Red and Green Algea

[sunnygirl]

So if both red and green algea obtain their food by photosynthesis, how come green alges cannot survive in deep water but red algea can?

[victor]

I think it depends on what class of red/green algae that you refer to..

[sunnygirl]

the green algea that make up the phylum chlorophyta

[ZachMorin]

Red algae are able to live at greater depths than green because of the types of light energy that they harvest. Red algae contain chlorophyll "a" and a pigment called phycobilin which enables them to photosynthesize blue light which travels down much farther than typical sunlight. Green algae contain both chlorophyll "a" and "b" which allows them to only photosynthesize sunlight energy. Thus green algae can only grow and survive in the littorals of bodies of water or as far down as sunlight can reach where as red algae will thrive as far down as blue light energy can reach.

[MrMistery]

Not true. Both red and green algae can use blue light. Chlorophil a can do that. The phicobilin pigments that red algae have enable them to use green and yellow light. so, light usage is like this:
green algae: mostly red and blue
red algae: mostly blue and green, but also some yellow light.

[Linn]

This is a very intersting subject

other factors in photosynthesis are carbon dioxide levels and temperture, which differ at the levels for red vs green algae.. but I think the main reason is the accessory pigments (phycobilins & phycoerythrin) which absorb the green light that is mostly present at great depts.

ps: some red algae also have chlorophyll d

[MrMistery]

Just a small correction: phicobilins include phycocianin, alophycocianin and phycoerytrin.

[Linn]

ahhh I guess my brain served me wrong thought they were distinct.