 3. Anura: Rana (bull
frog), Bufo (toad), Hyla (tree-frog).
Class 4. Reptilia (to crawl; creeping vertebrates) includes lizards, snakes,
crocodiles and tortoises.
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Ectothermic or cold-blooded, terrestrial or aquatic vertebrates with
a body covered with dry water-proof skin having horny epidermal
scales or dermal scute plates.
Body varies in form and is usually divided into head, neck, trunk
and tail.
Limbs are tetrapodous pentadacytle (five-toed) type, with clawed
digits (limbs are absent in snakes and some lizards).
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Chameleon
Tympanum is small and depressed.
Teeth are present in all reptiles except in tortoises and turtles.
Respiration is through lungs only. No gills are present.
Heart is three chambered and is divided into two auricles and an
incompletely divided ventricle. Only crocodiles have fourchambered heart.
Terrestrial reptiles such as snakes and lizards excrete uric acid
(uricotelic animals).
Fertilization is internal.
Most reptiles are oviparous and lay their eggs with tough covering
and do not need to lay their eggs in water. A few reptiles are
viviparous (e.g., lizards and snakes). No aquatic larval stage.
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Crocodilus
Chelone
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Naja
Flying lizard
(Draco)
House wall lizard
(Hemidactylus)
Examples: Testudo (land-tortoise), Calotes (garden-lizard),
Python(ajgar), Naja (cobra), Crocodilus(muggar), Gavialis
(gharial).
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Differences between Amphibia and Reptilia
Amphibia
Reptilia
1. Their skin is glandular, smooth and
moist
2. Scales are not present in them.
3.
4.
5.
6.
7.
1. Their skin is non-glandular, dry and
keratinised.
2. Horny scales are present over their body
surface.
Their digits do not possess claws.
3. Their digits end in claws.
They have a three-chambered heart.
4. Their heart is incompletely four chambered.
Fertilization is external.
5. Fertilization is internal.
Extra-embryonic membranes (e.g.,
6. Extra-embryonic membranes are
amnion, allantois, chorion) are absent.
present in them.
Their eggs have a soft covering.
7. Their eggs have a hard covering or shell.
Example, Frog, toad
Example. Lizard, snake, tortoise,
dinosaurs (extinct)
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Class 5. Aves (Birds)
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Warm-blooded, tetrapodous vertebrates with various flight
adaptations.
Size ranges from smallest humming bird to largest ostrich.
Horny scales persist on the feet but feathers cover most of the body
Cutaneous glands are absent.
Spindle-or boat-shaped body is divisible into head, neck, trunk and
tail.
Fore-limbs modified into wings for flight. Kiwis have vestigial
wings.
Hind-limbs bear four clawed digits and are adapted for walking,
perching, or swimming.
Narrow jaws form a horny beak, which is modified for different
purpose. Teeth are absent.
Bones of endoskeleton are light and spongy due to the presence of
air cavities.
They breathe through lungs.
Four-chambered heart with two auricles and two ventricles.
Cloaca is present.
Excrete semisolid urine having uric acid (uricotelic animals). No
bladder.
Birds have highly developed voice, hearing and vision. They also
have specialised sense for nest building and care for the young
(parental care).
Fertilization is internal. They are oviparous and lay large, yolkladen eggs having hard shell.
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Psittacula
Pavo
White Stork
Ostrich
Male Tufted Duck
(Ciconia ciconia) (Struthio camelus) (Aythya fuligula)
Examples: Passer (house sparrow), Corvus (crow),
Columba (pigeon), Psittacula (parrot), Bubo (owl),
Milvus (kite), Gypus (vulture).
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Class 6. Mammalia
 Mammals are warm-blooded and the most evolved animals of Animal
Kingdom.
 Hairs and the subcutaneous fat form an insulating layer. Cutaneous glands
such as sweat glands, scent glands and sebaceous (oil) glands are present.
 Body is divisible into head, neck, trunk and tail. Movable eyelids are
present.
 Females have milk-producing mammary glands which secrete milk for
the nourishment of the young.
 Fleshy external ear (pinnae) present. Middle ear with three ossicles.
 Teeth are thecodont (embedded in sockets in the jaws) and are heterodont
(differentiated into incisors, canines, premolars and molars).
 Two pairs of pentadactyl limbs are present. Digits in the fore-limbs and
hind-limbs are never more than five and end in claws, nails or hoofs.
 A muscular diaphragm separates thoracic and abdominal cavities.
 Respiration is through lungs only.
 Heart is four-chambered. Nonnucleated biconcave red blood corpuscles are
present.
 Excrete urea (ureotelic animals).
 Penis is always present. Fertilization is internal.
 Most mammals familiar to us, produce live young i.e., they are viviparous.
 Parental care is highly developed.
 Mammals live in all kinds of habitats. They are primarily terrestrial
animals.
