Phyllariopsis brevipes is a species of large brown algae, found in the subtidal zone in the Mediterranean Sea.

[2] Unlike other large brown macroalgae, it has a habitat requirement to grow on the living thalli of the crustose red alga Mesophyllum alternans.

The subtidal zone in the park is influenced by both the Mediterranean Sea and the Atlantic Ocean, and there are dense forests of kelp and other large brown macroalgae, including Cystoseira sp., Saccorhiza polyschides, Laminaria ochroleuca, Laminaria rodreguizii, Phyllariopsis purpurascens and Phyllariopsis brevipes.

[4] In general, kelp is affected by ultraviolet light and avoids shallow waters in the sunny Mediterranean.

The zoospores germinate and develop into dioecious (distinct male and female) gametophytes, which each consist of an isodiametric (roughly spherical) group of cells which clump together.