FOR KS3 STUDENTS DOING BOTH CAMBRIDGE AND IB

1. SENIOR ONE
BIOLOGY
CLASSIFICATION OF LIVING THINGS
2021

2. Characteristics of living
organisms
CBC learning 2021
Unit 1
Characteristics and Classification of Living Organisms

3. Learning Outcomes
Characteristics
• To be able to list and describe the characteristics of living organisms
• To define the terms
• Nutrition
• Excretion
• Respiration
• Sensitivity
• Reproduction
• Growth
• movement

4. Learning Outcomes
Classification
• To be able to define and describe the binomial system of naming species
• To be able to classify the five main classes of vertebrates
• To be able to list the main features used in the classification of flowering
plants, arthropods, annelids, nematodes and molluscs
• To be able to list the main features used in the classification of viruses,
bacteria and fungi, and their adaptation to the environment.

5. Biology
• Biology is the study of living organisms
• How do we decide if something is living or non living?

6. Introduction to Living Things

7. What is Life?

8. Aliens land on Earth and watch things carefully to tell whether
they are alive or not. Would an alien think this car is alive?

9. Characteristics of Living Things

10. Life Processes
• If something is alive it will carry out all of the seven life processes.
1. Movement
2. Respiration
3. Sensitivity
4. Growth
5. Reproduction
6. Excretion
7. Nutrition

11. Characteristics of Living Things
• M is for movement
• Animals move to find food, shelter or a mate.
• Plants do not move in the same way as animals but move towards sunlight.
• Some plants show movements when touched

12. Characteristics of Living Things
• R is for reproduction
• Animals lay eggs or have babies.
• Seeds from plants grow into new plants.
• Some plants do not reproduce by using seeds

13. Characteristics of Living Things
• S is for sensitivity.
• Animals find their way using their sense organs such as the eyes or skin.
• Plants don’t have sense organs but do respond to gravity and light.

14. Characteristics of Living Things
• G is for growth
• Growth is an increase in size
• Animals stop growing when they reach adult size.
• Plants grow throughout their lives.

15. Characteristics of Living Things
• R is for respiration
• Respiration is the release of energy from food.
• This usually needs oxygen.

16. Characteristics of Living Things
• E is for excretion
• All living things produce waste.
• The removal of this waste is called excretion.
• Animals excrete through their lungs, kidneys and skin.
• Plants shed their leaves in autumn

17. Characteristics of Living Things
• N is for nutrition
• All living things need food for energy, growth and repair.
• Animals have to find their own food and eat plants and other animals.
• Plants make their own food by the process of photosynthesis.

18. ORIGIN OF CLASSIFICATION
• HOW DID THE ACT OF CLASSIFICATION COME TO BE
KNOWN?
• WHY IS IT NECESSARY FOR US TO CLASSIFY LIVING
THINGS?

19. WHAT IS CLASSIFICATION?
• Classification is the process of placing animals and plants into
groups according to their similarities in structure, and behavioral.
• It involves collecting organisms, observing their structural
characteristics and sorting them into groups known as taxa.
• The branch of biology concerned with classification is called
taxonomy

20. WHY CLASSIFY?
• Classification is necessary because of the following reasons;
1. It helps in sorting organisms for easy reference.
2. It is important in recognizing the differences and similarities
between living things
3. It simplifies the study of organisms.
4. It helps in naming of organisms. These names can then be used
internationally.
5. Helps us to communicate information about organisms
internationally.

21. Early System of Classification
• Taxonomy is the branch of biology that
names and groups organisms according to
their characteristics and evolutionary
history.
• Organisms were first classified more than
2,000 years ago by the Greek philosopher
Aristotle.

22. Early System of Classification
• Organism’s were grouped into land dwellers, water dwellers, and air
dwellers.
• Plants were placed into three categories based on the differences in
their stems.
• As new organism’s were discovered, his system became inadequate.
• Categories were not specific enough.
• Common names did not describe a species accurately.
• Names were long and hard to remember.

23. Modern System: Hierarchy
Seven Levels of Organization
• Carolus Linnaeus (mid-1700’)s was a Swedish
biologist who established a simple system
for classifying and naming organisms.
• He developed a Hierarchy (a ranking system)
for classifying organisms that is the Basis for
Modern Taxonomy.
• For this reason, he is considered to be
“father” of modern taxonomy.

