by Survival Expert James Mandeville Disclaimer: The author does not assume liability for adverse reactions to the seaweeds featured in this article either by consuming them or coming into contact with them. They are handled and consumed at your own risk. Every reasonable care has been taken to ensure the accuracy of the information in this article but the author assumes no liability for any inaccuracies or omissions. Use of this website means you have read and accepted the above and accept all the conditions of use in our Disclaimer. Take note:
Edible seaweed are algae that can be eaten raw or cooked and are often used in the preparation of food. They are varied (there are over 650 different varieties of seaweed to be found around the British coast alone) and nearly all are edible, but some can upset the stomach or cause diarrhoea if eaten raw. It is always a good idea to blanch seaweed in boiling water for a couple of minutes or cook them by boiling, frying or roasting – if you have no alternative but to eat raw seaweed, take care to collect it from areas where the water is not polluted then wash it well in potable water.
Seaweeds typically contain high amounts of fibre and are a complete protein. They may belong to one of several groups of multicellular algae: the red algae, green algae, and brown algae. Most edible seaweeds are marine algae whereas most freshwater algae are mainly toxic. Some marine algae contain acids that irritate the digestion canal, while some others can have a laxative and electrolyte-balancing effect. People react differently to digestive irritation and you should use caution when trying seaweed and test small amounts first. Seaweeds are known to take up heavy metals, radionucleotides and various other pollutants. Therefore do not harvest from areas where industrial pollution could be a problem or in waters close to heavy shipping lanes. If seaweed smells strongly of iodine or sulphur it is best not to eat it. Seaweed tried by the author and normally regarded safe to eat Seaweed not tried by the author but normally regarded safe to eat.
Common edible seaweed Bladderwrack (Fucus vesiculosus), Fucaceae
Bladderwrack (Fucus vesiculosus), Fucaceae. Range:
Found on the coasts of the North Sea, the western Baltic Sea and the Atlantic and Pacific Oceans. Also known by the common names: Black tang, rockweed, bladder fucus, sea oak, black tany, cut weed, dyers fucus, red fucus and rock wrack. Habitat:
The species is common, especially on sheltered shores between the high and low tide levels. It is rare on exposed shores where any specimens may be short, stunted and without the air vesicles. Survival food value:
Bladderwrack is a good source of vitamins A and C. It also contains vitamins in the B–complex, those partly responsible for metabolism at the cellular level. Bladderwrack is rich in beneficial minerals, such as, iron, magnesium, potassium, calcium and zinc. In addition, it contains essential fatty acids and oils that regulate and promote healthy cardiac and respiratory functions. Preparation:
To prepare, Bladderwrack is burned, then ground into a powder, which can add flavour and texture to a number of dishes or used as an infusion to make "herbal tea". The plant is also eaten in basic form as a vegetable best mixed with other vegetables. Further information:
Bladderwrack was the original source of iodine, discovered in 1811 and was used extensively to treat goitre, a swelling of the thyroid gland related to iodine deficiency. Consuming high levels of iodine can cause some of the same symptoms as iodine deficiency, including goitre (an enlarged thyroid gland).
Carragheen (Mastocarpus stellatus),
Clúimhín Cait (cats' puff), or false Irish moss.
Carragheen (Mastocarpus stellatus). Range:
West coast of the United Kingdom, particularly Scotland and the west coast of Ireland. Atlantic coast in the USA reaching down to Cape Cod. Habitat:
It occurs commonly on rocks in the area between the high and low tide levels. Survival food value:
Mastocarpus stellatus is made up of a mucilaginous body, made of the polysaccharide carrageenan, which constitutes 55% of its weight. It consists of nearly 10% protein and about 15% mineral matter, and is rich in iodine and sulfur. It can be eaten raw; when boiled it forms a jelly, which is eaten warm. Not a pleasant flavour or texture; the iodine taste often comes through quite strongly. Further information:
Related to Irish Moss (Chondrus crispus). It is collected in Ireland and Scotland, together with Chondrus crispus as Irish Moss, dried, and sold for cooking and as the basis for a drink reputed to ward off colds and flu. The fronds are channelled, unlike those of Chondrus crispus, and it has a curved stipe, whereas Chondrus has a flat one.
