Seaweeds or Seaweeds or Macroalgae Macroalgae are the are the large primary producers of the large primary producers of the

sea.sea.

Though more complex than the Though more complex than the unicellular algae, seaweeds still unicellular algae, seaweeds still

lack the complex structures lack the complex structures found in land plants.found in land plants.

General StructureGeneral Structure

This is a very This is a very diverse group, diverse group, and although and although they lack true they lack true leaves, stems, leaves, stems, and roots, they and roots, they have a few have a few common common structures. structures.

The complete body The complete body is called the is called the thallusthallus no matter no matter the growth form.the growth form.

Usually, all regions Usually, all regions of the thallus can of the thallus can photosynthesize.photosynthesize.

The leaf-like The leaf-like flattened portions flattened portions are called are called bladesblades..

The blades are The blades are usually the main usually the main photosynthetic photosynthetic region.These are region.These are not true leaves not true leaves because they lack because they lack veins.veins.

Most seaweeds Most seaweeds have gas-filled have gas-filled bladdersbladders or or floatsfloats that will help them that will help them maximize sunlight maximize sunlight exposure. exposure. Sometime these Sometime these floats contain floats contain carbon monoxidecarbon monoxide..

Some seaweeds Some seaweeds have a stem-like have a stem-like structure called structure called the the stipestipe. This . This structure is not structure is not found on all found on all seaweeds.seaweeds.

The The stipestipe provides provides support and can support and can be long and be long and tough, as in the tough, as in the Giant Kelp.Giant Kelp.

The The stipestipe also also allows a place for allows a place for the attachment of the attachment of the blades.the blades.

A A holdfastholdfast is a is a root-like root-like structure that structure that holds the holds the seaweed to the seaweed to the bottom. This bottom. This structure does structure does not aid in not aid in gathering gathering nutrients.nutrients.

The The holdfast holdfast does does not penetrate not penetrate through sand or through sand or mud, so like this mud, so like this Sea PalmSea Palm, most , most macroalgae are macroalgae are only found on only found on hard sediments.hard sediments.

Types ofTypes ofMacroalgaeMacroalgae

The are three types of macroalgaeThe are three types of macroalgae

Green

Brown

and Red

Green AlgaeGreen Algae About 700 of the About 700 of the

7,000 species 7,000 species of green algae of green algae are marine. Of are marine. Of those, few are those, few are multicellular.multicellular.

Green AlgaeGreen Algae Green algae can Green algae can

be very be very common where common where the salinities the salinities vary a lot. vary a lot. ( Bays, ( Bays, Estuaries, Tide Estuaries, Tide Pools)Pools)

Green AlgaeGreen Algae They are usually They are usually

bright green bright green because the because the chlorophyll is chlorophyll is not masked by not masked by other pigments.other pigments.

Green AlgaeGreen Algae Green algae Green algae

have a simple have a simple thallus when thallus when compared to compared to red and brown red and brown algae.algae.

Green AlgaeGreen Algae

Many forms are Many forms are filamentous or filamentous or form paper-thin form paper-thin

sheets.sheets.

Green AlgaeGreen Algae Others form Others form spongy fingers spongy fingers

as in this as in this example of example of Dead Man’s Dead Man’s

FingersFingers..

Brown AlgaeBrown Algae Almost all species Almost all species

of brown algae of brown algae are marine. The are marine. The best know and the best know and the most complex are most complex are the kelps.the kelps.

Brown AlgaeBrown Algae Color varies from Color varies from

olive green to dark olive green to dark brown because brown because there are many there are many yellow-brown yellow-brown pigments that pigments that mask the color of mask the color of chlorophyll.chlorophyll.

Brown AlgaeBrown Algae Besides the well Besides the well

known kelps, known kelps, Sargasso weed Sargasso weed

is also a well is also a well known brown known brown

algae.algae.

Brown AlgaeBrown Algae Sargasso weed Sargasso weed often forms into often forms into large mats in the large mats in the

mid Atlantic where mid Atlantic where unique animals unique animals

and communities and communities can be found.can be found.

Brown AlgaeBrown Algae Notice anything Notice anything

here?here?

Can you see the Can you see the Sargassum Sargassum

Angler FishAngler Fish??

Red AlgaeRed Algae There are more There are more species of marine species of marine

red algae than red algae than green or brown.green or brown.

Most are actually Most are actually red!red!

Red AlgaeRed Algae Some red algae Some red algae

have have calcium calcium carbonate carbonate within within their cell walls.their cell walls.

These, help form These, help form coral reefs.coral reefs.

How about a quick quiz?How about a quick quiz?

1.1. The entire body of the The entire body of the seaweed is called the _____.seaweed is called the _____.

2.2. What is another name for What is another name for seaweeds?seaweeds?

3.3. Name the 3 types of Name the 3 types of seaweeds.seaweeds.

4. What is the stem-like 4. What is the stem-like structure called?structure called?

5. Which type of seaweed can 5. Which type of seaweed can be important in the formation be important in the formation of a coral reef?of a coral reef?

AnswersAnswers

1.1. MacroalgaeMacroalgae

2.2. ThallusThallus

3.3. Red, Green, and BrownRed, Green, and Brown

4.4. StipeStipe

5. Red5. Red