What is this?

[kjstallan]

Hello my name is Kasey and I am new to the saltwater hobby. I have been in the freshwater hobby for 10 years and have finally converted to the dark side . I currently have a new tank set up (2 months running) with live rock, a bicolour blenny and a PJ cardinal. When looking at my tank I notices these worm looking creatures. I am unsure of what they are exactly or if theyre toxic or harmful to my fish, they stretch out of the live rock then retract back inside. Any help would be much appreciated.

 

[fishywishy]

The video doesn’t work

 

[kjstallan]

Does this work,?

 

[ISpeakForTheSeas]

Does this work,?

Yes - that's a female spoon worm (it may or may not have tiny males living inside it):

That's a female Bonelliid Spoon Worm/Echiuran - most spoon worms are harmless detritivores (good CUC), but a few (likely including yours) have a toxin (Bonellin) on their proboscis (the forked "mouth" mentioned above) and/or skin; these eat things like small pods that succumb to the toxin when crawling on/over the proboscis.

These would probably be fine to keep in the tank as long as you think your critters are smart enough not to touch the proboscis, but it may carry some risk (especially for smaller critters, and especially if your female has one or more males - which are tiny - living with it so that it could reproduce):

be aware that it is toxic (the toxin is called Bonellin, and I’m not sure about it’s effects on people), and please handle it with care and a good pair of gloves.

If you decide to keep it, I'd probably suggest running carbon and doing regular water changes to be safe.

Bonelliid spoon worms exhibit extreme sexual dimorphism - the females are large while the males are extremely tiny and often/always live literally inside the female. So, by seeing the worm's regular-sized proboscis extended, you can tell it's female (no idea if it has a male with it or not though).

Unfortunately no idea how harmful the toxin is - as a general rule, the physically greener the worm, the more toxic I would expect it to be, but I don't know how much of the toxin it would take to harm a small fish.

 

[kjstallan]

Yes - that's a female spoon worm (it may or may not have tiny males living inside it):

I feared this was going to be the answer with the research ive been doing. I did see some small clear coloured worms coming out of the live rock too. How would i go about removing it? Im concerned itll hurt my fish or repopulate super fast. I cant find much about how to rid my tank of them

 

[ISpeakForTheSeas]

I feared this was going to be the answer with the research ive been doing. I did see some small clear coloured worms coming out of the live rock too. How would i go about removing it? Im concerned itll hurt my fish or repopulate super fast. I cant find much about how to rid my tank of them

Yeah, they're not common, so it's not surprising that no one has info on removal - the best way is probably manual removal; you could try sucking it out with a turkey baster or similar, pulling it out with tongs, or injecting something into the hole to try and either kill it or drive it out of the hole for removal (things like vinegar, lemon juice, kalkpaste, and boiling water are the typical choices for this).

 

[kjstallan]

Yeah, they're not common, so it's not surprising that no one has info on removal - the best way is probably manual removal; you could try sucking it out with a turkey baster or similar, pulling it out with tongs, or injecting something into the hole to try and either kill it or drive it out of the hole for removal (things like vinegar, lemon juice, kalkpaste, and boiling water are the typical choices for this).

Yeah, they're not common, so it's not surprising that no one has info on removal - the best way is probably manual removal; you could try sucking it out with a turkey baster or similar, pulling it out with tongs, or injecting something into the hole to try and either kill it or drive it out of the hole for removal (things like vinegar, lemon juice, kalkpaste, and boiling water are the typical choices for this).

I have witnessed 3 or 4 females. 2 or 3 in one live rock and one in another. How much of any of the above things would you suggest inject into the rock?? Should i take the rock out before injecting?? Im worried if i use tweezers or baster it may break it and it may just regrow.

 

[kjstallan]

Yeah, they're not common, so it's not surprising that no one has info on removal - the best way is probably manual removal; you could try sucking it out with a turkey baster or similar, pulling it out with tongs, or injecting something into the hole to try and either kill it or drive it out of the hole for removal (things like vinegar, lemon juice, kalkpaste, and boiling water are the typical choices for this).

Think i might remove those pieces that ive seen the worms in and inject it with one of the above with some gloves on to see if i can get them out or kill them. Thank you so much for your advice and time