[ Dulse above]Division Rhodophyta or the red algae: 3900 spp and 400 genera
Really different from other algae and higher plants; warm marine primarily
*Colors: like cyanobacteria, they have phycobilins- red color due to phycoerythrin but they can be black, purple or brown due to phycocyanins; this in addition to chl a and cartenoids;
Recently an encrusting coralline algae was found at a depth of 268m a greater depth than that recorded for any photosynthetic organism; this more than 100m lower than the depth to which light can penetrate water
* Storage product is floridean starch (branched polymer of glucose) but this is never stored in chloroplast ( in cytoplasm) plus other weird sugars only found in the reds;
[carrageenan below]
*
Cell wall of cellulose overlayed by thick layer of slimy mucilage (sulfated galactans) agar and carrageenan; the complete wall is quite thick, often as thick as protoplast is wide; since all but a few are multicellular, even internal cells have direct contact with the water
- 1. These are important commercially as thickening agents, suspending or stabilizing agents.
- Agar is used to make capsules that contain vitamins, drugs;dental impression material; base for cosmetics; culture medium (agar plates). Also anti-drying agent in bakery goods, preparation of fast setting jellies and desserts, temporary preservative for meat and fish in tropics.
- Carrageenan is used for to stabilize paints, cosmetics and dairy products ( in puddings, ice creams, cheeses, salad dressings).
- 2. Whole plant ia used as food -Nori- employs 30,000 people in Japan alone value $20M; sushi, soups etc.
* In the largest of the families, the Corallinaceae or coralline red algae, such large amounts of calcium carbonate are deposited in walls they they are rocklike . The productivity of coral reefs in relatively infertile waters depends directly on the algae forming a symbiotic relationship with the dinoflagellates (zooxanthellae) and coral reef animals. They are unjointed unlike other jointed corralines. They are an ancient group going back to the late Cambian period 500MYA
Calcareous algae are algae that deposit calcium carbonate (limestone) in their tissue. When the algae die, they leave a fossil "skeleton" behind. These plants do not have real skeletons, but the limestone deposits make it appear so. These skeletons build up sediment in tropical lagoons and reefs.
* Pit connections; a ring with a lens shaped protein plug held in the walls by equatorial grooves; don't know whether intercellular communication or transport? if 2 seperate filaments meet they form this pit.
* Numerous red algae are parasitic on other red algae (40 genera); basal cell penetrates into host forming secondary pit connections with host cells.
* Type of cell division is weird so majority don't form parenchyma tissue; only bodies of filaments held together by their mucilagenous walls. tissue thus is pseudoparenchymatous. True parenchyma only found in few species Porphyra.
* No true cell specialization; inner cells smaller, outer larger. Grow rhizoids to rocks etc.
