Natural History

Belonging to the phylum Porifera, sponges are the earliest branch in the history of animals (kingdom anamalia). By being the first branch, this means that these are the simplest organisms in the land of the animals. There are approximately 5,000 species that have been classified today! An interesting fact about sponges is that they have no mouth! Well, "how on Earth do they EAT?", you may ask. There are tiny pores in their outer walls where water can be drawn through them. The individual cells filter food in the water with flagella (spinning tail like objects to the cell). One cell cannot do all of this work - so the sponge has "intelligently designed" themselves (yes, normal people say "evolution") to put all of their cells to work to help the organism feed! The spicules on the sponges are made of silicate or calcium carbonate and organic fibers. Their "skeletons" (I air quote because there is not exo- or endo-skeleton...) are completely fibrous material. There are three types of sponges found, and this helps to classify them. The three types are:

Hexactinellida (Glass like, made of silica spicules)

Demospongia (90% of species belong here, all freshwater ones included, no silica in spicules)

Calcarea (sponges that are mostly made with calcium carbonate)

Porifera seen in class:

Suberites montiniger - (Possibly??)Peach Ball Sponge (Demosponge)