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Title: Lecture 2


1
Lecture 2 The Seaweeds
  • The Green Algae Chlorophyta (a few)
  • The Brown Algae Phaeophyta
  • The Red Algae - Rhodophyta

Campylaephora
Durvillaea
Cymopolia
2
But firstQAs
  • How many tons of algae produce how much O2?
  • Good question. 330 billion tons of O2?
  • Total primary production by algae in the oceans
    45-50 billion tons of carbon per year (c.f.
    45-68 Gt C/yr for land plants)
  • Algae-L !!!

3
http//www.gsfc.nasa.gov/gsfc/earth/pictures/20020
801plankton/greylandm.jpg
Phytoplankton concentrations have declined
substantially in northern oceans since the early
1980s. This world map compares satellite
data collected during the summer (July-September)
between 1979 and 1986 and 1997 to 2000 and
reflects the changes in phytoplankton
concentrations over the last 20 years in the
open ocean (away from the coast). Deep blues
show the greatest loss of phytoplankton, yellow
represents almost no change and browns, reds and
oranges show phytoplankton increases. Black
indicates that no data is available.
4
Lecture 2 The Seaweeds
  • The Green Algae Chlorophyta (some)
  • The Brown Algae Phaeophyta
  • The Red Algae - Rhodophyta

Campylaephora
Durvillaea
Cymopolia
5
The Chlorophyta - The Green Algae
Acetabularia (The Mermaids Cup) a siphonaceous
marine alga
6
General Information on the Chlorophyta 1.
Excludes Euglenophyta and Chlorarachniophyta and
includes the Charophyta sensu stricto
(Charales)
7
General Information on the Chlorophyta 1.
Excludes Euglenophyta and Chlorarachniophyta and
includes the Charophyta sensu stricto
(Charales) 2. Approx. 10 are marine, 90 are
freshwater
8
General Information on the Chlorophyta 1.
Excludes Euglenophyta and Chlorarachniophyta and
includes the Charophyta sensu stricto
(Charales) 2. Approx. 10 are marine, 90 are
freshwater 3. The basic taxonomy has been
altered by new results (from molecular
studies)
9
General Information on the Chlorophyta 1.
Excludes Euglenophyta and Chlorarachniophyta and
includes the Charophyta sensu stricto
(Charales) 2. Approx. 10 are marine, 90 are
freshwater 3. The basic taxonomy has been
altered by new results (from molecular
studies) 4. Many of the basic features of the
green algae will parallel features in other
groups
10
General Information on the Chlorophyta 1.
Excludes Euglenophyta and Chlorarachniophyta and
includes the Charophyta sensu stricto
(Charales) 2. Approx. 10 are marine, 90 are
freshwater 3. The basic taxonomy has been
altered by new results (from molecular
studies) 4. Many of the basic features of the
green algae will parallel features in other
groups 5. 6,000-8,000-20,000 species (spp.) of
green algae??
11
General Information on the Chlorophyta 1.
Excludes Euglenophyta and Chlorarachniophyta and
includes the Charophyta sensu stricto
(Charales) 2. Approx. 10 are marine, 90 are
freshwater 3. The basic taxonomy has been
altered by new results (from molecular
studies) 4. Many of the basic features of the
green algae will parallel features in other
groups 5. 20,000 species (spp.) of green
algae?? 6. The big four
12
The big four
13
The big four I. Cells Walls if present
cellulose (cf., higher plants)
14
The big four I. Cells Walls if present
cellulose (cf., higher plants) (may be calcified
or have a pectinaceous i.e. gelatinous outer
layer
15
The big four I. Cells Walls if present
cellulose (cf., higher plants) (may be calcified
or have a pectinaceous i.e. gelatinous outer
layer or include sporopollenin or have
polysaccharides other than cellulose)
16
The big four I. Cells Walls if present
cellulose (cf., higher plants) (may be calcified
or have a pectinaceous i.e. gelatinous outer
layer or include sporopollenin or have
polysaccharides other than cellulose) (may be
replaced by a pellicle)
17
The big four I. Cells Walls if present
cellulose (cf., higher plants) (may be
calcified or have a pectinaceous i.e.
gelatinous outer layer or include sporopollenin
or have polysaccharides other than
cellulose) (may be replaced by a pellicle)
II. Pigments (cf. higher plants) A. chls a
b B. carotenes C. carotenoids (also
non-photosynthetic pigments - phytochromes)
18
The big four I. Cells Walls if present
cellulose (cf., higher plants) (may be calcified
or have a pectinaceous i.e. gelatinous outer
layer or include sporopollenin or have
other polysaccharides) (may be replaced by a
pellicle) II. Pigments (cf. higher
plants) A. chls a b B. carotenes C.
carotenoids (also non-photosynthetic pigments -
phytochromes) III. Storage Products (cf.,
higher plants) A. true starch (IKI positive)
amylose unbranched with some amylopectin
branched stored in the chloroplast B.
lipids etc.
