Up until recently, not many people would have told you that they had purchased sponge(s) for their reef tank, moreover, what people knew about sponges(Phylum;Porifera) could probably fit on an index card at best. I'm guilty of this accusation-I knew that the dried up skeleton of a sponge worked wonders at keeping my car clean. I also felt that sponges were difficult to maintain, short-lived and toxic towards other living organisms in a reef tank.
Scientists, marine biologists, researchers and of course us, the reef enthusiasts/aquarists, are now just learning and seeking out these viable treasures of the sea to enhance reef tank life, as well as medical breakthroughs with respect to cancer research.
Sponges are a beneficial addition to any reef tank for a plethera of reasons, none more important than being a extraordinary living bio-filter. Some other benefits of sponges in a reef tank are food for other inverts, providing a living habitat for macro-and micro organisms, and are good water quality indicators.
Anatomy of a sponge: They make up the phylum Porifera, meaning "bearing opening". It also describes their means of feeding and eliminating waste as well as respiration. The intake of water through their porocytes(mouth), into their atrium(open space within their spicules), then out of one or more osculae(opening in their body walls) is evident by looking closely at a sponges physical make up. A sponge may be either Asconoid( one central chamber and are usually very small in size-less than 8mm), Syconoid( infolds of the body wall that greatly expands its surface area) or Leuconoid(having many incomming (incurrent)and outgoing(exhallent) channels within their body structure composition. Like many stonies(Scleractinia), sponges are polymorphic, meaning take on various forms, depending on light, water flow intensity and availability of food. The skeletal make up of a sponge is based on mineral elements called spicules. The various types of spicules(whether it be calcareous, siliceous or a combination of both) and the organic matter called spongin is what determines the different sponges Order.
Care of sponges in a reef tank can only be enhanced by placing them in well established reef tanks. Also, more importantly, the transpotation of sponges from lps to reef tank needs to be done so that the sponge is never allowed to be out of water. This can be detrimental to the overall health of a sponge. The use of super protein skimming and silicate removing chemical filtrant and uv sterilization-in otherwords, a so called pristine environment is counterproductive in a sponges ability to live and grow in your reef tank.
Sponges on the whole do not come from high light areas of our oceans. Therefore, strong lighting is to be dismissed as it will aid in the growth of unwanted algae which sponges have not evolved enough to rid themselves of. Feeding of sponges is not reliant of symbiotic zooanthellae. Blue/green algae(cyanobacteria)is responsible for the feeding of sugars to support the life of a sponge. However, they do require heterotrophic feeding as well, though not as a whole. The stirring up of a sand bed, or the offering of bacteria and nano-phytoplankton is beneficial to feeding Porifera. Lighting requirements of Porifera would be the same as that of zooanthids, corallimorphs and Octocorals(soft corals).
As far as water movement is concerned, few sponges are able to survive in low water movement occurrances and none are able to handle siltation problems basically causing suffocation.
The placement of sponges in a tank goes a long way in determining the fate of your prized sponge. Sponges come from a variety of biotropes in their natural environment. And knowing where your particular specimen comes from in the wild will aid in the survival of it in your tank. Obviously you wouldn't purchase a Rope sponge which is a deep water sponge and place it in your tank with 400watt metal halide lights. The high water flow and
indirect lighting of your tank would be the best for the success of your sponge. The placement of your sponge in a sump or refugium would also be appreciated by your sponge as their are minimal sediment problems and an abundance of bacteria in which to feed. As with corals, the placement in a tank is crucial so that chemical warfare is held in check... For example you wouldn't want to place a encrusting sponge next to a sessile invert, otherwise the sponge would overtake the invertebrate in the same manner as a fire coral(Millepora) would encrust and take over a Gorgonian.
Sponges reproduce by both sexual and asexual means. Budding and fragmenting occur in the aquarium trade frequently. It has also been studied that sponges can be placed into a blender and chopped up, placed back into a tank and the many pieces will begin to take root. Just be careful not to process it to long or the heat from the blade will break down the sponges tissue causing death.
When keeping sponges, be aware that though very toxic to most living reef inhabitants, I would be remminissed to mention that there are angels, triggers crustaceans, filefish, asteroids, cowries, snails, sea slugs etc. that will feed on your sponge. So be sure to read up on the list of organisms so that your sponge doesn't become an entree item at the buffet line.
In concluding, anyone contemplating the idea of adding a sponge to your reportoire in a reef tank, only needs to look at the vibrant myriad of color from purples to yellows, reds, blues, greens, white and shades in between. You too can enjoy the beauty and benefits of having a sponge as a welcome addition to your reef tank by following alittle heads up word of advice, which is to research the particular sponge you have in mind, and moreover, take note of the husbandry associated with your prized specimen.
Good luck to you, fellow reefers as you delve into the fascinating world of biological filter feeders we call SPONGES!!!!
Hope you have as much fun reading and enlightening yourself as I did researching and writing this about a new found friend in the sponge...
THIS THREAD HAS BEEN ADDED TO THE ARTICLES SECTION. PLEASE COMMENT ON IT THERE - MATT
SPONGES:Not just for cleaning your car is it? 
jb
