Being a coral in the wild is challenging, therefore, most corals have some form of chemical weaponry.
As corals start to encroach on each other, they can get very defensive. There is one group of corals in particular that are famous for their potent weapons, and those are corals from the phylum cnidaria, which are more commonly known as leather corals.
Are Leather Corals Toxic?
Leather corals can produce and release toxins; a process called allelopathy. The toxins they release are called terpenoids. Terpenoid toxins will stunt the growth of other corals in your aquarium, adversely affecting more sensitive corals like Acropora.
These toxins can be fatal to neighboring corals, both via direct contact and without contact. Your leather coral will release toxins as an anti-predatory response, in competition for space, during reproduction/shedding, and as a stress response.
Leather corals can also grow very large, very quickly. Some species, like the weeping willow leather coral, are known to take up to 80% of the tank, so, if you have a nano or pico reef tank, that may be an issue. Remember that placement is also key – allow at least 2 inches between coral frags in your aquarium to reduce fighting over space.
What To Do When Leather Corals Release Toxins?
Running carbon, and performing regular water changes, can reduce the detrimental effects that leather coral toxins have in aquariums. Most hobbyists will agree that running carbon and replacing it every 2-3 weeks has solved most of their chemical warfare issues.
Are Leather Corals Toxic To Humans?
All leather corals have a level of toxicity, however, if you accidentally brush up against your coral, it should not cause you harm.
Unless you have an open wound, there is no way for a leather coral’s toxin to get inside you because they do not have nematocysts like stony corals.
Saying that, there is no guarantee you will not get any irritation. No two people have the same tolerance for irritants. What may sting one person, may not sting another, so it really does depend on the person.
Can You Touch Leather Corals?
As mentioned above, generally, leather corals are not toxic to humans unless you have any open cuts on your hands. Plus, you shouldn’t be touching your leather corals unless you have to.
If you touch your leather coral, always wash your hands thoroughly afterwards. If you are prone to irritations, it is recommended you wear rubber gloves.
So, yes, you need to be cautious if handling leather corals, but you don’t need to wear a biohazard suit and welding gloves!
What you should be wary about, is the effect that you have touching your leather coral. If you have ever been snorkeling or scuba diving, then you probably remember from the briefing that you must not touch any marine life, not only for your safety but also for the safety of the plant or animal.
Even if you accidentally touch your leather coral, you can damage its protective layer. Not only will this expose your leather coral to pathogens and other diseases, but the damage can also trigger a stress response. If your leather coral is stressed or feels threatened, it will eject its zooxanthellae and/or it will release toxins into the aquarium water.
Are Toadstool Leather Corals Toxic?
Toadstool leather corals, known as Sarcophyton, are one of the most noxious chemical warriors in aquariums.
Toadstool leathers constantly release toxic chemicals into the water to fend off neighboring corals when they get too close. As aquariums are a closed system, these toxins and chemicals can pose major issues to other corals (and sometimes fish) in your reef tank.
If you notice strange behavior, such as your corals refusing to open, or suddenly dying despite maintaining tank stability (good water conditions, lighting, flow, etc.), then your toadstool leather coral may be to blame.
Do All Soft Corals Release Toxins?
Yes, all soft corals (softies) can engage in chemical warfare by releasing toxins into the water. This is why many aquarists will never mix LPS and SPS corals with softies.
As already mentioned, this is how soft corals battle for territory because they do not have long sweeper tentacles like their calcium carbonate skeleton friends (SPS and LPS).
The most toxic soft corals are:
- Leather corals (particularly the toadstool and devil’s hand leather)
- Xenia corals
- Anthelia corals
- Zoanthids
- Palythoas
Do Leather Corals Release Toxins When They Shed?
If your leather coral has started shrinking and appears more dark than usual, then do not panic yet, it is likely in the process of shedding its outer mucus layer. If you are unsure, shine a light on it when the lights are off – if it is shedding, it will have a shiny film over its body.
This shiny film is mucus, which is toxic.
How Often Do Leather Corals Shed?
Your leather coral will shed about every month or two, however, it may decide to do it more often, so do not worry if it does.
How Long Do Leather Corals Shed For?
Most leather corals will usually take around 7 days to fully shed their membrane, however, some like the devil’s hand can take weeks. This time allows your leather coral to clean its surface of dirt and debris and feel ‘reborn’.
If your leather coral is taking a long time to shed, be patient. Unless your leather starts disintegrating, I wouldn’t worry about it.
Conclusion
Like all soft corals, leather corals release a toxin, in a process called allelopathy. The toxins they release are called terpenoids, which can be fatal for other corals inside your aquarium.
This is why it is not recommended to mix soft corals with LPS and SPS corals, particularly if you have a nano or pico tank, as leather corals can grow very large, and very fast.
So, if you are having issues with your leather corals releasing toxins, or you are worried about the damage they will do to neighboring corals, remember to allow plenty of space between soft corals and run carbon in addition to your regular water changes.
