If we could have your attention please, this is an important public service announcement from your neighborhood Reef Builders to let you know to be very careful when handling your Palythoa zoanthids.
Zoanthids are hardy, neigh indestructible flower animals of the coral reef which reef keepers have enjoyed growing in aquariums since the inception of the hobby. Zoanthids come primarily from three genera, Zoanthus, Palythoa and Protopalythoa, although most any large polyp of zoanthid is generally referred to as a Palythoa, or simply ‘Paly’.
With zoanthids in general being so popular, we would hazard to say that nearly all, or something like 98% of reef tanks have zoanthids in them, of some sort of another. Despite zoanthids being so popular and widespread in the marine aquarium hobby, apparently their owners are fully aware of how dangerous and toxic these animals are.
Palythoa in particular, are synthesizers of Palytoxin, a very VERY dangerous substance that is toxic to all animals, other corals, fish, birds, cats, dogs and people included. While reefers “kind of” know that they should be careful when handling all manner of zoanthids, especially Palythoa, it seems that too many palythoa growers are not taking enough care and caution when handling these dangerously toxic polyps.
Humans have known about the toxicity of Palythoas for hundreds of years, with Palythoa toxica being one of the first described species of Palys. In Maui, ancient Hawaiian warriors used Palythoa much like poison dart frogs, tipping their spears with Palytoxin to essentially turn them into deadly weapons.
Previously, some believed that most zoanthids sold for home aquariums were not of the toxic varieties but research and dangerous experiences by reefers have proven otherwise. Coral reef researchers have identified that Palytoxin is commonly found in the Palythoa zoanthids sold in basic fish stores, and if that wasn’t enough, a recent report by the Center for Disease Control recounts one man’s hospitalization for exposure to Palytoxin.
An Alaskan reefer was admitted to the emergency room after simply adding zoanthids to his aquarium. The toxicity case was so acute that the hospital decided to launch an investigation into the incident. The report included a lot of very important information about Palytoxin in addition to reporting what actually happened to this Alaskan reefer.
Most interesting was a mention of the LD50 of Palytoxin. “The dose at which 50% of exposed animals die following intravenous administration of palytoxin (LD50) has been shown to be as low as 0.033 µg/kg body weight”. For a 200lb man, this means that intravenous exposure to palytoxin requires as little as 0.003 grams for half of people; that’s almost a tenth the weight of a grain of rice!
Ok so we won’t be shooting up any palytoxin any time soon, but that metric just goes to show you how dangerous Palytoxin can really be. As dangerous as Palytoxin is, it’s hard to get it out of the host Palythoa, and into the human body, and it’s often some silly act of being careless that exposes victims to the toxin. Boiling, showering, eating, or handling Palythoas without gloves or protective eye wear is a big no-no.
It’s easy enough for adults to follow these guidelines, but kids and pets don’t know any better. For one thing, we wouldn’t let any children have tanks with Palythoas in them, and of course be sure to keep all of your pets away from the tank, especially while you are working with Palys.
It seems that the aquarium hobby has generally known about the dangers of Palythoa toxicity for a really long time. But this message is not getting across to enough people, and not urgently enough, that it seems like every six months there’s a pour soul suffering the symptoms of Palytoxin poisoning to remind us to really watch out.
Next weekend at MACNA Julian Sprung will be giving a talk explicitly covering the dangers of Palytoxin poisoning, how to recognize it, how to avoid it, and everything in between. Whether or not you can make it to Julian’s talk, please remind yourself that working with Palythoa zoanthids can be very dangerous and you don’t want to be the next person making the headlines because you were careless in handling your zoanthids. [CDC]