19
The big four continued . . . IV.
Flagella A. 1, 2, 4, 8, or more (multiples of
two) stephanokont (e.g. Oedogonium) stephano
crown-like, kont oar
20
The big four continued . . . IV.
Flagella A. 1, 2, 4, 8, or more (multiples of
two) stephanokont (e.g. Oedogonium) stephano
crown-like, kont oar
21
The big four continued . . . IV.
Flagella A. 1, 2, 4, 8, or more (multiples of
two) stephanokont (e.g. Oedogonium) stephano
crown-like, kont oar
22
The big four continued . . . IV.
Flagella A. 1, 2, 4, 8, or more (multiples of
two) stephanokont (e.g. Oedogonium) stephano
crown-like, kont oar
23
The big four continued . . . IV.
Flagella A. 1, 2, 4, 8, or more (multiples of
two) stephanokont (e.g. Oedogonium) stephano
crown-like, kont oar B. generally isokont
(with exceptions) iso equal, kont
oar simple or whiplash (acronematic) acro
tip, nema thread some pleuronematic (e.g.
Haematococcus) pleuro multiple, nema
thread
24
The big four continued . . . IV.
Flagella A. 1, 2, 4, 8, or more (multiples of
two) stephanokont (e.g. Oedogonium) stephano
crown-like, kont oar B. generally isokont
(with exceptions) iso equal, kont
oar simple or whiplash (acronematic) acro
tip, nema thread some pleuronematic (e.g.
Haematococcus) pleuro multiple, nema
thread
Haematococcus (haem blood, coccus berry) the
bird bath alga
25
Haematococcus
26
The big four continued . . . IV.
Flagella A. 1, 2, 4, 8, or more (multiples of
two) stephanokont (e.g. Oedogonium) stephano
crown-like, kont oar B. generally isokont
(with exceptions) iso equal, kont
oar simple or whiplash (acronematic) acro
tip, nema thread some pleuronematic (e.g.
Haematococcus) pleuro multiple, nema
thread C. generally anteriorily inserted
flagella the number, type, and mode of
insertion
27
Chlorophyta - Additional Characteristics 1. True
eukaryotes uninucleate, multi- nucleate
coenocytic siphonaceous
Multinucleate, coenocytic
Uninucleate, multicellular
nucleus
Multinucleate, siphonaceous
28
Chlorophyta - Additional Characteristics 1. True
eukaryotes uninucleate, multi- nucleate
coenocytic siphonaceous 2. Principal vegetative
phase 1n or 2n
29
Chlorophyta - Additional Characteristics 1. True
eukaryotes uninucleate, multi- nucleate
coenocytic siphonaceous 2. Principal vegetative
phase 1n or 2n 3. Sexual reproduction
anisogamy
isogamy
egg
?sperm
oogamy
30
Chlorophyta - Additional Characteristics 1. True
eukaryotes uninucleate, multi- nucleate
coenocytic siphonaceous 2. Principal vegetative
phase 1n or 2n 3. Sexual reproduction isogamy,
anisogamy, oogamy
Why? Why?
31
Chlorophyta - Additional Characteristics 1. True
eukaryotes uninucleate, multi- nucleate
coenocytic siphonaceous 2. Principal vegetative
phase 1n or 2n 3. Sexual reproduction isogamy,
anisogamy, oogamy 4. Asexual reproduction
fragmentation, zoospore production,
aplanospore production (akinetes)
32
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33
The Big Four composition of the walls and the
storage compounds, the types of pigments, and
flagellar information (number, type, and mode of
insertion)
Three major features are biochemical. The fourth
is morphological.
34
Another important topic is alternation
of generations (those 1n haploid and 2n
diploid stages in the life cycles).
But more on that later.
