Signs that Allelopathy Might Be Agitating Your Inverts

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

Reef Threads Podcast #246


A little purple nephthea.

We return once again. This week we talk about salt, Gary’s new Live Aquaria t-shirt, the Reef Savvy Dream Tank giveaway, the Internet as a research tool, placing corals, and Level 1 and Level 2 fun. Download the podcast here, or subscribe to our podcasts at iTunes. Also, follow us on Twitter at reefthreads.—Gary and Christine

Sponsor: Rod’s Food
Rod’s Food website

Internet research
Is the Internet a Viable Resource for Marine Aquarium Research?, Jeff Kurtz, Saltwater Smarts

Coral placement
Need help with coral location, gam3ovr, Reef Central


 

The Hammer Coral: A Sizeable Stinger with Showpiece Potential

Hammer coral (Euphyllia ancora) can be quite variable in colorSeveral of the so-called large-polyp stony (LPS) corals offer the advantages of being very hardy, adaptable, and beautiful and, thus, make excellent reef aquarium candidates, even for relatively new reefkeepers. The hammer coral (Euphyllia ancora), however, I would characterize slightly differently. There’s no question this coral is gorgeous, but I would rate it as rather less forgiving than, say, Trachyphyllia geoffroyi. Still, if its care requirements and aggressive nature are given proper attention, this coral can be a showpiece reef aquarium resident. Physical traitsE. ancora has long, tubular tentacles with tips that resemble, as you might guess, the head of a hammer or an anchor. Most specimens I’ve come across have had brownish to grayish tentacles with the tips being some shade of green, gold, or cream, but the color can be quite variable. Colonies of this coral can get quite large—upwards of 3 feet across—which must be taken into consideration when determining tank size, placement, etc

Palytoxin!

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

Coral Letters

Two years ago, Barry and Aimee Brown began photographing “hidden” letters in the brain coral colonies around Curacao, the Caribbean island where they live. Their hunt, which sometimes took them as deep as 100 feet, gave them an even better understanding of...