''Porphyra'' is a genus of coldwater

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of '' Rhodophyta'' (red), ''Phaeophyta'' (brown) and '' Chlorophyta'' (green) macroalgae. Seaweed species such as ...

s that grow in cold, shallow

seawater Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...

. More specifically, it belongs to

red algae Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...

phylum of laver species (from which comes

laverbread Laverbread (; cy, bara lafwr or '; ga, sleabhac) is a food product made from laver, an edible seaweed (littoral alga) consumed mainly in Wales as part of local traditional cuisine. The seaweed is commonly found around the west coast of Great ...

), comprising approximately 70 species.Brodie, J.A. and Irvine, L.M. 2003. ''Seaweeds of the British Isles.'' Volume 1 Part 3b. The Natural History Museum, London. It grows in the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

, typically between the upper intertidal zone and the splash zone in cold waters of temperate oceans. In East Asia, it is used to produce the sea vegetable products '' nori'' (in Japan) and '' gim'' (in Korea). There are considered to be 60 to 70 species of ''Porphyra'' worldwide Kain, J.M. 1991. Cultivation of attached seaweeds. in Guiry, M.D. and Blunden, G. 1992. ''Seaweed Resources in Europe: Uses and Potential.'' John Wiley and Sons, Chichester and seven around Britain and Ireland where it has been traditionally used to produce edible sea vegetables on the Irish Sea coast.Hardy, F.G. and Guiry, M.D. 2006. ''A Check-list and Atlas of the Seaweeds of Britain and Ireland.'' British Phycological Society, London. The species Porphyra purpurea has one of the largest

plastid The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the cells of plants, algae, and some other eukaryotic organisms. They are considered to be intracellular endosymbiotic cyan ...

genomes known, with 251 genes.

Life cycle

''Porphyra'' displays a heteromorphic

alternation of generations Alternation of generations (also known as metagenesis or heterogenesis) is the predominant type of life cycle in plants and algae. It consists of a multicellular haploid sexual phase, the gametophyte, which has a single set of chromosomes alt ...

. The

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms ...

we see is the

haploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respective ...

generation; it can reproduce asexually by forming

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

s which grow to replicate the original thallus. It can also reproduce sexually. Both male and female

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...

s are formed on the one thallus. The female gametes while still on the thallus are fertilized by the released male gametes, which are non-motile. The fertilized, now

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectiv ...

, carposporangia after

mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintai ...

produce spores ( carpospores) which settle, then bore into shells, germinate and form a filamentous stage. This stage was originally thought to be a different species of alga, and was referred to as ''Conchocelis rosea''. That ''Conchocelis'' was the

stage of ''Porphyra'' was discovered in 1949 by the British phycologist Kathleen Mary Drew-Baker for the

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

an species ''

Porphyra umbilicalis Green laver (), known as ''aonori'' (; ) in Japan, ''sea cabbage'' () or ''hutai'' () in China, and ''parae'' () in Korean, is a type of edible green seaweed, including species from the genera ''Monostroma'' and ''Ulva'' ('' Ulva prolifera'', '' ...

''. It was later shown for species from other regions as well.Thomas, D. 2002. ''Seaweeds.'' The Natural History Museum, London.

Food

Most human cultures with access to use it as a food or somehow in the diet, making it perhaps the most domesticated of the marine algae,Mumford, T.F. and Miura, A. 4.''Porphyra'' as food: cultivation and economics. in Lembi, C.A. and Waaland, J.R. 1988. ''Algae and Human Affairs.'' Cambridge University Press, Cambridge. known as laver, ( Vietnamese), '' nori'' ( Japanese:), ''amanori'' (Japanese), ''zakai'', '' gim'' ( Korean:), ''zǐcài'' ( Chinese:), karengo, ''sloke'' or ''slukos''. The marine red alga ''Porphyra'' has been cultivated extensively in many

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

n countries as an edible seaweed used to wrap the rice and fish that compose the Japanese food sushi and the Korean food ''

gimbap ''Gimbap'' (), also romanized as kimbap, is a Korean dish made from cooked rice and ingredients such as vegetables, fish, and meats that are rolled in '' gim''—dried sheets of seaweed—and served in bite-sized slices. * The origins of gim ...

