CHAPTER 1 BIODIVERSITY

CHAPTER 1:

BIODIVERSITY

BIODIVERSITY

(variety and complexity of all life on earth)

Genetic diversity

Species diversity

Ecosystem

diversity

 Taxonomy – science of classifying organisms

 Linnaean taxonomic system – to group and categorise organisms

Father of taxonomy- Carolus Linnaeus (1707-1778)

Linnaeus developed binomial nomenclature system in naming organisms

Binomial Nomenclature

Genus name

+

Species name Scientific name

a) Each organism has two part name b) First part, the genus

c) Second part, the species

d) First letter in the genus is capitalized

e) All the letters in the species name are lowercase f) Both the genus and species name:

underlined (if handwritten) or italicized (if type)

Homo sapiens

Examples:

Panthera tigris

Hierarchical system of classification - 8 levels

Five Kingdom System of Classification

• \

Bacteria

 unicellular, range in size from 1 to 10 µm in length, lack of nucleus

Oxygen requirement

Autotrophs- obtain carbon source from inorganic carbon dioxide

Heterotrophs- obtain carbon source from organic molecules

 Photoheterotrophs- obtain energy from sunlight

 Chemoautotrophs –harvest energy by oxidizing inorganic substances- ammonia or nitrate

Domain - Bacteria & Archaea

Prokaryotes

Aerobes (require oxygen to carry out cellular respiration)

obligate anaerobes (unable to grow in the presence of oxygen)

facultative anaerobes (able to grow either in the presence or absence of oxygen)

Domain Bacteria

Gram negative Gram positive

Shapes of bacteria -including cyanobacteria

Position of the bacterial flagella

a) Bacteria

Cyanobacteria (blue-green algae)

Akinetes/resting spores – formed during periods of unfavourable environmental conditions- darkness, drying, freezing - thick-serve to protect organism - Elliptical shape

Gas vesicle: common in species - live in open waters (planktonic species)

Heterocyst-specialized nitrogen fixing cells -Arise from vegetative cells

-Thick cell wall-impervious to oxygen, create anaerobic environment inside

-Anaerobic environment important- because oxygen inhibits enzyme nitrogenase.

-Have intracellular connection with adjacent vegetative cells for exchange of materials between cells

Vegetative cells

Heterocyst

Akinetes

Mucilagenous sheath

 Phototrophic prokaryotes with no nuclear membrane and membrane bound organelles

 Habitat: nature in terrestrial, freshwater and marine.

 Type: Unicellular/ filamentous

 Filaments called trichomes, surrounded by gelatinous sheath

 Have symbiotic relationship with fungi- compose lichens

Known as extremophiles

Live in harsh environments- hotsprings, thermal vents and salt basins

Domain Archaea

Methagons

 Found in swamps,

marshes and intestinal tracts of animals

 Obligate anaerobes, survive only in oxygen- free environment

 Chemoautotrophs-use H₂ as source of electrons for reducing CO2 to

obtain energy ,methane (by –product)

Halophiles

 Aerobic

microorganism

 Found in extreme saline environments – Great Salt Lake, US &

the Dead Sea

 Use osmotic pressure and chemical

substances-control salt inside cell

Thermoacidophiles

 Resistant to high

temperatures (70 -80) &

high acid concentration (pH 2 and 3)

 Have plasma membrane- contains high amounts of saturated fats and its

enzymes-able to withstand extreme conditions without denaturation

 Found in hot & acidic

environment- Yellowstone National Park, US.

Classification of archae

based on habitats

Bacteria Archae Cell wall compose of

peptidoglycan

Cell do not contain peptidolygan Lipids in plasma

membrane –composed of unbranched

hydrocarbon chains connected to glycerol by

ester linkages

Lipids in plasma membrane –composed

of branched hydrocarbon chains connected to glycerol by

ester linkages Ribosomal protein and

RNA polymerase – different form

eukaryotes

Ribosomal protein and RNA Polymerase very

similar Genes are not

interrupted by introns

Present introns E.g. Escherichia coli,

Bacillus subtilis

Example: Sulfolobus, Methanococcus

Important of bacteria 1. Recycling of

chemical elements in the ecosystem 2. Symbiotics

3. Pathogenic 4. Research &

technology

Differences

Protista

Algae

 Contain chlorophyll and carry photosynthesis

 Unicellular/colonial

 arranged end-end -filamentous algae: branched/ unbranched

 Found in salt/ fresh water /moist soil /rocks

 presence of cell walls and vacuoles

 Lack true stem, leaves, roots

Protozoa

 Unicellular, eukaryotic microorganism - exhibit – like characteristics

 Colourless and motile

 Heterotroph- obtain food by ingesting other organism

 Found in freshwater and marine

habitats, soil, human, aerial habitats

Phylum Euglenophyta - Euglena Phylum Rhizopoda - Ameoba

Phylum Ciliophora - Paramecium Phylum Apicomplexa - Plasmodium Phylum Chlorophyta

