brown alga

noun

1. an alga of the class Phaeophyceae, usually brown owing to the presence of brown pigments in addition to the chlorophyll.

brown alga

1. Any of various photosynthetic protists belonging to the phylum Phaeophyta, almost all of which live in marine environments. Brown algae have chlorophylls a and c as well large quantities of the pigment fucoxanthin, which gives the group their characteristic brownish colors. This pigment absorbs the range of blue light frequencies available to brown algae when they are submerged and allows them to live in deeper waters than green algae. The brown algae store their food in a compound called laminarin and transport it throughout their bodies in a compound called mannitol (unlike plants and green algae). The cell walls of brown algae are made of cellulose and algin. Their bodies vary from small filaments to the immense leaflike thalli of kelp. Species of brown algae dominate shoreline and coastal ecosystems in cooler waters, and huge masses of the brown alga Sargassum cover the warm Sargasso sea in the Atlantic.

2. See more at alga

Word History and Origins

Origin of brown alga¹

First recorded in 1900–05

Example Sentences

"With our study, we sought to understand the mechanism of this process, to benefit the application of this brown alga feeding system to the biofuel industry," adds co-first author Yuxin Ye, Postdoctor at the Faculty of Advanced Life Science, Hokkaido University.

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Kelp, a type of brown alga, growing off the coast of California.Credit:

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The green alga Chlorodesmis, top left, and the brown alga Dictyota, top right, in contact with corals.

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Fucoxanthin, C40H54O6, is a brownish-red pigment, found in fresh brown algæ, and in some brown sea-weeds.

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The diatoms, which are placed in this class simply on account of the color, are probably not closely related to the other brown algæ, but just where they should be placed is difficult to say.

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