24. Modern System a Nested Hierarchy-Seven
Levels of Organization
• Linnaeus used an organisms morphology (form and structure), to
categorize it.
• His system is still being used today.
• His system allowed organisms to be grouped with similar
organisms.
• He first divided all organisms into two Kingdoms, Plantae (Plants)
AND Animalia (animals).
• This was the same as Aristotle’s main categories.

25. The Seven Levels of Organization
• Modern System:
• Each kingdom (plant and animal) was divided into a phylum* (division for plants)
• Each phylum into a smaller groups called class.
• Each class was divided into an order.
• Each order was divided into family (families).
• Each family was divided into a genus (plural-genera)
• Each genus was divided into a species. (scientific name)
*Note: Phyla and family were not in Linnaeus’s classification system but were added by
modern scientists.

26. Levels of organization
KINGDOM
PHYLUM
CLASS
ORDER
FAMILY
GENUS
SPECIES

27. Seven Levels of Organization
• Modern System: What does it contain?
• Each kingdom (plant and animal) was divided into a phylum* (division for
plants)
• Each phylum into a smaller groups called class.
• Each class was divided into an order.
• Each order was divided into family (families).
• Each family was divided into a genus (plural-genera)
• Each genus was divided into a species. (scientific name)

28. Levels of Classification
• Remember: King Philip Came Over For Grandma’s Soup.
Kingdom
Phylum
Class
Order
Family
Genus
Species
Others include: Tribes. Forms, varieties

29. The naming of living things.
• All known living things have scientific names so that they can easily
be identified.
• This involves assigning two names to each organism, a system that
was developed by Linnaeus in 1735.
• The rules followed when naming organisms are as follows;
1. The first name is the name of the genus to is written beginning with a
capital letter.
2. The second name is the name of the species is written beginning with a
small letter.
3. The two names are separately underlined if hand written and should be in
italics if printed or typewritten as in textbooks

30. Binomial system of naming living things:
• Binomial nomenclature is the system of giving a scientific name to an organism.
• The word binomial comes from two words bi- meaning two and nomial meaning
name.
• The first accepted classification and nomenclature was introduced by a Swedish
scientist called Carl Linnaeus (1707 - 1778).
• Examples
• Human – scientific name is Homo sapiens.
• Maize – scientific name is Zea mays.

31. Keys and identification
• Keys are used to identify different species.
• A key will usually ask questions based on easily identifiable features of an
organism.
• Dichotomous keys use questions to which there are only two answers.
• They can be presented as a table of questions, or as a branching tree of
questions.
•

32. Branching tree example
• This tree could help you identify a new vertebrate.
• For example, if it had no fur or feathers and dry skin, you would
follow the right-hand pathway at the first and second junctions, but
the left-hand pathway at the third junction.
• This would lead you to identify the animal as a reptile.

34. The five kingdom classification
• In 1982, a system of classification was devised which placed
organisms into five kingdoms.
• Earlier before, the bacteria and fungi were placed in
kingdoms of plants and Kingdom of animals.
• But the new system placed fungi and bacteria into separate
kingdoms.

35. The five kingdoms
• Monera
• Very small and single-celled, no nucleus
• Protoctists
• Single celled, with a nucleus
• Fungi
• Cell walls contain chitin, with a nucleus
• Plants
• Multicellular organisms
• Can make food through photosynthesis
• Animals
• Multicellular
• Have to obtain food

36. Kingdom Monera
• What are the characteristics of livings in kingdom
Monera?
Are microscopic living things
Body made up of a single/one cell
Do not have a nucleus and other organelles with
membranes
Divided into two:
1. Bacteria
2. Blue green algae/cyanobacteria

37. 1. Bacteria
• Small/microscopic
• Cell wall, cell membrane and cytoplasm
• No nucleus, DNA is a single coil
• Some have a slime capsule
• Some have flagella (for movement)

39. How does bacteria carry out life processes?
1. Movement:- some have a flagellum for movement
2. Reproduction:- asexually by fission/binary fission- divides into two after every 20 minutes
3. Sensitivity:- lacks special structures but uses its cell wall to sense food and other chemicals
like drugs
4. Growth: the cells can grow in size, before dividing
5. Respiration: Aerobic and anaerobic
6. Excretion:- no special structures, but occur via the cell surface
7.Nutrition:- Saprophytic, Parasitic or symbiotic

40. Classifying bacteria: How do we group bacteria?
• Grouped into many groups, depending on the shapes of the cells they have:
Group Description Example
Cocci/coccus Have round /spherical cells Staphylococcus aureus, Streptococcus
pneumonae, diplococcus
Bacilli/bacillus Have rod-shaped cells Clostridium tetani,-causes tetanus
and bacillus anthracis- causes
anthrax
spirilla Are spiral shaped. Have helical rod appearance with
single nucleus
Treponema which causes syphilis
(Kabotongo)
Comma-shaped Have comma-shaped cells Vibrio cholerae

