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# Understanding Text 1
@ Practice Problems with,
their Answers 8,18, 27,52, 99, 44,52
ADDITIONAL USEFUL,
INFORMATIONS, 10, 14, 17, 20, 22,25
(For Competitive Examinations) 29,31, 35,39, 42, 44,47, 54"
(CHAPTER SUMMARY 55,
KEY TERMS. a
NCERT FILE
@ NCERT Exercise Questions
(with Answers) a7
4 NCERT Exemplar Problems. hi
(with Answers & Hints) 36,
HOTS & BRAIN TWISTING QUESTIONS 63)
QUICK MEMORY TEST ote
REVISION EXERCISES y
(vith previous years’ CBSE & Other State Boards
Examinations)
© Very Short Answer Questions -
‘One mark each with Answers 66
‘ short Answer Questions ~Ty40.matks each (with
Answvers) o
+ Short Ansiver Questions “Thee marks each @
© Long Answer Questions Five arks each w
(COMPETITION FILE (WITH ANSWERS
& HINTS)
‘# Multiple Choice Questions From.
AIPMT & Other Competitive Exams)
(© CBSE-PMT (Main Examination)
Questions
# Matching Type Questions
‘© Assertion Type Questions
# Additional Multiple Choice Questions
(CHAPTER PRACTICE TEST
s
SaEse
NEED OF CLASSIFICATION
There are about 7.7 million animal species (of
which 953, 434 animal species have been described
and catalogued) which show a great diversity of lite.
‘Though the animals are metozoans like the plants but
these differ from plants in a mumber of characters like
aheonce af plastids, coll wall and conteal vaenale; and
having centrosome in their cells. These are exclusively
heterotrophic and are mostly holozoic in their nutrition,
These also’pass through certain larval stages during,
their development
According to their mode of living, animals may be
solitary (found alone ¢ g. Tapeworm) or gregarious (live
ingroups butwithoutobligatory interactionse.g- Locust)
or colonial (live in a social hive and show obligatory
Interdependence eg. honey bees, wasps, termites, etc)
‘These may be free living or sedentary.
‘The free living organisms develop certain organs of,
locomotion to locate their food, shelier or mate, while
the sedentary animals. eg., sponges, maintain a water
current to drav food to them.
Another peculiar character of animalsis the presence
of some kind of receptors or nervous system to guide
and inform them about theirenvironment. These systems
receive stimuli from the environment and respond by
showing certain animal behaviour. Notable exceptions
are sponges which do not have nerve cells.
So to express the relationship between different
organisms, there is need of classification. It involves
arrangement of organisms into different groups on the
basis of theirsimilarities and differences. So classification
helps in assigning a definite taxonomic systematic
position to a species.
GENERAL FEATURES OF ANIMALS AS BASIS
‘OF CLASSIFICATION HABITAT
Definition. It is the place where an organism lives.
On the basis of habitat, animals are divided into the
following categories
(a) Aquatic animals. These are those animals which
are found in water. On the basis of nature of water,
aquatic animals may be marine (those found in sea-
water ¢g, all echinoderms and cartilage fishes; and
most of sponges and coelenterates) or fresh-water
animals (those found in ponds, rivers, streams etc. eg.
Amoeba, Paramecium, Prawn etc). (b) Terrestrial animals. These animals live on land
and are again of following types
() Fossorial animals. These live inside the burrows
eg, earthworm, snake, rabbit ete.
(i) Arboreal animals. These live on the trees ¢..,
most of birds, bats, monkeys etc.
(ii) Scansorial animals. These clinsb the walls, rocks
etc. eg,, wall lizards, flying squirrels etc.
(iv) Aerial animals. These can go in air eg., most
of insects and birds, bats etc.
(v) Cursorial animals. These are fast-runners ¢.,
horse, rabbit, lion etc
LEVELS OF ORGANISATION
Animals are divided into four categories on the
basis of their organisation
1. Cellulas ungantivativns Theansianal buy is forse
of loosly arranged cell aggregates but the cells show
no coordination to form tissues eg., sponges. In them,
division of labour occurs at cellular level.
2. Tissue organisation. The animal body is formed
of many cells which coordinate for the specific function
and form four types of tissues ¢g., epithelial tissue,
connective tissue, muscular tissue and nervous tissue
eg, coelenterates like Hydra and Ctenophores.
3. Organ level organisation. In this, tissues
coordinate to form organs to perform specific function
eg, Platyhelminthes (Fasciola).
4. Organ-system organisation. The body is
multicellular and organs coordinate to form, systems,
each specialised for a specific function eg, from,
Roundworms to mammals.
BODY PLAN
A body plan is a group of structural and
developmental characteristics that can beused toidentify,
a group of animals. The shape and size of the animals
show great diversity and on these basis, animals have
three types of body plan
1. Cell aggregate plan (Fig. 1 A). Inthis, the body is
just an aggregate of cells with no coordination between,
them and little differentiation eg., sponges.
2. Blind sac plan (Fig. 1 B). In this, multicellular
animal has tissue’ ot organ-system organisation but
MODERN’S abe + OF BIOLOGY-KI
there is incomplete alimentary canal in which single
opening acts as both mouth (for ingestion) and anus
(for egestion) eg, flatworms (Fasciola hepatica — liver
fluke). It is also found in coelenterates (Hydra).
3. Tube-within-a-tube plan (Fig. 1 ©). In this,
nulticellular animal has organ-system organisation and
iswith complete alimentary canal having two separate
openings — mouth for ingestion at the anterior end and
anus or cloacal aperture for egestion at the posterior
end. It is again of two types :
(a) Protostomous (Fig. 1 €). In this, blastopore
of archenteron of gasteula larva forms mouth and is,
formed earlier than anus¢g., insoundworms, annelids,
molluscs and arthropods.
(b) Deuterostomous (Fig. 1 D). In this, blastopore
of gastrula forms ants, so anus is formed earlier than
mouth eg, int echinoderms and chordates.
‘SYMMETRY
It is the arrangement of similar body parts on two
sides of main axis of body. On the basis of symmetry,
animals are of two types :
1. Asymmetrical animals and 2. Symmetrical
animals.
1. Asymmetrical (Fig. 2 A). When body cannot be
divided in two similar parts from any direction eg.
Amoeba, snails, certain sponges.
2. Symmetrical. When body can be divided in two
similar parts which are mirror images of each other by
one or more planes. On the basis of planes of division,
symunetry in animals is of three types :
(a) Spherical or Universal Symmetry (Fig. 2B).
When body can be divided into two similar parts
by any plane passing through the centre of body «g.,
Voloox and radiolarian protozoans.
(b) Radial Symmetry (Fig. 2C). Body canbe divided
in two similar parts by any plane along central axis of
bodyeg.,coelenterates, ctenophoresand echinoderms.
(6) Bilateral Symmetry (Fig. 2 D). Body can be
divided in two similar paris by only one plane along,
longitudinal axis of body «g., annelids, arthropods
and. vertebrates.
Mount Mount
PROTOSTEMA peuTEROSTOMA
>
Fig. 1. Types of Body plan A. Cell Aggregate plan, B. Blind Sac Plan. C & D, Lubeswithinvactube plan, ANIMAL KINGDOM
‘Table 1. Differences between Protostomes and Deuterostomes.
