This document summarizes information about three main groups of seaweeds - brown algae, green algae, and red algae. It describes their structures and life cycles, including reproduction processes like meiosis. Some key species are described like giant kelp that can grow to 300 feet. The document also discusses the health benefits of compounds found in seaweeds and how seaweeds are used in food products and other applications.

1. Seaweeds Kingdom Protista
by Annie Cloutier 2013 Science Department Sandwich High School

2. Marine algae is called “seaweed”
 There are three main
groups of salt water
seaweeds
 Brown algae
 Green algae
 Red algae
copyright acloutier 2013 2

3. Structures of brown algae
 Thallus (pl. thalli)
 multicellular bodies usually flattened
 Holdfast
 Stipe
 Blades
 Bladder (float)
copyright acloutier 2013 3

4. Sargassum Sea
copyright acloutier 2013 4

5. Giant kelp Macrocystis pyrifera
May grow up to 300 feet
 Brown pigments called
fucoxanthin with
chlorophyll and other
pigments
 Giant stalks have stem
like stipes to help support
them and grow towards
the sunlight
copyright acloutier 2013 5

6. Fucus rockweed we love to pop
 Separate male and female
thalli are produced
 Both sexes may develop
on the same thallus
 Puffy fertile areas call
receptacles develop at the
tips of the branches of the
thallus
copyright acloutier 2013 6

7. Life cycle of Fucus
copyright acloutier 2013 7

8. Gametangia ….. (algae reproductive structures
 Within every receptacle are dotted pores (visible
to the naked eye) that open into special spherical
hollow chambers called conceptacles
 Within a conceptacle gametangia (cell structures
where gametes are produced) form
 Eight eggs are formed in the oogonium (female
gametangium)
 Meiosis happens (the process of two successive nuclear divisions
through which segregation of genes occurs and a single diploid (2n) cell
becomes four haploid (n) cells )
copyright acloutier 2013 8

9. Feathery red Polysiphonia has three types of
thallus, male , female and tetrasporophyte.
 Meiosis happens on the
tetrasporophyte
 Male thallus produces
spermatangium , non
motile (can’t move on its
own)
 Female thallus , has a
carpogonia, which
produces one egg, non
motile too
 Ocean waters transport the
two for fertilization
copyright acloutier 2013 9

10. the Zygotes journey
 The pericarp (an urn shaped body, of the outer part of which the female
gametophyte thallus) is the destination
 The zygote begins to divide and eventually forms clusters of
carposporangia
 The pericarp and carposporangia combine to form
the cystocarp
 Diploid asexual spores called carpospores are
produced and released into the ocean
 Eventually fasten themselves to bottom rock or
hull of a boat and grow into a tetrasporophyte
copyright acloutier 2013 10

11. Seaweed life cycle with terms
copyright acloutier 2013 11

12. Completing the life cycle of Phylum
Rhodophyta
 The terosporangium
undergo meiosis
 They develop into four
haploid tetraspores
 Tetraspores germinate
 Then develop into male
gametophytes or female
gametophytes
copyright acloutier 2013 12

13. Super foods from seaweeds
are packed with vitamins, antioxidants and minerals we need
copyright acloutier 2013 13

14. Red algae Rhodophyta
 Sulfated polysaccharides
are found in some red
algae
 These complex
carbohydrates contain
sulfate
 Improve auto immune
system functions
 Have been found to
stimulate anti tumor agents
our bodies produce
copyright acloutier 2013 14

15. Green algae Chlorophyta
 Important part of the
plankton community
 Free floating often
 The smallest eukaryotic
cell known is a
Chlorophyta called
Micromonas
 Can camouflage animals
 Can reproduce sexually
and asexually
copyright acloutier 2013 15

16. Brown algae Phaeophyceae
 Can be olive green to
brown color
 Many are large algae
 Most are marine (salt water
algae)
 Giant kelp
 Fucus rockweed
 Sargassum seaweed
belongs to brown algae
copyright acloutier 2013 16

17. AGAR
 Agar was discovered by
accident in Japan when some
extracted seaweed was left
outside the door of a mountain
inn and froze overnight. On
thawing the innkeeper
discovered that the impurities
were carried away and with
repeated thawing and freezing
—a process still used today for
the most valued food agars—a
quality product with the mouth
feel that appeals to Japanese
tastes. This is called kanten in
Japan and has become so
popular recently that some
restaurants serve nothing but
kanten in all sorts of guises for
the diet-conscious young
executive
copyright acloutier 2013 17

18. ALGIN uses > food, paper, textiles pharmaceuticals
cosmetics, industrial uses, brewing
 Printing paste and  Food stabilizer in ice cream,
improves dye dispersal in chocolate milk, gravies,
textiles jellies, frosting
 Thickening agent cough  Electric insulations, beauty
syrups, antibiotic mask
 Suspension liquids  Tooth paste
 Cleaners  Frozen food batters
 Acids  Marshmallows
 Welding flux  Solvents
 Brewing creamier beers
foams
copyright acloutier 2013 18

19. Seaweed …
walk along the beaches of Cape Cod and notice the marine plants
copyright acloutier 2013 19