Background algae Acetabularia (the mermaids
cup)
35
Common green seaweeds
Ulva (sea lettuce)
36
Cladophora
37
Enteromorpha
38
Codium (an east coast weed siphonaceous
moving north)
39
Caulerpa
40
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41
The Phaeophyta - The Brown Algae
The Macho Algae
42
The Brown Algae
1. seaweeds - generally large, complex thalli
some small filaments (no unicells or colonies)
43
The Brown Algae
1. seaweeds - generally large, complex thalli
some small filaments (no unicells or
colonies) 2. almost all are marine (maybe 6 FW
genera)
44
The Brown Algae
1. seaweeds - generally large, complex thalli
some small filaments (no unicells or
colonies) 2. almost all are marine (maybe 6 FW
genera) 3. chlorophylls a c, beta carotene,
fucoxanthin violaxanthin (color brown,
olive-green, yellow-brown)
45
The Brown Algae
  • 1. seaweeds - generally large, complex thalli
    some small
  • filaments (no unicells or colonies)
  • 2. almost all are marine (maybe 6 FW genera)
  • 3. chlorophylls a c, beta carotene,
    fucoxanthin
  • violaxanthin (color brown, olive-green,
    yellow-brown)
  • walls a little bit of cellulose pectinaceous
    materials
  • including algin and fucoidan rarely, the
    walls are
  • calcified (e.g., in Padina)

46
alginic acid a polymer of mannuronic and
guluronic acids their Na, K, Mg, and Ca
salts Hundreds of uses
fucoidan (a sulfated polysaccharide) industrial
medicinal uses
47
The Brown Algae
  • 1. seaweeds - generally large, complex thalli
    some small
  • filaments (no unicells or colonies)
  • 2. almost all are marine (maybe 6 FW genera)
  • 3. chlorophylls a c, beta carotene,
    fucoxanthin
  • violaxanthin (color brown, olive-green,
    yellow-brown)
  • 4. walls a little bit ofcellulose,
    pectinaceous materials
  • including algin and fucoidan rarely, the
    walls are
  • calcified (e.g., in Padina)
  • 5. storage products are laminarin (B, 1-3
    polyglucoside),
  • mannitol (polyhydroxy alcohol, also in red
    algae,
  • is an antifreeze), some fats, some sterols
  • (fucosterol), some proteins (iodoamino acid)

48
The Brown Algae
1. seaweeds - generally large, complex thalli
some small filaments (no unicells or
colonies) 2. almost all are marine (maybe 6 FW
genera) 3. chlorophylls a c, beta carotene,
fucoxanthin violaxanthin (color brown,
olive-green, yellow-brown) 4. walls cellulose
and pectinaceous materials including algin and
fucoidan rarely, the walls are
calcified (e.g., in Padina) 5. storage products
are laminarin (B, 1-3 polyglucoside), mannitol
(polyhydroxy alcohol, also in red algae, is an
antifreeze), some fats, some sterols
(fucosterol), some proteins (iodoamino acid) 6.
flagella 2 heterokont laterally inserted (some
uniflag.)
49
The Brown Algae
General Features
1. in general, never coenocytic or siphonaceous
50
The Brown Algae
General Features
1. in general, never coenocytic or
siphonaceous 2. no resistant spores or zygotes
51
The Brown Algae
General Features
1. in general, never coenocytic or
siphonaceous 2. no resistant spores or zygotes 3.
in general, sporophytes are annual or
perennial whereas, gametophytes are annual
52
The Brown Algae
General Features
1. in general, never coenocytic or
siphonaceous 2. no resistant spores or zygotes 3.
in general, sporophytes are annual or
perennial whereas, gametophytes are annual 4.
approx. 250 genera and gt1500 (2,200?) spp
(other numbers?)
53
The Brown Algae
General Features
1. in general, never coenocytic or
siphonaceous 2. no resistant spores or zygotes 3.
in general, sporophytes are annual or
perennial whereas, gametophytes are annual 4.
approx. 250 genera and gt1500 (2,200?) spp
(other numbers?) 5. asexual repro. by zoospores,
tetraspores (e.g. in Dictyotales), multicellular
propagules, 4n mono- spores
54
The Brown Algae
General Features
1. in general, never coenocytic or
siphonaceous 2. no resistant spores or zygotes 3.
in general, sporophytes are annual or
perennial whereas, gametophytes are annual 4.
approx. 250 genera and gt1500 (2,200?) spp
(other numbers?) 5. asexual repro. by zoospores,
tetraspores (e.g. in Dictyotales), multicellular
propagules, 4n mono- spores 6. CER (chloroplast
endoplasmic reticulum) (as in Tribophyceae,
Chrysophyceae, diatoms and cryptophytes and
others)
55
The Brown Algae
General Features
1. in general, never coenocytic or
siphonaceous 2. no resistant spores or zygotes 3.
