SEAWEEDSEAWEED(Marine Algae =(Marine Algae =

multicellularalgae)multicellularalgae)

Types of AlgaeTypes of Algae

Chlorophyta = Chlorophyta = GreenGreenPhaeophyta = Phaeophyta = BrownBrownRhodophyta = Rhodophyta = RedRed

REPRODUCTION OF REPRODUCTION OF SEAWEEDSEAWEED

FragmentationFragmentation-asexual reproduction in -asexual reproduction in which the thallus breaks up into pieces, which the thallus breaks up into pieces, which grow into new algae.which grow into new algae.

Through spore formationThrough spore formation:-:- haploid spores ae formed are within an haploid spores ae formed are within an

area of the thallus(sporangium) through area of the thallus(sporangium) through meoisismeoisis

Sporophyte- stage of the life cycle that Sporophyte- stage of the life cycle that produce spores which is diploidproduce spores which is diploid

Cont..Cont..

OedogoniumOedogonium is a multicellular, is a multicellular, filamentous filamentous green algaegreen algae with specialized with specialized cells called gametangia that form cells called gametangia that form gametesgametes

The male gametangia or antheridium The male gametangia or antheridium makes sperm, & the female gametangia makes sperm, & the female gametangia or oogonium makes eggsor oogonium makes eggs

Sperm are released into the water & Sperm are released into the water & swim to the egg to fertilize themswim to the egg to fertilize them

Cont..Cont..

The fertilized egg or zygote is released The fertilized egg or zygote is released from the oogonium & forms thick-walled from the oogonium & forms thick-walled zoospores Zoosporeszoospores Zoospores

undergo meiosis so one cell attaches to undergo meiosis so one cell attaches to the bottom & develops a holdfast while the bottom & develops a holdfast while the other zoospores divide & form a the other zoospores divide & form a filamentfilament

OedogoniumOedogonium Life Cycle Life Cycle

Conjugation Tube between Conjugation Tube between SpirogyraSpirogyra

SpirogyraSpirogyra, another filamentous green algae, , another filamentous green algae, reproduces by conjugationreproduces by conjugation

Two filaments align side by side, their Two filaments align side by side, their adjacent cell walls dissolve, & a conjugation adjacent cell walls dissolve, & a conjugation tube forms between themtube forms between them

Fertilization occurs when a + gamete cell Fertilization occurs when a + gamete cell moves through the tube & fuses to the - moves through the tube & fuses to the - gamete cell gamete cell 

Zygote forms a thick walled spore Zygote forms a thick walled spore (sporangium) that breaks away from the (sporangium) that breaks away from the parent & forms a new filamentparent & forms a new filament

Conjugation Tube between Conjugation Tube between SpirogyraSpirogyra

Cont..Cont..

Sexual reproductionSexual reproduction Gametes fuses to form a diploid Gametes fuses to form a diploid

zygotezygote Gametophyte- stage of the life cycle Gametophyte- stage of the life cycle

that produce gametes that produce gametes Gametangia- structure where Gametangia- structure where

gametes are typically produced.gametes are typically produced.

Alternation of generationAlternation of generation The adult seaweed plant cells are The adult seaweed plant cells are

diploiddiploid,contain two sets of ,contain two sets of chromosomes.chromosomes.

Diploid plants, Diploid plants, sporophytessporophytes, produce , produce and release haploid spores ,by and release haploid spores ,by meiosis(n)meiosis(n)

the haploid spores settle and grow the haploid spores settle and grow into into gametophytesgametophytes

• The gametophytes produce sperm or The gametophytes produce sperm or eggs. eggs.

• When the sperm and eggare When the sperm and eggare fused fused togethertogether(diploid cell) , and as the (diploid cell) , and as the zygotes develop into diploid zygotes develop into diploid sporophytes, the cycle continues.sporophytes, the cycle continues.

Alternation of generationsAlternation of generations

The Green Algae(chlorophyta)The Green Algae(chlorophyta)

Have the same pigments as land Have the same pigments as land plantsplants

Have Have chlorophyll a and bchlorophyll a and b Marine algae are “macro”Marine algae are “macro” Reproduction-Reproduction-Alternation of Alternation of

generationsgenerations(2 or more separate (2 or more separate multicellular stages)multicellular stages)

motile ,have two apical or subapical motile ,have two apical or subapical flagellaflagella

AcetabulariaAcetabularia

CaulerpaCaulerpa spsp..

Caulerpa spCaulerpa sp..

Caulerpa floridanaCaulerpa floridana

Caulerpa racemosaCaulerpa racemosa

Caulerpa Caulerpa spsp..

Caulerpa sp.Caulerpa sp.

Chaetomorpha sp.Chaetomorpha sp.

Halimeda Halimeda sp.sp.

Udotea sp.Udotea sp.

Ventricularia sp.Ventricularia sp.

Ulva lactucaUlva lactuca

Life cycle Life cycle ulva sp.ulva sp.

Phaeophyta(brown algae)Phaeophyta(brown algae) Largest and most complex of the Largest and most complex of the

algaealgae All are marineAll are marine Have Have chlorophyll a chlorophyll a and and cc Brown color comes from accessory Brown color comes from accessory

pigments (pigments (fucoxanthinfucoxanthin))

have evolved an interesting type of alternation of generations, in which physiologically independent haploid gametophyte plants produce gametes, the fusion of which initiates the diploid sporophyte generation. 

DictyotaDictyota

FucusFucus

LaminariaLaminaria

PadinaPadina

TurbinariaTurbinaria

SargassumSargassum

KelpKelp

Life cycle fucusLife cycle fucus

Rhodophyta(red algae)Rhodophyta(red algae) Greek word “Rhodos” = Greek word “Rhodos” = RedRed Have Have chlorophyll achlorophyll a and and dd Accessory Accessory pigment phycoerythrin pigment phycoerythrin gives the gives the

red color plus allows them to survive at red color plus allows them to survive at greater depths.greater depths.

Phycoerythrins are also found in cyanobacteriaPhycoerythrins are also found in cyanobacteria not flagellated; none has motile cells of any not flagellated; none has motile cells of any

kind.kind. extremely complex, involving one haploid extremely complex, involving one haploid

phase and two diploid phasesphase and two diploid phases

HalimeniaHalimenia sp. sp.

Halimenia sp.Halimenia sp.

RenouxiaRenouxia sp. sp.

RhodogrodonRhodogrodon sp.sp.

SebdeniaSebdenia sp. sp.

TrichoglowiaTrichoglowia sp. sp.

Corraline red algaCorraline red alga

HydrolythonHydrolython sp. sp.

PeyssonelliaPeyssonellia sp. sp.

Life cycle red algaeLife cycle red algae