All Sources -
Updated Media sources (1) About content Print Topic Share Topic
views updated

Demospongea (Demospongiae; phylum Porifera) A class of sponges that first appears in the Cambrian. The soft tissue of the skeleton is supported by siliceous spicules, each spicule consisting of either a single ray (monaxon) or four rays (tetraxon) diverging at 60° or 120°. Most fossil species are represented by their spicules only, but they can usually be referred to modern families.

views updated

Demospongea See DEMOSPONGIAE.