Sponges
Phylum Porifera

Sponges are the simplest of multicellular creatures. There are four classes, 5 subclasses, 28 orders, 232 families, and 977 valid genera, and probably over 15,000 species. Most are found in marine waters, and vary in size, shape, and color. They posses no nervous, digestive or excretory systems, and feed by filtering suspended bacteria and fine detritus. Strong water movement is vital to almost all, not only for carrying food to these sessile creatures but also to carry waste/unused matter away. In fact, a sponge the size of a baseball can filter fifty gallons of water per hour! Most do best only in low light areas and where currents are quite swift.

Each sponge has both female and male reproduction capabilities. Cutting a piece from the healthy tissue and simply relocating it to another area can form new colonies. Bear in mind the new specimen should not be exposed to air during the procedure as that may kill it. New purchases should be bagged under water with no oxygen added or should the bag contain an air space while being transported. They are not too sensitive to temperature changes, yet sudden changes in salinity may have drastic effects.

New specimens should not contain any gray or white tissue, which is generally a sign of dying or dead tissue. However, it is possible to cut that section out, of course under water. Sponges should be placed in shaded areas where water movement is very good and detritus or algae do not accumulate on their surface. They feed upon plankton and suspended detritus, and requires numerous feedings per day of live and/or preserved commercial phytoplankton products or that of animal and plant powders that produce suspended products in the bulk water.

Even though there appears to be four Classes of Sponges, (Demospongiae; Calcarea; Hexactinellida; and, Archaeocyatha) only two contain anything that might even remotely interest aquarists having tropical or temperate aquaria. Furthermore, the taxonomy relating to these creatures is confusing, especially for a non-scientist such as myself. I've tried to note which species are or could be of interest to aquarists, both for temperate and tropical aquaria. Yet, without a doubt, most sponges should remain in the wild, as they are difficult to impossible to maintain in captivity, and/or simply not suited for confinement in closed systems.

I've also tried to put this phylum in an up-to-date sequence, which may be the first time any hobbyist has made such an attempt! In doing so, John N. A. Hooper's "Sponguide: Guide To Sponge Collection And Identification" was quite helpful.

Subphylum Cellularia
Class Demospongiae
Subclass Homoscleromorpha

Order: Homosclerophorida

Family Plakinidae

Oscarella