Phylum Phaeophyta

Chlorophyta

Green algae

Most aquatic, some terrestrial, found in moist soils

Unicellular, multicellular, coenocytic or colonial

Contains chlorophylls a and b

Store food as starch in plastids

Chlamydomonas

microscopic, green in colour round- shaped, two flagella at anterior end, eyespot-receive light –help direct its swimming, cup-shaped chloroplast containing pyrenoid –starch

synthesized.

Phaeophyta

Brown algae, familiar seaweeds

Contains chlorophylls a, c and carotenoids- fucoxanthin in chloroplast

Fucus

Plant body – thallus- lacks true roots, stem and leaves

Leaf-like blade- dichotomously branched-provide surface for photosynthesis

Stem-like stripe –supports the blades &

withstand wave action

Root like holdfast anchors – to maintain a firm foothold

Have air bladders-provide buoyancy- keep afloat - photosynthetic tissue exposed to sunlight

Receptacles contains conceptacles- gametes are formed

Euglenophyta

Genus-Euglena

-small, freshwater organisms

Have chloroplast-able to synthesize food by photosynthesis, lack ones ingest /absorb food

Reservoir-2 flagella attached base of flask- shaped opening

Stigma (eyespot) –sensitive to light and aids organism towards light.

Contains chloroplast with chlorophyll a, b, carotoids

Pellicle-able to change its shape

Contractile vacuole- to rid body of excess water

Rhizopoda

Move by pseudopodia –greek word: ‘false feet’-extensions of cytoplasm- use to

capture prey & locomotion

Heterotrophic, feed on wide range of bacteria, algae and other protists

Amoeba proteus

-freshwater habitats

Feed on other protozoans Have 3 types of vacuole:

a) Digestive vacuole- helps in digesting food particles

b) Food vacuole-digest food

c) Contractile vacuole- to rid body of excess water-does not burst (osmoregulation)

Ciliophora

Ciliates –complex protozoans Paramecium

Fixed body shape-slipper

Cilia –swimming through freshwater &

marine habitats- beat in synchronized pattern over body surface

Pellicle- protects & maintain shape of organism

Trichocysts-discharge filaments- aid in trapping prey

Holozoic- ingests bacteria / other small protista

Has 2 types nucleic:

i) Macronucleus- control in cell metabolism

& growth

ii) Micronucleus- generating genetic variation during sexual reproduction Contractile vacuole- expel excess water

Apicomplexa

Sporozoans- large group of parasitic; spore forming protest

Lack specific structures for locomotion, they move by flexing

Named after their apical complex of

microtubules –enable to penetrate & attach to the tissues of their host.

Have complex life cycles – involve asexual &

sexual phases involving multiple species as hosts

E.g. Plasmodium sp.

1. Roles in biosphere (CO₂ fixation) o fixes carbon via photosynthesis

o Carbon enter planktonic food web –respired to provide metabolic energy/accumulates as biomass or detritus

2. Food source

o seaweed (kelps) – edible & used to overcome shortage of food in the world.

o Japan & Korea- brown algae, Laminaria in soups & red algae, Porphyra –to wrap sushi

o Spirulina – good protein source

o Chlorella high in protein & packed with calories, fats & vitamins- growth & repair body‘s tissue

3. Eutrophication

o Process- water bodies such as lakes, estuaries / slow –moving streams receive

excess nutrients –stimulate excessive growth of algae. Enhanced algal growth -Algal bloom

o Excess nutrients from fertilizer, erosion of soil containing nutrients, sewage treatment plant discharges

o Algae bloom reduces dissolved oxygen in the water when dead plant material decomposes & cause death of other aquatic organisms.

Important of Protozoans

4. Red tide

o Common name for estuarine / marine algal bloom

o Caused by dinoflagelllates of red algae-turn waters into deep reddish –brown hue o Some produce neutrotoxin –attacks nervous system and kills fish

o Human eat shellfish that eats diniflagellates –suffer paralytic shellfish poisoning in respiratory muscles become paralysed. Death from respiratory failure.