Characters Protostomes Deuterostomes
T. Fate of blastopare Forns mouth, Foams ans,
2 Cleavage Spiral and determinate. Radial and indeterminate,
3. Examples Roundworms, annelids, Echinoderms and chordates.
molluscs and arthropods
PosTERIOR
aly
Fig. 2. Types of symmetry. A. Asymmetry—Amoet. B. Spherical -Volnor. ©: Radial - Aurelia, . Bilateral - Fish
SEGMENTATION (METAMERISM)
In annelids, arthropods, and vertebrates, there
is repetition of internal body parts witich is termed
metamerism. Tt is not found in roundworms, molluscs
and echinoderms
In annelids (¢g., earthworm), body is externally
divided into segments called metameres or somites
by grooves called annuli and body cavity is intemally.
divided by septa. External division corresponds to.
intemal division and is called metameric segmentation.
But in the vertebrates, there is only internal
metamerism as shown by repetition of ribs, vertebrae,
nerves, muscles etc., while metamerism is only extemal
in arthropods
COBLOM (BODY CAVITY)
Coclomis the space between body wall and gut
‘wall and is lined by mesoderm. It helps in classification
of animals. On the basis of nature of coelom, animals
are divided into the following categories:
1L Acoelomates. Among invertebrates upto flatworms,
there is no coelom and they are called acoelomates
(Hig. 3 A). In flatworms, semisolid mesodermal tissues
hhold the body organs in place.
2.Pseudocoelomates.In Aschelminthes (roundworms
2g,, Ascaris) colomis presentbutisonly partly lined by the
tissues derived frommesodermand iscalled pseudocoel or
false-coelom, so the roundworms are pseudocoelomates
(Fig, 3B). Mesodermal pouches are present between
‘ectoderm and endoderm,
© Radial symmetry (RS, is again of following types:
— Tetramerous R.S. : Body paris arranged in four or multiple of four eg., Jellyfish.
— Pentamerous R.
jody parts arranged in five or multiple of five ¢g., echinoderms.
— Hexamerous R.S;: Body parts arranged in six or multiple of six eg., sea anemone.
The animals with radial symmetry have only oral and aboral sides.
(On the basis of their feeding, the animals are called:
— Herbivores : Eat upon only vegetable food ¢ g. cow, buffalo, sheep, goat, ete.
— Carnivores : Fat upon only animal food e.. frog, lion, tiger, etc
— Omnivores : Eat upon both vegetable and animal food eg. cockroach, human beings, ete
— Sanguivores : Feed upon blood of other animal eg. leech, bed bug, ete.
— Frugivorous : Feed upon fruits e.g. flying fox, parrot, ete.
— Saprophagous : Feed upon dead organic matter eg. earthworms.
— Coprophagous : Feed upon faeces eg. pigs, ete.
© Biradial symmetry : When body can be divided into two similar parts by two vertical planes but
the parts formed by one plane are not similar to those formed by other plane eg. sea anemones and,
comb jellies. It represents a combination of redial and bilateral symmetry.
© For sessile animals (e.g. sponges), radial symmetry is advantageous as it allows capturing of food
from all the sides, while for nektonic and benthonic animals, bilateral symmetry is advantageous as
these show cephalization.
LEARNING PLUS MODERN’S abe + OF BIOLOGY-KI
‘© Cephalization is differentiation of head at anterior end of body.
molluscs.
=)
rs
© Pseudocoel is developed from blastocoel,
CURIOUS
efficient unidirectional movements,
3. Bucoelomates. From annelids to mammals, body
cavity is present between mesodermal peritoneal layers.
‘These are parietal peritoneum on outer side and visceral
peritoneum on inner side. It is called true-coelom,
so these are called true coelomate or eucoelomates
(Fig. 30)
SLATER
‘© Schizocoelic coelom : Body cavity formed by splitting of mesoderm ¢g., annelids, arthropods and
‘© Enterocoelic coelom : Body cavity formed from the enteron of gastrula eg. echinoderms and chordates,
Alimentary canal is absent in sponges and tapeworms.
‘ Bilateral symmetry has a number of advantages like cephalization, streamlining of body and more
4. Haemocoelomates. In Asthropods and molluscs,
true coelom is reduced and body cavity is a pseudocoel
with blood and is called haemocoel and animals are
called haemocoelomates.
Fig. 3. A. Acoslomate, B, Foeudocoslomate, C. Eucoelomate.
GERM LAYERS
The layers of gastrula from which all the body-
organs are formed, are called germ-layers. These give
rise to all the tissues of an animal during the process
of organogenesis
On the basis of number of layers, the animals are
divided into two categories :
1. Diploblastic animals. In sponges, coclenterates,
and ctenophores, gastrula is with wo layers, outer
ectoderm and inner endoderm, so.are called diploblastic
animals Between these germ layers, an undifferentiated,
rnon-cellular and gelatinous mesoglea is present.
2. Triploblasic animals (Fig. 4). From flatworms to
‘mammals, gastrula larva iswvith three germ layers, outer
ectoderm, middle mesoderm and inner endoderm. So
these are called triploblastic animals.
RESPIRATORY SYSTEM
In sponges and coelenterates, every cell of body is in
direct contact with surrounding water and exchange
Fig. 4. Primary germ layers,
of gases occurs through their body surface. But higher
animals have thick body wall so they have special
respiratory organs and modes of respiration. These
are summarised in Table 2
Table 2. Modes of Respiration.
Mode of respiration | Respiratory organ Txamples
TD Wody-surlace respiration Body-surtace ‘Sponges Ctenophares and coolenterates (yara)
2. Branchial respiration Gills (Crustaceans (Prawn), Cartilage and bony fishes,
3. Cutaneus respiration Skin. Annelids (earthworm) and amphibians (02)
4. Tracheal respiration Tracheae (ectoclermal tubes) | Insects (cockroach), Centipedes, millipedes.
5. Pulmonary respiration Lungs. ‘Most of tetrapods,
6. Book-lung respiration Book-lungs. Arachnids (spiders and scorpions)
7. Book-gill respiration Book-gills Limulus (King- in environmental temperature change in environmental temperature.
2 Metabolic rate Low, High,
3. Hibernation ‘Undergo hibernation during witter montis. } Donot undergo hibernation.
4. Examples Fishes, amphibians and reptiles Birds and mammals.
‘Table 7, Differerices Between Endoskeleton and Exoskeleton.
Characters Endoskeleton Fxoskeleton
1. Position Inside the body ‘Outside the body.
2 Nature of elements Living struchures, Dead structures,
3. Type of elements ‘Cariilages ad bones. + Sclerites of arthropods;
+ Shell of molhuses;
++ Epidermal scales in reptiles;
‘Feathers in birds;
+ Hair, nails, homs, hoofs in mammals.
‘Metamorphosis : Sum of all the changes which transform a larva into the adult
Progressive metamorphosis : Simple larva changes into complex adult e.., frog.
Retrogressive metamorphosis : Advanced larva changes into a degenerate adult eg., Herdmania
and wards,
for limited period only.
