Ask the WWM Crew
|Please visit our Sponsors|
The Big Three Aquarium Problems with Nudibranchs:
Most species of Nudibranchs have proven to be very specialized feeders. Some Aeolids feed only on one species of hydroids, a group in the Phylum Cnidaria. Some Dorids similarly limit themselves to one food source, typically a type of sponge. How can solve this predator-prey/food problem? Most species of Nudibranchs have proven to be very specialized feeders. Some Aeolids feed only on one species of hydroids, a group in the Phylum Cnidaria. Some Dorids similarly limit themselves to one food source, typically a type of sponge. How can solve this predator-prey/food problem?
The best way to guarantee that you've matched such a finicky feeder is to procure (collect or buy) them together.
The second best is to consult the pertinent literature and try to bring both together.
The next to last method is to supply as much potential matter in a huge, diverse live-rock type habitat and let your naked-gill snails choose what/if they will.
The worst is to buy them and hope they will accept prepared foods. The vast majority will not.
Nudibranchs are carnivores that feed on attached animals; hydroids, sea anemones, soft corals, bryozoans, sponges, ascidians, barnacles, fish eggs... Each family is generally restricted to one kind of prey; this is not surprising, as much of their higher classification is based on tooth and related machinery arrangement, directly related to food-type.
Another major difficulty is that these snails are empowered with skin glands that produce potent poisons; some species make sulfuric acid, others non-acidic noxious substances. There are celebrated species that use the cnidocysts (stinging cells, nematocysts) they reprocess from eating stinging-celled animals. Others have spicules embedded in their mantle. With their sudden and mysterious death, this stuff ends up in your water.
To reduce the potential for disaster you need good chemical filtration with adequate circulation, regular partial water changes and a watchful eye on what you have and where it's at in your system.
To emphasize the above point I like to recount my experience with a certain Spanish dancer, a swimming Nudibranch. That's right, some of these snails are truly butterflies of the sea; in constant motion. Once at a Sears-Roebucks in the early seventies, when they were in the live pet business, we had a tank that whatever fish we put in, it would become shy and perish within a few days. We tried all the usual; massive water changes, dumping the tank completely, even throwing away the gravel, including the decor, all to no avail. Enough study and discussion led us finally to realize that the Spanish Dancer (swimming Nudibranch) that had been in the tank had bumped up against the tank walls depositing stinging cells all over. These were zapping and debilitating everything they came in contact with. Once more we dumped, acid-bleach washed and salt-scrubbed the sides of the tank. Subsequently we were able to keep other livestock alive. Some of these snails even feed on the Portuguese-man-o-war. Yowch!
The third Nudibranch problem in our triad. These snails and more notably their live food require optimized and stable conditions; for tropical and deeper water forms, narrow temperature range, high (@8.3) pH, no detectable evidence of nitrogen anomaly; that is no ammonia, nitrite and minimal nitrate.
Medication? Don't even think about it. Sea slugs are very sensitive to metals and dyes. Treatments other than tolerable manipulation of specific gravity must be done in a separate system, or optimally avoided via dip/quarantine procedures.
So, you're still not discouraged from trying to keep them? You really are an aquatics fanatic. Read on.
Nudibranchs can be bought or ordered from time to time all year. They range in cost from a few to a few tens of dollars. Nudibranchs can be bought or ordered from time to time all year. They range in cost from a few to a few tens of dollars.
Can be done worldwide (check re local permits) in shallow cool to tropical seas. You have to look closely. Some are only a few millimeters long; big ones are only inches. Often they are cryptically colored and patterned, blending in with the habitat; generally their preferred food. Which brings us to eating again. Collect or buy their food with them. Make sure you're getting what they're feeding on. You can tell by observing carefully. Look for a "chew trail" (Okay, I just made up that last term). Can be done worldwide (check re local permits) in shallow cool to tropical seas. You have to look closely. Some are only a few millimeters long; big ones are only inches. Often they are cryptically colored and patterned, blending in with the habitat; generally their preferred food. Which brings us to eating again. Collect or buy their food with them. Make sure you're getting what they're feeding on. You can tell by observing carefully. Look for a "chew trail" (Okay, I just made up that last term).
Don't worry about your snail becoming lonely. Don't overcrowd. One per ten or twenty gallons is plenty. If they run out of food, or dissolve... the fewer the better. Oh, and mixing species is okay as long as food habits... did I mention some species eat other Nudibranchs and there are a few noted cannibals? Study up.