Carola (Callophyllis variegata)
Carola (Callophyllis variegata). Range:
Concepción de Chile and other parts of South America such as Peru, the Falkland Islands, Tierra del Fuego. But also in New Guinea, South Africa, Australia, New Zealand, Alaska, St. Paul Island (Indian Ocean), Antarctic and subantarctic islands such as the Graham Land, Kerguelen, Macquarie Island, South Georgia, and the South Orkney Islands. Habitat:
It grows in subtidal or intertidal areas on a rocky substrate, between 5 and 15 meters deep. Survival food value:
High in minerals and vitamins, it is edible raw or boiled and has a bitter–sweet taste. Further information:
In Chile, the demand for edible seaweeds has increased and Callophyllis variegata ("carola") is one of the most popular. Its consumption rose from zero in 1995 to 84 wet tonnes in 1999. This red seaweed has a high commercial value but knowledge of its nutritional use is restricted.
Cochayuyo (Durvillaea antarctica)
Cochayuyo (Durvillaea antarctica). Range:
Durvillaea antarctica or Cochayuyo is a large, tough bull kelp species and the dominant seaweed in southern New Zealand and Chile. D. antarctica has a circumpolar distribution between the latitudes of 29°S (in Chile) and 55°S (on Macquarie Island). Habitat:
It is found on exposed shores, especially in the northern parts of its range, and attaches itself with a strong hold–fast. D. antarctica, an alga, does not have air bladders, but floats due to a unique honeycomb structure within the alga's blades, which also helps it to avoid being damaged by the strong waves. Survival food value:
It is practically fat free (0.3% by weight), low in calories and high in protein (11.3% by weight), and has over 100% of the Recommended Daily Allowances for fibre, calcium, iron, magnesium, iodine. It is high in sodium (3.5% by weight). It also contains phosphorous. Preparation:
Traditionally Cochayuyo is preserved by sun–dried and softened up by soaking in potable water overnight before cooking by boiling for 20 minutes. Chop into chunks and eat it on its own or with other food, such as beans if you have them. It tastes bland and has a chewy texture.
Dulse (Rhodymenia palmata), Rhodymeniaceae family
Dulse (Rhodymenia palmata). Range:
Found in the Atlantic and the Mediterranean, Dulse is purple red, lobed, with fan–shaped fronds and short stems. Habitat:
Shoreline – It is commonly found from June to September and can be collected by hand when the tide is out. Preparation:
Can be eaten raw after washing in several changes of fresh water (used as a famine food in Scotland and Ireland), has a sweet taste, but is chewy. It is best boiled until tender. Can be dried and saved for later use. Dried Dulse supposedly has a pleasant "nutty" flavour, depending on your taste buds and imagination, but to me it was closest to the aftertaste you have in your mouth after eating black walnuts mixed with modelling clay. It turns crispy when fried in a little oil and in my opinion is the tastiest way of eating it. Survival food value:
Dulse is a good source of minerals and vitamins comparable with many vegetables. It contains almost all the trace elements needed by humans and has high protein content (18%). beta carotene, vitamin C, vitamin E, and most of the B vitamins, including B6, contains high levels of iodine, as well as calcium, iron, manganese, magnesium, potassium, phosphorus, organic sodium and zinc. A quarter-ounce of dulse provides about 30 percent of the recommended daily allowance of iron, and one cup of dulse can provide 4 to 6 grams (0.14 to 0.21 oz) of protein. Preparation:
Shake off small snails and debris then wash in clean water and spread it out to dry. Fresh dulse can be eaten directly off the rocks. Sun–dried dulse is eaten as is, or is ground to flakes or a powder.
The tradition in Iceland is to eat it with butter. It can also be pan–fried quickly into chips, baked in the oven covered with cheese, with salsa, or simply microwaved briefly. It can also be used in soups, chowders, sandwiches and salads, or added to bread/pizza dough. Finely diced, it can also be used as a flavour enhancer in meat dishes in place of monosodium glutamate. Further information:
Commonly referred to as "Dillisk" on the west coast of Ireland. Dillisk is usually dried and sold as a snack food on stalls in seaside towns by periwinkle sellers. Dulse is a valuable survival food. It is also used as fodder for animals in some countries.