''. In Japan, the annual production of ''Porphyra'' species is valued at 100 billion yen (US$1 billion).Aoki, Y. and Kamei, Y. 2006 Preparation of recombinant polysaccharide-degrading enzymes from the marine bacterium, ''Pseudomonas'' sp. ND137 for the production of protoplasts of ''Porphyra yezoensis'' ''Eur. J. Phycol.'' 41: 321-328. is harvested from the coasts of Great Britain and Ireland, where it has a variety of culinary uses including

. In Hawaii, "the species is considered a great delicacy, called ". Porphyra was also harvested by the

Southern Kwakiutl Laich-kwil-tach (also spelled Ligwilda'xw), is the Anglicization of the Kwak'wala autonomy by the "Southern Kwakiutl" people of Quadra Island and Campbell River in British Columbia, Canada. There are today two main groups (of perhaps five orig ...

Haida Haida may refer to: Places * Haida, an old name for Nový Bor * Haida Gwaii, meaning "Islands of the People", formerly called the Queen Charlotte Islands * Haida Islands, a different archipelago near Bella Bella, British Columbia Ships * , a ...

, Seechelt, Squawmish,

Nuu-chah-nulth The Nuu-chah-nulth (; Nuučaan̓uł: ), also formerly referred to as the Nootka, Nutka, Aht, Nuuchahnulth or Tahkaht, are one of the indigenous peoples of the Pacific Northwest Coast in Canada. The term Nuu-chah-nulth is used to describe fifte ...

, Nuxalk,

Tsimshian The Tsimshian (; tsi, Ts’msyan or Tsm'syen) are an Indigenous people of the Pacific Northwest Coast. Their communities are mostly in coastal British Columbia in Terrace and Prince Rupert, and Metlakatla, Alaska on Annette Island, the only r ...

, and Tlingit peoples of the North American Pacific coast.

Vitamin B12

Porphyra contains vitamin B12 and one study suggests that it is the most suitable non-meat source of this essential vitamin. In the view of the Academy of Nutrition and Dietetics, it may not provide an adequate source of it for

vegan Veganism is the practice of abstaining from the use of animal product—particularly in diet—and an associated philosophy that rejects the commodity status of animals. An individual who follows the diet or philosophy is known as a vegan. ...

Species

Following a major reassessment of the genus in 2011, many species previously included in ''Porphyra'' have been transferred to '' Pyropia'', for example ''

Pyropia tenera ''Pyropia tenera'', also known as gim or nori, is a red algal species in the genus ''Pyropia''. The specific name, ''tenera'', means "delicate" and alludes to its small size. It typically grows to lengths between 20 and 50 cm. It is most ...

'', ''

Pyropia yezoensis ''Pyropia'' is a genus of red algae eaweedin the family Bangiaceae. It is found around the world in intertidal zones and shallow water. The genus has folding frond-like blades which are either red, brown or green. Some ''Pyropia'' species are ...

'' and the species from New Zealand ''

Pyropia rakiura ''Pyropia rakiura'', formerly known as ''Porphyra rakiura'', is a red alga species in the genus ''Pyropia'', known from New Zealand. It is monostromatic, monoecious, and grows in the intertidal zone, predominantly on rock substrata. With '' P. ...

'' and ''

Pyropia virididentata ''Pyropia virididentata'', formerly known as ''Porphyra virididentata'', is a red alga species in the genus '' Pyropia.'' It is endemic to New Zealand. It is monostromatic, monoecious, and grows in the intertidal zone, predominantly on rock s ...

'', leaving only five species out of seventy still within ''Porphyra'' itself.

References

External links

* *
Video footage of Laverbread or Bara Lawr
{{Taxonbar, from=Q2104475 Red algae genera Bangiophyceae Edible seaweeds Seaweeds Edible algae Taxa named by Carl Adolph Agardh