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(a) Ornithorhynchus
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(b) Macropus
(c) Pteropus
(d) Balaenoptera
Examples: Macropus (kangaroo), Panthera (lion, tiger, leopard),
Canis (dog), Camelus (camel), Rhinoceros, Elephas (elephant),
Ursus (bear), Macaca (monkey), Homo (human being).
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Differences between Aves and Mammalia
Aves
Mammalia
1. Forelimbs are modified into wings.
2. The body is covered with feathers and
scales.
3. Skin is dry only a single preen gland
is present.
4. Mammary glands are absent.
1. Wings are absent except in bats.
2. Feathers and scales are absent. Hairs are
present.
3. Skin bears a number of sweat and oil
glands.
4. Females have mammary glands for
feeding the young.
5. A muscular partition called diaphragm is
present between thorax and abdomen.
6. Jaws do not form beak. Teeth are
present.
7. Bones of mammals do not possess air
cavities.
8. Larynx of mammals is functional. Syrinx
is absent.
9. External air sacs do not occur in lungs.
10. Eggs have no or tiny amount of yolk,
such eggs are called microlecithal eggs.
11. Mammals are viviparous with the
exception of prototherians.
5. A diaphragm is absent.
6. A toothless beak is present.
7. Bones of birds are hollow or
pneumatic.
8. Larynx of birds is non-functional.
Instead syrinx is present.
9. Lungs contain external air sacs.
10. Eggs possess great amount of yolk.
They are called macrolecithal eggs.
11. Birds are oviparous.
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Class-9th (Biology)
Topic:
Diversity in Living Organisms
Worksheet- 3
1. How do poriferan animals differ from coelenterate animals ?
2. How do annelid animals differ from arthropods ?
3. What are the differences between amphibians and reptiles ?
4. What are the differences between animals belonging to the Aves group and
those in the mammalia group ?
5. Explain how animals in vertebrata are classified into further subgroups.
6. List any three differences between the aves and reptilia group.
7. Identify two features of chordates.
8. Define the terms and give one example each of:
(a) Bilateral symmetry
(b) Coelom
(c) Triploblastic.
9. Write any three differences between amphibia and mammalia belonging to
kingdom Animalia.
10. Identify animal groups having:
(a) soft bodied animals supported by calcareous shells.
(b) spiny body with radial body symmetry.
(c) Bones light and hollow.
(d) External ear or pinna.
11. Give one point of difference between notochord and nerve cord.
12. List a few flight adaptations in Birds.
13. Why whales are not grouped in the fishes ?
14. How do animals of Porifera differ from animals of Cnidaria ?
15. Write down four general characters of cnidarians (coelenterates). Give two
examples.
16. Write down four main characters of Platyhelminthes. Give two examples.
17. Write four characters of Annelida.
18. Define the term hermaphrodite. Give two examples.
19. Write down four main characteristics of Arthropoda. Give two examples.
20. Write the scientific names of:(a) Prawn
(b) Squid
(c) House fly (d) Apple snail
(e) Star fish (d) Fresh water mussel.
21. What are adaptations in fishes due to which they are aquatic ?
22. What are differences between:(a) Cartilaginous fishes and bony fishes.
(b) Amphibia and Reptilia.
23. Name major phyla of Animal kingdom. Write down one character and one
example of each of them.
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24. What are Pisces ? Classify and explain two different kinds of fishes with the
help of suitable examples.
HOTS
1. What are the difficulties that you would face in classification of animals, if
common fundamental features are not taken into account ?
2. How useful is the study of the nature of body cavity and coelom in the
classification of animals ?
3. Distinguish between intracellular and extracellular digestion.
4. What is the difference between direct and indirect development ?
5. What are the peculiar features that you find in parasitic platyhelminthes ?
6. What are the reasons that you think of for the arthropods to constitute the largest
group of the animal kingdom ?
7. “All vertebrates are chordates but all chordates are not vertebrates”. Justify the
statement .
8. How important is the presence of air bladder in Pisces ?
9. What are the modifications that are observed in birds that help them fly ?
10. Segmentation in the body is first observed in which of the following:
(a) Platyhelminthes (b) Aschelminthes
(c) Annelida
(d) Arthropoda.
