Gelidium sesquipedale
species of alga
Gelidium sesquipedale is a commercially important species of red algae. It is a thalloid seaweed, branching on a single axis. A clonal species, it grows in stands on rocky bottoms in the subtidal zone in areas with high water movement and exposed to wave action.
Distribution
It is found in the Atlantic Ocean between the coasts of the Great Britain and Mauritania. However, the most important concentrations of the species are found along the rocky coasts of France, Northern Spain, Portugal and Morocco.
Commercial use
The species is an important commercial source of agar. The species are harvested either by commercial divers in Portugal and Morocco whereas in Spain and France floating detached thalli and beach coast are gathered. The former method may not be as sustainable however, yields and populations are in decline/have collapsed in Portugal as of the 2000s. Populations are also in decline in Morocco, the world's leading producer, leading to trade restrictions and to shortages of agar on the world market, notably for laboratory-grade product.
More recently, the species has started to be used in cosmetics, as a skin care and sunscreen ingredient.
This brief starts where responsible research should: with the source description of “Gelidium sesquipedale” as species of alga. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the science & nature register because the source frames it as species of alga. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Datasets, specimens, observations and peer-reviewed methods provide the appropriate test for the technical claims summarized here. The source revision retrieved here is dated Jul 23, 2026. The linked authority identifier is Q106293232. None of the 0 selected statements returned an explicit reference.
Current terminology should not be projected backward without checking the classification used when the underlying evidence was created. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Gelidium sesquipedale” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.