Coral reef aquaria, and the science of maintaining them, have advanced by leaps and bounds in the last decade. Much of this owes to progress in the area of foods and feeding. Many marine creatures (especially filter-feeding invertebrates like sponges) that were once deemed difficult or even impossible to keep are now cultured with regularity. These developments will surely result in a much greater selection and availability of “oddball” aquarium livestock in coming years.
Sponges, at least as a group, are not rare in any way. Indeed, they are found in great abundance and diversity on most coral reefs. If anything, they are rather poorly represented in the aquarium hobby. Despite their sometimes stunning beauty, they are unusual to aquarists for one reason: They have a really, really bad record of survivability in captivity. This low success rate is attributable to several things. Sometimes, it’s as simple as bad pairing. For example, a single pomacanthid angelfish can consume a large sponge in a matter of days. Other reasons are not always so obvious; too often, improper harvesting/handling practices (e.g. air exposure) dooms an otherwise healthy specimen before it even reaches a retailer. But the biggest longstanding concern for captive sponges is nutrition.
To address this concern, it may be helpful to understand the basic anatomy of these “animals” and how they feed.
Many Many Mouths
Of all animals, sponges (Phylum Porifera) are most closely related to the colonial choanoflagellates that are the progenitors of the animal kingdom. These very primitive creatures are so simple in structure that they really are a lot more like colonies than distinct organisms. They lack nerves and muscles. In fact, overall, their cells are so unspecialized that they lack (at least in the opinion of some biologists) true tissues. In a lot of ways, sponges are really just a big pile of loosely associated cells.
That being said, individual cells can not only sense and react to environmental stimuli but communicate with other cells. The simplest of sponge bodies are composed of a hollow sack or sheet that is perforated with numerous tiny pores. The body is more or less composed of just two kinds of cells, the flagellated choanocytes and the wandering amoebocytes. The sponge draws water into itself through these pores whereupon it enters a central cavity called a spongocoel. From there, water exits through a duct called an osculum.
Alright, it can get a little bit more complicated than that. More advanced sponges exhibit modest structural complexity in the form of distinct body shapes (candelabras, vases, etc.), folded body walls, highly branched water canals, multiple oscula, etc. But the body plan of all sponges is very much centered on their feeding activity.
Sponges are (with few exceptions) filter-feeders. Aside from the frenetic activity of their many flagella, sponges are almost completely incapable of any kind of deliberate movement. Thus, to eat, they must push tiny morsels to and through their bodies via miniscule, self-generated water currents. It is the choanocyte that pushes water and traps food particles; it is the amoebocyte that engulfs and digests them. A sponge must, on average, filter approximately 275 gallons of water to capture enough food to gain three ounces of biomass.
[Phyto]
Feeding your Captive Sponges
The vast majority of sponges are nanoplanktivores, feeding upon the tiniest of plankton. This group includes bacteria and the smallest species of phytoplankton. In some cases, minute bits of particulate organic matter may be consumed. In just a few cases, sponges can harbor zooxanthellate algae much like corals and tridacnid clams.
Aside from good water quality and strong water movement, captive sponges need lots and lots of planktonic foods of the appropriate size. Some of this food certainly is produced in situ, as most systems have at least minimal amounts of bacteria and phytoplankton in the water column. Blooms of heterotrophic bacterioplankton, for example, take place for short periods of time following carbon dosing. Of all the planktonic organisms in aquarium water, however, nanoplankton are the first to be removed/killed by UV sterilization and protein skimming. And then, of course, there is competition from other filter-feeders. Corals, clams, tube worms and other filter-feeders can very selectively (and very quickly!) clear the water of choice planktonic food items, including marine snow.
For these reasons and more, successfully maintaining sponges long-term in aquaria requires that foods be added frequently. This usually cannot be the willy-nilly addition of artificial, liquid “invert” diets. While each sponge species has its own dietary requirements, sponges generally demand a live nanoplankter. Such can be supplied with the nutritious bacteria (Rhodopseudomonas palustris) in PNS Probio or PNS YelloSno by Hydrospace LLC, or with the very small algae (Nannochloropsis gaditana) in OceanMagik. Used as directed, these products likely supply sufficient nourishment for a single specimen in the average system. However, in a system that is packed with sponges and/or other fine filter-feeders, more frequent additions or even continuous dosing may be necessary!
The Future for Aquarium Sponges
There are many species of sponge that show up (albeit sporadically) in the trade. The red finger sponge (Haliclona rubens), for example, appears from time to time. Their curious and famous ability to regenerate from small fragments might cause one to imagine a day when they will be sold on small plugs. Attractive, fascinating and rewarding, these simple animals could become far more popular as quality live aquarium foods continue to become available.
[Phyto]
Asad Khan says
I did not know sponges had their own specific diet and needed to be target fed. very interesting.
Jonathan says
Never have much luck with sponges.
Nickn says
I find sponges very interesting and not just becaue of spongebob but i dont think id have the means to keep one happy
Mike Mijarez says
Would it be a good idea for reef tank?
robert vice says
I tried to save a spider so he for a friend with no luck
Kinue says
Sponges very rarely do well in my tanks. Good info to try new things though.
dartagnon_1965 says
I believe my uncle had a sponge in his tank..it died.
F Fudge says
#nailedit
Joe car says
I need a sponge!!!
Becky says
I don’t really like any sponges but they help clean up the water so that is good.
Wilfredo Robles says
in my refuguim i have a few
Cassandre-Leigh Klaasen says
Wow – didn’t know they were so hard to get rid of !
Richard Baer says
There are definitely some beautiful sponges, but I find them less satisfying to care for an look at than corals and inverts, so I’ll stay away for now.
polygonreef says
Never knew!
Michgander reefer says
Not a big fan of sponges but good read
Matt Blefeld says
Have a bunch in my tank, purple variety, and they help keep the water crystal clear
Joseph Striegel says
Have a red finger sponge for 1 year now doing great
Joseph Striegel says
Have a red finger sponge for 1 year now doing great
Steven Rodriguez says
I have a couple in my tank they are awesome
liesle_memmott says
I get a few hiding in my rocks and sump. I try to leave them alone due to the beneficial. I don’t think I’d like them taking over my reef though in an image fashion
Christopher Burns says
cool
Dallas Tippie says
My tank is filled with sponges!
daroberts87 says
Happy thanksgiving
Brett says
Cool info!
whwhunt says
I really like the macro sponges but can never expose them to air.
Liz McDaneld says
Would love to have a sponge oneday
Liz McDaneld says
Would love to have a sponge some day
Feather says
Good blog to read and learn more on sponges
Aaron says
sponges would be kewl in my tank
Nicholas Steele says
Would be cool to have but I don’t think I could provide the food for them.
Richard Gorelick says
Looking forward to trying some sort of Atlantic sponge in my Caribbean nano, should I be worried about my Cherub Angel?
Tim Kubajak says
Thanks for the great info!
Echo says
Sponges are really cool looking. I am thinking about sponges when I get a larger tank.
dcallahan56789 says
I have pineapple sponges on the underside of rockwork and everywhere in my sump and refugium. I know they are beneficial, any science on how beneficial? How much water they will actually filter? What pineapple sponges eat?
Wesley Spangler says
Years ago I had a blue sponge that did really well until I started to carbon dose.
phyllis owens says
love sponges
Luis Aceves says
Thank you for the info.
James says
I have had sponges since I set up my tank, but any that I bought have not fared well.
Carol L Brown says
I have had. Hundreds of the white sponges start growing in my seahorse tank? Will they affect or hurt my horses??
James says
Store bought bad luck,hitchhikers good luck.