5. Human health o Apicomplexans

o Plasmodium – causes malaria, transmitted to host through bite of infected female Anopheles mosquito

Fungi

Kingdom Fungi

Lack chloroplast

Heterotrophs-depend on other organism for carbon source

Storage carbohydrates- glycogen

Most multicellular, some unicellular- yeast

Septum has pores- allow movement of cytoplasm &

organelles from

segment to segment

Septate hyphae Coenocytic hyphae

Hyphae without septa- consist of continuous cytoplasmic mass with hundreds /thousands of nucleic

 Classified into 3 major phyla : i) Phylum Zygomycota- Rhizopus ii) Phylum Ascomycota- Penicillium ,

Saccharomyces

iii) Phylum Basidiomycota- Agaricus

Zygomycota

Sporangium fungi/ common molds

Hyphae- non-septate & coenocytic

Reproduce asexually- producing spores within sac- sporangium

Born on stalks- sporangiosphores

Sexual reproduction –sexual spores- zygospores-contained within

zygosporangium

Ascomycota

Sac fungi- include yeast, cup fungi truffles &

morrels

Vegetative hyphae-septate with perforated walls ; haploid nucleus per cell.

Reproduce asexually, sexually

Asexually- formation of conidia-produce from conidiophores, multinucleate spores

Yeast –unicellular ascomycete-reproduce asexually – budding /cell fission

Sexual reproduction – formation of ascus, sac-like structure , formed within ascocarp, contain 8 haploid spores

E.g. Penicillium & Saccharomyces

Basidiomycota

Mushrooms, shelf life, puffballs, rust & smuts.

E.g. Agaricus

Club fungi –produce small like reproductive structure –basidia.

Mushrooms-filamentous fungi-form fruiting bodies.

Seldom reproduce asexually

Reproduce sexually-forming spores in basidium found in lining gills inside basidiocarp

Basidiocarp-consist of stem called a stalk and flattened structure known as cap/pileus

Each gills is lined with thousands of dikaryotic basidia- a cell that contain 2 nuclei

2 nuclei fuse to form zygote undergoes

meiosis to form 4 haploid nuclei-develop into 4 basidiospores –released into air

Under favourable conditions germinate &

grow new hyphae & mycelia.

THE IMPORTANCE OF FUNGI

Decomposer

Symbionts Pathogens

Commercial importance in food production

Pharmaceutical

(Penicillin)

Plantae

Plants classified into 4 major divisions:

• Bryophytes

• Pteridophytes

• Gymnosperms

• Angiosperms

All plants share the common ancestor of green algae Characteristics:

i) The same photosynthetic pigments in similar chloroplasts ii) Cell wall with cellulose

iii) Food stored as starch

Plants adapted to live on land

i) Have vascular tissues for transport of water & nutrients throughout plant body

ii) To protect against dessication, covered by waxy cuticle iii) Leaves have stomata-gaseous exchange; hot dry

weather stomata closed to prevent water loss iv) Protected reproductive structures & retention of

embryonic sporophyte within female gametophyte Have multicellular sex organs –gametangia

Archegonium-female organ –produces a single egg Antheridium-male organ – produces sperm

Fertilised egg develops in female gametangium

sporophyte

MITOSIS

FERTILISATION

Alternation of generations in plants

Gametophyte

generation (haploid n) –produces

gametes (sex cells)

Sporophyte generation=

(diploid 2n) –

produces spores by meiosis

Bryophytes

Include liverworts, hornworts & mosses Found in moist environment

Small or low growing plants due to lack vascular tissue and do not have lignified tissues for support.

Classified into 3 phyla

a) Phylum bryophyta- Polytrichum sp b) Phylum hepatophyta – Marchantia sp.

c) Phylum Anthocerophyta – Anthoceros sp.

