Seaweeds and Plants

1
Seaweeds and Plants
2

• The term seaweed refers to the large marine algae
  that grow almost exclusively in the shallow
  waters at the edge of the world's oceans. They
  provide home and food for many different sea
  animals, lend beauty to the underwater landscape,
  and are directly valuable to man as a food and
  industrial raw material.

3
Structure of Seaweeds(also called macropyhtes
and macroalgae)

• thallus the complete body
• blades- the leaf-like, flattened portions of the
  thallus
• pneumatocysts- gas filled bladders which help
  keep the blades near the surface
• Why would blades need to be near the surface?
• stipe- stem-like structure providing support
• holdfast- attaches the thallus to the bottom

4
(No Transcript)
5
Types of Seaweeds

• Green
• Brown
• Red

6
Green Algae

• Live in freshwater, terrestrial and marine
  environments only a small percentage are marine
• Typically bright green because chlorophyll is not
  masked by other pigments

7
Common Green Algae

• Ulva also known as sea lettuce
• Codium dead mans fingers
• Halimedia numerous segments with deposits of
  calcium carbonate important in the formation of
  reefs
• Enteromorpha often found in polluted areas

8

• Sea Lettuce
• Dead Mans fingers

9
Brown Algae

• Almost all species are marine and the most
  complex of all seaweeds
• Color varies from olive green to dark brown
• The color is a result of more yellowbrown
  pigments(fucoxanthin) then chlorophyll

10
Common Brown Algae

• Ectocarpus simplest brown algae which is widely
  
  distributed

11

• Dictyota thallus is flat and branched
• Both found in the tropics
• Padina fan- shaped and lightly calcified

12

• Desmarestia the dominant species in cold water
  known as Witchs Hair
• Fucus have gas filled floats commonly found on
  both the Atlantic and Pacific coasts known as
  rockweeds

13

• Sargassum also have air bladders -found growing
  on rocks but also found floating in huge masses
• Particularly common in the Gulf of Mexico and the
  Sargasso Sea

14

• Kelps the most complex and largest of all the
  browns. They occur in great abundance found
  below the low tide level in temperate and
  subpolar latitudes, providing food and shelter.
• Common Kelps
• Laminaria made up of a single large blade
  harvested for food

15

• Postelsia grows where the waves crash known
  as sea palm
• Nereocystis 100 ft long stipes bull kelp

16

• Macrocystis the largest of all the kelps, can
  grow 20 inches a day and get 330 feet. Grow close
  together and form kelp beds (forests)

17
Red Algae

• More species of red algae then green and brown
  combined
• Red pigments called phycobilins which hide the
  chlorophyll
• Inhabit most shallow marine environments

18
Common Red Algae

• Dense clumps are common on rocky shores exposed
  at low tides

• Longer- flatter branches predominate in areas
  less exposed to air

19

• Chondrus called Irish moss can tolerate wide
  ranges of temperature, salinity and light and it
  shape varies depending on the conditions

20

• Rhodymenia- common in the North Atlantic has
  the most common shape of the red algaes

21

• Coralline algae red algae that deposit calcium
  carbonate - important for reef formation
• Variety of shapes thin discs, branches with
  many joints, smooth or rough encrusting growths
  on rocks
• Common variety - Corallina

22
Life History

• Reproduction in seaweeds is by asexual and sexual
  means
• Four basic types of reproduction

23
Most Common form

• The sporophyte produces spores by meiosis. These
  spores develop into a gametophyte. Both the
  spores and the resulting gametophyte are haploid.
• The mature gametophyte produces male or female
  gametes (or both) by mitosis. The fusion of male
  and female gametes produces a diploid zygote
  which develops into a new sporophyte.
• This cycle is known as alternation of generations.

24
Carposporophyte Generation

• Very similar to sporophyte, except has a third
  generation a diploid carpospore which develops
  into a sporophyte
• Still has alternation of generations

25
Easiest of all

• Thallus produces haploid gametes by meiosis (both
  male and female) which fuse to form diploid
  zygote which develops into new thallus (brand new
  plant).

26
Last of four types

• The thallus is haploid and produces haploid
  gametes.
• Fertilization occurs and forms diploid zygote
  which undergoes meiosis forming haploid spores
  which develop into new thallus.

27
(No Transcript)
28
Economic Importance

• Uses
• to make paint
• as a thickener in making shampoos, shaving cream
• to thicken printing paste to provide sharper
  images
• to make rubber products
• making paper
• cosmetics
• found in fertilizers
• wound dressings in hospitals

29
Food Uses

• Phycocolloids useful because they form gels at
  low concentrations
• Algin used as a stabilizer and emulsifier
  (think dairy)
• Carrageenan used as emulsifier as well.

30
Flowering plants

• Seagrasses truly marine, live below water
• Salt-marsh plants land plants tolerant of salt
• both salt marsh plants and mangroves live in
  estuaries and have only their roots below the
  water
• Mangroves trees or shrubs adapted to live along
  tropical and subtropical shores around the world

31
Seagrass
Zostera called eelgrass

• Look like grass, but not really a grass
• Stems called rhizomes
• Roots and shoots grow from stems
• Small flowers Why dont they need pretty and
  large flowers?
• Very important for providing shelter and food

32
Salt Marsh and Mangroves

• Provide habitat and breeding ground, protection
  against erosion, and provide a natural water
  purification system.

Spartina called cordgrass
Mangrove forest