in general, sporophytes are annual or
perennial whereas, gametophytes are annual 4.
approx. 250 genera and gt1500 spp (other
numbers?) 5. asexual repro. by zoospores,
tetraspores (e.g. in Dictyotales), multicellular
propagules, 4n mono- spores 6. CER (PER) (as in
Tribophyceae, Chrysophyceae, diatoms and
cryptophytes and others) 7. plethysmothallus a
protonema stage (2n microscopic phase can
reproduce via zoospores)
56
The Brown Algae
General Features
1. in general, never coenocytic or
siphonaceous 2. no resistant spores or zygotes 3.
in general, sporophytes are annual or
perennial whereas, gametophytes are annual 4.
approx. 250 genera and gt1500 spp (other
numbers?) 5. asexual repro. by zoospores,
tetraspores (e.g. in Dictyotales), multicellular
propagules, 4n mono- spores 6. CER (PER) (as in
Tribophyceae, Chrysophyceae, diatoms and
cryptophytes and others) 7. plethysmothallus a
protonema stage (2n microscopic phase can
reproduce via zoospores) 8. many are cold water
algae El Niño a big problem
57
The Brown Algae - The Phaeophyceae (aka
Phaeophyta)
Morphology - Structural Forms 1.
haplostichous a. simple heterotrichy (e.g.
Ectocarpus) b. heterotrichous branches held
together with mucilage (Leathesia) c.
multiaxial d. pseudoparenchymatous
aggregations, crusts 2. polystichous
(parenchymatous) a. terete, solid axes
unbranched b. terete, solid axes branched c.
blades (Punctaria) d. elaborate complex thalli
(Laminariales Fucales)
58
The Brown Algae - The Phaeophyceae (aka
Phaeophyta)
Life Cycles (14 orders, three major groups) 1.
isogeneratae - alternation of isomorphic
generations a. isogamy anisogamy (e.g.
Ectocarpales) b. oogamy (Dictyotales)
59
Alternation of Isomorphic Generations
1n gametophyte
60
Ectocarpus
61
Ectocarpus
unilocular sporangium
62
Ectocarpus
plurilocular structures
63
Dictyota
apical cells
64
The Brown Algae - The Phaeophyceae (aka
Phaeophyta)
Life Cycles (14 orders, three major groups) 1.
isogeneratae - alternation of isomorphic
generations a. isogamy anisogamy (e.g.
Ectocarpales) b. oogamy (Dictyotales) 2.
heterogeneratae - altern. of heteromorphic
generations a. sporophytes small
(Cutleriales) b. sporophytes large i.
isogamous (Chordariales) ii. oogamous
(Laminariales)
65
The Brown Algae - The Phaeophyceae (aka
Phaeophyta)
The Kelps (order Laminariales) 1. large seaweeds
(sporophytes) 2. generally need cold water and
hard substrate 3. haptera (holdfast), stipe
(stem), and blades (fronds) 4. meristematic
tissue (cell divisions) meristoderm 6.
pneumatocysts (air bladders) 7. California kelp
industry Macrocystis pyrifera sea urchins sea
otters abalone Russians
66
Cutleria
67
Chorda filum
68
Padina
Slide 30
69
Desmarestia
70
Laminaria digitata
71
Postelsia palmaeformis
72
Nereocystis (the bull kelp)
73
Macrocystis
74
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75
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76
30 meters
77
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78
The Brown Algae
  • isogeneratae
  • heterogeneratae
  • 3. cyclosporeae - Fucales and Durvillaeales
  • a. common seaweeds
  • b. appear to have 2n plants producing 1n gametes
    by
  • meiosis
  • c. have receptacles with conceptacles

79
Fucus
80
Fucus
receptacles
conceptacles
81
Fucus
conceptacles
monoecious both oogonia antheridia in each
conceptacle dioecious oogonia antheridia in
separate conceptacles
82
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83
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84
Ascophyllum
85
Sargassum
86
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87
Hormosira (Neptunes Necklace)
Dr. Mike Wynne
Durvillaea
88
Dr. Suzanne Fredericq, University of Louisiana
Lafayette
89
Baldauf, 2003. The Deep Roots of Eukaryotes,
Science 300 1703-6
90
Sandi Baldauf Leeds University 2009
91
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92
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93
Red Algae are a widespread group of uni-and
multicellular eukaryotes exhibiting a broad
variety of morphologies and life histories.
