The Family Tree

Sponges, or porifera, constitute an entire phylum of the animal kingdom. Such development is due to the fact that the ancestors of sponges originated approximately one billion years ago. More recent predecessors of modern sponges appeared six hundred million years ago during the Cambrian period. Examples of these species are Chaetetes, Guettardia, and Syphonia. Currently, there are ten thousand species, which have existed for over four hundred million years. Fossils of these phenomena were preserved by spicules, tiny needles that cover the exterior tissues of sponges.

In the modern geologic period, the phylum porifera is divided into four primary classes: calcarea, hexactinellida, demonspongiae, and sclerospongiae. Calcarea sponges are located in the oceans. They are principally composed of calcium carbonate; hence, the name. Hexactinellida, in comparison, are deep sea creatures comprised of silica. Common shapes include six-pointed stars and glass sponges. Demospongiae constitute 95% of all species, and this contains all fresh water species. Their fundamental component is a soft fiber, known as spongin. Bath sponges are derived from this class. Also, sclerospongiae are composed of both silica and spongin. Their central body, however, is a voluminous calcareous skeleton. To help you better understand the sponge family, we invite you to explore one of the classes which have been discussed above, or you may view a breakdown of the entire family tree.