Classes of the Phylum Porifera
Class Calcerea
Contain sponges with calcium carbonate (CaCO3) spicules that may be needle shaped or have 3 or 4 rays.
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Class Hexactinellida
Composed of sponges with silicaceous spicules that are 6 rayed.
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Class Demospongiae
Sponges with silcaceous spicules that are needle shaped or 4 rayed, or have spongin with mesoglea. Only family with freshwater sponges
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