Sponges are the most primitive macroinvertebrates living on N.A. west-coast shores. Intertidal forms tend to be low and encrusting, and are often colourful; subtidal forms are usually more erect, but often more drably coloured. 

NOTE from the Old English sponge or spunge, derived from the L. spongia, referring to the animal. There are 3 main classes of sponges in the Phylum Porifera. Representatives of each live on the west coast, but largest and most visually obvious are the demosponges, and these comprise about 95% of all sponges commonly seen in the intertidal and shallow subtidal regions. Glass sponges of Class Hexactinellida live mostly in deep water. They are included in the ODYSSEY because of interesting work being done on them in British Columbia and because of the presence of unique glass-sponge reefs in this same province

Phylum Porifera (lit. “pore bearing” L.)

Class Demospongiae (lit. “fat sponge” G.) possess spongin and spicules made of glass (oxide of silicon), such as Halichondria, Haliclona, Suberites, Tetilla, Cliona, Myxilla.

Class Calcarea (refers to the calcareous nature of the spicules) possess spongin and spicules of calcium carbonate (chalk), such as Sycon.

Class Hexactinellida (lit. “six rays” G.) spongin is absent in glass sponges; structural support is provided by a complex lattice-work of fused glass spicules; about 500 species known world-wide, such as Aphrocallistes, Rhabdocalyptus.

NOTE recent restructuring of the Phylum Porifera proposes that two Subphyla be erected: one, the Cellularia, would include sponges of primary cellular organisation, such as Class Demospongiae, Class Calcarea, and Class Sclerospongiae (a small group not included in the above list). A second Subphylum, the Symplasma, would include sponges of primary symplasmic or syncytial organisation, such as Class Hexactinellida. Hexactinellids appear to have diverged first from a common ancestor to the Calcarea and Demospongiae, which both appeared later. It is not clear how widely accepted are these new subphyla so, for convenience in the ODYSSEY, the older classification will be used. Reiswig & Mackie 1983 Phil Trans Roy Soc Lond B 301: 419: Kruse et al. 1998 J Mol Evol 46: 721.

NOTE glass sponges can be divided into 2 morphological categories based on type of skeleton: lyssacine sponges have a loose spicule construction, held together by strands of cytoplasmic tissue.  In contrast, dictyonine sponges have a fused spicule skeleton that forms a rigid 3-dimensional scaffold.  For a review of glass sponges see Leys et al. 2007 Adv Mar Biol 52: 1.

NOTE the 500-600 species comprising the Hexactinellida have recently been re-classified into 2 main lineages based on the shape and type of microscleres: Subclass Amphidiscophora and Subclass Hexasterophora.  Reiswig 2006 Can J Zool 84: 195.