Unlike green plants, animals even brown
algae, red algae have attained this diversity
without having evolved true tissue
differentiation. The molecular and
biochemical mechanisms of their development
remain largely unexplored.
94
Red algae were first defined as a taxonomic
group based on their pigmentation.
Historically, the red algae were considered
plants that typically lacked true roots,
shoots, leaves, seeds, or water-conducting
tissues. Until recently, the relationship
between the Red Algae or Rhodophyta other
Algae or Protists remained inconclusive
often contradictory. Our understanding of
algal phylogeny has dramatically increased
with molecular evolutionary methods the latest
research indicates that the Rhodophyta is a
distinct eukaryotic lineage that likely
shares a most common ancestry with the green
algae (Van der Auwera et al. 1998, Burger et
al., 1999, Moreira et al., 2000).
95
Cavalier-Smith (2000) even goes as far as to
support a Kingdom Plantae composed of green
plants, red algae glaucophytes, Saunders
Hommersand (2004) erected the new Subkingdom
Rhodoplantae vs. Viridiplantae Chloroplast
structure and genome analyses support the
hypothesis that green plants (green algae
land plants), red algae and glaucophytes
(e.g. Cyanophora) originated from a single
endosymbiotic event between a cyanobacterium and
an eukaryotic host. These results are an
important step towards universal acceptance
of a monophyletic origin of plastids.
96
CER
97
There is no significant fossil record of the
evolutionary history of the marine red algae,
except for the order Corallinales which extends
back as far as the Jurassic (206-144 mya)
(Johansen, 1981). The oldest taxonomically
resolved eukaryote on record, ca. 1,200 MY from
arctic Canada, is identified as a bangiophyte red
alga, Bangiomorpha pubescens, on the basis of
diagnostic cell division patterns in its
multicellular filaments, marks the onset of a
major protistan radiation near the
Mesoproterozoic/Neoproerozoic boundary
(Butterfield, 2000).
98
There are over 10,000 described species of red
algae worldwide Most are marine and 3-10 are
freshwater. Red algae are most common on
hard-bottom habitats in marine environments,
as epiphytes on other algae, seagrasses or
mangrove roots, epizooic on animals, epilithic on
pebbles rocks, or psammophilic in sand.
99
They occur at all latitudes from the Arctic to
the Antarctic occupy the entire range of
depths inhabitable by photosynthetic
organisms, from high intertidal regions to
subtidal depths as great as 268 m (San
Salvador I, Bahamas is the greatest depth for
known plant life) (Littler et al., 1985).
Some red algae, the corallines, are important in
the formation of tropical reefs.
100
The red color is due to the presence of
phycoerythrin which reflects red light and
absorbs blue light. Phycoerythin occurs in at
least five forms in the red algae which differ
in their absorption spectra, although all have
peaks in the green part of the spectrum (500-570
nm).
101
The color varies according to the ratio of
phycoerythrin to phycocyanin they may appear
green or bluish from the chlorophyll and other
masking pigments.
Because blue light penetrates water to a greater
depth than light of longer wavelengths, these
pigments allow red algae to photo- synthesize
live at somewhat greater depths than most other
algae. Such light harvesting pigments are also
found in cyanobacteria cryptophytes.
102
Accessory pigments, such as the phycobilins
phycoerythrin, phycocyanin and allophycocyanin
occur attached to proteins, forming a class of
compounds called phycobiliproteins that are
located on the thylakoid surface in granular
phycobilisomes, the principal light-harvesting
complexes (Gantt 1990).
103
Each chloroplast is surrounded only by its own
double-membrane envelope, and not by an
additional layer of endoplasmic reticulum.
The only chlorophyll present is chl a. The
thylakoids are singly within the chloroplasts.
104
Carotenoids are present with the most important
ones beta-carotene, lutein and zeaxanthin.
Only a few red algae have chloroplasts that
contain pyrenoids in the center of the
chloroplast, but because reserve starch are
produced in the cytoplasm, the exact function is
not known. The chloroplast DNA is organized
into numerous small, nucleoids scattered
throughout the chloroplast. The most important
food reserve is a polysaccharide, floridean
starch, consisting of units of glucose which is
similar to glycogen or the branched amylopectin
fraction of green algal higher plant starch,
but lacks amylose, the unbranched fraction of
green algal starch. The low-molecular mass
carbohydrate floridoside has an osmoregulatory
function.
105
The cell walls of red algae consist of
cellulosic fibers embedded in a matrix of
non-fibrillar materials, the phycocolloids.
