Algae are eukaryotic photosynthetic micro- and macroorganisms found in marine and fresh waters and in soils. Some are colorless and even phagotrophic or saprophytic. They may be picoplankton, almost too small to be seen in the light microscope, or they could be up to 180 feet long, such as the kelp in the kelp forests in the Pacific Ocean.

Algae are simple, nucleated plants divided into seven taxa: (1) Chlorophyta (green algae), (2) Charophyta (stoneworts), (3) Euglenophyta (euglenas), (4) Chrysophyta (golden-brown, yellow-green algae and diatoms), (5) Phaeophyta (brown algae), (6) Pyrrophyta (dinoflagellates), and (7) Rhodophyta (red algae). A taxon of simple, nonnucleated plants (prokaryotes) called Cyanobacteria (blue-green bacteria) is also included in the following discussion as they have a long history as human food.

Algae are eaten by many freshwater and marine animals as well as by several terrestrial domesticated animals such as sheep, cattle, and two species of primates: Macaca fuscata in Japan (Izawa and Nishida 1963) and Homo sapiens. The human consumption of algae, or phycophagy, developed thousands of years ago, predominantly among coastal peoples and, less commonly, among some inland peoples. In terms of quantity and variety of species of algae eaten, phycophagy is, and has been, most prevalent among the coastal peoples of Southeast Asia, such as the ancient and modern Chinese, Japanese, Koreans, Filipinos, and Hawaiians.

History and Geography

The earliest archaeological evidence for the consumption of algae found thus far was discovered in ancient middens along the coast of Peru. Kelp was found in middens at Pampa, dated to circa 2500 B.C. (Moseley 1975); at Playa Hermosa (2500–2275 B.C.); at Concha (2275–1900 B.C.); at Gaviota (1900–1750 B.C.); and at Ancon (1400–1300 B.C.) (Patterson and Moseley 1968). T. C. Patterson and M. E. Moseley (1968) believe that these finds indicate that marine algae were employed by the ancient Peruvians to supplement their diets.