Halopteris filicina has a bushy thallus, with numerous regular branches; the structure has the appearance of a thin, flat feather (1; 2). The ramification is regular, and the alga is attached to the substrate with dense rhizoidal branches (1). H. filicina has a height of 20-100mm; the main axes having a basal height of 1-2mm, tapering thinner towards the top (1). The colouration is a dark olive brown.
There are eleven species within the genus Halopteris (3); none of the species are listed under the IUCN Redlist (4). H. filicina is similar in appearance to Stypocaulon scoparium, which appears in dense populations, and Sphacelaria, which differs in the appearance of the ramifications (1).
H. filicina is solitary, and occasionally found as an epiphyte on Laminaria (1).
H. filicina is found on rocky substrates in the infra-littoral and medio-littoral zones; in depths of 21-80m (1).
H. filicina is an annual species (1).
H. filicina is distributed in the north-east Atlantic, Mediterranean, Black Sea and the Pacific Ocean (1).
H. filicina uses photosynthesis, as well as requiring various inorganic nutrients, such as carbon dioxide, phosphorus and fixed nitrogen (2).
Not listed under the IUCN Redlist (4).
Description written by Ben Harvey (2009)
(1) Cabioc’H, J., Floc’H, J. & Le Toquin, A., 1992. Guide mes algues des mers d’Europe. Paris: Delachaux et Niestle.
(2) Graham, L.E. & Wilcox, L.W., 2000. Algae. New Jersey: Prentice-Hall Inc.
(3) WoRMS (2009). Halopteris Kützing 1843. In: Guiry, M.D. & Guiry, G.M. (2009). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Accessed through the World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=144274 on 2009-09-02
(4) IUCN, 2009. IUCN Red List of Threatened Species. [Online] (2009.1) Available at: www.iucnredlist.org [Accessed 01 September 2009].