Marine Algae

• Scientists who study seaweeds are called

phycologists

What is algae? • Commonly known as seaweed

• Plantlike aquatic organisms that vary in size from microscopic to macroscopic

• Although multicellular- they are classified in the kingdom Protista

• Live in sunlight waters

Not the same as land plants!! Why?

- Algae do not have true stems, roots, or leaves

How similar to land plants?

- Produce food and oxygen though photosynthesis

Why are they important to the sea? Important to the sea: both directly and indirectly

• All animal life in the ocean is in some way linked to

marine plants and seaweeds are essential to ocean

health

- Chloroplasts are food factories- the place where sugar is

manufactured

- Some marine animals eat algae for this benefit

- When algae dies, it decomposes and the sugar

(glucose) and other nutrients are released into the

water where microscopic algae and filter feeders take

in the nutrients

- Oxygen producers

Why are they important to

humans?

• Some 400 different species around the

world are used by people for food, stock

feed, medicines, and fertilizers

• You probably have eaten some seaweeds

today –extracts from seaweeds are used

in toothpaste, ice cream, and many other

foods

5.1 Marine Algae cont.

• Agar: chemical found

in other red algae

used to make

– Food

– medicinal product

– medium for growing

bacteria in labs.

What are the 3 types of Algae?

• Brown Algae- The Phaeophyta

• Red Algae- The Rhodophyta

• Green Algae- The Chlorophyta

5.1 Marine Algae cont.

Green Algae

• Classified in phylum Chlorophyta,

– most closely related to plant, due to pigments

– lack typical roots, stems, and leaves

– nonvascular plants water passes directly into

algae’s cells from their surroundings.

– 3 types Enteromorpha, Codium, Acetabularie

Green: Chlorophyta

Ulva (sea lettuce)- thin,

leafy, bright green,

shallow water

Enteromorpha-

Filamentous, on rocks,

intertidal zone

Codium- spongy,

bracnching, subtidal zone

5.1 Marine Algae cont.

Brown Algae

• Classified in phylum Phaeophyta,

– color brown or olive-green due pigments in cell,

chlorophyll and yellow pigment zanthophyll.

– Important member of ecosystems

– providing shelter or nutrients for other organisms.

– People eat algae raw or cooked.

• 3 types Sargassum, Laminaria, Fucus

Brown: Phaeophyta

Laminaria (kelp)- long

fronds, holdfast on rocks,

subtidal zone

Sargassum – floats,

branching, provides

cover, open sea

Fucus (rockweed)- air

bladders, branching,

intertidal zone

• Kelp: the brown algae – Largest seaweed in the ocean.

– Grows rapidly from the seafloor to the surface.

– One species of kelp, Laminaria, thrives in the colder waters.

– Giant kelp Nereocystis and Marcrocystie reach 60 meters and more.

– used in different industries, • ingredient in prepared foods,

• Medicines

• Paints

• paper product.

• Holdfast: keeps the kelp tightly anchored

to the ground, so it won’t be pushed away

by the waves; must glue on to a rock or

hard substrate, not soft, sifting sand;

different from roots because it doesn’t

actually grab nutrients from the ground --

instead, nutrients can enter any part of the

plant, all of which can photosynthesize.

• Stipe: long like a stem, with room for many

“branches”, but doesn’t have tubes and

“sap”.

• Blades: analogous to leaves; long and

broad in order to collect as much sunlight

as possible for photosynthesis.

• Bladders: air sacs to hold the plant up; the

stipe isn’t a strong support, and the blades

need to reach the water’s surface to get

sunlight, so these air bubbles make the top

of the plant float.

• http://www.youtube.com/watch?v=GcbU4b

fkDA4

Red Algae

• Most abundant and commercially valuable. phylum Rhodophyta.

• 3 types of red algae – Coralline algae (Corrallina)

– Irish moss (Chondrus crispus)

– Porphyra.

• Found on rocky shores from the in intertidal to the subtidal zones, also found at much greater depths than either brown or green algae.

• Red pigment phycoerythrin and the blue pigment phycocyanin enable red algae to use limited light at deep depths to carry out photosynthesis.

Red Rhodophyta • Chondrus (irish moss)-

short, bushy, covers

rocks, subtidal zone

• Porphyra- thin leaves,

attaches to rocks,

intertidial zone

• Corallina- hard, brittle,

branching, intertidal

zone

Effects of temperature on

seaweed distribution • The greatest diversity of algal species is in

tropical waters

• Marine algae in colder waters are

PERENNIALS meaning it completes its life

cycle in more than two growing seasons

• During the colder seasons only part of the

alga remains alive, sometimes as a mass

of stem-like structures. When the temp

warms up in the spring, this body part

initiates the new growth

• http://www.youtube.com/watch?v=QP_Hb

Q5cWSk