Multicellular PrimaryProducers ~

Seaweeds

Seaweeds – marine Macroalgae• Threee types – red,

brown, and green algae• Most species are benthic• Can be fouling

communities – live on bulkheads, pilings or artificial surface

• Distinguished by the type of pigment used for photosynthesis and the composition of the cell wall.

• Abiotic factors – light, temp., tides, wave action, salinity, nutrients

• Chromatic adaptation – ability of plants to alter photosynthetic pigments in response to light conditions

• Perennials – live longer than a year

Seaweeds – marine Macroalgae

Red Algae – phylum Rhodophyta

Red algae

• Mostly marine

• Epiphytes – live on other plants

• Adaptations to predation– Make thallus less edible

– Changing growing patters(out instead of up)

– Complex life cycles

• Uses– Agar culture material

– Thickening agents in foods and pharmaceuticals

– Carrageenan – binding agent in ice cream, pudding and salad dressing

– Cosmetics

– Sushi, soups and seasonings

– Animal feed

– fertilizer

Red algae life cycle

Brown algae – phylum

Phaeophyta

Brown algae- kelp, sargassum • Mostly marine• Mostly benthic• Microscopic to 100

meters• Very defined holdfast,

stipe and blade• Gas filled bladders

• Uses– Thickening agents in

textiles, dental and cosmetics and food

– Human consumption

– Cattle feed

- thin, broad blades allow for floating on top of water where they can use light to photosynthesize 

- anchors allow them to stay in one place and not float off to places where the conditions may not be as advantageous to their survival 

- waxy blades prevent them from drying up 

- pigment fucoxanthin well adapted for absorbing wavelengths of light in their environment to maximize efficiency of photosynthesis 

- reproduction by flagellate spores allow offspring to be anchored in places where the environment is equally advantageous for their survival.

Brown algae- Adaptations

Kombu Japanese Kelp dish

an edible brown seaweed used, typically in dried form, in Chinese and Japanese cooking

Seaweed laid out for making Maki rolls 

Green algae – phylum

Chlorophyta

Examplesea lettuce

• Very few marine macroalgae

• Most are fresh water and phytoplankton

• Adaptations to predation:– Rapid growth and reproduction– Can occupy small crevices predators can’t– Deposits calcium carbonate in

cell walls– toxins