Algae

Infographic by onlab

Algae produce roughly half the oxygen on Earth. So far, around 80,000 different kinds of algae have been identified, but researchers estimate that closer to 400,000 types are out there. Humans use fewer than 200 types of them. A few kinds of algae include:

Palmaria palmata (dulse)

Type: red algae
Color and size: reddish-brown to purple; 5 to 100 cm
Found in: chiefly the North Atlantic
Habitat: on rocks, shells, and other algae, on shores and in shallow waters (up to 20 m deep)
Uses: food source, consumed in Ireland and Scotland for more than 1,400 years.
Delesseria sanguinea (sea beech)

Type: red algae
Color and size: crimson to deep pink; 5 to 30 cm
Found in: North Atlantic, North Sea, Baltic Sea
Habitat: on rocks, in shaded tide pools and deeper bodies of water (up to 35m deep)
Uses: research, medicine, cosmetics
Chondrus crispus (Irish moss)

Type: red algae
Color and size: purple to reddish-brown; 10 to 20 cm
Found in: North Atlantic, North Sea, Baltic Sea
Habitat: on rocks, in tide pools and shallow waters (up to 20m deep)
Uses: treatment of respiratory ailments; production of carageen, a gelling agent and thickener; food (salad)
Porphyra purpurea (nori)

Type: red algae
Color and size: red to reddish-brown; 10 to 300 cm
Found in: across the world, chiefly the Pacific and Indian Ocean
Habitat: on pebbles and on larger specimens of algae
Uses: nori has been popular as a food for thousands of years, especially in Japan, Korea and China (e.g. as an ingredient for sushi)
Gelidium amansii

Type: red algae
Color and size: red to reddish-yellow; 8 to 30 cm
Found in: Pacific, chiefly Korea, China, and Japan
Habitat: shallow coastlines (3 to 10 m deep)
Uses: production of agar
Ulva lactuca (sea lettuce)

Type: green algae
Color and size: light to dark green; up to 100 cm
Found in: all the world’s oceans and along the coasts of all continents
Habitat: grows on pebbles, but also on shells and seaweed (in waters up to 15 m deep)
Uses: food, used raw as lettuce or ground as seasoning
Chlamydomonas reinhardtii

Type: green algae
Color and size: green; 0.003 to 0.01 mm
Found in: around the world
Habitat: freshwater
Uses: as a model organism in basic research into bioreactors and hydrogen production
Himanthalia elongata (thongweed, sea spaghetti)

Type: brown algae
Color and size: yellowish-green to brown; 1 to 7 m
Found in: a limited geographical range: North Atlantic, Baltic Sea
Habitat: gently sloping cliffs
Uses: food (sea spaghetti)
Durvillaea antarctica (cochayuyo, bull kelp)

Type: brown algae
Color and size: green to golden-brown; up to 15 m
Found in: chiefly in coastal regions between Chile and New Zealand
Habitat: on rocks, areas of deep water with strong waves
Uses: a staple food in Chile
Ascophyllum nodosum (knotted kelp)

Type: brown algae
Color and size: olive-green to dark brown; up to 2 m
Found in: North Atlantic
Habitat: rocky coastal regions
Uses: in the production of alginic acid; biotechnology; food industry, and pharmaceutical industry; fibers for clothing
Undaria pinnatifida (wakame)

Type: brown algae
Color and size: yellow to brown; 1 to 3 m
Found in: chiefly the West Pacific; first introduced in Brittany for commercial purposes, now found across the world
Habitat: rocks, pebbles, hulls of ships
Uses: a delicacy, especially in Asian cooking; one of the most popular sea greens alongside nori
Laminaria japonica (Japanese seaweed, kelp)

Type: brown algae
Color and size: dark green, olive-green; 1 to 6 m
Found in: North Pacific
Habitat: mostly on rocks (in waters up to 10 m deep)
Uses: kombu; several million tons are harvested as food every year