Aminotelis
ete
a
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ra
72
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=
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ir
a
5S
fe}
we)
Hibernation : Period of inactivity in winter months so also called winter sleep ¢.¢. amphibians (frog)
Aestivation : Period of inactivity in summer months so also called summer sleep ¢. frog.
Cold blooded animals cannot survive in cold alpine and arctic areas. These are active in hot deserts
: Main nitrogenous wastes are amino acids. It is found in star fish, sea cucumber, Unio, ae] ooERWS abe + OF SioL0ate
‘Table 8. Broad classification of kingdom Animalia based on common fundamental characters.
Kingdom Animalia
(Multicellular animals)
asi oH
1. Level of organisation : Cellular level,
2, Symmetry : Radial symmetry Bilateral symmetry
Cnidaria Ctenophora
Porifera 1
3. Body cavity or Colom; Acoelomates Psetudocoelomates Eucoelomates
(No body cavity) (False body cavity) (True body cavity)
Platyfielminthes Aschelininthes
Annelida Mollusca Arthropoda Echinodermata Hemichordata Chordata
IM PRACTICE PROBLEMS—GENERAL CHARACTERS OF KINGDOM ANIMALIA=
1. How donektonic and benthanic animals difier from each other?
2. Give one example of each of cellar and tissue organisation.
3. What are deuterostomous animals? Give ene example.
4. What are protostomous animals? Give one example.
5. Differentiate radial symmetry and bilateral sy:nmetry.
6. Define metameric segmentation,
17. What ace psewdocoelomates? Give one example.
8, Define haemocoel. Name two groups of animals in which it is present.
9, Name the respiratory organs of insects and scorpion,
10. Flow do diploblastic and triploblastic animals differ from each other?
LL. What is closed circulatory system? Name tivo groups of animals having this type of circulation.
12, Name the excretory organs of annelids and insects
13, Which type of nervous system is found in flat worms?
114. Define sexual dimorphism.
15, What is hermaphroditism? Name two hermaphoditic animals,
16, What are viviparous animals? Name a nor-mammal viviparous animal,
17. What do you mean by poikilothermal nature? Name two groups of animals with such a condition.
118, Define retrogressive metamorphosis. Give one example
19, What is hibernation? What isits significance?
20. Nae lwo ernoshelelal elessent
ANSWERS TO PRACTICE PROBLEMS
|. Noktonic are actively swwimuning aniunals (eg, fishes), while benthos are bottom dwellers (eg. sponges).
. (i) Cellular ozganisation = sponges; (i) Tissue organisation = coclenterates,
Animals in which blastopore of gastrula forms anus ¢g. echinoderms and chordates,
J. Animals in which blastopore forms mouth e.g arthropods, annelids, ete
1
2
3.
4 smo oa
5. Inradial symmetry, body can be divided info two similar halves by any plane passing through the centre; whilein bilateral
symmetry, body can be divided into two similar halves by only one plane along longitudinal axis of body
6, When extemal division of body by arasuli corresponds to intemal division of coelom by septa eg. in annelids,
7. Animals having false body cavity called pseudocoel eg. nematodes like Ascaris.
8. A pseudocoel with blood is called haemocoel e.g, arthropods and molluscs,
9.
0.
. (i) Insects = Trachea; (ii) Scorpion = Book lungs.
|. Diploblastic animals develop from primary gerin layers of gostrula (eg. sponges), while triploblastic animals are developed
from: primary germ layers (e.g flatworms to mammals),
111, In this, blood always flows in the blood vessels only e.g. all the verlebrates and most of annelids.
12. (i) Annelids = Nephridia: Gi) Insects = Malpighian tubules.
1B, Ladder - type nervous system.
114, When two sexes of a species are different in their morphology and physiology e.g. cockroach, Iusman beings, te
15. When an animal has both types of sex organs (e.g. testes and ovaries) eg. earthworm, and leech,
16. Animals which give bisth to youngones eg, sea snake.
17. These have variable body temperature which changes with change in environmental temperature e.g. fishes, amphibians
and reptiles.
18, When an advanced larva changes into a degenerate adult eg. Herdmania.
19. Also called winter sleep in which animal hides itself and becomes inactive in winter months. It protects the animals in
‘unfavourable conden,
20, Carlilages and bones.
Table 9. Classification of kingdom Animalia.
Kingdom Animalia is divided into 35 phyla (sing. Phylum) of which 11 are considered as major phyla and
rest are called minor phyla. About 95% per cent of animals are without backbone and are called invertebrates,
while the animals having a backbone, are called vertebrates.
‘On the basis of notochord, kingdom Animalia is divided into two sections :
Section I. Non-chordata Section IL. Chordata
(Notochord is absent) (Notochord is present at least
in some stages of development)
Non-chordata accounts for 95% of total animal species and is
divided into following phyla
Phylum Porifera (Sponges)
Phyikim Coelenterata (Cnidarians)
Phylum Ctenophora (Comb jellies)
Phyikim Platyhelminthes (Flatworms)
Phylum Aschelminthes (Roundworms)
Phylum Annelida (Segmented worms)
Phyl Arthropoda (Animals with jointed legs)
Phylum Mollusca Golt-bodied animals)
Phyium Echinodermata (Spiny-skinned animals)
Phylum Hemichordata (Half chowiates)
On the basis of fate of notochord, Chordata is divided into 3 sub-phyla
Sub-Phylum Urochordata Sub-Phylum Cephalochordata ‘Sub-Phylum or Division Vertebrata
(Notochord only in the (Notochord extends upto (Notochord replaced,
Tal of larval stage) the tip of head) by verlebral column)
On the basis of Jaws, Vertebrata is divided into 2 sub-divisions:
Lert
Agnathéstomata Gnathostomata
‘Jaws absent) (Jaws present)
Single class - Cyelostomata On the basis of locomotory
‘organs, itis divided into
2 super classes :
o-oo a P
Super-class Pisces Super-clast Tetrapoda
(Locomotion by fins) (Locomotion by four limbs)
'
Divided in 2 classes on the basis of skeleton Divided in 4 classes on the basis of skint:
1. Chondrichthyes - Cartilage fishes, 1. Amphibia - Skin is thin and moist
HL. Osteichthyes - Bony fishes. IL. Reptilia - Skin covered by epidermal scales
TIL, Aves - Skin covered by feathers
IV. Mamunalia - Skin covered by hair, OD
MODERN’S abe + OF BIOLOGY-KI
(© Radiata : Group including radial symmetrical animals eg. sponges, coelenterates and echinoderms,
(© Bilateria : Group inclusing bilaterally symmertical animalse. flatworms, roundworms, annelids, arthropods, molluscs
and vertebrates.
(© Pscudometamerism : New segments are formed from the nec (anterior side of body) by transverse fision culled strobilation.
It is found in tapeworms.
(© Bload anscular gystent is absent upto round worms. Armelids are frst anituals to have Blood ensclla system.
(© Sponges and coelenterntes have teater circulation, flat roorms are with parenchymal circslation, while nematodes have
pseudocoelomic circulation.