Phylum Bryophyta

Mosses-largest group, grow in damp &

shaded habitats

Borne on gametophytes

Consist

i) seta (elongated stalk -connect sporangium to gametophyte)

ii) foot (base of seta-transfer nutrients &

water from gametophyte to capsule) iii) capsule (main body of sporophyte- produce spores)

Sporangium consists of sporogenous layer, columella, peristome teeth &

operculum

Calyptra- protect developing sporangium (except Sphagnum)

Peristome teeth-hygroscopic & aid in spore dispersal

Spores give rise to protonema –then give rise to several gametophytes

Hydroids (water – conducting tissue)

Leptoids (food – conducting tissue)

Phylum Hepatophyta

Liverworts

Small, 2-20 mm wide less than 10 cm long

Flattened thallus/ leafy appearance- exhibits apical growth

 lobed thallus more familiar

Lack stomata, only air pores

Have gametophyte-dominant life cycle, sporophyte dependent on gametophyte

Plant cells haploid

Sporophytes –short lived –withering away after releasing spores

E.g. Marchantia sp.

Phylum Anthocerophyta

Hornworts

Grow in moist ,shaded habitats in

subtropical & warm temperate regions

Thallus –rosette-like & less than 2 cm in diameter.

E.g Anthoceros sp. – unisexual & other bisexual

Antheridia & archegonia –embedded deep in gametophyte

Numerous sporophyte-develop on same gametophyte-gain their nutrition

Sporophyte –photosynthetic & provide energy –growth & reproduction

Pteridophytes

Ferns-largest group of seedless, vascular plants –found in tropical & subtropical region

Have true roots , leave & stems

Contain vascular tissue – transport of water & food

Alternation of generation – sporophyte generation is dominant Reproductive system – dependent on water for fertilization Ferns reproduce sexually by producing spores

Homosporous (producing only 1 type of spores), produce bisexual gametophytes;

E.g. Locopodium

Heterosporous (producing 2 different types of spores; microspores & megaspores), produce unisexual gametophytes; Selaginella (spike moss)

Microspore Male gametophyte Sperm

Sporophyte Megaspore Female gametophyte Egg

Sporophyte One type of spore Bisexual gametophyte Egg & sperm

Classified into 2 phyla:

a) Phylum Lycopodophyta; E.g. Lycopodium sp., Selaginella sp.

b) Phylum Pteridophyta; E.g. Dryopteris sp,

Phylum Lycopodophyta

Club mosses/ ground pines, fern allies

Sporophytes have upright stems with small,scale like leaves- microphylls with single mid-vein

Lycopodium sp.- homosporous plant

Selaginella sp (spike moss)-small club moss- heterosporous

Selaginella sp.

Lcyopodium sp.

Phylum Pteridophyta

Dryopteris sp.

Sporophyte stage – consist of true stem, leaves & roots

Roots- fibrous , similar to roots of seed plants

Stem – underground creeping rhizome/

above-ground creeping stolon/ above – ground erect semi-woody trunk

Fern leaf- frond. One/ more fronds –

megaphylls- attached to rhizome by stalk- stipe

Frond develop from fiddlehead/crozier (coiled leaf bud); pattern of coiled leaf arrangement in bud- circinate vernation

Gametophyte stage –prothallus & rhizoids

Reproduce sexually –making spores

Gymnosperms

Produce seed –totally exposed /borne on scales of cones (naked seed)

- pine, spruce, fir & ginkgo

- Reproductive structure- cones & strobili - Heterosporous

Classified into 4 phyla:

a) Phylum Coniferophyta; E.g. Pinus sp.

b) Phylum Cycadophyta; E.g. Cycas sp, c) Phylum Gingkophyta; E.g. Gingko sp.

d) Phylum Gnetophyta; E.g Gnetum sp.

Phylum Coniferophyta



Conifers- pines, spruce & firs



Pinus –largest genus in confers



Woody trees & shrubs,; exhibit

secondary growth by producing wood &

bark needle like leaves; thick cuticle, sunken stomata & no air spaces within mesophyll to conserve water



Produce resin-protects the plant from attack of fungi/ insects



Monoecious-have separate male &

female reproductive parts in different locations on same plant



Borne in strobili/cones



Heterosporous



Sporophyte generation –dominant &

gametophyte generation –microscopic structure in cones



Air current , wind carries pine pollen

grains to female cones & non-motile

sperm cells –fertilization by moving

through a pollen tube to egg.

Staminate/ male cones/

pollen cones

Ovulate / female cones/

seed cones

Male cones

 smaller than female cones

 Found lower branches of the tree

 Consists of sporophylls; leaf –like structures-bear microsporangia on underside.

 Microsporangia contain microsporocyte/

microspore mother cell.

 Microsporocyte undergo meiosis to form haploid microspores- develop male gametophyte, pollen grain- carry by wind to female cones.