41. Classification of bacteria ………………cont`d

42. Grouping bacteria according to shape of cells

43. Diseases caused by some bacteria
1. Diphtheria
2. Whooping cough
3. Cholera
4. Tuberculosis
5. Food poisoning
6. Typhoid

44. 2. Blue-green algae
• Has a pigment/coloured substance
• Caries out photosynthesis
• When in huge numbers, we can be able to see them

45. Where does blue green algae live/grow?
• Seas
• Oceans
• Lakes
• Wet sides of rocks along the water bodies

46. Roles of bacteria in life/economic roles of
bacteria
• What value/ role does bacteria do in life?

47. Economic roles of bacteria
• Bacteria cause decay of dead plants and animals to form nutrients
• Fixing nitrogen in the soil into nitrates in the soils.
• Bacteria manufacture vitamin B12 and K.
• Used in curing tea and tobacco, making silage /retting flax.
• Bacteria destroys harmful organisms in sewage in the sewage treatment.
• Used in industrial processing of food like vinegar, cheese, and yoghurt.
• Symbiotic bacteria in some animals e.g cows help in digesting cellulose
• Bacteria cause decay and food spoilage.
• Denitrifying bacteria converts nitrates into free nitrogen in the soil hence reducing soil fertility
• Making vaccines
• For research purposes

48. Why is bacteria sometimes bad? Disadvantages--- with examples
• Cause diseases like cholera
• They cause spoilage of food
• They cause rotting of fruits
• Destroy crops
• Damage metal pipes by producing acids
• Cause animal diseases
• Cause plant diseases e.g the banana bacterial wilt disease

49. Kingdom Protoctista / Protista
• They are unicellular organisms/ single celled organisms.
• They have a true nucleus with a nuclear membrane.
• They have double membrane organelles.
• Some members MOVE freely using either:
1. Pseudopodia (False Legs) In Amoeba,
2. Cilia In Paramecium Or
3. Flagella In Euglena And Trypanosomes.
• Nutrition differs e.g
1. Autotrophic e.g Photosynthesis:- euglena and Chlamydomonas
2. Heterotrophic like:- amoeba and paramecium and simple absorption of
digested food by trypanosomes.
• They live mostly in water or watery environments like wet lands.

50. Groups of protists
• Three Main groups of protists;
•Protozoans
•Algae
•Fungus-like

51. Watch this !!!!!!!!

52. Protozoans: animal-like protists
 Grouped by movement
• Amoeboid protozoans:- pseudopods
• Ciliated protozoans:- ciliates
• Flagellated protozoans:- flagellates
• Sporozoid protozoans/parasites- no movement

53. Watch again!!!

54. Protozoan Characteristics
• No cell wall on their cells
• May live freely or in bodies of
other animals as parasites
• Feed on other living things
• Where do they live?-
water/aquatic (ponds,lakes,
oceans)
• Examples: amoeba,
paramecium, dinoflagellates

55. Example 1: Protozoans - amoebas
• Amoebas
• shapeless, aquatic
•

56. How does bacteria carry out life processes?
1. Movement:- pseudopodia
2. Reproduction:- asexually by fission/binary fission-
3. Sensitivity:- lacks special structures but uses its cell wall to sense food
4. Growth: the cells can grow in size, before dividing
5. Respiration: Aerobic
6. Excretion:- contractile vacuole
7.Nutrition:- pseudopodia for feeding

57. How does amoeba carry out life processes?

58. Pseudopods in Amoebas

59. How Amoebas feed?
• Feeding structures-
• food vacuole
• digestive enzymes
• diffusion

60. Getting Rid of Waste:- excretion
They use Contracting vacuole –
collect excess water from inside the cell and
gets rid of it.

