You are cordially invited
To visit the Porifera family
Though there are many members
You may proceed leisurely
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.