Female cones

 Found on upper branches of tree & bear seeds after reproduction

 Each cone scale bear 2 ovules/ megasporangia on its upper surface- undergo meiosis to produce 4 haploid megaspores; only one megaspore will develop into female gametophyte with archegonia containing egg

 Ovule is ready to receive pollen –produces sticky droplets at opening – pollen grains land

Phylum Cycadophyta

Most species now extinct

Tropical & subtropical plants with stout, trunk-like stems & compound leaves resemble palms/ferns

Dioecious – seed cones- on female plants &

pollen cones –on male plants

Have motile sperm cells (hair -like flagella)

Pollen grains carries by air /insects to seed cones on female plants

During pollination, pollen grains develop pollen tubes & release flagellated sperms- swim to egg.

Phylum Ginkgophyta

 Ginkgo biloba- maidenhair tree

 Dioecious- separate male &

female trees

Fan-like leaves –turn gold &

deciduous in autumn

Phylum Gnetophyta

Seed bearing plants-grow as shrubs, trees/

vines

3 genera- Gnetum, Ephedra & Welwitschia- distinctive morphology & architecture of sporophyte

Share numerous characters with angiosperm:

a) leaves- reticulate venation- resembles leaves of dicot angiosperm

b) Xylem possesses both tracheids & vessel elements

c) Reproductive structure (cluster of cones) are flower-like

d) Double fertilization- 2 eggs cells produced- fertilized; one become embryo-other

does not complete development into embryo &

no provide nutrition to developing embryo as does endosperm of angiosperm

Angiosperms

- Grouped in phylum Anthophyta/

Magnoliophyta

- Flowering plants & successful of all plant group

- Refinement in vascular tissue-xylem xylem tracheids, vessel elements & fibre cells.

- Tracheid-long , tapered cells –functioning both mechanical support & water transport - Vessel elements-shorter & wider than

tracheid-arranged end-to-end into

continuous tubes as xylem vessels-more efficient in transporting water

- Fibre cells- support

- Ovules- enclosed within ovary

- Seeds- enclosed in fruits-develop from ovary

- Body of angiosperm-sporophyte

- Gametophyte –confined to flower, male &

female together

Angiosperm

Simple fruits -(arise from one ovary in one flower) E.g.

cucumber, tomato, apple

Aggregate fruits -(arise from

several ovaries in one flower) E.g. raspberry, strawberry Multiple fruits

-(arise from ovaries in several , tightly – clustered flowers – grow together into 1 fruit)

E.g. pineapple, mulberry

Monocots/

Monocotyledonae

Dicots / Dicotyledonae 1 cotyledon in seeds 2 cotyledon in seeds

Flower parts in 3s /multiples of 3

Flower parts in 4s / 5s / multiples of 4 / 5

herbaceous Woody /herbaceous Leave veins parallel with

each other

Leave veins branch out from a central vein

Vascular bundle –scattered throughout stem but a ring

pattern in root

Vascular bundle –arranged in a ring around stem but in

root they are centrally located

Fibrous root taproot

Animalia

Classification of Animalia

1. Porifera

2. Cnidaria

3. Platyhelminthes

4. Nematoda 8. Echinodermata

5. Annelida

7. Mollusca

6. Arthropoda

9. Chordata

Different levels of organization of animal body structure – 1. Germ layer

- 2. Symmetry body plan

- 3. Type of coelom (body cavities) - 4. Presence of segmentation

A. GERM LAYER

Diploblastic Triploblastic

• two germ layers : ectoderm &

endoderm

• three germ layers :

ectoderm,endoderm&

mesoderm

Lack of symmetry - animals that

are irregular in shape

Any imaginary plane through the body divides it into similar

halves; parts of the body are arranged around a central axis

A body plan with right and left halves that

are mirror images of one

another

B. SYMMETRY BODY PLAN

ASYMMETRY RADIAL SYMMETRY BILATERAL SYMMETRY

Bilateral Symmetry Radial Symmetry

C. TYPE OF CEOLEM (BODY CAVITIES)

1. Acoelomate

- No fluid filled body cavity (coelom)

between the gut & outer body wall

- Example:

platyhelminthes

2. Pseudocoelomate

- Fluid filled body cavity (coelom) is not

completely enclosed by tissues derived from mesoderm

- Eg: nematode, rotifer

3.Coelomate

- Coelem is completely enclosed by mesoderm - Eg: annelid Outer body wall Gut

Coelom

Body cavities(Coelom)

- Coelom: body cavity that has two opening (anterior and posterior), lined by mesoderm.