61. Reproduction of Amoeba
• asexual reproduction
• Binary fission

62. Movement in amoeba:- uses pseudopodia
Uses pseudopodia to drift/move
from one place to the next.

63. Amoebiasis or amoebic dysentery
• Is an infection caused by any of the
amoebae of the Entamoeba genus
Symptoms:
1. loss of weight,
2. colon ulcer,
3. abdominal pain,
4. diarrhea, or bloody diarrhea

64. 2. Example 2: Protozoans: Ciliates
Locomotion - Cilia
1. Paracmecium - fresh water
ciliate
The paramecium has two
nuclei

65. How do Paramecium eat?
Feed on bacteria
• Food enters oral groove,
• moves to the food vacoule,
• anal pore

66. Paramecium Reproduction
Asexual-by conjugation where it create identical organisms
Conjucation - sexual reproduction
• exchange of genetic information
• Not identical - addsdiversity

67. 3. Example 3: Protozoans - Flagellates
Locomotion - use flagella
Examples:
2. Trypanosoma - causes African
Sleeping Sickness
• spread by tsetse fly


68. Picture showing trypanosomes in the blood system of certain mammals as seen
through a microscope

69. Are protozoans important to us?

70. Algae
• This is commonly found floating on water surface of ponds, lakes and
slow-moving streams.
• It consists of filaments in colonies of identical cells held by slimy
material called mucilage. e.g. spirogyra.
• They range in size from microscopic ones to giant types e.g kelps that
reach 60 metres (200 feet) in length
• They make their own food by using sunlight
• Have pigment chlorphyll

71. How do they look like?- 1. Spirogyra

72. HOW DOES SPYROGYRA CARRY OUT LIFE PROCESSES?
• The spirogyra reproduces both by sexual and asexual means.
• Asexual reproduction is by fragmentation which occurs when
conditions are favorable.
• Binary fission also occurs in favorable conditions.
• When conditions are not favorable like drying of the ponds,
reproduction is by sexual means in a process called
conjugation.

73. CONJUGATION IN SPIROGYRA

74. Fragmentation in spirogyra

75. 2. The giant kelp: Sea weeds

76. Importance of algae
1) It provides food to organisms like fish and man feeds on fish.
2) They pollute the water, blocking light, transparency and visibility of
things.
3) Some die and decay producing foul smell.
4) Used in the manufacture of cosmetics, ice creams and paints.
5) The algae produce oxygen required for respiration by other living
organisms in water.
6) Use carbon dioxide, hemce removing it from environment

77. Products made from algae

79. Why are they grouped as `microorganisms`?
Why are members in this kingdom called `microorganis`, yet some are
large enough to be seen by a naked eye?
Reason: At some stage in their life, they cannot be seen by naked eyes,
since they exist as spores

80. KINGDOM FUNGI
• Mostly have multicellular eukaryotic organisms
• Some are unicellular like yeast.
• They are heterotrophic (cannot make their own food)
• Other examples include toad stool, smuts, penicilium, mucor (grows on
soil and dead plants), Rhizopus (common bread mould).
• Rhizopus is saprophytic fungus which grows on decaying food like bread
and fruits.

81. Characteristics of fungi
• The are multicellular except a few which are unicellular e.g. yeast.
• Fungi inhabit damp or aquatic plants
• They reproduce by means of spores.
• They have saprophytic, mutualistic or parasitic mode of nutrition.
• Most vegetative body called mycelium which has a network of hyphae.
• They have cell walls which consist of a material called chitin.
• They lack chlorophyll though majority are plant-like.
• Are heterotrophic( cannot make their own food)

82. The body of a fungus: How does it look like?

83. The body of a fungus: How does it look like?
• Has a vegetative body called ------- Mycelium/mycelia
• mycelium has many root-like branches called--------Hyphae
• different mycelia are connected by structures called ----------stolons
• Some hyphae may grow into food and are called--------Rhizoids
• Rhizoids are for support of the fungus and also absorb food
• Some hyphae may grow upwards, are called---------Sporangiospores
• At the tip of sporangiospore is a ....................... Sporangium with spores
• The hyphae produces chemicals called enzymes to break down food

84. How does fungi reproduce?
• Asexually: By using spores , budding and by fragmentation
• Sexually: By conjugation
• Note: All fungi reproduce by using spores.
• Spores are microscopic cells or group of cells that scatter from the
parent fungus by wind or water

85. Examples of fungi

86. Importance of fungi-----
Penicillium on fruits and chips
Blight on tomatoes
Ringworm on skin

87. Importance of fungi
1. Fungi decay dead organic materials to release materials needed by plants
2. Yeast produce alcohol by respiring for brewers and wine makers.
3. Yeast cells are a source for vitamin B extract.
4. Fungi produce antibiotics e.g. penicillum.
5. Fungi provide food e.g. mushroom also used in making cheese.
6. Fungi can spoil food e.g. Rhizopus and penicillum on the bread, cakes,
fruits and jam.
7. Fungi causes plant disease e.g. rust, white bright and smut.
8. Fungi destroy timber of houses e.g dry rot
9. Fungi causes diseases to man e.g. ringworm, athlete’s foot, candida
10. Fungi can be used by military to prepare biological weapons to be used in
the war fare