Euchema cottonii. Range:
Hawaii, Tonga, East Africa, China, the Philippines, and around the Pacific Ocean. Habitat:
Eucheuma are typically found below the low tide mark to the upper subtidal zone of a reef, growing on sand to rocky seafloor areas along a coral reef, where water movement is slow to moderate. Survival food value:
Contains around 0.1% of Vitamin E, also calcium 0.7% Iron 0.7%, Magnesium 0,6%, Phosphorus 0.14%, Sodium 6.31% Preparation:
Soak in several changes of potable water for 6 hours, then cut up and eat it raw. If you boil it it will totally dissolve in the water.
Gutweed (Enteromorpha intestinalis), Ulvaceae family:
Gutweed (Enteromorpha intestinalis). Range:
Often abundant in cooler waters around the world and wherever there is brackish water. It is commonly found from June to September and can be collected by hand when the tide is out. Habitat:
Found in rock pools and salt marshes, growing on rocks, in mud and in sand. Survival food value:
The whole plant is edible, either fresh or dried, and may be pulverised for later use. As a survival food, it is edible raw, toasted or steamed. It is useful as animal feed and as medicine for an upset stomach. Further information:
There are 10 species of Enteromorpha and it can be difficult to tell them apart, but they are all edible. Enteromorpha intestinalis is a conspicuous bright, grass–green seaweed. It has pods and un–branched fronds growing 10 – 30 cm (4 – 12 inches) long.
Hijiki or Hiziki (Sargassum fusiforme)
Hijiki or Hiziki (Sargassum fusiforme). Range:
Asia: China (Tseng 1984), Hong Kong (Setchell 1931), Japan. Multiple distributions in coastal areas north of Liaodong Peninsula and south in the Leizhou peninsula. Habitat:
Grows in the low tide rock band. Survival food value:
High in calcium and other vitamins and trace minerals. Strong tasting, salty. Preparation:
Soak overnight in several changes of potable water overnight. Cook by boiling, the seaweed turns black and expands. Further information:
Sargassum fusiforme is a brown algae of the genus Sargassum. Variation of leaf is large with many shapes. Recognized as having the highest food value of edible marine algae. The Japanese called it a "longevity vegetable."
Irish moss (Chondrus crispus), Gigartinaceae family
Irish moss (Chondrus crispus). Range:
Atlantic coasts. Often growing in dense beds. It has tough, dark, purplish–red fronds, frequently iridescent under water when in good condition. It grows up to 15 cm (6 inches) high. Habitat:
Can be found on rocks, in pools, lower intertidal and shallow subtidal areas; it is widely distributed and abundant. Survival food value:
As a food, it is a source of carrageenan (a sulphated polysaccharide, thickening agent) and is harvested commercially for use as a thickening agent. Wash the seaweed well in fresh water and boil it. When it cools, it will set like gelatine. Fronds may be sun–dried for storage; they go bleached white in appearance when they are dehydrated. When soaked in water, Irish moss can hold 20–200 times its own weight of water. It has limited survival food value, but it does contain 10% protein and is rich in iodine and sulphur. It has a taste that is hard to describe – slightly sweet and sulphurous. Its main value is to reduce hunger pangs when eaten in small quantities. Further information:
I grew up in the Hebrides (where Irish moss is known as (An) Cairgean in Scottish Gaelic). My Grandmother swore by it. She used to boil it in milk, strain the liquid off and then add sugar and cinnamon to make a dessert that resembled tapioca; never my favourite dish. My Grandfather used to add a generous quantity of whisky to his, "To keep away colds and other illnesses." I can't verify it does this, but I never saw him get ill and he died when he was 93 and my Grandmother died 2 days before her 100th birthday. Was their longevity attributed to eating Irish moss, or to consuming single malt? I'll never know.
