Bristle Worms
This is not the first time I've written about them ... & it won't be the last.  As long as I continue to hear that people are afraid of them, I will continue to write about them.

Bristle worms are present in EVERY reef aquarium.  They arrive in our tanks as hitchhikers in live rock, live sand & corals purchased.  There are hundreds of different species.  99% of the time they are "GOOD GUYS!" and need to be looked at as a harmless garden worm - doing the same necessary functions...breaking down wastes, keeping the substrate supple & live rock clean.  You just don't want to touch them as Mother Nature provided them with ample "bristles" which can sting.  This along with the fact that they're almost always present at a death scene is probably how they got their undeserved bad reputation.  Understand, they are just cleaning up the mess...not the cause of it.

Honestly folks, in all the many years I've been in this hobby I've NEVER seen, nor been able to attribute, any fish deaths or anything negative to the common Bristle worms.  Believe me when I say I've seen good sized specimens here & there & yet again, without incident.

If you are seeing lots of these worms in your tank it is probably a result of overfeeding = high nutrients in your tank.  These worms (like many other creatures, i.e. flatworms, feather dusters etc.) only grow in numbers that the tank provides food for.  Not seeing them?  Trust me, they're there...quietly doing their jobs...cleaning our tanks.

What About Those LARGE Worms?
I have always maintained that Bristle worms are harmless at any size (again, just don’t touch them as their bristles sting!) just as Night Crawlers are no more harmful than tiny earth worms.  BUT, we are working with a hobby that has the potential to hitchhike any number of creatures from the ocean into our tanks.  Add to that the fact that our AquaCorals systems are so healthy that we’re seeing things we never saw before.  Though I can ID many critters I certainly do not know what everything is so if you see something different than what’s pictured here, I suggest you watch its behavior, research the critter on-line, determine if you think it’s a bad or good guy & share your findings.  If you can get a picture of your critter that would be great!  The best place to research these things (plan to spend some time!) is:  www.wetwebmedia.com

Lastly, if what you’re seeing is a true Bristle worm then no, he’s not eating your snails but rather going in to clean up one that fell & is dying.  That’s why it’s important that we do a daily “snail check” & right any we see that have fallen or they will die within 24 hours.  Of coarse we don’t always see them all so having some die-off is normal, to be expected & numbers replaced occasionally.  Unlike Hermit crabs (all species) who will purposely make a snail fall in order to have an expensive lunch, Bristles are strictly clean-up guys.  They “smell” the stress and flesh decay from dead/dying snails just like Nassarius snails smell the fish food & pop up out of the sand.  The larger Bristles tend to only come out at night after our lights are out (another comparison to Night Crawlers).