Worm ID?

[Peter Houde]

Please help me identify the worm in the attached photos and videos. I've seen all manner of strange and surprising things turn up in the tank, but nothing ever like this. It actively forages, but seems to have been anchored to the same place for the three days I've seen it. I was able to see as much as ~5 cm of it when it was extended while foraging on floating or settled detritus. It has a ring of seemingly bilaterally symmetrical tentacles that can be fully withdrawn into the mouth end. The rostral end quickly 'grows' (or retracts) from the very tip (see videos), NOT merely stretching itself. When extended, the rostral end is black with white spots dorsally and white ventrally. It is banded black and white more caudally (I thought it was my banded serpent star the first time I saw it). I can't see that it lives in a hard tube, but I've never been able to see the full length of the animal so I can't swear it doesn't have one. It is not obviously segmented, and it seems to completely lack parapodia. I was unable to see whether there were eyes or jaws of any sort as it would not face me and my aquarium glass is too scratched up. Possibly a ribbon worm of some kind?

I'm afraid to think of what's living in the rock work where I can't see.


https://youtube.com/shorts/-XzalJTvGB0

 

[JonoH]

Not sure what type...but doesnt look like a good one.

 

[AydenLincoln]

That is definitely the end of a peanut worm which are completely harmless! Most likely Phascolosoma agassizii which is the scientific name.

 

[Peter Houde]

That is definitely the end of a peanut worm which are completely harmless! Most likely Phascolosoma agassizii which is the scientific name.

A-ha! Cool! Thanks so much!