''Eucheuma'', commonly known as gusô (), is a rhodophyte seaweed that may vary in color (red, brown, and green). ''Eucheuma'' species are used in the production of

carrageenan Carrageenans or carrageenins ( ; ) are a family of natural linear sulfated polysaccharides that are extracted from red edible seaweeds. Carrageenans are widely used in the food industry, for their gelling, thickening, and stabilizing properties. T ...

, an ingredient for

cosmetics Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protect ...

, food processing, and industrial manufacturing, as well as a food source for people in the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

and parts of

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

and

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

. ''Eucheuma cottonii'' – cultivated in the Philippines – is the particular species known as gusô. Other species include ''Betaphycus gelatinae'', ''Eucheuma denticulatum'', and several species of the genus ''Kappaphycus'', including ''K. alvarezii''. Since the mid-1970s, ''Kappaphycus'' and ''Eucheuma'' have been a major source for the expansion of the carrageenan industry. Commercial

seaweed farming Seaweed farming or kelp farming is the practice of cultivating and harvesting seaweed. In its simplest form, it consists of the management of naturally found batches. In its most advanced form, it consists of fully controlling the life cycle ...

of gusô (as well as ''

Kappaphycus ''Kappaphycus'' is a genus of red algae. Species are distributed in the waters of East Africa, Indonesia, Malaysia, Hainan Island, the Philippines, and Micronesia.Guiry, M. D. In: Guiry, M. D. & G. M. Guiry. 2013''Kappaphycus''.AlgaeBase. Natio ...

'') was pioneered in the

. Though commercially significant, species of ''Eucheuma'' are difficult to identify without the aid of close scientific examination, as different species may have similar morphologies. Some eighteen to twenty species alone fall within the genus ''Eucheuma'', represented by the groups ''Cottoniformia'', ''Gelatiformia'', and ''Anaxiferae''. ''Gusô'' is listed in the

Ark of Taste The Ark of Taste is an international catalogue of endangered heritage foods which is maintained by the global Slow Food movement. The Ark is designed to preserve at-risk foods that are sustainably produced, unique in taste, and part of a distin ...

international catalogue of endangered heritage foods of the

by the

Slow Food Slow Food is an organization that promotes local food and traditional cooking. It was founded by Carlo Petrini in Italy in 1986 and has since spread worldwide. Promoted as an alternative to fast food, it strives to preserve traditional and re ...

movement.

Distribution

''Eucheuma'' are naturally found within the range of 20 degrees either side of the Equator in the Indo-Pacific region from eastern Africa to

Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...

, and are most concentrated in

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainlan ...

. A few species are found on

Lord Howe Island Lord Howe Island (; formerly Lord Howe's Island) is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, part of the Australian state of New South Wales. It lies directly east of mainland P ...

and in

southwestern Australia Southwest Australia is a biogeographic region in Western Australia. It includes the Mediterranean-climate area of southwestern Australia, which is home to a diverse and distinctive flora and fauna. The region is also known as the Southwest Au ...

. As a commercial crop, ''Eucheuma'' has since been distributed to many regions away from their original natural habitats, including Japan, Hawaii, and island nations in the South Pacific.

Habitat and biology

''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. Their growth is similar to terrestrial plant species, where ''Eucheuma'' have a growing tip, or apical

meristem The meristem is a type of tissue found in plants. It consists of undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells conti ...

, which is also capable of dividing to form new growing branches. They also show a triphasic life cycle, consisting of a

gametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the ...

(n) ( dioecious),

carposporophyte {{Short pages monitor