title: A chemical view of the most ancient metazoa--biomarker chemotaxonomy of hexactinellid sponges.
abstract: Hexactinellid sponges are often considered to be the most ancient metazoans. Lipid biomarkers from 23 species were studied for information on their phylogenetic properties, particularly their disputed relation to the two other sponge classes (Demospongiae, Calcarea). The most prominent lipid compounds in the Hexactinellida comprise C28 to C32 polyenoic fatty acids. Their structures parallel the unique patterns found in demosponge membrane fatty acids ('demospongic acids') and strongly support a close phylogenetic association of the Demospongiae and the Hexactinellida. Both taxa also show unusual mid-chain methylated fatty acids (C15-C25) and irregular C25- and C40-isoprenoid hydrocarbons, tracers for specific eubacteria and Archaea, respectively. These biomarkers indicate a similar, highly conservative symbiont community, although some shift in the abundance of the associated microbiota was observed. The lack of these features in calcareous sponges further contradicts the still common view that Calcarea and Demospongiae are more closely related to each other than either is to the Hexactinellida.
authors.affiliation: Institut für Biogeochemie und Meereschemie, Universität Hamburg, Germany. thiel@geowiss.uni-hamburg.de
authors.forename: Volker
authors.initials: V
authors.lastname: Thiel
authors.forename: Martin
authors.initials: M
authors.lastname: Blumenberg
authors.forename: Jens
authors.initials: J
authors.lastname: Hefter
authors.forename: Thomas
authors.initials: T
authors.lastname: Pape
authors.forename: Shirley
authors.initials: S
authors.lastname: Pomponi
authors.forename: John
authors.initials: J
authors.lastname: Reed
authors.forename: Joachim
authors.initials: J
authors.lastname: Reitner
authors.forename: Gert
authors.initials: G
authors.lastname: Wörheide
authors.forename: Walter
authors.initials: W
authors.lastname: Michaelis
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D005843:Geography; D010802:Phylogeny; D011161:Porifera / Q000145:classification*
chemical_list: D015415:Biomarkers