• A body cavity has many functions:

– Its fluid cushions the internal organs, helping to prevent internal injury.

– As a hydrostatic skeleton against which muscles can work.

– Enables the internal organs to grow and move independently

of the outer body wall.

- Acoelomate:

No coelom

- Pseudocoelom:

Coelom not completely

lined by mesoderm

Body

cavities(Coelom)

- Coelomate:

Coelom completely

lined by mesoderm

D. PRESENCE OF SEGMENTATION

• Segmentation : repeating organizational unit of a body plan

• In earthworms, each ring is a distinct segment

•

Lobsters have developed

specialized appendages on many segments

• Fish exhibit segmentation in

their muscles and backbones

Phylum Porifera

Parazoa –Sponges- only surviving & most primitive of all animals

Porifera means pore-bearing’

Multicellular

Loosely associated & do not form tissues/organ

Aquatic animal; marine, fresh water.

Lack body symmetry (asymmetrical)

E.g. Leucosolenia

Are sessile filter feeders

 sexual reproduction: hermaphroditic

(have both sexes), gonochoristic (separate sexes)

Asexual reproduction: budding &

fragmentation.

Phylum Cnidaria

Live in marine environments, some in fresh water.

Radial symmetry

Organised as 2 - layered, hollow sac with mouth & surrounding tentacles at one end

2 basic body forms (dimorphism): polyp &

medusa.

Stinging cell (cnidocytes) to capture prey

Diploblastic –have 2 definite tissue layers;

ectoderm & endoterm

Carnivores –feeding on live prey-use tentacles to capture prey & push it into mouth-leads to gastrovascular cavity- digestion take place

Nerve net –simple nervous system

Scyphozoa

Jellyfish

Medusa –main stage

Have poly stage or much reduced polyp stage

Anthozoa

 Sea anemones &

corals

 No medusa stage in their

development

 Have either individual

/colonial polyps only

Hydrozoa

 Hydra & Obelia

 Freshwater ponds &

streams

 Poly form

 Reproduce

 Asexual-budding when favourable

environment

 Unfavorable condition reproduce sexually &

form resistant zygotes – remain dormant until conditions improve

 Hermaphrodites

Cnidarian

Phylum Platyhelminthes

Flatworms

 Soft, unsegmented & flattened dorso-

ventrally, with mouth & genital pore located in ventral position

Triploblastic animals- 3 cell layers (ectoderm, endoderm & mesoderm)

Bilaterally symmetrical

No internal body cavity-acoelomate

Exhibit cephalization

Ladder –type nervous system

Digestive system –incomplete

Asexually – transversal bipartition sexually

Hemaphrodites

Excretion & Osmoregulation-controlled by ciliated flame cells located in protonephridia

Trematoda

Leaf –like

parasitic flukes

Simple digestive system with

mouth at anterior end

Fasciola hepatica- common liver

fluke/ sheep liver fluke

Cause disease - fascioliasis

Turbellaria

 Planarians; free- living Dugesia

 Carnivorous found in freshwater near stones, leaves/

debris

 Head is blunt &

arrow-shaped

 Ingest food using tube-like pharynx located in centre of ventral surface of body

Cestoda

 Tapeworm; Taenia saginata

 Gut of human

 Endoparasitic

 Lack cephalization but carries hooks / sucker for attachment to host

 Obtain nutrients from host

 Bodies covered with tegument-resistant to host digestive juices

Platyhelminthes

Phylum Nematoda

Nematodes-roundworms

Numerous animals –found anywhere in sea, fresh water & soil

Parasites

Bilaterally symmetrical, unsegmented worms

Body –elongated ,cylindrical & tapered at both ends.

Triploblastic pseudocoelomates

First animal phylum exhibit complete digestive system with mouth & anus

No organs for circulation/ excretion.

Dissolved gas diffuse directly through body wall.

Sexual –miniature adults hatching directly from egg & moulting 4 times before reach size of adults.