(© Blastocoel : Also called segmentation cavity: Cavity of Dlstuta,
NON-CHORDATA
PHYLUM PORIFERA
jores; pherwin = hearing) (The sponges)
Characters :
1 These are Pore-bearing animals and are commonly
called sponges. Pores are of two types: numerous and
smaller ostia and one or few larger oscula which act
as inlets and outlets of water currents,
2. These have cellular organisation and cell
aggregate plan, and are mostly asymmetrical.
3. These are diploblastic animals. The adult body
wall is formed of 2 layers : outer dermal layer oF
pinacoderm of flat pinacocytes (Fig, 6 A) and inner
xgastral layer or choanoderm of flagellated collar cells
or choanocytes (Fig. 6 B) whose flagella beat and
‘maintain a water current. Between two layers, there is
gelatinous and non-cellular mesoglea or mesenchyme
and has many types of amochocytes.
4. These are omnivorous and holozoic in nuttition
and digestion is intracellular.
5. Sponges lack mobility, sensory and nerve cells.
6. Respiration and excretion occur through general
body surface. These are ammonotelic
7. These are mostly marine but about 150 sponge
species inhabit fresh-water habitats e.g, Spongiia,
8. These have a peculiar canal system (of
interconnected canals) whose central cavity is called
paragastric cavity or spongocoel. A water current flows
through canal systemandihelps in nutrition, respiration,
excretion and reproduction,
9. These have an endoskeleton of either calcareous
spicules (needles made up of CaCO.) or silicious
spicules (needles macle up of silicic acid) or of spongin
fibres.
10. Asexual reproduction generally occurs by
fragmentation or external budding of gemmules
(Fig. 6C) (Internal buds)
‘IL These have very high power of regeneration.
12. Most of sponges are bisexual or hermaphrodite
ormonoecious. Fertilization is internal. Development is
indirect and includes a free-swimming amphiblastula
larva (half flagellated and half non-flagellated) or
parenchymula larva for dispersal.
(Ge pan
(© Archenteron : Cnoity of giatrule.
‘SPCULE
Fig, 6. Characteristics of Sponges.
‘There are about 5,000 living species of sponges.
CLASSIFICATION OF PORIFERA FOR
COMPETITIVE EXAMINATIONS
PPrifera is divided int three classes onthe basis of
ereetatei elect
‘A. Class Calcspongiae ot Calcarea(L cl = lime).
Endosieleton is formed of calcareous spicules (of CaCO.)
eg., Leucosolenia (simplest knovn sponge), Scypha (Sycon).
css Heats or Halen eno
Saeed
re eee Eee ee
basket) and Falonena (Glass-rope sponge)
C. Class Demospongiae (Ge. demos = fame; sponges =
sponge) Endoskeleton stormed of either spongin fibres or
other siliceous spicules (I r3yed) or both eg. Ensyongia
Gath sponge, Sponge (Fresh-water sponge) ANIMAL KINGDOM on
COSCULAR SEVE PLATE coscuta
PARIETAL GAPS
1. EUPLEGTELLA
ig, 7. Important Poviferans.
ames s 7): Sapa yon Sponita,Ching Characters :
(Dead man's finger sponge), Cliona (Boring or sulphut: 1. These have acentral cavity called coelenteron, also
sponge), Euplecclla (Venus flower basket), Euspeugit \ caied gentrovarcular cavity, tehich helps in digestion
(Bath sponge), etc. and circulation of food.
PHYLUM COELENTERATA, 2. These have tissue - organisation, blind-sac plan
(coel = cavity; enter = intestine; «fa = group) 4 are radially symmetrical.
or Cnidaria (Gr. knie = stinging cells).
© MEDUSA
Fig. 8, Important characters of Coelenterata. 3. These are diploblastic animals and body wall
{in adult coelenterates is formed of two layers—outer
epidermis and inner gastrodermis. Epidermis has
peculiar stinging cells called cnidoblasts or nematoblasts
(Fig. 8B) which inject hypnotoxin into prey to paralyse
it, Due to presence of cnidoblasts, it is also called
Cnidaria. Cnidoblasts help in anchorage, defence and
food capturing. Between epidermis and gastrodermis,
there is anon-cellular gelatinous layer, called mesoglea.
MODERN’S abe + OF BIOLOGY-KI
4. These are carnivorous and holozoic in nutrition.
Digestion is partly intercellular (in coelenteron) and
parily intracellular (in gastrodermal cells). Coelenteron,
has single opening mouth which helps in both ingestion
and egestion.
5. Respiration and Excretion occur through general
body surface, These are ammonotelic.
6. Coelom, These are acoelomates.
Fig,
ADANEIA (SHOWING PROTO. COOPERATION)
). portant coelenterates ANIMAL KINGDOM
7. Habitats, All are marine except Hydra.
8. A few coelenterates are solitary e.g. Hura, Jelly
fish and sea anemone, but most of coelenterates are
colonial. Members of colony are called zooids which are
basically of wo types :sessile, flower-like and nutritive
polyp and solitary, free swimming, saucershaped and
reproductive medusa (Fig. 8 C). Some coelenterates
show polymorphism e., Physalia, Valetla, Porpita, etc.
9. These have diffused nervous system.
10. Reproduction and Development. Coelenterates
show asexual reproduction by budding and sexual
reproduction by medusae, Development is generally
indirect (except Hydra) and includes planula larva
for dispersal. It shows alternation of generations
(Metagenesis) in which polyps produce medusae by
vegetative budding and medusae form the Obelia colony
and polyps by sexual reproduction.
There are about 11,000 species of coelenterates
CLASSIFICATION FOR COELENTERATA FOR
‘COMPETITIVE EXAMINATIONS
Phylum Coolenterata is divided into three classes on
the basis of development of zooids:
A-Class Hydrozoa (Ge. iydros = water; on = animal).
oth mevusa and polyp are well developed except Hydra
Animalsare radially symetsicale gyro, belia Sea fas}
Physalia Portuguese-man of wat), Valella (Sail-by-win).
BB, Class Scyphozoa (Gr. skyphos = cup). Media is
‘well developed but polypoid phase i reduced; symmnely’
is tetramerous radial eg. Aurelia (elly fish).
. Class Anthozoa or Actinozea (GH anihos
= flower). Polypoid phase is well developed
‘while medusa absent. Symmetry is hexamerons radial
8. Adlamsia (Sea anemone), Furgin (mushroom coral),
Astraes (Star coral), Penola (Sea pen), Gorgonia (Sea
fan), Mafreyorn (Stag horn coral)
Examples (Fig. 9) : Hira, Porpita, Vallela, Physaia
(Portuguese man-of-war), Aveta (elly fish), Adamsia
(Gea anemone), Perniatitla (Sea pen), Gorgonia (Sea fan),
‘Meanidrina (Brain coral), Tubipora ( Organ pipe coral), etc.
PHYLUM CTENOPHORA
(Gr. ktends-= conib; pherein = bearing)
Characters :
1. These are generally marine and planktonic
2. These are biradially symmetrical with an oral-
aboral axis
3. These are diploblastic animals but mesoglea is
with many amoebocytes and smooth muscle fibres and
is developed from mesoderm so is called mesoblast.
