Not a bristle worm...what is it???

mameloot

Premium Member
Just got back from the LFS.
While floating a bag of GSP I noticed a different sort of worm running around on it.

I don't have my camera at home, or I'd take a pic.

It looks like a centepede, but it's not a bristle worm. It may be a relative, but not too close of one.

It's a tanish white, about 3", maybe 4" long (hard to tell as it's twined around).
it has a row of single legs on each side of it's body. They are fleshy , but flexible legs, not hairlike bristles.
each leg is around 1cm long and when it's moving and needs to go through a narrow opening, it can curl each leg into a tight curlicue (curls up, not down).
It's REALLY cool when doing this, never saw anything like it. Most animals the legs would joint or roll down. This is definitely curling up, towards the top of it's body.

It's head is not like a eunice worm or bristle worm with insect like jaws. It looks like it has a small flexible proboscus instead. It has two longer antenae on top/front, and a few smaller ones around them (kind of like it's legs).

It moves FAST, like a centipede.

Never seen anything like this on a hitchhiker thread/website before.

My gut says it's harmless, based on the shape of it's mouth/proboscus.
However, my head says, if it goes in the tank...I'll never get it out.
My head is winning out, unless anyone can tell me not to worry about it.

Would like to keep him, if he's harmless.
I'll try to get some pics tomorrow.

Any ideas?
 
From the detail about the "legs" curling up into tight curlicues I'm pretty sure it's a polychaete in the family Syllidae. They've always been thought to be predators on sessile inverts like sponges & on algae. Thanks to a couple of posts here & other boards I've learned that some of them prey on soft corals. I've never actually seen one under a microscope so I don't know what species' do this and can't possibly tell you if yours is a coral predator or not. On the other hand, since predators like to stay near their food it's likely that it's helping itself to your new GSP.

I've listed the urls for a couple of RC posts with pictures of syllids. There are at least 3 genera with different feeding strategies in them. One eats xenias. The shorter ones - probably genus Amblyosyllis or something like it - are sponge eaters.

How do you feel about sending it off to me? I've love to check one out & see what it is & would be happy to pay for shippng.


http://www.reefcentral.com/forums/showthread.php?s=&threadid=385562&highlight=syllidae
http://www.reefcentral.com/forums/showthread.php?s=&threadid=737886&highlight=syllidae
http://www.reefcentral.com/forums/showthread.php?s=&threadid=809065&highlight=syllidae
http://www.reefcentral.com/forums/showthread.php?s=&threadid=849501&highlight=syllidae
http://www.reefcentral.com/forums/showthread.php?s=&threadid=891402&highlight=syllidae
 
Dear Leslie,
It's the xenia eating one in the 4th pic.
I got it off the rock in one piece, and can see the features better now. He's actually between 4-5" long.
Has tiny pinchers(?)
caterpillar like feet under each set of hair like feelers (the curlicues)
the end of his tail is flatter, and muscular, possibly for helping to grab/retract back to host rock? No digestive tract there.
there is a small collar, like that of an earthworm, near the head.
I don't know if my camera is good enough to get a good pic. His features are really small.

I can try sending it, but I don't have the materials, and it's cold out. So I'll have to try to get to my LFS and see if they can sell me a heat pac and small styro box.

How sensitive are they?
Any suggestions to packing/shipping to help it survive?

PM me your address, and I'll try to get this in the mail tomorrow afternoon.
 
Super! I'm really happy to have the chance to look at one of these.

Don't worry about sending it alive. It's much too cold & its eventual fate would be a bottle of 70% alcohol even if you did. It's also much easy to look at worms under a microscope when they're not wriggling!

Put the worm into 70% alcohol & leave it overnight to make sure the body tissues are saturated. Isopropyl alcohol from the drugstore diluted down to 70% would be fine. Even white rum or vodka are okay as long as they're at least 150 proof (= 70%). You can ship it in a small container like a pill bottle provided the cap is tight & doesn't leak. The post office hates leaking alcohol so wrap the container in a couple of ziplocks. It can then go regular mail.

I'll send you my address in a PM as you suggested.
Thanks much! I'll post some images explaining the various parts once I get it.
 
The worm arrived today and it turns out to be a very cool one - at least as far as I'm concerned. :D It is indeed in the family Syllidae and appears to be Syllis onkylochaeta. The species name refers to the type of bristles (= setae) it has which are big curved hooks. Polychaetes with this type of hooked setae are usually commensals which live on other animals. It was found on a Xenia in an aquarium in Germany and it was feeding on the Xenia as well. The Xenia was thought to come from Bali.


I've put an image of a similar syllid into the photo gallery. It's from California but the body structures are the same. There are 4 red eyes and 3 antennae on the head. The body is made up of segments all of which have a pair of parapodia (feet) and a pair of dorsal cirri (fleshy appendages) which are the "curliques" you mentioned. The worm in my picrure has been narcotized for photography so the dorsal cirri are relaxed and extended rather than curled. The bristles that give the group it's name (polychaete means many bristles) are very small unlike the conspicuous bristles of fireworms. They're embedded in the parapodia.

I'm not sure what you meant by the "collar" near the head. Possibily you were referring to a swollen area? That would be the area which contains the feeding apparatus. The flattened tail on your worm is not muscular. Instead, it's full of eggs and transforming itself. The setae are becoming more paddle-like and a pair of big eyes is forming. Eventually this posterior region will break off to become a free-swimming epitoke.

Thanks again for sending the worm.
http://reefcentral.com/gallery/data...amanteus_LH04-074_SFB_RAS_2004_2composite.jpg
 
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