Rhodophyta

1. Rhodophyta • They are also known as red algae or rhodophytes. • They are multicellular organisms. • Characterized by photosynthetic pigments such as phycoerythrin, phycocyanin and allophycocyanins, and the absence of flagella and centrioles. • They don’t have chloroplast endoplasmic reticulum. • Store sugars as glycogen or Floridean starch • A long chain of glucose sugars with lots of side branches. • Characterized by their branching. • They are able to thrive at deeper depths of the ocean compared to other algae. • They are mostly found along the coastal and continental shelf areas of tropical, temperate and cold-water regions. • It consists of approximately 5000 genera and 5000 species. • It is one of the most ancient eukaryotes, with fossils that date back to the mid-proterozoic.

2. Structures • Open protoplasmic connection • connects daughter cells. • Pitplug • closes the connection between 2 daughter cells. • Red, algal cell wall • An inner layer with cellulose. • Gelatinous outer layer. • Contain amorphous mucilages (shapeless mucuses). • Nuclei • Chloroplasts • Contain phycobilins, chlorophyll a, carotenes, xanthophylls. • Phycobilisomes • Involved in photosynthesis • Spermatangia • Male reproductive organ, filled with spermatia (male reproductive cell). • Carpogonium • Female reproductive organ. • Trichogyne • Hair like receptor of the carpogonium. • Cytoplasm • Forms floridean starch

3. Reproduction • Reproduce both sexually and asexually. • The spermatium relies on water to reach the carpogonium. • It makes contact with trichogyneand its nucleus merges with that of the carpogonium. • The carpogonium forms a large bulb, which separates and becomes young red algae.

4. Nutrition • They obtain energy through photosynthesis. • Some rhodophyteswere found to be parasitic in nature.

5. Ecology • Coralline red alga is essential in marine ecosystems because they are reef-building organisms. • They produce calcium carbonate in their cell walls. • Some red algae have been found to be parasitic • Some transport nutrients from their host through a haustoria. • Some transfer their nuclei into the host plant and hijack the host. • Most are found in marine ecosystems, while a few are found in freshwater. • They live attached to surfaces. • They harness light efficiently, which enables them to live at great depths.

6. Examples • Appear green in their early stages. • Appear brownish-purple or purple-red in maturity. • They live on exposed coasts and are attached to rocks or mollusks. • They can also be found in the midtidal to splash zone. • They are most abundant in temperatures between 4-9 °C • They are often found attached to rocks or mollusk shells. It is abundant especially on exposed coasts. • The calcium carbonate within its cell walls strengthens its structure and causes it to appear pink. This substance also protects them from being eaten by shore grazers. • Serve as a home for small organisms which eat the microorganisms living on it. • Corallinaofficinalis • Marine species, also known as coral weed. • Whitish-pink to lilac in color. • Its calcified, branching and segmented fronds reach up to 12 cm in length from a crustose, disk shaped root. • Urn-shaped reproductive organs. • 60-70 mm high • Galaxauraspp. • Tubular thicket algae. • Heavily calcified and forms hemispherical domes, up to 15 cm, attached by a single holdfast or root. • Its segments branch out dichotomously. • Its segments are tubular in shape, smooth, and hard with flexible joints • The tips of its branches have a central hole. • They are redish to orange and off-white in color. • They are most commonly found attached to rocks or rocky surfaces. Porphyratenera • It is also known as nori. • Small, red alga. • They have crinkled edges and are able to reach a width of 20 cm. • They are irregularly shaped, leaf-like and membranous.

7. Sources • http://www.ehow.com/how-does_4574307_algae-reproduce.html • http://lifeofplant.blogspot.com/2011/01/red-algae.html • http://marinelife.about.com/od/plants/p/redalgae.htm • http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artmar99/red.html • http://university.uog.edu/botany/Plant_Di/rhodophyta.htm • http://www.algaebase.org/search/species/detail/?species_id=107 • http://www.marlin.ac.uk/speciesinformation.php?speciesID=3039 • http://porphyra.wetpaint.com/ • http://www.fao.org/fishery/species/2790/en