As long as adequate food is available, other considerations, the amount and type of decor, substrate, lighting pale. Nudibranchs are extrovert, crawling, possibly floating and/or swimming around the whole tank.
Sea slugs are generally solitary, getting together with a member of their species only for mating, and with more than one in a tank they frequently do get together. Nudibranchs are true hermaphrodites, both male and female, reproducing by exchanging sperm, fertilizing each other's eggs.
Each species lays its fertilized eggs in a characteristically shaped cluster; some in spirals, strings or flat sheets. Eggs develop and hatch as free-swimming veliger larvae with a rudimentary coiled shell. The shell is lost with the larvae metamorphosing into a miniature adult settling on the bottom.
Captive rearing is complicated due to the unicellular algae diets and prolonged planktonic phases of the veligers.
When I first came to the "States" in the sixties (having grown up as a military dependent overseas) I volunteered at the San Diego Natural History Museum. An early project called for cooking up a recipe to preserve Nudibranchs for public display. Retaining color was not the greatest of our concerns. All attempts at using different pickling agents on them; alcohols, formalin/formaldehyde, gluteraldehyde... resulted in the same. Totally dissolved, invisible specimens in a few days!
Why not show live animals? At the time Natural History Museums were more like necropolis', cities of the dead. Thank-goodness this is a changing trend. Ultimately the museum settle on fiberglass look-alike models. Not very realistic but quite sturdy.
You might feel like resorting to resin if you try keeping live Nudibranchs; they're not easy by any measure. Heed the advice above. Follow the biology of the snails and provide them and their living food with livable conditions, and a lack of medication.
Sea slugs certainly rank among the oceans most beautiful creatures. With the advent of multimedia computers, I can't wait for mobile Nudibranch screen savers. It is unfortunate that the grace and gaudiness of the Nudibranchs is coupled with their difficulty as aquarium specimens.
The Sea Slug Forum (great online scientific resource)
Barnes, Robert. 1987. Invertebrate Zoology. 5th Ed. Saunders.
Burgess, Warren E. Salts from the seven seas (on Nudibranchs). TFH 2/76.
Cranston, Bob & Cathy. 1992. The sea tiger; a truly impressive predator. Discover Diving 3-4/92.
Daum, Wolfgang. Undated. Sea slugs- exotic additions to the marine aquarium. Aquarium Digest International #26 pp 27-30.
DeGiorgis, Joseph A. 1985. Bountiful Color: Nudibranchia. Freshwater and Marine Aquarium, 1/85.
Fenner, Robert. 1996. Nudibranchs. The beautiful naked-gilled seaslugs. TFH 2/96.
Glodek, Garrett. 1995. The biology of Nudibranchs. FAMA 5/95.
Glodek, Garrett. 1996. A little bit about Nudibranchs. FAMA 11/96.
Hunziker, Ray. 1988. Nudibranchs: Blessing or Curse? Tropical Fish Hobbyist, 12/88.
Jewell, Jack. 1997. Breeding the Aiptasia eater. FAMA 12/97.
Kerstitch, Alex. 1988. Living Rainbows of the Sea. Freshwater and Marine Aquarium, 3/88.
Kloth, Thomas. 1979. Those Magnificent Nudibranchs. Freshwater and Marine Aquarium, 4/79.
McPeak, Ron, Glantz, Dale and Shaw, Carole. 1988. The Amber Forest: Beauty and Biology of California's Submarine Forests. Watersport Publishing, Inc. San Diego.
Miklosz, Joan. 1972. Butterflies of the Sea. Marine Aquarist, 3(4)/72.
Niesen, Thomas N. 1982. The Marine Biology Coloring Book. Barnes and Noble Books.
Shimek, Ronald. 1996. Nudibranchs: The bad nudes of the reef. Aquarium Frontiers 3/4, 96.
Smith, Ralph I. and James T. Carlton. 1975. Light's Manual, Intertidal Invertebrates of the Central California Coast. #rd Ed. U.C. Press.
Tavares, Iggy. 1998. Beautiful slugs!? FAMA 2/98
Wickstein, Mary K. 1975. Nourishment for Nudibranchs. TFH 6/75.
Wickstein, Mary K. 1980. Cheidonura inermis: a colorful carnivore. TFH 7/80.