Invertebrates: Worms

The “Invertebrate” series of posts is to help with identifying various critters in your saltwater aquarium…or to just see what you may come across one day.  Most of these were hitchhikers on corals and live rock.  Not all are good, so it’s extremely important to quarantine. 

Feather Dusters – Reef Safe
Feather dusters are actually filter-feeding worms that live in a paper-like or cement-like tube (often encased in rock or the sand.)  Most that come in as hitchhikers will do just fine in the home aquarium, but larger ones sold at stores often slowly perish in all but the largest aquariums (likely from a lack of food).  The “feathers” are actually called radioles, and cilia (finger-like projections) on the radioles move captured food particles and sediment to the center.  The sediment is used to build the tube. 
Feather dusters are in the Phylum Annelida, Class Polychaeta, and Family Sabellidae (usually soft-tubed) or Family Serpulidae (usually hard-tubed).
Two problems are frequently encountered with feather dusters:  they leave their tube or drop the crown of feathers (worm remains in the tube).  Dropping the crown may suggest unsatisfactory water conditions or starvation.  Be patient, and the worm will likely regrow the crown when conditions improve.  If the worm leaves the tube, do not try to shove it back in.  Just leave it alone, and it will find a new spot in most cases.
Basically, if you have a feather duster hitchhiker, place it in lower flow (cilia are more efficient) and enjoy it!
Feather duster hitchhiker
Spirorbid Snails – Reef Safe
These are like miniature hard-tube feather dusters that over cover glass in low-flow areas.  They are harmless filter feeders.
Scary Worms – May or May Not be Reef Safe
I find worms like this very frequently on new corals.  I’m not sure what this one was, but I prefer to just keep them out of the aquarium.  Some “scary” worms enjoy munching on corals.

Bristle Worms – Reef Safe with Caution
I have to admit, these things terrify me to death. My husband has had quite a few chuckles from watching me doing the “heebie-jeebie” dance from almost touching one. The stings from touching one are quite painful and the first aid protocol is to soak stung area in vinegar then hot water (don’t burn yourself) (of course, seek professional medical attention when needed).

Regardless of their scary outer appearance, these worms are scavengers. They eat detritus and decaying matter (dying fish, poo, etc.) If you see one on a dead fish, the fish was likely dead when the worm came along (these rarely kill fish). However, some of these can become insanely huge and predatory. Removal is best for large worms.

Black Worms – Reef Safe with Caution
While I was cycling a fairly new tank, these extremely tiny black worms (below…on a piece of eggcrate) appeared in full force.  They appeared to only eat algae, and within a few weeks I never saw them again.  I assume they were herbivores, and as soon as the tank finished its cycle, the food supply ran out.  According to LeslieH on ReefCentral, they were probably oligochaetes or a small polychaete (both are harmless). 
Peanut Worm – Reef Safe
This Sipunculid worm is a harmless filter feeder.
Unknown Flatworm – ?
I have no idea what type of flatworm this one is, but it was removed during quarantine.  Better safe than sorry in my opinion.
Unknown Flatworm – Not Reef Safe
Flatworms are usually very picky eaters – they usually only eat one thing and will starve if not provided a regular diet.  I’m not 100% sure of the species of this one, but it resembles some predatory flatworms I’ve seen before.  
Polyclad Flatworm – Not Reef Safe
This is a very large, very predatory flatworm known to feed on snails and sometimes mollusks. I had several of these come in on a coral, and it took about every chemical in my arsenal to kill them. Once they make it in to the aquarium, they’re nearly impossible to remove.

Acropora-Eating Flatworm (AEFW) – Not Reef Safe
These flatworms eat Acropora corals and reproduce rapidly.  If your Acroporas look sickly, inspect them for small white bite marks.  These flatworms blend in very well with whatever color the Acropora is, so bite marks are usually the most easily distinguishable clue.  Treatment is with Levamisole or repeated dips over several weeks with CoralRx.

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  1. Invertebrates: Egg Identification » Reef'd Up Aquatics

    […] These massive flatworms are not reef safe due to their predatory behavior.  I found one of these flatworms inside a hole in the live rock attached to a coral along with the eggs shown below.  Although I am not 100% certain the eggs are from the flatworm, there were no other large invertebrates within the live rock.  Additionally, the eggs resembled very large Acropora-eating Flatworm (AEFW) eggs, another polyclad flatworm species.  More info on flatworms here. […]

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