Kelps: Alaria, (Alariaceae family) and Laminaria, (Laminariaceae family):
Kelp bed at low tide in Cornwall UK
Most Kelps have short, cylindrical stems and a laminate blade that can be 3 metres (10 feet) long. They are olive green to brown in colour. Range:
The Laminariaceae family are common on all coasts of Britain and Ireland (except for the south–east coast of England) and from Yorkshire to the N coast of Kent; otherwise distributed from Svalbard, Iceland and North Russia south to Brittany. Also in the Western Atlantic from the north–east coast of Greenland and south to Cape Cod and, although less common, to Long Island USA. Not known elsewhere.
Kelps: Alaria (Alariacae)
Bladder kelp, Alaria (Alariacae family).
Kelp and seagrass. Habitat:
Most Alariaceae look similar to the uninformed. Kelps are very common in the lower intertidal and shallow subtidal waters; they form extensive 'meadows' at low water. Survival food value:
All kelps are edible raw (wash well in clean water, several changes), but are more digestible if boiled until tender, as they are a very chewy plant. Kelp has a mild, semi–sweet flavour. Sugar kelp (Laminaria saccharina)
Sugar kelp Range:
Widespread all around the shores of the British Isles from the Shetlands to the Channel Islands. Europe: Portugal, Atlantic coasts of Spain and France, Netherlands, Helgoland, Baltic Sea, Norway, Sweden, Faroes, Jan Mayen and Bjornoya, Spitzbergen and Iceland. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Rhode Island, Connecticut and Long Island, Pacific coast of North America from Alaska to California. Habitat:
The most nutritious edible kelp, sugar kelp (Laminaria saccharina), photo above, can be found in the surging shallows during low tide, usually growing in thick beds anchored to rocky bottoms. Survival food value:
The most nutritious edible kelp, sugar kelp (Laminaria saccharina), photo above, can be found in the surging shallows during low tide, usually growing in thick beds anchored to rocky bottoms.
Kelp makes a nutritious additive to chowders, soups and stews. It may be eaten as a vegetable raw or cooked. Further information:
Edible kelp has a characteristically long and wavy central frond about 15 cm (6 inches) wide, growing from 1 to 3 metres (3 – 10 feet) high from a short basal stem, where a number of shorter fronds grow radially outward. It is olive–green or brown in colour, and is frequently found floating freely in the water, but a little wading and tugging will invariably produce lots to eat.
Kombu (Saccharina japonica)
Kombu (Saccharina japonica) Range:
Saccharina japonica (Dashi kombu) is a marine species of Phaeophyceae (brown algae), a type of kelp or seaweed, that is extensively cultivated in China, Japan and Korea. The species is native to Japan, but has been cultivated in China, Japan, Russia, France, and Korea. It is one of the two most consumed species of kelp in China and Japan. Photo above (inset) shows Saccharina japonica being sun dried. Habitat:
Shallows, growing in thick beds anchored to the bottom. Survival food value:
Best dried, ground up or shaved and drunk as an infusion. It is edible raw, can be added to soups or fried. Further information:
In China it is regarded as a health food because of its high vitamin and mineral content, especially in Northern China where winter green vegetables are scarce.
Lavers (Porphyra, var. species), Bangiaceae family
They are found in both the Atlantic and the Pacific Oceans. Habitat:
It is smooth and fine, often clinging to rocks. Survival food value:
Lavers have irregularly shaped, thin, red or purplish fronds. Lavers has to be tenderized by boiling and are best mashed up and eaten with other food. The high iodine content gives the seaweed a distinctive flavour, a bit like green olives. Lavers are very nutritious, being high in minerals and vitamins. Further information:
The principal variety is purple laver (Porphyra laciniata/Porphyra umbilicalis) illustrated above. This tends to be a brownish colour, but boils down to a dark green pulp when prepared.
