MULTICELLULAR PRIMARY PRODUCERS: SEAWEEDS AND PLANTS

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Multicellular algae- the seaweeds

Macrophytes or macroalgae Multicellular Eukaryotic

General structure Lack true leaves, stems and roots Complete body called a thallus

Blades- leaf-like, flattened portion; main photosynthetic regions; don’t have veins Pneumatocysts- gas-filled bladders; keep blades

close to the surface Stipe- stem-like structure where blades

originate Holdfast- looks like roots; attaches the thallus

to the bottom

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TYPES OF SEAWEEDS

Three types Green algae- Brown algae Red algae

GREEN ALGAE

Phylum Chlorophyta Live in fresh and terrestrial

environments Only 10% of 7000 species marine Believe land plants evolved from green

algae may be filamentous

Enteromorpha- thin thallus is a hollow tube; in polluted areas

Ulva latica or sea lettuce- common where fresh water meets thesea

Valonia- forms large spheres or spherical clustersin the tropics and subtropics

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Caulerpa- has thin filaments or tubes

Codium- dead man’s fingers Codium setchelli

Some green algae are calcareous- they deposit calcium carbonate to help build the coral reef

Halimeda

BROWN ALGAE

Color varies from olive green to dark brown due to pigments called fucoxanthin

1500 known species Dominant primary producers on

temperate and polar rocky coasts Largest seaweeds

Usually exposed at low tide on rocky shores

Thick, leathery thalli can stand exposure to air

Some known as rockweeds or wracks

Fucus

Kelp- most complex and largest of all brown algae

Found below the low tide level in temperate and sub-polar latititudes

Some consist of a single large blade which may be harvested for food

Laminaria

Laminaria

Macrocystis- larges of the kelps Can reach 100m Form kelp beds or forests

RED ALGAE

More abundant Have red pigments called phycoobilins 4000 species mostly marine Live in shallow water Some are parasites of other seaweeds Some are heterotrophs Most are filamentous

Gigartina

Coralline algae- red algae that deposit calcium carbonate within their cell walls; some help with the development of coral reefs

LIFE HISTORY OF SEAWEEDS

Asexual is common fragments of thallmus can grow into new

individuals Spores (cells that are specialized for

dispersal) Zoospores= spores with flagella for

movement

Sexual Reproduction- production of gametes

4 basic types of life histories Type A- 2 types of thalli; most common

form; 2n (diploid) sporophyte produces haploid spores that are motile which eventually divide and produce the second kind of thallus, a haploid gametophyte

SUMMARY Algae produces most of the oxygen that we breathe. Multicellular algae, or seaweed, is classified in three colors: red, green, and brown. Unicellular Algae is broken down into two groups Diatoms and Dinoflagellates. All of these organisms have special and unique adaptations that enable them to

survive their environments. Plankton is a combination of uni and multicellular algae and forms the basis of all

life in the ocean.