Seaweeds. The Multicellular Marine Algae. Seaweeds or Macroalgae are the large primary producers of the sea. Though more complex than the unicellular algae, seaweeds still lack the complex structures found in land plants. General Structure.
Though more complex than the unicellular algae, seaweeds still lack the complex structures found in land plants.
Usually, all regions of the thallus can photosynthesize.
The blades are usually the main photosynthetic region.These are not true leaves because they lack veins.
The stipe also allows a place for the attachment of the blades.
About 700 of the 7,000 species of green algae are marine. Of those, few are multicellular.
Green algae can be very common where the salinities vary a lot. ( Bays, Estuaries, Tide Pools)
They are usually bright green because the chlorophyll is not masked by other pigments.
Green algae have a simple thallus when compared to red and brown algae.
Many forms are filamentous or form paper-thin sheets.
Others form spongy fingers as in this example of Dead Man’s Fingers.
Almost all species of brown algae are marine. The best know and the most complex are the kelps.
Color varies from olive green to dark brown because there are many yellow-brown pigments that mask the color of chlorophyll.
Besides the well known kelps, Sargasso weed is also a well known brown algae.
Sargasso weed often forms into large mats in the mid Atlantic where unique animals and communities can be found.
Notice anything here?
Can you see the Sargassum Angler Fish?
There are more species of marine red algae than green or brown.
Most are actually red!
Some red algae have calcium carbonate within their cell walls.
These, help form coral reefs.
5. Which type of seaweed can be important in the formation of a coral reef?