88. Kingdom plantae
Identify the following groups of plants;

90. What are the unique features found only in plants?

91. Characteristics of plants
• They are mostly green in colour
• They are multicellular.
• They do not locomote; but limited movements such as
opening and closing of petals etc.
• Their cells are surrounded by cellulose cell wall.
• They respond slowly to external stimuli

92. Where did plants originate from?

93. Classification of plants
• Divided into two:
1. Non vascular plants (Bryophytes):- without
vessels
2. Vascular plants (spermatophytes and
pteridophytes): plants with vessels

94. Division/classification of plants

95. Division Bryophyta
• Bryophytes are an informal group consisting of three divisions
of non-vascular land plants:- the liverworts, hornworts and
mosses

96. • They are sometimes called the amphibians of the plant
kingdom
• Why????
• Because they grow on land, but still require water to
complete their cycle of sexual reproduction

97. Characteristics of bryophytes
1. They have simple leaves
2. lack proper roots but have rhizoids
3. lack vessels like xylem and phloem (vascular tissue) thus
depend on diffusion for movement of materials.
4. They carry out photosynthesis because chlorophyll is present
5. They are found in sheltered and wet areas.
6. Their life cycle consists of the two generations which
alternate a gametophyte and sporophyte generation.

98. External features of a moss

99. Assignment .1: Research about the roles of each of the
labeled parts of a moss plant

100. USES/IMPORTANCE OF BRYOPHYTES
• what are some of the uses of bryophytes to humans and to the environment?
Watch the video cautiously,
and list at least three uses of
bryophytes

101. Uses of bryophytes
1. Used in making antibiotics
2. Used as fuel
3. Used in making preservatives
4. They aid in the formation of soil by breaking rock
5. They bind soil particles together
6. Used as indicators of soil conditions like acidic and basic
7. Used as food for other living things
8. Prevent soil erosion by splashing rain water or wind
9. When they die, they decompose to form soil.
10.Used in making medicines like for treatment of TB

102. Pteridophytes
QUILLWORTS
HORSETAILS
CLUB MOSSES
FERNS
SPORES

103. Characteristics of pteridophytes
1. They grow in moist and shady places or on sandy soil
2. They have well developed stems, leaves and roots called a sporophyte
3. The stem is underground
4. Some have small leaves called microphylls and others have large leaves
called megaphylls
5. Leaves may have spores on the underside and are called sporophylls
6. Have a well developed vascular system, with the xylem and phloem

104. Examples of pteridophytes
• Spike mosses
• Horse tails
• Quillworts
• Ferns
• Club mosses

105. Angiosperms- flowering plants
• Flowering plants can be classified according to the nature of
their seeds, seedlings and leaves.
• The two largest groups of flowering plants are:
• monocotyledons
• dicotyledons

106. What some of the parts of a flowering plant?

107. What are the parts of a flowering plant?

108. Monocotyledonous plants
• The seeds of monocotyledons each contain one embryonic leaf (the
‘cotyledon’).
• Many monocotyledons have leaves with parallel veins and the parts
of their flowers come in threes. Examples of monocotyledons
include:
• palms
• orchids
• grasses

109. KINGDOM ANIMALIA

110. INVERTEBRATES: Identify The Following Animals;

111. INVERTEBRATES

112. VERTEBRATES

114. • General characteristics of organisms in kingdom animalia.
1. Animals carry out locomotion.
2. They have heterotrophic mode of nutrition
(cannot make their own food)
3. They are multicellular organisms.
4. Their body has a definite shape.
5. They have cells without cellulose but contain
true nucleus.

115. HOW ARE ANIMALS CLASSIFIED

116. CLASSIFICATION OF ANIMALS

117. PHYLUM PORIFERA
What do you think is the function(s) of each one
of the two pores?

118. 1. Possess simple bodies which are hollow and sac-like.
2. They are marine dwellers.
3. They are sedimentary or sessile organisms found attached to the rocks or coral reefs. They do
not move
4. Some can live in colonies or individually.
5. They lack a nervous system.
6. They have only one opening in their bodies.
7. They have a body made up of two layers of cells i.e. ectoderm and endoderm.
8. Hermaphrodites
9. Have two layers of cells
CHARACTERISTICS OF PORIFERA

119. PHYLUM COELENTRATA:- CNIDARIANS
• Phylum: Coelenterata (Cnidaria).
• Examples include the following;
1. Jelly fish.
2. Sea anemones.
3. Portuguese man of war.
4. Hydra and corals.