Phylum Annelida

Earthworms, polychaete worms & leeches

Habitats: moist environment, moist soil, freshwater &marine water

Metamerically segmented

Have parapodia & chitinous setae –used for locomotion

Triploblastic with bilateral symmetry and well-developed true coelom

Internal organs: well-developed

Nephridia -Excretion of metabolic wastes &

osmoregulation

Closed circulatory system

Monoecious/dioecious

Development- direct with no larval stages

Polychaeta

Free-living marine worms

Ragworms/clam worms- Nereis

Polychaetes – ‘many setae/ chaetae

Well-developed

head, sense organs , eye, antennae &

sensory palps

Fertilisation – external &

development

proceeds indirectly through trochophore larva

Hirudinea

 Leeches-most specialized

 freshwater & marine water, many found in tropical region

 Dorso-ventrally flattened annelids with suckers at both ends.

 Have setae nor parapodia

 Fixed number of segments- 34

 Coelom -not divided by septa & filled with muscle & connective tissues

 Carnivorous / parasitic Oligochaeta

 Earthworm; Pheretima

 No parapodia- only 8 small setae per body segment

 Complex digestive system

 No well-developed head.

Simple brain & nerve cord

 No respiratory organ.

Oxygen & carbon dioxide diffuse directly through its skin

 Hemaphrodites-have both testes & ovaries

 Require 2 worms to mate & reproduce

Annelida

Phylum Arthropoda

 Largest phylum

triploblastic, coelomate & bilaterally symmetrical

Exhibit metameric segmentation

Covered by chitinous exoskeleton-provides support & protection

Have paired jointed appendages

Growth by ecdysis/moulting

Have complete digestive tract with specialized mouth parts

Body divided into head, thorax & abdomen

Open circulatory system with dorsal heart

& arteries

Respiration –body surface, gills ( aquatic), trachea/ lungs

Well developed central nervous system

Factors contributing to the success of arthropods:

Segmentation/metamerism

Exoskeleton

Paired & jointed appendages

Well-developed sense organs

Variety of respiratory organs

metamorphosis

Chilopoda

 Centipede (hundred- leggers)

 Dorso-ventrally flattened & fast moving terrestrial predators

 Divided into 2 regions : head &

trunk

 First pair of legs modified as

venomous fangs- capture prey

 Long bodies

composed of 14-20 segments

 E.g. Scolopendra

Diplopoda

 Millipedes

 Lack poisonous fangs

& do not bite

 Most -herbivores/

scavengers

 Habitats: decaying plant & animal matter in moist microhabitats

 Long bodies composed of 50

segments-each has 2 pair of legs

Crustacea

 Decapods-familiar &

numerous

 Shrimp, lobsters, crayfish

& crabs

 Respiratory system – gills

 Have 10-14 legs

 Have 2 body region:

cephalothorax &

abdomen

 Have 2 pair of antennae

 E.g. Macrobrachium

Arthropoda

Arachnida

8 legged

Scorpions, spiders, ticks

& mites

Have 2 body regions:

cephalothorax

(prosoma) & abdomen (opisthosoma)

Has 6 pairs of

appendages-first pair of appendages modified into pincer-like/ fang- like structure

(chelicerae)

Respire –trachea/ book lungs)

No antennae/ wings

Carnivorous

Merostomata Merostomes –extinct Horseshoe crabs 9 Tachypleus sp.

Body covered by carapace

Divided into 2 regions:

cephalothorax &

abdomen

First pair-feeding legs (pedipalps)

Have book gills- exchange of gaseous

Telson –long, spike-like tail –locomotion.

Insecta

 Great majority &

successful group

 Head, thorax & abdomen

 Nervous system complex:

ganglia, ventral, double nerve cord

 Dioecious & mostly internal fertilization

 Undergo complete &

incomplete

metamorphosis

 Respiratory system – system of internal tubes

& sac

 Malpighian- Excretion of nitrogenous waste

Arthropoda

Phylum Mollusca

Molluscs

Triploblastic & bilaterally symmetrical, coelomate animals

Complete digestive tract and ciliated with mouth , anus & complex stomach

Complex nervous system

Open circulatory system

Soft body-protected by hard shell-calcium carbonate

Squids, slugs ,octopuses

Head-foot / muscular foot, visceral mass &

mantle

Toothed tongue (radula)

Pass through one or more larval stages.