5. Locomotion is by ciliary movements of 8
vertically arranged comb plates (Fig. 10) or tenes, so
are cominonly called comb-jellies or sea walnuts.
4. These have tissue level of organisation.
6. Body appendages. These generally have one
pair of long, solid and retractile tentacles which have
special adhesive cells, called colloblasts or lasso cells,
but donot have cnidoblasts s0 is called Aenidaria,
7. These are acoelomates.
8, These have complete alimentary canal and
carnivorous. Digestion is partly intercellularand partly
intra-cellular. Anus is aboral,
9. Respiration and excretion occur through body
surface. These arc ammonotclic
10. Nervous system. It is of diffused type.
11, Bioluminescence (releasing light) is well marked.
12, Peculiar sense organ of ctenophores is
statoeyst which lies in a pitat the aboral pole and helps
in equilibrium.
138: Asexual reproduction is absent.
14, Sexual reproduction, These are bisexual
or hermaphrodite. Fertilization is external and
development includes a ciliated cydipid larva.
‘There are about 100 living species of Ctenophora.
Examples: Ctenoplana, Pleurobrachia (Fig, 10) (se0-
gooseberry), Beroe Velanum, Cestum (Venus's girdle),
and Hormiphora
(statocyst)
BME RIDIONAL.
sromacn
SHEATH
Pranic ‘reNTAGLE
PHARYNGEAL’
‘savas oom CRAY
Goue PLATES
Fig, 10. Pleurobrachia (eft) MoDERWS abe + 0F BoLOGY=A
ADDITIONAL USEFUL INFORMATIONS ABOUT PORIFERA, COELENTERATA
AND CTENOPHORA FOR COMPETITIVE EXAMINATIONS
A. PORIFERA (SPONGES) :
orifora is probably oldest animal group including the simplest multicellular aniveals
Sponges lack specialised digestive, neroous and circulatory systems.
Sponges are lowest metazoans and are placed in sub-tingsom Parazoa. Parazoology : Scientific study of sponges:
Fossil records show that sponges inhabited around 600 miltin years ago.
Sponges are master filters. Some of them can filter an amount of water about 100,000 times their size each day.
Dermal ostia of sponges are analogous to mouths, while osculunt is analogous to anus.
-Mesoglen of sponges is also called mesenchyme or mesophyl
© Amoebocytes found in the mesoglea of sponges:
% Chromocytes : Pigment cells, give colour tothe sponges
© Trophooytes : Digest te foo.
© Thesocytes : Store the fod as glycogen or fats.
Collencytes: Secrte collagen fibres,
= Myocytes : Contractile celts, form sphincters around the apertures like osculum, der ostin et.
= Phagocytes : Enguif excreta and damaged cells,
% Sclerocytes : Spicnle forming cells
© Archacocytes : Totipotent cll for regeneration and reproduction
© Gemmute : An internat bud of Spongilta (a fesh-amiter sponge). Its fronted of a wns of archaeocytes surrouruted by a coat of
niphidisk spices. It helps in perennation. These act.as spores of sponges ill Heir formation is called Gemmation. Gentmales
are ao found in some marine sponges eg. Ficulina, Tethya. etc.
In the cavity of Euplectelia, a pair of crustacean - Venusta spongicola lives tll det
Scypha (Sycom) : Shows cros fertitiation due to protogynous condition. Development includes amphiblastula larva,
Euplectella: Its dried skeleton is used os marriage gift in [apan as a symbol of “Union till death’.
Spongilla + It the only fresh-roater sponge. It reproduces asexually by gemmulation.
Hyalonema (Glass rope sponge) : Its fied in the mud by a root tu of twisted spicules.
Cliona (Boring or Sulphur sponge): Its larea bores through andl daniges the skeleton of corals and shells of mollusks. I is
harmful to pear industry.
Chalina (Dead man’s finger sponge) : Sponge is branched and branches give the appearance of «hand with many fingers
Proterospongia : With both amoeboid and colar eels so ac's as a connecting Fink betzeen Protozoa and Porifera.
Hippospongia is a horse sponge, whole Falichoniri ts called crumb of bread sponge.
Phyllospongia is leaf sponge, while Pheronema is clied bowl sponge.
LLaffa sponge: It is nota sponge but ts dried and fibrous skeleton of gourd
Euspongia (Bath sponges): Its skeleton is formed of only spongin fibres. Its dred skeleton is sed for bathing, wwshing, et.
Leucosolenia : Sinplest sponge with asconoid type canal system and has parenchyrsula and stereogastrula (solid gastrula)
Taro stages,
Oscarella is the sponge with no skeleton.
Asconoid canal system is found in Leucasolenia, Syconoid C.S. i fond in Sycon and Grantia while Leuconoid C. 8. is
{ound in Euspongia, Spongilla, etc
© Laroal form of members of class:Demospongite is rhagon larva,
B. COELENTERATA :
CCoelenterates are simplest, invertebrate himals with simple living tissues,
CCovlenteraes are commorly called enidarians due to presence of cuaoblasts, so study of coelentrates is called enidology.
Trambly (1744): First to report regeneration in Fiydra
CCeolenterates cannot digest starch as have no amylase enzyme.
In ccelenterates, interstitial cells act as totipotent cells
Nerve cells appeared first of alin coclenterates and are non polarized,
Germ cells are ectodermal in origin in Hyarozoans, while are endodermal in origin in Scyphocoans and Anthacoans.
Stimulus for discharge of cnidoblasts is partly mechanical (ie. weight or touch of the prey) and parity cemical (presence of
‘glutathione in te prey).
Metagenesis : Alternation betzocen asexual and sexual generations in coclenterats, both bing diploid
Statocyst (a sense orga for balance) is develope for first time in Cnidaria
Eee to Cmte a ie i eee ere
© HL oligactis is brown coloured (due to symbiotic brown alga Zooxanthellae in gastrodermal cells), while
H.viridissima is green coloured (due to symbiotic green alga Zoochlorella in gastrodernal cells). H. vulgaris is pale in colour.
© Obelia (Fig. 9B): Seafur, a marine sedentary and trimorphic colonial coelenterate. It has 3 types of zooids: nutritive an flower-
like polyp enclosed in a hydrotheca; long and cylinrical routhless blastostyle enclosed in a gonotheca; avd umibreliacike
‘medusa with gonads and developed as « bud on tie blastostye. I is commonly called coophyte due to its plant like appearance.
© Physatia isa polymorphic covlenterate and bears dactylozooids (for defence), gastrozooids (for food capturing), gonozooids
(bear metusae) and gonophores (bear gonais). It shows proto-cooperation with Nomeus fish. It is commonly calle Portuguese-
‘man-of war due to is suiden appearance, It secretes neurotoxin in sea ioater so is nuisance tothe bathers ANIMAL KINGDOM Zn
(© Aurelia (Jelly fish or Moon jelly) inoolves internal and crss-fertilization. Lifecycle inootoes the formation of Plamula lar,
Scyphistoma iarca (a reduced polyp) and Ephiyra larva which undergoes meinmorphosis,
© Adanisia (Sea anemone) shows proto-cooperation with Eupagurus (Hernit-crab-a crustacean)
© Conall rubrum : Aiso called red coral (moonga) and is used in jewellery; while Meandrina is commonly called brain
coral as has conzotutions ike human brain,
© Aleyonium : Commonly called Dead man's finger coral or soft coral as zooids are entbuded in a gelatinous mesoglea called
‘covnenchyme,
© Corgonia is commonly called sea fan or horny coral (as sivleton is formed of horny gorgonin protein).