120. COELENTRATES: Drawing of Coelenterates

121. 1. They are multicellular organisms.
2. They are aquatic or marine organisms.
3. They have soft bodies which are sac-like with body cavity called enteron.
4. They have radial body symmetry.
5. They have a single body opening.
6. They have tentacles.
7. They possess specialized cells such as the stinging cells used for defense
or paralyzing their prey.
8. They have a ring of tentacles for capturing prey
CHARACTERISTICS OF COELENTRATES:- CNIDARIANS

122. Did you know?
• The infamous box jellyfish has frighteningly powerful venom to instantly
stun or kill prey, like fish and shrimp, so their struggle to escape wouldn’t
damage its delicate tentacles. It can also kill humans.
• Their venom is considered to be among the most deadly in the world,
containing toxins that attack the heart, nervous system, and skin cells.
• It is so overpoweringly painful, human victims have been known to go into
shock and drown or die of heart failure before even reaching shore.
Survivors can experience considerable pain for weeks and often have
significant scarring where the tentacles made contact.

123. Phylum: Platyhelminthes (flat worms).

124. Identify the following platyhelminthes:

125. CHARACTTERISTICS OF PLATYHELMINTHES
1. They have dorso-ventrally flattened body
2. They have bilateral body symmetry.
3. They are damp, moist or aquatic dwellers.
4. They are parasitic organisms.
5. They have alimentary canal without mouth.
6. The body wall has three body layers of cells (triploblastic)
7. The gut is branched
8. They are hermaphrodites; have both male and female organs in the same
organism.
9. They lack blood circulatory system and gaseous exchange occurs by simple
diffusion all over the body surface.

126. LIVERFLUKE

127. DIESEASES CAUSED BY PLATYHELMINTHES
• Bilharzia
• Liver cirrhosis
• Anaemia
• malnutrition

128. Nematodes:- Phylum Nematoda

129. What characteristics are common to the following nematodes

130. Phylum: Nematoda (round worms
1. They have segmented bodies.
2. They have elongated and cylindrical bodies pointed at both
ends.
3. They have closed circulatory system.
4. They have gaseous exchange occurs all over the body surface.
5. They have a complete digestive system with both mouth and
anus.
6. Some are parasitic and others are free living.

131. Examples of nematodes
• The phylum has the examples like:-
1. Hookworms,
2. Pin worms,
3. Guinea worms,
4. Whip worms and
5. Ascaris lumbricoides/giant round worms.

132. • These are the ringed or segmented worms e.g.
1. Earthworms,
2. Leeches,
3. Rag worms,
4. Lugworms, etc.
Phylum: Annelida (ring worm).

133. Characteristics of annelids
1. The body wall has three body layers of cells
2. They have true coelom.
3. They have a closed circulatory system.
4. They have gaseous exchange all over body surface.
5. They have complete digestive system with both anterior (oral) and posterior (Anal)
openings.
6. They are hermaphrodites and reproduce sexually but they often promote cross
fertilization.
7. They are carnivorous and some live as external parasites.
8. They have bodies divided into section called septae.
9. Externally the body shows ring- like segments.

134. Phylum: Mollusca.
The organisms are generally
aquatic and live both on fresh
water and marine. Examples
include snails,
1. slugs,
2.octopus,
3.squids,
4.mussels and
5.oysters.

135. Drawings of some common molluscs

136. Characteristics of molluscs
1. They have soft and unsegmented bodies.
2. Nearly all have shells with exception of octopus and squids.
3. The foot is used for locomotion and attachment to the
substratum.

137. .
Phylum: Echinodermata

138. DIAGRAMS OF DIFFERENT ECHINODERMS

139. Characteristics of echinoderms
1. They have unsegmented bodies.
2. They have radial body symmetry.
3. The bodies have five arms.
4. The body wall has three body layers of cells (triploblastic)
5. They have feet for locomotion and capturing the food (feeding).
6. They have spiny skin which is a hard plate.
7. They have water vascular system instead of blood circulatory
system.

140. Echinoderms;;

141. PHYLUM ARTHROPODA.
• Arthropoda has a wide variety of animals.
• These animals occupy a wide variety of habitats on land, sea and
fresh water.

142. VERTEBRATES

143. Classification of vertebrates