Cephalopoda

Head foot ; squid &

octopus

Has complex brain

Completely merged &

foot ,with ring of arms /tentacles

surrounding head

Arm ,tentacles &

funnel –derivatives of foot

Horny beak by walls of buccal cavity & radula within buccal cavity

Sac-release a black fluid when they are threatened /excited

Bivalvia

 Clams, oysters, mussels & scallops

 Shell consisting of 2 rounded plates- valves joined at one edge by flexible ligament -

hinge

 No head, very little cephalization & no radula

 Foot is present but laterally compressed

 Large mantle cavity with ciliated gills

 Filter feeders Gastropoda

 Largest group

 Snails, whelks & slugs

 Well-developed head region, eyes & tentacles project from coiled shell

 Gills in mantle cavity of aquatic gastropods,

mantle functions as lungs in terrestrial

 Single, spirally-coiled shell-can withdrawn ut the shell is lost /reduced in some groups; slugs

Mollusca

Phylum Echinodermata

Marine organisms

Triploblastic, coelomate & unsegmented

Simple animals, lacking brain & complex sense organs

Start off as bilaterally symmetrical larvae but later come radially symmetrical adults

Presence of internal skeleton covered with spines & skins

Water vascular system, ending in tube feet

Extend /contract its tube feet for

locomotion ,food collection & respiration.

Some –carnivorous & scavenge the oceon floor, others –filter feeders

Reproduction-usually sexual but several reproduce asexually

Holothuroidea

no

Radial symmetry

Bilateral symmetry with dorsal & ventral sides

Sea cucumbers

Elongated, muscular &

flexible body with mouth at one end &

anus at the other

Tentacles- feeding

Tube feet- locomotion

Echinoidea

 Sea urchins

 Radially symmentry body with external chitinous skeleton

 Mouth –underside of body

 Anus –upperside of animal

 Aristotle’s lantern- consist of 5 strong teeth –allow to scrape algae off rocks

 Skeleton –test-rigid shell made of flat &

fused calcareous ossicles

Asteroidea

 Sea stars- starfish

 Five arm radiating from central discwith mouthon underside

 Water vascular system- locomotion

 Made of embedded ossicles-form internal framework to support connective tissues

 Reproduce : asexually- by regeneration & sexually

Echinodermata

Crinoidea

Feather star

Ophiuroidea

 Brittle stars

 Most mobile, fragile &

inconspicuous group

 Have distinct central disc

 Tube feet lack suckers

 Have no anus, waste eliminated through

mouth-underside centre

 Skeleton made of calcareous plates (ossicles) embedded beneath their skin

Echinodermata

Phylum Chordata

Well known vertebrates: fishes, reptiles, amphibians , birds and mammals

A dorsal supporting rod- notochord - Located just below nerve cord

Dorsal tubular nerve cord

Pharyngeal pouches or slits

A post-anal tail

Myotomes

Osteichthyes

Bony fish, most numerous

Habitat: salt &

freshwater

Fish-gills covered by operculum

Few have lungs

Swim bladder-air sac – control buoyancy

Sharks, bony fish-hold still at any depth &

not sink

Amphibia

 Lives in both water &

land

 Newts,salamanders, frogs, toads & caecilians

 Tetrapods (4 limbs) – able to move on land

 Thin, soft , moist & lack scales except in

caecilians

 Ectothermic (cold- blooded)

 Gills (larvae stage) &

lungs (adult stage

 3 chambered heart-2 atria & 1 ventricles

 Complex

metamorphosis as grow into adulthood

Chondrichthyes

 Cartilaginous fish- sharks, skates & rays

 Have cartilage skeleton rather than bones

 Lack swim bladder –helps stay buoyant in water

 Have lateral line system- detects differences in water pressure.

 Lack gill cover (operculum)-found in bony fish

 Pectoral fins –enlarged into large, wing –like fins

 Sharks & rays reproduce by passing sperm from male to female using claspers.

Vertebrates

Aves

Bird-ability to fly & lay eggs

Endothermic

Skin covered with feathers

Feathers used in flight, temperature regulation &

colouration (display &

camouflage)

Four-chambered heart

Their bones –

lightweight & hollow

Forelimbs-modified as wings

Mammalia

 3 middle ear bones, hair & production of milk (not found in other animals)

 Differentiate teeth &

developed brain

 Endothermic &

homeothermic with separate sexes

 Live in terrestrial &

aquatic habitats

 Monotremes (egg- laying mammals)

 Marsupials (mammals with pouches)

 Eutherian (placenta mammals)

Reptilia

 Turtles, snakes, lizards &

crocodiles.

 Amniotes

 Horny epidermal scales – protect them from

abrasion & loss of body moisture.

 Breathe-lungs , many turtles –use moist

surface of their cloaca for gas exchange

Vertebrates