Millipore is called stinging coral, and Madrepora or Acropora is commonly called stag-horn coval.
© Corals are skeleton secreting anthozoans, zhile sea-anemones are anthozoans ith no skeleton.
© Corallite is indiitual calcareous skeleton of a coral coelenterate wile coenosteum is colonial calcareots skeleton formed by
{fusion of coralites.
© Cora reefs +A coral reef isa rilge in the sen and is formed of skeletons ofthe coclenterates eal! corals: I 8 manly formed
of skeletons of stony corals lke Madrepora but is inypregnaed by skeletons of Millipora and Tubipora. eis mainly formed of
calcium carbonate. Coral reef form stable marine ecosystems. These are of 3 types (by Hyman, 1940)
Fringing reefs, These extend front the shore upto a distance of 400 metres into the ae,
‘© Barrier reefs These run parallel to the shore lut are separated from shore by a water boty elled lagoon. Largest barrier reef
fs Great Barrier Reef i the nori-east coast of Australia and is 1920 km lone.
© Atoll, It is circular coral ref surrounding a quiet water body called lagoon. Its also called coval island.
In India, Lakshadweep islands are formed of coral islands. Fiji and Matoe islands are also coral islands
‘These are mainly four in warm (70°F) and shallow waters of tropical sens: The pacific porte-eastof Australia scaled coral sea.
©. CTENOPHORA
© Phylum Ctenophorn is algo called Acnidaria as these lack enidoblast.
-Mesogien of ctenophores is of collenchymal nature (oth may ceils
© Differences between Coelenterates and Ctenophores
© Coelenterates are more diversified in terms of runtber of species,
44948
PHYLUM PLATYHELMINTHES:
(Ge. platys = flat; hetmins = worms) (FLAT WORMS),
Characters:
L Bodyiseitherleaf-likeorribborlike dorsoventrally
flat. It lacks true segments. These are soft-bodied
2. These are first animals to have organ-level
organisation and bilateral symmetry. These have blind
sae body plan.
3. These are triploblastic and acoelomate animals,
4. Spaces between the body organs are filled with
a mesodermal connective tissue, called parenchyma.
5. Habitat. These are mostly parasitie but some are
sree living (e.g. planarians). Parasitic forms have hooks
find suckers for adhesion on their host
6. Excretion and osmoregulation occur by peculiar
cellscalled flame cellsor protonephridia or solenocytes
(Fig. 11 A). These are amntonotelic.
7. Gut. These have incomplete alimentary canal.
It is absent in tape worms
8. Nervous system. It is ladder-tike (Pig, 118)
9. These are first animals to show cephalization.
10, Reproduction. These are mostly hermaphrodite,
Fertilization is internal and may be self or cross-
fertilization. Development includes larval stages so is
indirect. Turbellarians undergo asexual reproduction
by transverse fission.
‘1. Planarians have very high power of morpholactic
regeneration.
oelenterates are mestly marine, rote clenophores are exclusively marine.
Covlenterates ae radially symmetrical while ctenophores are Viradially symmetrical.
Cudoblasts present only in the coetenterates, while etenephones lee colloblasts to capture pre.
Digestive tract i complete in ctenophores but is incomplete sn the coelenterates.
Comb plates present in only ctenophores but are absent font the coelenterates,
‘There are about 25,000 species of flatworms.
CLASSIFICATION OF PLATYHELMINTHES FOR
COMPETITIVE EXAMINATIONS
It is divided in three classes on the basis of body
shape, mouth position and habitat.
‘A, Class Turbellaria (L. turbella = stirring). @) Body
is leafilike and unsegmented. (i) Mouth is present on
ventral side of middle of body and pharynx is protrusibe.
(Gi) These are free-living. (iv) Body is externally covered
bby a ciliated epidermis but there is no cuticle
‘These are commonly called planarians eg. Planari,
Dugesia,
'B.Class Trematoda (Gr. tema, = hole; fdas = form).()
Body is leat-like and unsegmented. (i) Mouth is present
fon anterior end of body. (i) These are either ecto- oF
cendoparasites. (iv) Body is externally covered with living,
tegument produced info spinnules.
‘These are commonly called flukes e, Fasciola (Sheep
liver-fluke), Schistosoma (blood flake), et.
Class Cestoda (Gr, estos = gindle; eis = form).
6) Body is ribbon-like and divided into segments called
pproglottids. (i) Mouth and alimentation absent so absorb
the nutrients through their body surface. (il) These are
only endoparasites. (iv) Body is externally covered with
a living tegument but with no spines.
‘These are commonly called tapeworms eg. Taenia
solu (Pork tapeworm) and T. saginaia (Beef tapeworm). Parasitic adaptations in Flukes and Tapeworms:
1. Absence of epidermis and presence of tough and
resistant horny cuticle on the body wall
2, The sense organs like eye-spots are either
reduced or absent.
3. These have some adhesive structures like suckers
or hooks or both or other structures.
4.One or more intermediate hostsin thellfe history
to reduce their period of exposure.
5. Absence of organs of locomotion.
6. Alimentation absent in tapeworms.
Examples (Fig. 12) : Teemtia (Tapeworm), Fasciola
(Liver fluke), Echinococcus (Dog tapeworm) and Planaria.
MODERN’S abe + OF BIOLOGY-KI
Fig. 11. Important characters of Platyhelminthes,
‘Table 10. Differences between Planarians, Flukes anid TapéWorms.
Characters Pianaviane Fakes Tapeworine
1. Body form Teablike and unsegmented. | Teablike and vmegmented, | Ribbon like and segmented.
2. Position of mouth | On middle of ventral side of | Onventral sideof anteriorend | Absent.
body. of body,
3. Mode of living Free-living. Ectopartsitic or endoparasitc. | Always endoparasitic,
4. Body covering (Giiated epidermis, spiny cuticle Non-spiny cuticle.
5. Examples Planaria, Dugesia, etc. Fasciola, Schistosoma, etc. Tuenia, Hymenotepis, ee.
munis
‘A DUGESIA
1. FASCIOUA HEPATICA
Fig, 12. Important Flatworms ANIMAL KINGDOM
© Term platyhelminthes was given by Gegenbaur (1859)
© Around 80 per cent ofthe flatworms are parasitic in nature.
(© Alimentation i altogether absent fre any stage of the tapeworms.
© Turbellarians (Planarians) :
© Dugesia is with a triangular ead with too auricles, ule Planaria is with a truncated head.
= Like Hydra, Planar also has morpholactic regeneration,
= Bipalium : Only terrestrial planarian.
= Morpholactic regeneration : One part of body can form the whole body
© Trematodes (Flukes):
= Fasciola
Sheep liver fluke-an endoparasit of ile duct of sheep. Its ife cycle is digeitie(sheep an sna), complex
‘and shows poly-embryomy (a number of aro stages like mracidiu,sporacyst, redia,ceearia and metacercaria are formed).
