Filter feeding animals such as corals, tubeworms, sea cucumbers, sponges, and related invertebrates have long been the bane of aquarists because of their unique and highly specialized diets. Most of these animals continuously pump or otherwise circulate water through their bodies, removing plankton and other microorganisms and detritus in the process. In the past, such species were kept mainly in public aquariums that were located close to an ocean, so that fresh seawater could be pumped into the tanks in which the animals were living (the circulating seawater provided the sponges, corals, and other creatures with a natural source of plankton and other food). Today, however, a number of liquid diets formulated specifically for filter feeding aquatic invertebrates are commercially available. Although such has by no means made the keeping of filter feeding organisms easy, it certainly has allowed for great strides to be made in the husbandry of these fascinating animals. In addition to liquid diets, you might consider the use of newly hatched brine shrimp when feeding such invertebrates. Finely meshed plankton nets may be purchased from biological supply houses by those with an interest in maintaining corals and other filter feeders. For the aquarist with ready access to a saltwater environment, the use of wild caught plankton provides perhaps the best opportunity for success in maintaining delicate sponges, corals, tubeworms, certain species of jellyfish, and similar creatures.

Remember that many species of corals, clams, and other filter feeding invertebrates actually depend upon zooxanthellae (algae) living within their bodies for a good deal of their nutrition. The food is produced by the photosynthetic processes of these unique types of algae, and such can occur only in the presence of light of the proper wavelength and intensity. With-out proper lighting, the host animals (the clams, corals, or sponges) will fail to thrive. Consult Chapter 4 about lighting before you consider maintaining animals that depend upon the presence of zooxanthellae for their survival.