friend or foe?

Thanks for the ideas, I'm going to research them and get a definite match. Until then, I'm going to leave him in the bag and not take a chance.
 
I'm pretty sure that's a lumbrinerid (family Lumbrineridae) of some sort. Although I've seen some photos of peanut worms (sipunculids/family Sipunculidae) that do appear very similar (see this link: http://www.wildsingapore.com/wildfacts/worm/sipuncula/sipuncula.htm ), your individual appears to have parapodia (leg-like appendages), is uniformly narrow along its length (sipunculids typically have a bulbous posterior end) and is segmented (sipunculids can appear so, but they're not). The head area (prostomium) is also typical of lumbrinerids (bare, spherical or conical with no apparent eyes or tentacles/antennae).

Lumbrinerids are in the order Eunicida, have large eversible jaws (like we see in Eunice spp. worms) and are typically, but not exclusively, carnivorous (some apparently are deposit-feeders/detritritivores, and some eat plant material). As for the carnivorous species, prey items include other polycheates (like tube worms), little brittlestars, 'pods, nemerteans, etc..Interestingly enough, I read about one species, Lumbrineris flabellicola, that's a commensal with corals in the family Flabellidae (genus Flabellum) and Caryophylliidae (genus Caryophyllia). According to the report, they grab food from the coral, but don't actually prey on the coral itself.

All in all, Lumbrinerids are interesting little critters. I guess the elephant in the room is whether one would be a safe addition to your system. On the plus-side, these guys typically stay pretty small, so even if it's a largely carnivorous species, livestock loss should be limited to the small stuff. Also, if it's a deposit-feeder, you'll have one more critter in there to help with detritus removal. It's up to you.

Here are some links with more info/photos:
http://personal.cityu.edu.hk/~bhworm/errant/lumbrineridae.htm
Unknown species, but a lumbrinerid similar to yours (may be the same genus): http://www.roboastra.com/brunsworm/brwo378.htm
This is a good link (pdf file) for species in NE Atlantic waters, but it's got some terrific general information and photos: http://www.nmbaqcs.org/media/11296/lumbrineridae_guide_nmbaqc_2010_ver3_2.pdf
 
Lynn Z said:
I'm pretty sure that's a lumbrinerid (family Lumbrineridae) of some sort. Although I've seen some photos of peanut worms (sipunculids/family Sipunculidae) that do appear very similar (see this link: http://www.wildsingapore.com/wildfacts/worm/sipuncula/sipuncula.htm ), your individual appears to have parapodia (leg-like appendages), is uniformly narrow along its length (sipunculids typically have a bulbous posterior end) and is segmented (sipunculids can appear so, but they're not). The head area (prostomium) is also typical of lumbrinerids (bare, spherical or conical with no apparent eyes or tentacles/antennae).

Lumbrinerids are in the order Eunicida, have large eversible jaws (like we see in Eunice spp. worms) and are typically, but not exclusively, carnivorous (some apparently are deposit-feeders/detritritivores, and some eat plant material). As for the carnivorous species, prey items include other polycheates (like tube worms), little brittlestars, 'pods, nemerteans, etc..Interestingly enough, I read about one species, Lumbrineris flabellicola, that's a commensal with corals in the family Flabellidae (genus Flabellum) and Caryophylliidae (genus Caryophyllia). According to the report, they grab food from the coral, but don't actually prey on the coral itself.

All in all, Lumbrinerids are interesting little critters. I guess the elephant in the room is whether one would be a safe addition to your system. On the plus-side, these guys typically stay pretty small, so even if it's a largely carnivorous species, livestock loss should be limited to the small stuff. Also, if it's a deposit-feeder, you'll have one more critter in there to help with detritus removal. It's up to you.

Here are some links with more info/photos:
http://personal.cityu.edu.hk/~bhworm/errant/lumbrineridae.htm
Unknown species, but a lumbrinerid similar to yours (may be the same genus): http://www.roboastra.com/brunsworm/brwo378.htm
This is a good link (pdf file) for species in NE Atlantic waters, but it's got some terrific general information and photos: http://www.nmbaqcs.org/media/11296/lumbrineridae_guide_nmbaqc_2010_ver3_2.pdf
Click to expand...

You're like some sort of biological identification deux ex machina Lynn. I love your participation here.

Dan, if you decide to ditch or destroy he is always welcome in Herbie's tank o' misfit critters.
 
Thanks Nate; I'm certainly not infallible, but I try! It also helps that I've been at this for awhile and have a good image recall. I just wish my memory for names was as dependable! I can't tell you how many times I've recognized something but haven't been able to remember the family, much less the genus - as in D'oh!! At any rate, I got lucky this time and recognized it right off the bat. As for the info, I have a zillion species/family sheets that I've built up/compiled over the years so when something like this comes up, I can refer to it/them. I'd love to say that I have all this stuff in my head but that is soooo not true! :)

By the way, I love the fact that you've got the "tank of misfit critters". That's just so great. I love all the weird little critters that pop up in our tanks. In this case, I've gone back and forth trying to figure out what I would do. I always go through the list:
  • Is it dangerous/toxic/venomous (like Conus spp/cone snails, fireworm bristles, etc.)? In this case, I don't think so but I wouldn't handle it!
  • What kind of livestock will it threaten? See prey list - mostly small stuff.
  • What's the likelihood of it reproducing successfully in my tank? Unless there are more already in the system, probably not going to happen - at least not successfully.
  • How big will it get? These are typically small and stay that way.
  • Can it harm the tank/equipment - for example: chitons are great, but can leave rasp marks in acrylic tank walls, and some small snails (like Collonistas) can get stuck in intakes, pumps, powerheads, etc. I can't see these worms causing any equipment issues.
  • If it dies, will it lead to a toxic mess (like a big flatworm die-off, or some cukes)? Nah, it's just a tiny worm.

I think the only real issue here is the worm possibly preying on small, beneficial organisms. Again, because it's a small worm and likely to stay that way, it probably wouldn't have too much impact unless the system was very small. I hate to say it, but if I were in this position, I'd probably donate the worm to you - only on the theory that it's currently isolated in a bag, and not wanting to add a potential predator to an already stable system (that I'm sure already has its fair share of unseen predatory worms, etc. anyway). If, however, the worm was already in the tank, I wouldn't think twice about it.
 
Thanks Lynn, it looks like you got it right. I'm going to play it safe and not add it to the tank.

Nate, I would be happy to save it for your misfit tank, but we live about 65 miles apart. I work in Carol Stream which would cut that distance in half if you're interested in meeting somewhere around there.
 
definately not a peanut worm. 100% belongs to the polycheat family. so it is a bristle worm. Not sure if it is a friend or foe though
 
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