Transcript BI 102 Lecture 8 Other major algal phyla in Kingdom protista

School of Sciences, Lautoka Campus
BIO509 Botany Lecture 7: Other major
algal phyla in Kingdom Protista
Other major algal phyla in
Kingdom protista apart from
green algae
Phylum Chromophyta
Phylum Rhodophyta
Phylum Euglenophyta
Phylum Dinophyta
Phylum Charophyta
Learning outcomes
• Know the distinguishing features of Chromophyta,
Rhodophyta, Dinophyta and Euglenophyta and
Charophyta.
• Understand why Chromophyta, Rhodophyta,
Dinophyta and Euglenophyta and Charophyta are
different from Chlorophyta.
• Know the structure and function of holdfast, stipes,
blades, bladders and thalli.
• Understand and appreciate the importance of these
algae.
Phylum Chromophyta
• Phylum Chromophyta
• Roughly 7600 species.
• Mostly unicellular or colonial, few filamentous and tissue
like forms.
• Have chlorophyll a and c, the colour of which is largely
masked by abundance of pigment known as fucoxanthin.
• Food reserves are stored as oils, fats, mannitol and
laminarian.
• Reproduction is asexual (fragmentation and zoospore
formation and sexual (alternation of generations).
Phylum Chromophyta has several classes
that share the several features
Vaucheria
Xanthophyceae
- yellow green algae
Dictyocha
Chrysophyceae
-
Golden-brown algae
Diatoms
Bacillariophyceae
-
Diatoms
Phaeophyceae
- Brown algae
Sargassum
Diatoms
Around 5,600 living species
Freshwater and marine inhabitants,
some are terrestrial.
Unicellular
Two part cell wall structure known as
frustules
95% of cell wall content is silica.
May have one, two or many
chloroplasts – chlorophyll a, c1 and c2
Lack flagella
Have fine groves and pores which aid
in movement.
Reproduction
Mainly asexual
Half of cells become progressively smaller through several
generations until the original size is restored through a
sexual process. Zygotes are known as auxospores
Human and Ecological relevance
• Diatoms are important components of phytoplankton.
• Primary source of food for many aquatic organisms.
• Diatoms form diatomaceous earth which is widely used in a
variety of industrial and domestic uses.
• When in high concentration can be destructive to fish.
Brown algae
More than 1,500 species of seaweeds.
Multicellular body, but not organized
into leaves and stems.
Have holdfast, stipe and blades thallus.
Stipe often hollow structure has food
conducting cells.
Blades are photosynthetic.
Fucoxanthin, chlorophyll a and c.
Main food reserve is laminarian.
Asexual reproduction by
fragmentation
Sexual reproduction involves
alternation of generations.
Human and Ecological relevance
• Good iodine source.
• High in nitrogen and potassium and
used as fertilizer.
• Used as livestock feed.
• Used as food
• Kelp produces algin that has the
unique ability to regulate water
‘behaviour’ in a number of products:
e.g. ice cream, salad dressing, beer,
jelly beans, latex paints, penicillin
suspension, etc.
Phylum Rhodophyta
• About 4000-6000 species.
• Mostly filamentous.
• Contains chlorophyll a that is
masked by a pigment known as
phycobillin and give the algae a
red colour.
• Main food reserve is floridean
starch and maninitol
• Complex life cycle, involves
alternation of 3 generations –
gametophyte, carposporophyte
and tetrasporophyte
Human and Ecological relevance
• Used a food. Porphyra species –
nori.
• Agar – is produced by the red alga
Gelidium. It has gelatin-like
consistency and is used in
laboratories and media laboratories
as a culture medium for growth of
bacteria. It is also used in tissue
culture.
• Bulking and thickening agent.
• Contain a number of substances of
potential medicinal value.
• Gracilaria species
Phylum Euglenophyta – the Euglenoids
• About 900 species.
• Unicellular.
• Mostly occur in freshwater, some
are marine.
• Have chlorophyll a and b.
• Main food reserve is paramylon.
• Have single flagellum, contractile
vacuole and red eyespot.
• Reproduction is asexual by binary
fission.
Phylum Dinophyta – the Dinoflagellates
• About 2000- 4000 species.
• Unicellular biflagellate, bizarre in
appearance.
• Have stiff cellulose plates forming a
wall or theca.
• Contain chlorophylls a and c that is
masked by pigment known as
peridinin.
• Store food as starch.
• Reproduction is by cell divison.
• Sexual reproduction is very rare.
Human and Ecological relevance
• Cause toxic red tides that are
harmful to fish and humans.
• Many dinoflagellate species are
bioluminescent.
Phylum Charophyta – the Stoneworts
Occurs as extensive meadows in
freshwater lakes and streams
with low phosphate
concentrations.
Branched filaments differentiated
into apex, nodes, basal region.
A single apical meristematic cell is
responsible for length growth
Have chlorophyll a and b and store
food as starch.
Reproduction is primarly sexual.
Oogonium
Sexual reproduction is
oogamous, antheridia are
multicellular.
haplontic life cycle with
anisomorpic gametes
gametangia are covered with a
protective, non-reproductive
cell layers for protection, these
cells originate from node cells
Antheridium
Mature antheridia are bright
orange due to carotene in an
outer layer of cells; biflagellated
spermatozoids are produced in
long strings
Oogonia produce a single egg
cell, protected by tube cells and
crown cells
The zygote forms with a thick,
dark-brown wall; the zygote is
released when the parent dies
Meiosis in the zygote but
probably only a single cell
survives
Attaches to substrate and new
adult develops
Readings
Chapter 18
Stern’s Introductory Plant Biology
Questions??