The most abundant of these polysaccharides are
referred to either as agars and carrageenans,
and are of economic importance. Agar is
used as a nutrient medium for growing bacteria
and fungi also in the food and drug industries.
Carrageenan is used as a substitute for
gelatin, or as food in Japan the Philippines.
106
The red algae share a suite of characters that
do not occur together in any other eukaryote.
They are unique by a complete lack of
flagellated stages including absence of
centrioles, flagellar basal bodies, or other 92
structures.
107
In Asia, red algae are important sources of food
with a high vitamin protein content, such as
nori. Many red algae metabolize
polyunsaturated fatty acids to oxidized products
resembling the eicosanoid hormones from
mammals (prostaglandins, prostacyclins,
thromboxanes, leukotrienes). Because of
their biological properties, seaweed-derived
oxylipins have potential utility as
pharmaceutical and research biochemicals
(Gerwick et al., 1993). (at SIO at
UCSD)
108
Some species reproduce by vegetative
fragmentation or spore formation, but most
undergo a complex life cycle involving an
alternation of generations. Reproduction is
typically oogamous. It was only after culture
methods were introduced (von Stosch 1965) that
it was finally verified that in most red algae
there is a fundamental linkage of the sexual
system and a life history consisting of three
phases. It has been argued that selection has
favored the evolution of a triphasic life
history in red algae as a compensation for an
inefficient fertilization in the absence of
motile gametes (Searles, 1968).
109
As a result of fertilization of the female egg
cell by an unflagellated male gamete carried by
water currents to the elongated tip (trichogyne)
of a carpogonium, a diploid carposporophyte
develops directly in situ, parasitically, on the
female gametophyte.
110
Some taxa are parasitic on other red algal
hosts. Morphological similarities of many
parasites their hosts have led to the
speculation that some groups of red algal
parasites may have developed directly from their
hosts. These parasites, termed
adelphoparasites may evolve monophyletically
from one host and radiate secondarily to other
hosts or, these parasites may arise
polyphyletically, each arising from its own host
(Goff et al., 1996, 1997).
111
Cell walls of red algae consist of a fibrillar
part that gives wall its strength an amorphous
part in which fibrils are embedded (
phycocolloids). most abundant of amorphous
cell wall matrix compounds that are commercially
exploited are galactans or polymers of galactose
which are alternatively b-1,3 and b-1,4 linked
agars carrageenans agar composed of 2
polysacharides agarose agaropectin These
mucilages may constitute up to 70 of dry weight
of cell wall.
112
phycolloid insoluble in cold water but readily
soluble in hot water with a 1 solution being
clear forming solid elastic gel on
cooling. in traditional processing procedure,
plants are bleached in sun with several washings
in freshwater material is boiled for several
hours extract is acidified extract then
frozen thawed. On thawing water flows from
agar, carrying impurities with it agar that
remains is dried marketed as flakes or
cakes more modern method extracts agar under
pressure in autoclaves agar is decolorized
deodorized with activated charcoal, filtered
under pressure evaporated under reduced
pressure. Further purification by freezing is
then undertaken.
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non-toxic used in food preparation and in
pharmaceutical industry as gelling thickening
agent canning of meat fish for protection
against shaking in transit, manufacture of
processed cheese, mayonnaise, puddings, creams,
jellies Japan most important producer of agar,
about 3500 tons annually used on large scale
for preparation of gels agar-agar
microbiological investigations agar gels
contain nutrients for bacteria fungi but gel
itself is resistant to degradation by these
organisms
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Callophyllis sp.
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Crustose coralline red alga
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Halymenia sp.
Heterosiphonia sp.
Lithophylum frondosum
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Chondrus crispus (Irish Moss)
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The end!
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Sea fans, Order Gorgonacea, are colonial
Anthozoans anchored on hard substrates, supported
by an internal, central horny/wood-like skeleton.
They're colonies are covered by a thick
"rind-like" skin. Unlike anemones, but like
corals, sea fan polyps are interconnected by an
internal germ layer (gastrodermis) and mesoglea.
This feature explains much regarding how one part
can feed and sustain the rest of the colony, and
unfortunately how disease can easily spread.
Common genera include Gorgonia, the purple sea
fan from Florida/Caribbean, the dried
"ornamental" fan skeletons in stores. Corallium
is the beautiful red sea fan used in jewelry.
Paragorgia, Pterogorgia, and Pseudopterogorgia
and others are often encountered, offered for
aquarium use.Gorgonians are found worldwide in
tropical seas. They are prominent of most reefs,
attached to rocks, corals, oriented to prevailing
currents.
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