Green lavers, sometimes called Sea Lettuce, (Ulva lactuca Linnaeus) Range:
Asia: Taiwan. South–east Asia: Indonesia, Singapore, Vietnam. Pacific Islands: Fiji, French Polynesia, Hawaiian Islands, Samoan Archipelago. Abundant in the surf zone and on rocky coasts. Short thick blades with prickly margins and spherical gas bladders. Habitat:
Fairly common in brackish water, or where estuaries run into the sea, it grows on rocks and in pools. Survival food value:
Green lavers is also edible just like the Purple Laver (Porphyra umbilicalis (Linnaeus) Agardh), but is not typically collected and eaten as its texture is not pleasant and it has low food value and may be regarded as a desperate survival food if there is nothing else to eat. Further information:
It is like a broad, flat, crumpled green sheet, very thin (only two cells thick) and translucent. It starts off being attached to stones and rocks by a small hold–fast, but easily becomes detached. It can still live and thrive free–floating in the sea. The colour of green is variable and sometimes it has white edges — which occur after it has shed its reproductive products into the water. I confess I have never tried it, the only time I came across it, the seawater looked polluted so, of course, I didn't want to risk eating anything from that particular stretch of water. It is, however, regarded as being quite safe to eat under normal conditions.
Mozuku (Cladosiphon okamuranus)
Cladosiphon okamuranus Range:
Cladosiphon okamuranus is a type of edible seaweed in the genus Cladosiphon, naturally found in Okinawa, Japan. Habitat:
Shallows: Lower–intertidal and shallow subtidal areas. Survival food value:
Calories (kcal) 150/100 gm, Protein 0.8%, Fat 0.6%, Carbohydrate 6.3%, Sodium 1.9%, Sugars 0.3%. Contains potassium, magnesium and calcium. Further information:
Most of the mozuku now is farmed by locals, and sold to processing factories. The main use of mozuku is as food, and as source of one type of sulphated polysaccharide called Fucoidan used in cancer treatment aid health supplements.
Oarweed, Laminaria digitata
Oarweed, Laminaria digitata Range:
UK coast. Scarce along the east coast of England, particularly between the Ouse and Thames estuaries, due to turbidity and lack of hard substrata. Habitat:
Very common in the lower–intertidal and shallow subtidal areas, growing on rock in Britain and Ireland. Survival food value:
Total Fat 0.1%; Sodium 1.0%, Carbohydrate 0.3%, Dietary Fibre 0.50%, Protein 0.3%, Vitamin A 0.2%, Vitamin C 0.5%, Calcium 1.68%, Iron 1.60% and Potassium 0.30%. Further information:
May form extensive meadows at low water. Underwater plants are more golden in colour in sunlight.
Ogonori (Gracilaria) Range:
In the north-eastern Atlantic, known from southern Norway southwards to northern Spain. Also known outside the area. Japan, Hawaii, Philippines. Habitat:
On rocks and stones, intertidal and subtidal, especially on sandy shores, generally distributed, common. Survival food value:
Per 100 gm: Calories 20, protein 1 gm, carbohydrate 8.8 gm. Contains vitamins: A, E, K, B1, B2, niacin and folate. Minerals (trace amounts): Sodium. potassium, calcium, magnesium, phosphorous, iron, zinc, copper and manganese. Further information:
Gracilaria is widely used as nutritious food in Asia, especially by Japanese, Hawaiian, and Filipino cultures. In Japan it is called ogo.
Sargassum echinocarpum) Range:
Asia: Taiwan. South–east Asia: Indonesia, Singapore, Vietnam.
Pacific Islands: Fiji, French Polynesia, Hawaiian Islands, Samoan Archipelago. Habitat:
Abundant in the surf zone and on rocky coasts. Sargassum echinocarpum is commonly found on wave–swept rocky intertidal benches, in tide pools, and on reef flats. Survival food value:
Rich in soluble dietary fibres, proteins, minerals, vitamins, antioxidants, phytochemicals, and polyunsaturated fatty acids, with low caloric value. They are an excellent source of vitamins A, B1, B2, B3, B12, C, D, E. Preparation:
Can be washed in potable water, blanched in boiling water and eaten raw. Has a fairly bland taste, although it can vary and have a strong, rather unpleasant taste – if this is the case, boil for two minutes in 2 – 3 changes of water. Further information:
Short thick blades with prickly margins and spherical gas bladders. Two free–floating, common species, found along the coast of Florida, Sargassum natans and Sargassum fluitans are both edible and slightly bitter tasting. Both Florida species can be boiled for a couple of minutes then eaten or added to other foods.
