Marine Worms. . . Repulsive Creatures Unworthy Of Attention

Many aquarists need an attitude adjustment when it comes to letting polychaetes other than feather duster worms be in their aquariums.

FishChannel online exclusiveBurrowing in sand and mud, lying under stones and in crevices of rocks, concealed in various types of tubular cases which are free or attached to stones or shells, crawling over the ground or seaweeds, swimming free or attached to other animals, is found in abundance a class of animals commonly known as WORMS and generally regarded as repulsive creatures unworthy of attention.” (Arnold, Augusta Foote. 1901. The Sea Beach at Ebb Tide. New York, Century Press.)

Any new reef aquarium hobbyist faces a daunting blizzard of information and unfamiliar terms. Compared to the familiarity of freshwater animals and plants, the creatures found in marine aquaria may seem totally out of this world. In fact, many people, including marine biologists, have emphasized just how really strange and alien is the marine subtidal environment.  It is the closest any of us will get to a wholly different world, where strange creatures live adapted to very unfamiliar – and, to humans, unforgiving and deadly – conditions.  

Most marine organisms are found nowhere else and are truly unlike anything found on land or in freshwater. It often takes years of specialized training and experience to learn what many of the creatures are and how to take care of them, as a result, many of them often wholly unfamiliar to hobbyists. 

Fortunately, such ignorance is a disease with an easy cure. The beauty and interesting attributes of many aquarium animals makes learning about them an easy and pleasurable proposition. Nonetheless, there were some old aquarist’s tales that seem to have evolved and become entrenched in the hobby’s lore.  Some of the most bizarre examples of this myth-information relate to what are generally among the most harmless and beneficial of animals, the bristly worms.

Early in the hobby’s history, bristleworms of all sorts, but particularly fireworms, acquired a bad reputation. This was probably due to a number of factors, not the least of which was that they simply were worms. When some aquarists finish setting up their first tank, and finally get to sit down and enjoy it, the last thing they want, or expect, to see is a “worm.” Without ever looking closely at them, such worms are considered to be ugly.  And “ugly” is the last thing an aquarist who has just spent hundreds to thousands of dollars on an aquarium system wants to see.

Even worse, after a while, our aquarist looks into their tank, and notices a favored critter, be it a sea anemone, or fish, or…  is dead, and covered in worms that are eating it. Those worms often have very definite bristles, a fact that becomes further impressed on the aquarist when a barehanded removal of the worms is attempted, and the bristles sting and “POISON” the aquarist. Obviously, those — many expletives deleted — worms killed their beautiful animal. It had to be the worms that killed the animal; after all, the worms are ugly, their bristles sting and their bristles are poisonous, and the animal that died was beautiful, and the worms are eating it, and … and … obviously, They stung it with their bristles!  And that killed it!  Bristleworms are awful.  What to do next?  The first response often seems to be to follow the standard exercise of when in worry, when in doubt, run in circles, scream and shout.  Eventually, bristleworm traps are broken out, and a lot of effort is fruitlessly spent in trying to eradicate the worms.

Or so the evil bristleworm myth was born. Very early in the hobby, there were no references and word of mouth was limited; the hobby really started to take off in the late 1980s, and the Internet was in its infancy. Knowledge was in short supply, so ignorance answered ignorance, and became legend and that became lore.  By the time the first references were written much of this lore was incorporated into them and instantly turned into unquestioned fact.  After all, it was written in a book, so it had to be true!  Later references seldom added new information, but rather they seemed primarily to recycle the old information in new manner with a pretty book jacket or cover. Within about four or five years, everybody KNEW for a fact that bristleworms killed by bristle stinging and then ate everything and anything in tank. Yeah, sure, you betcha! Interestingly in this whole process, aquarium reference authors seldom, if ever, investigated the immense volume of the peer-reviewed scientific literature to see what was known about these worms.

With the advent of deep sandbeds in the mid-1990s, and more knowledgeable people on the various Internet forums, coupled with more online information access, good information began to accumulate and good experiences started to be known. Probably the first part of the myth to fade was the part about fireworms stinging animals. Sure enough, a fish that bit one got a mouth full of spines, but casual contact between any fireworm and other animals generally resulted in nothing to either party. Then more information about Hermodice, the predatory fireworms, and Eurythoe, the scavengers, became available and slowly. It was realized that most fireworms were scavengers, and the predators were rare and easily dealt with.

As a result, the general prejudice against fireworms began to fade.  Soon, the bristles simply became “painful” not “poisonous.” Then as experiences and knowledge replaced ignorance, aquarists began to notice how these worms took care of “the mess” in tanks: the excess detritus, excess food and the occasional casualty.Aquarists began to realize that not only were the worms not a detriment, but they were a positive benefit.

Finally, as deep sandbeds became common, the positive benefits of bristleworms, in general, became evident. They help clean the substrate, they incorporate excess nutrients into their own tissue, reducing the nitrate and phosphate loads in a tank, they aerate a sandbed and their spawn provides food for corals and other suspension-feeding animals.  

Although, an occasional utterance against bristleworms is still heard, it generally relates to their presumed lack of beauty. Interestingly enough, however, quite a number of photographs of beautiful worms, and not just the feather dusters have been published as people begin to examine their worms with a hand lens, microscope or macro lens. The poet Ralph Waldo Emerson (1803 to 1882) said, “There’s no god dare wrong a worm.”
So please, don’t you do it either!

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