11. Prepare a list of some animals that are found parasitic on human beings.
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Topic:
Diversity in Living Organisms
Worksheet- 4
Multiple Choice Questions
1. Find out incorrect sentence
(a) Protista includes unicellular eukaryotic organisms
(b) Whittaker considered cell structure, mode and source of nutrition for
classifying the organisms in five kingdoms
(c) Both Monera and Protista may be autotrophic and heterotrophic
(d) Monerans have well defined nucleus
2. Which among the following has specialised tissue for conduction of water ?
(i) Thallophyta
(ii) Bryophyta
(iii) Pteridophyta (iv) Gymnosperms
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
3. Which among the following produce seeds ?
(a) Thallophyta
(b) Bryophyta
(c) Pteridophyta
(d) Gymnosperms
4. Which one is a true fish ?
(a) Jellyfish
(b) Starfish
(c) Dogfish
(d) Silverfish
5. Which among the following is exclusively marine ?
(a) Porifera
(b) Echinodermata
(c) Mollusca
(d) Pisces
6. Which among the following have open circulatory system ?
(i) Arthropoda (ii) Mollusca
(iii) Annelida
(iv) Coelenterata
(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iii)
(d) (ii) and (iv)
7. In which group of animals, coelom is filled with blood?
(a) Arthropoda
(b) Annelida
(c) Nematoda
(d) Echinodermata
8. Elephantiasis is caused by:
(a) Wuchereria
(b) Pinworm
(c) Planarians
(d) Liver flukes
9. Which one is the most striking or (common) character of the vertebrates?
(a) Presence of notochord
(b) Presence of triploblastic condition
(c) Presence of gill pouches (d) Presence of coelom
10. Which among the following have scales ?
(i) Amphibians
(ii) Pisces
(iii) Reptiles
(iv) Mammals
(a) (i) and (iii)
(b) (iii) and (iv)
(c) (ii) and (iii)
(d) (i) and (ii)
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11. Find out the false statement
(a) Aves are warm blooded, egg laying and have four chambered heart
(b) Aves have feather covered body, fore limbs are modified as wing and
breathe through lungs
(c) Most of the mammals are viviparous
(d) Fishes, amphibians and reptiles are oviparous
12. Pteridophyta do not have
(a) root
(b) stem
(c) flowers
(d) leaves
13. Identify a member of porifera
(a) Spongilla
(b) Euglena
(c) Penicillium
(d) Hydra
14. Which is not an aquatic animal?
(a) Hydra
(b) Jelly fish
(c) Corals
(d) Filaria
15. Amphibians do not have the following
(a)Three chambered heart
(b) Gills or lungs
(c) Scales
(d) Mucus glands
16. Organisms without nucleus and cell organelles belong to
(i) fungi
(ii) protista
(iii) cyano bacteria (iv) archae bacteria
(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iv)
(d) (ii) and (iii)
17. Which of the following is not a criterion for classification of living organisms?
(a) Body design of the organism
(b) Ability to produce one’s own food
(c) Membrane bound nucleus and cell organelles
(d) Height of the plant
18. The feature that is not a characteristic of protochordata?
(a) Presence of notochord
(b) Bilateral symmetry and coelom
(c) Jointed legs
(d) Presence of circulatory system
19. The locomotory organs of Echinodermata are
(a) tube feet
(b) muscular feet
(c) jointed legs
(d) parapodia
20. Corals are
(a) Poriferans attached to some solid support
(b) Cnidarians, that are solitary living
(c) Poriferans present at the sea bed
(d) Cnidarians that live in colonies
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21. Who introduced the system of scientific nomenclature of organisms
(a) Robert Whittaker
(b) Carolus Linnaeus
(c) Robert Hooke
(d) Ernst Haeckel
22. Two chambered heart occurs in
(a) crocodiles
(b) fish
(c) aves
(d) amphibians
23. Skeleton is made entirely of cartilage in
(a) Sharks
(b) Tuna
(c) Rohu
(d) None of these
24. One of the following is not an Annelid
(a) Earthworm
(b) Nereis
(c) Leech
(d) Urchins
25. The book Systema Naturae was written by
(a) Linnaeus
(b) Haeckel
(c) Whittaker
(d) Robert Brown
26. Carl Von Linnaeus was involved with which branch of science?
(a) Morphology
(b) Taxonomy
(c) Physiology
(d) Medicine
27. Real organs are absent in
(a) Mollusca
(b) Coelenterata
(c) Arthropoda
(d) Echinodermata
28. Hard calcium carbonate structures are used as skeleton by
(a) Echinodermata
(b) Protochordata
(c) Arthropoda
(d) Nematoda
29. Differentiation in segmental fashion occurs in
(a) Leech
(b) Starfish
(c) Snails
(d) Ascaris
30. In taxonomic hierarchy family comes between
(a) Class and Order
(b) Order and Genus
(c) Genus and Species
(d) Division and Class
31. 5-Kingdom classification has given by
(a) Morgan
(b) R. Whittaker
(c) Linnaeus
(d) Haeckel
32. Well defined nucleus is absent in
(a) blue green algae
(b) diatoms
(c) algae
(d) yeast
33. The ‘Origin of Species’ is written by
(a) Linnaeus
(b) Darwin
(c) Hackel
(d) Whittaker
34. Meena and Hari observed an animal in their garden. Hari called it an insect
while Meena said it was an earthworm. Choose the character from the following
which confirms that it is an insect.
(a) Bilateral symmetrical body
(b) Body with jointed legs
(c) Cylindrical body
(d) Body with little segmentation
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