What is this worm living under a rock?

[Just John]

I think they live in sand tubes under the rockwork. I found this one when I turned a rock over.

 

[fishguy242]

peanut worm ?

 

[musel101]

peanut worm ?

Are you talking about the kind that flips over corals?

 

[fishguy242]

Are you talking about the kind that flips over corals?

no, usually harmless cuc.

 

[vetteguy53081]

I think they live in sand tubes under the rockwork. I found this one when I turned a rock over.

Looks like a peanut worm but other possibility is a Sigalionid worm. Both spend their time in the sand or mud feeding off uneaten food and detritus

 

[Just John]

peanut worm ?

When I look at images of peanut worms they always have a stumpy end with "hairs" on them and don't look as segmented as this one does. Maybe it is though.

 

[vetteguy53081]

When I look at images of peanut worms they always have a stumpy end with "hairs" on them and don't look as segmented as this one does. Maybe it is though.

These follicles retract and extend as they feed

 

[fishguy242]

When I look at images of peanut worms they always have a stumpy end with "hairs" on them and don't look as segmented as this one does. Maybe it is though.

google images ,many different species

 

[ISpeakForTheSeas]

When I look at images of peanut worms they always have a stumpy end with "hairs" on them and don't look as segmented as this one does. Maybe it is though.

Your worm appears to be a Bamboo/Maldanid Worm (taxonomic family Maldanidae) - it's harmless/beneficial and a pretty rare hitchhiker. Neat find! As you observed, they build tubes to live in, and they feed on stuff like detritus.

With regards to peanut worms, though, that stumpy end with "hairs" (they're tentacles in this case) is actually the everted proboscis of the worm (basically the mouth of the worm when it's open) - it isn't always visibly "hairy" like in the pic you shared, because it isn't always everted; when the worm's mouth is "closed," the proboscis is basically tucked away inside the worm, and not visible.

 

[Just John]

Your worm appears to be a Bamboo/Maldanid Worm (taxonomic family Maldanidae) - it's harmless/beneficial and a pretty rare hitchhiker. Neat find! As you observed, they build tubes to live in, and they feed on stuff like detritus.

With regards to peanut worms, though, that stumpy end with "hairs" (they're tentacles in this case) is actually the everted proboscis of the worm (basically the mouth of the worm when it's open) - it isn't always visibly "hairy" like in the pic you shared, because it isn't always everted; when the worm's mouth is "closed," the proboscis is basically tucked away inside the worm, and not visible.

Thanks so much! Apparently they get up to 4" long, so not too big.