A small red alga with thallus small, irregularly shaped, folliaceus (leaf-like) and membranaceous but tough attached to the substrat (e.g. rocks) by small discoid hold-fast. Frond more or less divided, crinkled and undulate at edges. Colour green in its earlier stages, becoming brownish purple, or purplish-red. Geographical Distribution NW Pacific: Japan, China. Indian Ocean: Mauritius. Habitat and Biology Inhabit rocks, and sometimes even settled on molluscs and on other seaweed species. It inhabits between the tide levels, midtidal to splash zone.It is generally abundant, especially on exposed coasts.Primary producer. Porphyra has a trimorphic life history, comprising a thallus stage, carposporophyte stage and a filamentous Conchocelis phase. This last phase, a stage in the life history of Porphyra, was attibuted til 1949 as pertaining to Conchocelis rosea as an independent algae species. Spores of Porphyra settle during autumn. Porphyra tenera inhabits from the midtidal level to splash zone, being adapted to exposed coasts. The alga flourishes in winter at temperatures between 4-9Â°C. Warm water temperature limits its distribution in tropical regions. For many centuries traditionally cultivated in Japan and other coastal areas as nori. Fishermen planted bamboo in shallow waters to increase the substratum for nori cultivation. Modern cultivation of Porphyra did not occur until the 1960's, as a result of the discovery of the Conchocelis phase. In China and Japan, there are 7 main species used in commercial cultivation (Porphyra yezoensis, Porphyra tenera, Porphyra haitanensis, Porphyra pseudolinearis, Porphyra kunideai, Porphyra arasaki, and Porphyra seriata). Some available statistics data from the 1960's, give a dried annual production of cultivated Porphyra tenera around 5000 tons. In 1977, some 300,000 t wet weight of Porphyra spp. were harvested in Japan and the production volume increased by 25% per annum in the 1970s. For food, consumed in a variety of forms. Nori is, for instance, sold in sheets, once toasted they are flaked and added to sauces, soups and broths. It have a high protein content (25-35% of dry weight), vitamins (e.g. vitamin C) and mineral salts, especially iodine.