Division PHAEOPHYTA

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Division PHAEOPHYTA the Brown Algae
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Brown Algae (Division PHAEOPHYTA) Some General
Characteristics
Almost all are marine Contain Chlorophyll a
and c, fucoxanthin and other carotenoids Have
cell walls of cellulose, alginic acid and
sulphated polysaccharides The carbohydrates
stored are laminarin and mannitol Flagella are
two, and lateral, the anterior one tinsel and
the posterior whiplash
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Typical Brown Algal Zoöspore
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Filamentous Brown Algae, e.g. Ectocarpus
(filaments with plurilocular and unilocular
sporangia)
ltPlurilocular sporangium
ltUnilocular sporangium
Habitat - Ocean shores, on rocks and larger
seaweeds, worldwide
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Sporophytegt
Diploid
n.b. MEIOSIS occurs in UNILOCULAR sporangia and
MITOSIS in PLURILOCULAR sporangia
Fertilization
Diploid zoöspores
Meiosis
Haploid
Gametes
Life History of Ectocarpus - Isomorphic
Alternation of Generations
Mitosis
Haploid zoöspores
Gametophytegt
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Large, Thalloid Brown Algae (Kelps) exhibiting
Sporic Meiosis and Heteromorphic Alternation of
Generations e.g. Laminaria (from Raven)
Male zoöspore (n)
Unilocular sporangium
Male gametophyte
Female zoöspore (n)
MEIOSIS
Blade
Female gametophyte
Sperm
Egg
Fertilization
Stipe
Zygote
Holdfast
Mature sporophyte
Developing sporophyte
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Macrocystis - the Giant Kelp of the West
Coast of N. America
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Macrocystis pyrifera grows to up to 150 feet in
length off the West Coast of N.A., but has a
life span of only 5 years.
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Brown Algae exhibiting Gametic Meiosis and
Oögamy, e.g. Fucus vesiculosus (the common
rockweed)
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The Life History of Fucus, the Rockweed (from
Raven) n.b. gametic meiosis is relatively rare
in plants
Floating egg sac
8 eggs in oögonium
Meiosis
Antheridia
Sperm packet
Conceptacle
c.s. receptacle
Fertilization
Diploid individual
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A tropical relative of the Rockweeds - Sargassum
n.b. floats are on separate branches. Two
species of Sargassum (S. natans and S. fluitans,
are free-floating, and are not know to reproduce
sexually. Typical of the Sargasso Sea, and known
as Sargasso Weed or Gulf Weed.
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Traditional and Economic Uses of Brown Algae
In Europe, kelps and rockweeds were burned for
their soda, used in glazing and glass making,
from the 17th Century. In the early 19th Century,
iodine was extracted from kelp ash. Algin, first
discovered in the 1880s, is a complex organic
compound used in dozens of different products,
including toothpaste, ice cream, milk shakes and
textiles. In parts of Europe, kelps and rockweeds
are used as manure, and occasionally as livestock
feed. The Japanese use Laminaria spp. to make
Kombu and another brown alga, Undaria, to make
Wakame
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Red Algae (Division RHODOPHYTA) Some General
Characteristics
Mostly marine, a few freshwater Contain
Chlorophyll a, carotenoids phycobilins
(especially PHYCOERYTHRIN) Have cell walls of
cellulose, pectin and calcium salts The
carbohydrate stored is floridean starch There
are no flagellated stages
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Branched, Filamentous Red Algae, e.g.
Polysiphonia lanosa Epiphytic on one of the
Rockweeds (Ascophyllum nodosum)
ltAscophyllum
ltPolysiphonia
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Peculiarities of the Life Cycle of Polysiphonia
TWO sporophytic and one gametophytic phase
The oögonium has a unique appearance and
function, and is therefore called a CARPOGONIUM
Because the male gametes are non-motile, they are
known as SPERMATIA The first sporophytic phase,
known as the CARPOSPOROPHYTE, is small, and
remains attached to the female gametophyte. It
produces CARPOSPORES by mitosis Carpospores
germinate into TETRASPOROPHYTES, which look like
the gametophyte, but produce haploid TETRASPORES
by meiosis.
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Life History of Polysiphonia (from Moore) (n.b .
TRICHOGYNE)
Meiosis
Trichogyne
Spermatangium
Tetraspores (n)
Tetrasporangia
Tetrasporophyte
HAPLOID
Carpogonium with egg
Spermatia
Male gametophyte
Female gametophyte
Fertilization
Carpospores (2n)
Zygote nucleus migrates
DIPLOID
Carposporophyte
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Corallina, encrusted with calcium and magnesium
carbonate, contributes to reef formation
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Porphyra (Nori, Laver), a Red Alga Widely
Consumed as Food
Planting Brush Bundles
Growth Habit
Drying as Sheets on Bamboo Splints
Washing the Nori
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Dulse (Rhodymenia palmata), a Tasty Snack Food
in Ireland and Nova Scotia
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Irish Moss, Black Moss or Carrageen (Chondrus
crispus), a Source of carrageenin, used for many
of the same purposes as algin (ice cream,
cosmetics etc.)