Sea Grapes or Green caviar (Caulerpa lentillifera)
Sea Grapes or Green caviar (Caulerpa lentillifera) Range:
Indian Ocean: from Saudi Arabia to South Africa, including the Red Sea and Madagascar, east to Pakistan and south to Dampier, Western Australia, including Maldives; Pacific Ocean: from Japan to the South China Sea, south to Queensland, Australia, including Federated States of Micronesia, Marshall, and Solomon Islands, east to the Hawaiian Islands. Habitat:
Commonly inhabits shallow, sandy to muddy lagoon and reef flats which are not exposed during low tides and where the water is generally calm. It may form an extensive bed in exceptionally good habitats. Survival food value:
Round sea grapes are a popular edible species in some places. In the Philippines, the seaweed is eaten fresh as a salad, or salted so it can be eaten later. Small quantities are also exported to Japan. It is also eaten in Malaysia and Indonesia. The seaweed is high in minerals and tastes refreshing. Further information:
The seaweed resembles bunches of little grapes. Each 'grape' is a tiny spherical bead, and these are tightly packed on a vertical 'stem' to form a sausage–like shape. The 'grape' has a distinct constriction where it attaches to the 'stem'. These bunches of 'grapes' emerge from a long horizontal 'stem' that creeps over the surface. It grows on coral rubble or on rocks. Colours range from bright green to bluish and olive green. It is also reported to have antibacterial and antifungal properties, and is used to treat high blood pressure and rheumatism. However, some Caulerpa species produce toxins to protect themselves from browsing fish. This also makes them toxic to humans so correct identification is essential and it is best to consult locals before eating.
This seaweed is commercially farmed in Cebu, Philippines. Cuttings are planted by hand in muddy mangrove ponds and harvested about two months later. The seaweed is also fed to livestock and fish.
Spirulina (Arthrospira platensis and Arthrospira maxima)
Spirulina (Arthrospira platensis and Arthrospira maxima) Range:
Arthrospira platensis and Arthrospira maxima occur naturally in tropical and subtropical lakes with high pH and high concentrations of carbonate and bicarbonate. Arthrospira platensis occurs in Africa, Asia, and South America, whereas Arthrospira maxima is confined to Central America, and Arthrospira pacifica is endemic to the Hawaiian islands. Habitat:
Found in alkaline marine environments with a pH of up to 11. Survival food value:
Humans have been eating Spirulina since prehistory, and today, this tiny aquatic plant is widely regarded as the world's greatest 'super food' — its long, thin, spiralling threads consisting of up to 70% protein (dry weight), the elements of which consist of 18 types of amino acids, vitamins A, C, E, K, B (1, 2, 3, 6, 12), various minerals, enzymes, anti–oxidants, and phytonutrients including essential fatty acids, polysaccharides, and sulfo–lipids, and chlorophyll and carotenoids, which give Spirulina its dark green colour. Preparation:
Wash in potable water several times. Can be eaten raw or after blanching for a minute in boiling water. It can also be dried, powdered and added to other foods. Further information:
It has green credentials too, producing more protein per acre than any other food source on the planet. The blue colour in Spirulina comes from phytonutrient called 'phycocyanin', which in one study was shown to inhibit cancer–colony formation.
Spirulina is cultivated, the largest commercial producers of spirulina are located in the United States, Thailand, India, Taiwan, China, Pakistan, Burma, Greece and Chile.
Thongweed (Thong Weed) Himanthalia elongata
Thongweed. Himanthalia elongata Range:
Common along all coasts of Britain and Ireland, except south–eastern England. Habitat:
Lower rocky shores, especially in semi-exposed locations. Survival food value:
Boil for 10 – 15 minutes, also good eaten raw but needs blanching for a couple of minutes in boiling water. Turns bright green when cooked. Further information:
A common green or brown seaweed of the lower shoreline. The strap–like reproductive fronds grow quickly between February and May, reaching a length of up to 2 meters (6.6 feet). The plant releases gametes from June until the winter when it starts to decay. Plants commonly live for 2–3 years and reproduce once before dying. Also commonly known as sea thong