Its heawy inf
ian causes liver rot disease in sheep.
Schistosoma (Blood-fluke).Itis the onty unisexuat flue found in the veins of mah. Female & presenti the onchosphere
ioral canal (a groove on ventral side) of male, It causes schistosomiasis Ctracierie by intestinal disorders. [tis
‘also called Bitharsia.
‘= Opisthorchis sinensis + Chinese lier fluke of man. = | Paragomimus + Lime fluke of man.
= Monogenetie flukes : With monogenetic ife cycle eg. Diplozoan (ectoparasite of gills of fishes), Gyrodactylus,
© Digenetic flukes : With two hosts i life cycle eg. Fasciola, Schistosoma, etc.
= Prohaptor : Anterior sucker of flukes.
© Cestodes (Tapeworms) :
‘= Opisthaptor: Posterior sicker of flukes.
© Taenia solium (Pork Taperoorm); tis digenetie( an and pig) and hermaphrodic apetoorm. Development includes onchosphere
Ihexacanth and cysticercus larae. Worm causes taeniasis disease zhilelaraae cause cysticercosis disease.
‘* Taenia saginata (Beef-tapeworm). I s found in small intestine of mart. Secondary host és cow. Human infection is by
taking undercooked mensly bee. Is scolex is without hooks and rostellum while strobila is formed of about 2,000 progiotids.
© Apolys
Loss of grav prog fram posterior end of ay
© Strobilation : Formation of new progiottids from neck, cls euled pseadometamerism.
© Diphyllobothrium : Largest tepeworm (18 mt.)
(© Hymemolepis : Duar} tapeworm (2-4.5 cm). tis monogenete tapeworm of man
© Cehinococcus i also called dog tape worm.
World population suffers more from Taeniasaginat' thay. sliuet due to more beef eters
PHYLUM NEMATHELMINTHES OR
‘ASCHELMINTHES,
(Ge. nema = thread; heinins = worms)
(Thread or roundworms)
Character
1. Body form. These are commonly called
roundworms or threadworms or bagworms (iskos =
bag) because the body is long, cylindrical, vermiform,
unsegmented, thread-like with no lateral appendages.
So their cross section is always circular.
2. These have organ-system organization and
bilateral symmetry.
3. These are triploblastic animals (Mesoderm is
present as scattered pouches between ectoderm and
endoderm)
4. These are either free-living or parasitic. Free
living round worms are extremely abundant in soils,
5. These are pseudocoelomates.
6. These are first animals to have straight and
complete alimentary canal. Pharynx is muscular and
{ri-adiate. Intestine is non-muscular. So these have
tube-within-a-tube plan.
7. Exeretion. Excretory system is H-shaped and
intracellular called Rennett cell. These are ammonotelic.
8. Body wall is formed of outer nowliving cuticle
of keratin (a scleroprotein), syncitial (multinucleate)
epidermis and only longitudinal muscle fibres. Circular
muscles are absent.
9. Number of cellsis fixed in every system ofbody
(Eutyly). These show auxetic growth.
10. Nervous system. It is formed of a
circumpharyngeal nerve ring giving rise to anterior as
‘well as posterior nerves interconnected by connectives.
So it is of ladder type.
‘Table 11. Differences between Flatworms and Round worms.
Characters Flatworms Round worms
1. Body form Dorsoventrally fattened, Long and cylindrical
2. Body cavity Acoolomates. Paexidacoelomates,
3. Alimentary canal | Absent or incomplete Complete.
4. Excretory structures | Flame cell, Rennet coll
5. Epidermis [Non-syncitial and unilaminar or absent ‘Symctial epidermis,
6. Sexes Generally bisexual. Always unisextal
7. Examples Planaria, Foscola, Tenia, et. “Ascaris, Wuchereria, Ancylostoma, ee Pa
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MODERN’S abe + OF BIOLOGY-KI
‘© Sponges are considered as most primitive multicelhilar animals.
a Er is ascon type (eg., Leucosolenia) or sycon type (eg, Scypha) or leucon type (eg,
© Farenciyma of flatworms acs as hydraulic skeleton and circulation,
© Ascaris is an endoparasitic nematode of children. It shows sexual dimorphism. Life cycle is
monogenetic. Its heavy infection causes ascariasis, Male Ascaris is smaller in size, has curved
posterior end, cloacal aperture (amus in female) and two spicules.
© Male Ascaris is monorchie (with single set of male reproductive system).
© Female Ascaris is didelphic (with double set of female reproductive system).
© Ancyostoma (commonly called hook worm)is endoparasite of duodenum of small intestine of man,
‘Male has a copulatory bursa at its posterior end while female has a caudal spine at posterior end.
© Amphids are olfactory chemoreceptors of nematodes, while phasmids are glandulosecretory
structures of nematodes.
© Recently discovered new phylim is Loreifera.
11, Sexes are unisexual or divecious and always microfilariae iat Wuchereriuy; mhabdiuiform larva i
show sexual-dimorphism. Male is smaller in size, has Ascaris and Enferobius.
penial spicules, and cloacal aperture (anus in female)
Fertilisation is intemal, Most of nematodes show indirect
development e.
It includes about 15,000 living species out of which,
about 50 species are parasites of man.
Examples (Fig. 13): Ascaris, Wuchereri Filarial worm),
filariform larva in Ancylostoma; —_Ancylosioni (Hook worm), Enierobis (Pin worm), etc.
(GENITAL APERTURE
Fig. 13. Important Nematodes.
[Ml PRACTICE PROBLEMS—PORIFERA TO ASCHELMINTHES
21, What are choanocytes? Give their function.
22. Why are sponges and coelenterates called diploblastic animals?
23, Name two types of pores on the body of sponges. Give their function. sms
24, Name a fresh water sponge and a coclenterate,
25. On which basis, the phylum Porifera is classified?
26, Why is Euplecteta called venus-flovier basket?
27. What are gemunles?
28, Name the sponge having only spongin fibres as its endoskeleton.
29. Why is coelenteron called gastrovascular cavity?
30, What are cnidoblasts? Give their function.
31. Define polymorphism. Name one coclenterate showing polymorphism.
‘Name tivo basic types of zooicls of coelenterates. Give tis function,
[Name three classes of phylum Coelenterata
Why is Plysalia called Portuguese-man of waz?
What aze coral reefs? Which sea i called coral sea?
Give two peculiar characters of phylum Platyhelminthes,
17. Which types of animals are grouped in class Trematoda and Cestoda?
‘Why are Fasciola and Taenia called digenetic animals?
). Name ree parts of body of Toes. List their function
). What is apolysis? Give its significance,
. List two peculiar characters of phylum Aschelminthes,
._ Give the habitat of Ascaris. List two differences between male anél female Asears
5. Give the scientific name of filarial worm, How is it spread from mati te man?
ANSWERS TO PRACTICE PROBLEMS |
RaEES
BeEBEE
21. Choanocytes are collar cells of sponges. Their flagella beat and maintain a water current.
Inboth ofthese groups of animals, body is developed from two primary germ layers.