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Agar-agar - the Product of a Number of Red Alga
genera, including Gelidium and Gracilaria
Gracilaria
Gelidium
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Division CHRYSOPHYTA The Golden-brown Algae,
Diatoms and Yellow-green Algae
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Division CHRYSOPHYTA Some General
Characteristics
Marine or freshwater some terrestrial
Contain chlorophyll a and c, fucoxanthin and
other carotenoids (cf. brown algae, to which they
are closely related) Have cell walls of
cellulose or a silica shell sometimes absent
The carbohydrate stored is chrysolaminarin
Flagella are none, one or two, whiplash or tinsel
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Division CHRYSOPHYTA Class Bacillariophyceae
The Diatoms
Mostly unicellular with unique box-like,
ornamented wall of pectin impregnated with silica
May be bilaterally symmetrical (pennate) or
radially symmetrical (centric)
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SEMs (Scanning Electron Micrographs) of Pennate
and Centric Diatoms
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Valve and Girdle Views of Pennate and Centric
Diatoms
Girdle
Valve
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Locomotion in Pennate Diatoms
Crystalline substances secreted by pores take up
water, forming sticky fibres which expand along
the central groove called the RAPHE. They adhere
to anything they touch, then contract, dragging
the cell along.
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Pennate Diatom Life History
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Economic and Scientific Importance of Diatoms
An important component of the aquatic food
chain Frustules mined as DIATOMACEOUS EARTH
(Kieselguhr), used as an abrasive and in
filters The fine markings on the frustule can
be used in the calibration of optical equipment
Used in the palaeobiology of lake sediments
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Division CHRYSOPHYTA Class
Chrysophyceae The
Golden-Brown Algae
Since these are rarely encountered in great
numbers, we shall only concern ourselves with an
interesting colonial representative, Dinobryon
Each cell divides longitudinally and one product
migrates to the edge of the lorica, and forms one
of its own
The protoplast is naked and the LORICA is of a
firm gelatinous material similar to pectin.
The longer flagellum is tinsel, the shorter
whiplash
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Division CHRYSOPHYTA Class
Xanthophyceae
The Yellow-Green Algae
Vaucheria, the Water-Felt
Forms mats in quiet pools, running water, or
on greenhouse flower pots Coenocytic Forms
large, multiflagellate (compound) zoöspores
Oögamous, with large gametangia
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Vaucheria
Gametangia (Antheridium and Oögonium) and
Fertilization
Zoöspore Formation
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Division PYRROPHYTA the Dinoflagellates
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Division PYRROPHYTA Some General Characteristics
Marine or freshwater Contain chlorophyll a
and c, peridinin and other carotenoids Cell
wall of armor-like cellulose plates sometimes
absent The carbohydrate stored is starch
Flagella two, lateral, tinsel, one belt-like, one
trailing
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The armor-plating of Dinoflagellates
Sculpturing of the thecae
Peridinium and Gonyaulax
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Red Tides
Blooms of Gymnodinium breve cause fish death,
e.g. off the Florida gulf coast Blooms of
Gonyaulax can poison molluscs and other
invertebrates Blooms of Gonyaulax tamarensis
(east coast) and Gymnodinium catenella (west
coast) cause PSP (paralytic shellfish poisoning)
in humans and other vertebrates, due to
concentration of the toxins by filter-feeders
The toxins involved are nerve poisons
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Bioluminescence in Dinoflagellates
Can be a persistent glow or flashes of light
when water is disturbed Generation of light
requires ATP, oxygen, the substrate LUCIFERIN and
the enzyme LUCIFERASE
The function of bioluminescence in
dinoflagellates remains an enigma
Noctiluca
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Symbiosis in Dinoflagellates and Closely-Related
Cryptomonads -
Zooxanthellae
Found in sponges, jellyfish, sea anemones,
corals, flatworms, etc. In case of corals, they
provide carbon dioxide, protection and nutrients
(wastes) In case of algae, they provide oxygen,
waste removal carbohydrates
Zooxanthellae in coral
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Division EUGLENOPHYTA the Euglenoids
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Division EUGLENOPHYTA Some General
Characteristics
Marine or freshwater Contain chlorophyll a
and b, carotenoids Cell-wall absent cell
surrounded by a flexible PELLICLE or PERIPLAST
The carbohydrate stored is paramylon Flagella
1-3, tinsel
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Euglena
--Flagellum
---Canal
---Reservoir
Stigma--
c.v.---
--Chloroplast
--Paramylum
n.b. paramylum periplast
--Nucleus
Periplast--
n.b. single flagellum
c.v. Contractile Vacuole
n.b. changing shape
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Some new terms that you have encountered in
Lecture 2
Unilocular and plurilocular sporangia Holdfast,
stipe and lamina or blade Receptacle and
conceptacle Carpogonium and trichogyne Spermatangi
um and spermatia Carposporophyte and
carpospores Tetrasporophyte and tetraspores
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More new terms from Lecture 2
Pennate and centric (diatoms) Frustule Raphe Valve
and girdle view Auxospore Lorica Thecae
(epitheca and hypotheca) Paralytic shellfish
poisoning (PSP) Bioluminescence
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and more...
Pellicle or periplast Contractile vacuole
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Photosynthetic Pigments, Cell Wall Constituents
and Carbohydrates Stored in the Algae
For a summary of these features, see Table 27.1
in Moore, Clark Vodopich