Coral Eating Nudibranch
With no exception the sea slugs most certainly provide the most amazing array of both shape and color in all species that inhabit the reef. These animals actually are quite troublesome to keep in captivity because of specific diets, and a short life span. Nudibranches are not a good showpiece for your display and more common than not they come in unwanted. With such a wide array of species and certain diet requirements it’s difficult to predict what exactly there food source is, there are a few however that have been documented and are cause for concern in our display systems.
The nudibranch to the right for example preys upon and consumes zoanthus polyps. So small often remains unseen to the observer, but they do tend to notice the shrinking size of the zoanthus colonies. John Susbilla whom submitted this photo stated that this particular nudibranch in his aquarium had been spotted in two different colors which blended in with his polyp populous. There was one, a brown shown here amongst his brown colonies, and another green amongst the green colonies. This is certainly an adversary worth eradicating from your system. From my experience usually requires a quick dip in freshwater, repeat the process daily for a week. Another Nudibranch that could not only reek havoc but wipe out an entire SPS tank, is the Aeolid.
This predator is small nearly transparent and reproduces at an alarming rate. The order of Nudibranchia is classified as a Gastropod within the Phylum of Mollusc. The Aeolid belongs to the suborder Aeolidoidea, and is very unique amongst other Nudibranch relative to its defense mechanism. My first instinct for controlling this nuisance was to identify a predator. I soon learned that Aeolids mainly feeds on hydroids and corals, which possess stinging cells, and there has been no recorded preditation amongst the suborder. The Nudibranch actually separates these stinging cells within its digestive track. Interestingly the stinging cells (nematocysts) are not digested at all, but relocated to the tips of its extremities. Basically when a fish or any animal would attempt a bite it would receive a mouthful of stings that would have been delivered by the original host. Further more the Aeolid can maintain the stinging cells for some time itself similar to the host organism.
This species systematically goes through the sps in your tank until there is not much left in the way of a food source. I did find for whatever reason the individuals I had were not interested in Porities, not even when I had removed every other sps from the tank After multiple attempts to eradicate this predatory from my system I eventually turned to the freshwater bath, which after 10 seconds seemed to drop the organism right off the host. A method for controlling the population I found valuable was to drop the temperature of the system. Fortunately at the time I had a 1/3 horsepower chiller which I have since sold, but I lowered the overall temperature from 80 degrees to 75.5 degrees and this seemed to retard the reproductive cycle. I’m sure the corals, nor the fish enjoyed the drop but it was a necessary evil, In addition I dropped the salinity of the tank from 1.024 to 1.019, unfortunately I did this shortly after the temperature drop so I’m not certain of it’s effects on the nudibranch, but it is a practiced method in controlling other marine parasites.