(0 Ostia are inlets of water current and (i) Osculm ads as outlet of water current.
Sponge = Spongils; i) Coelenterate = Hydra
(On the basis oftheir endoskeletal elements.
Its dried skeleton is sed asa marriage gift in Japan andi symbol of “Union til death”.
7. Gemmules are internal buds of Spogila. These help in perennation and multiplication,
. Enspongia (Bath sponge)
9. Ibis cavity in which both digestion and citealation occur.
Also called stinging cells These paralyze the prey as these inject a poisonous chemical called hypnotoxin.
1. Polymorphism is presence of man types of zoids (individuals in a colonial coslenteate e.g Phyl
. (i) Polyp or Hydrant ~Nutsition i) Medusa = Reproduction as has gonads.
Hydrozoa, Seyphozo8 and Anthozoa
‘Due to its sudden appearance and disappearance like navy ships of Portugal
5. A coral zeef is sound in the sea and is formed by stelotons of ceztain coral coelenterates, The pacific nortlveast of
‘Australia is called coral sea.
36, First animals fo be triploblastie and organ-system organisation. Body is fat.
37. (i) Tremaloda inclutles flukes. i) Cestoda includes tapeworms.
38, These complete their life cycle in two hosts.
39, ()Scolex= Adhesion to intestine; lly Neck = Adding now segments; il) Strobila with 630-1000 proglottids with reproductive
organs,
40, Shedding of ripe proglottids from the end of body is apolysis, These are eaten by pig which acts as intermediate host,
41. (i) Fist animals with complete gut (i) Pseudocoelomates (ii) Fixed number of cells,
42, Found in intestine of children, Male is with curved posterior end and is smaller, while female is straight and longer.
43, Wuchereriabancrofi. Its spread by Culer mosquitoes
RREBR
2eeRs
BEER MODERN’S abe + OF BIOLOGY-KI
(© Most of nematodes are parasitic. Oy few of them are free-ling.
© Nene is called monorchic cohen with one se of male reproductive system, wile i called diorchic cohen with to sels of
anal reproductive system.
© Nenutaie is monodeiphic wien with one set of female repructve syste, while is didelphic wen with two set of female
reproductive systems.
(© Wiuchereria bancroft (Flarial-worn), An endoparasitic, digenetic nematode of lynph vessels of man (primary hast) aud
satoary gland of Culex mosquito (Secondary tos). causes filariasis (also caledelephastiasis-swotlen Fegs) in mar defo
biockage of lymph veel of legs. is youngs are called mcroflariae which show nocturnal periodicity.
(© Enterobius (Oxyurs) ~ Pinworm. An endoparaste of lege intestine of man. It is monogenetie: It causes enterobiasis
characterize by seplesness, digestive al mental disorders, abdominal pain ete.
{© Trichinella(Trichina worm). An intestinal endoparasitc worm of man. Reservoir hase pigs dogs, cos ec. Larae become
spirally coiled in the voluntary muscles. I causes trihinosis characterized ly nausea, msc pat, te.
(© Dracunculus (Guinea worm). An endoparasitic worm of subcutanens tissue of mar. I is digenetic and its econdary hosts
Cyclops. It muses guinea-tvorm disease 18 earliest oto nematade and tots earlier called. "Fiery Serpent”.
(©: Trichurus (whip worm): Monogeneticenioparast ofcaecu au colon of eid, I ousestricuriasis which is characterised
by abdominal pain, dysentry and anaemtia
Ascaris (Additional informations) :
Juana intestine.
(© Rhabditis and Meloidogyne : Soil vematoves,
Phasmids : Two in mumber and are chemoreceptor unicellular lah,
Amphids : Tao in number (one on each ventrolateral lip) and aregustat@ry.
Infectce stage is encapsulated second juvenile, called thabditiform area.
Life cycle of Ascaris invotoes four moults: first in the open; secon and thin! moult in lung alveoti, and fourth moult ia
(© Loa loa (Eye worm) Asults sometimes pass across the eye bill Its vector is Tebanus fly.
PHYLUM ANNELIDA.
(L. amnelus = ring; eidos = form) (Segmented worms)
Characters
1. Habitat. These are aquatic or terrestrial, free
living or parasitic animals.
2. Body is externally divided into segments called
‘metameres or somites by ring-like groovescalled annuli,
so called ringworms or segmented worms.
3. These have organ-system organization and
bilateral symmetry.
4. These are triploblastic animals and first true-
coelomate (schizocoelie in origin) animals. Coelom is
with a watery coelomic fluid which acts as hydraulic
skeleton and helps in locomotion.
5. Body wall. It is formed of cuticle, single-layered
epidermis and only smooth muscle fibres (both circular
and longitudinal). Cuticle is never moulted,
6. These show metameric segmentation.
7. Alimentary canal is straight and complete so
these have tube-within-a-tube body plan, Digestion is
entirely extracellular.
8. Excretion and osmoregulation occur by
segmentally arranged and metamerically disposed
ectodermal coiled organs, nephric
9. Nervous system is formed of circum-pharyngeal
nerve ringand asolid, double, ventral and ganglionated
nerve cord.
10. These are the first animals to have generally
closed circulatory system, Colour of blood is red due
to the presence of erythrocruorin in plasma. In leeches,
there is no true blood vascular system.
11. These generally show cutaneous or skin
respiration ¢g., earthworm, Some have branchial (gill)
respiration (e.g. Amphitrite).
12, Organs of locomotion are setae ¢g. earthworm,
or unjointed segmental appendages called parapodia
(eg. Nereis) or suckers (eg. Leecl). This forms the basis
of classification of Annelida,
1, Sexes may be unisexual (e.g,, Nereis) or bisexual
(eg, Earthworm, Leech). Fertilization is generally cross
and may be external (¢., Nereis) or internal (eg., Leech)
Development is direct in hermaphroditic annelids
(arthnworm, Leech) or indirect in unisexual annelids
(Nereis) and includesa free-swimuning trochophore larva.
Phylum Annelida includes about 17,000 living,
spe
Examples (Fig. 14) : Pheretima (earthworm), Tubifex,
Nereis, Aphrodite (sea mouse), Chaetopierus (paddle
‘wormn), Hirudinaria (leech), et. ANIMAL KINGDOM
Annelida is divided into three classes on the basis of organs of locomotion:
‘CLASSIFICATION OF ANNELIDA FOR COMPETITIVE EXAMINATIONS
Characters | A. Class Oligochaeta |B, Class Polychaeta Class Hirudinea
(Gr. oligo = few, (Gr. poly = many; (tru = leech)
ctueta = baie) uta = ait)
1. Organs of || A few setae per ‘Many setae on parapodia, one | Suckers,
Tocometion | segment. pair per sepment
2 Clitellum Permanent citelium ‘Absent Citta developed in
‘present. Breeding season only.
3. Sexes Hermaphrodite. Unisex “Hermaphtodite.
4. Development | Direct. Indizect with trochophore lava, | Direct
5. Examples Pheretima posthume, | Nereis (Sand worm), Ewnise, | Hirudinaria (Leech),
Luombricus, Tubifec etc. | _ Apatite, ete. ieee
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