by Saltwater Smarts | Oct 19, 2015 | Corals, Invertebrates, Science
Some soft coral species, such as Sinularia, are well-known for their chemical warfare tendenciesSince corals and other sessile invertebrates are more or less stuck in place and can’t chase away competitors or run from predators, many of them—particularly among the soft corals—have evolved the tactic of exuding toxins into the water to prevent other inverts from encroaching and to discourage predation. As you can imagine, this “chemical warfare,” known as allelopathy, can become problematic in closed aquaria because even the largest tank can’t remotely approximate the ocean’s capacity to dilute these noxious chemicals. Some inverts subjected to these toxins in an aquarium may be unaffected, others may remain in a contracted state, while still others may become stunted, suffer tissue necrosis, or even die as a result of the exposure.Of course, there’s no practical way to test for these toxins and all sorts of environmental issues can cause similar problems in corals, so the challenge from the hobbyist’s standpoint is determining when issues with invertebrate livestock might be attributable to allelopathy versus water quality or some other environmental problem (e.g. inappropriate lighting or current). Here are some signs that might indicate allelopathy is to blame: Your tank contains a lively mix of soft and stony corals In the typical “coral garden” tank stuffed with all different kinds of soft and stony corals, it’s not so much a question of whether allelopathy is going on but to what degree it’s going on. In this setting and assuming water parameters and other environmental factors check out okay, “chemical warfare” is often the best explanation for the odd coral refusing to open up for prolonged periods or the occasional inexplicable death or necrosis of specimens. Your tank contains species known to be toxic Some corals are just notorious for creating allelopathy issues. For instance, among the soft corals, various Sarcophyton, Lobophytum, Sinularia, and Lemnalia species are well known for their toxic tendencies by Saltwater Smarts | Sep 18, 2015 | Cephalopods, Corals, Fish, Invertebrates, MACNA, Science, Tanks
Palythoa grandisMany of us are inspired to keep marine life for its exotic beauty or interesting behavior. But if we’re being perfectly honest, we have to admit there’s also something intriguing about keeping—and displaying to our friends and family—marine organisms that have dangerous or potentially deadly defense mechanisms, such as venomous spines, potent toxins, or razor-sharp teeth. For those hobbyists who like to flirt with danger, the marine aquarium trade certainly offers its share of prickly and poisonous characters—from venomous fishes to deadly cephalopods to noxious sessile invertebrates. There are even organisms we can buy that offer stunning beauty and potency in equal measure.Among these best-of-both-worlds critters are many of the zoanthids we’re so fond of keeping in our reef systems. These polyps (most of the ones we keep being from the Zoanthus and Palythoa genera) have much to recommend them, being very hardy and often stunningly beautiful. But some of them also contain a potent neurotoxin, called palytoxin, in their tissues and mucus that can make people very sick or even cause death if they’re not handled properly. Of course, blithely mentioning that certain popular zoanthids have the potential to sicken or kill people raises a whole host of questions that demand prompt, thorough answers. Among them: What is the nature of palytoxin
