Bristle worms are good

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Oh, Those Horrible Worms!—Part 1

by Ronald L. Shimek, Ph. D.

The Scenario...
Some few days or few weeks after setting up a coral reef aquarium, an aquarist sits down in a comfortable chair and with favored beverage in hand begins to contemplate the sheer beauty of their captive universe. Perhaps it is the gentle motion of the soft corals waving in the currents, perhaps the action of the colorful fishes; no matter, whatever the reason for delight, it is there. The measured joy and deep aesthetic pleasure of a well set-up and maintained reef system is truly an aesthetic boon and soothing balm to a frazzled soul. Our hero, newly home from a day of rat racing, takes a generous sip of aforementioned favored beverage.

Then, out from behind the corner of a rock, or out of a burrow in the sand or, horrors of horrors, out from under a bazillion buck specimen of spitfire gold and electric blue Tridacna expensivus, appears the head of something so utterly loathsome that the mouthful of favored beverage is discharged in what a shotgun aficionado could only call a “full choke” pattern over the side of the tank, the living room and the previously recumbent, but now damply upright and indignant, specimen of man’s best friend. What our hero has just seen is the bane of all reef aquarists, his first large “bristle” worm. It won’t be his last...

Nor should it be!
Reef aquarium information is a hit or myth proposition. Having been an aquarist of one sort or another for some 45 years, and a marine aquarist as well as marine scientist for 30 of them, the state of aquarium lore both amuses and frustrates me. Probably due to the complexity of the natural systems that we get our animals from, and that we try in some regards to emulate, the amount of mythinformation that has accrued in the reef hobby is truly impressive. It seems, at times, that we are dealing with a Baron Munchausen’s “Guide To The Care Of Coral Reef Animals,” and that it is tangent upon reality only due to accident.

Aquarium Myth #349:
Bristle Worms Should Be Removed From Your Tank Because They Are: _________.
1) Dangerous,
2) Eat Corals,
3) Eat Clams,
4) Eat... Anything (as long as it is expensive or desirable), and
5) They Are Ugly.
This is multiple choice myth. Pick one, any combination of, or all of the above to complete it.

Don’t Make The Common Mythtakes About Bristle Worms!
The reality of the situation is considerably different from the myth. To start at the beginning we need to know just what exactly our hero in the scenario above was dealing with. Bristle worms are, well, worms with bristles. And, there are not a just a few of them either. Bristle worms are related to the common earthworms in their basic anatomy. That means they are segmented. In other words, their body is made of repeated units, or modules, called segments. In earthworms the segments look like rings, or “annuli,” of tissue. This appearance gives the worm’s animal group the name, Annelida. Most folks call them annelid worms.

Bristle worms differ from earthworms by being mostly found in marine environments, whilst earthworms are mostly terrestrial. They also have appendages on their bodies, whereas the earthworms are smooth. Finally, all earthworms are hermaphrodites, having both sexes simultaneously active in the same body, whereas most bristle worms have but one gender per worm.

Probably the most obvious difference between these types of annelids, though, is the presence of appendages all along the sides of the bristle worm’s body. These appendages, which often look like small legs, are tipped in many bristles. The common name for the group, “bristle worms” is relatively apt. Biologists who study these worms call them Polychaete Worms. Sounds rather pretentious until you realize that “Poly” means “many” and “Chaeta” means “bristle.” So, polychaete worm can be translated into the common vernacular as the “worm with many bristles.” Bristle worm will do. Unfortunately, the name is used much too carelessly to be useful. As it turns out there are well over 10,000 described species of bristle worms, and a truly sizeable number of those can make it into reef aquaria.

Ron Shimek is the author of PocketExpert Guide: Marine Invertebrates and Host Sea Anemone Secrets. 

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