Slimy thing

Hi Guys,

I recently saw this slimy thing slithering on the sand in Indonesia.

It may well be something common, but I've never come accross anything like it before, and I can't find it in books.

Description in short: about 1m long, 2cm wide, and 3-4mm thick.

The second photo shows what should be the head (?), from which it was probing and moving ahead.

Anyone knows what this is?

Thanks,

Mat

It's a sea cucumber. Phylum Echinodermata, Class Holothuroidea, maybe Euapta godfreyi or one of the Synapta species. It feeds by probing the sand with its sticky oral tentacles for tasty bits then inserting the food-laden tentacle into its mouth -- sort of like a kid licking his fingers.

Thanks!

Just don't put them in your salad.

Don't laugh too fast - they're popular food items in many parts of the world!

Joe - I kept thinking I knew you but couldn't remember why. Today the brain cells kicked in: didn't we both work at MBC in the mid-80s? I was in the tax lab, & you were a field tech?

Hi guys

I am not sure that this is a sea cucumber !

there are some "slimy" ones - synaptids for example, but they are not that flat ! 3-4 mm ..

I would say it's a nemertean worm, I know some are very long (exceed 1 m)

but maybe I am wrong ..

cheerio

Art

I thought about that possibility but decided against it as this animal is translucent (you can see right through it). I've never seen a nemertean that wasn't completely opaque. Still, I'll send it to Jon or Megan and see what they think. If it's a nemertean they'll recognize at first glance.

Leslie

some nemerteans are pelagic !!! have some references (but see also Brusca & Brusca)

so why not a semitransparent benthic one ?

but we'll see .. on the other side, I don't know of any really flattened holothurians either

Art

I know, I use to work on them. I'm willing to be convinced and equally willing to admit I'm wrong!

I know, I use to work on them.  I'm willing to be convinced and equally willing to admit I'm wrong! 

<{POST_SNAPBACK}>

And I am wrong. It's a nemertean. Good thing you're around to keep me in line!

Well, since I'm trolling through here looking for nemerteans...

My first hope was nemertean, but dashed that hope the instant I saw it was translucent. Sorry, no translucent benthic nemerteans. They have way to much muscle tissue (almost lacking in pelagic nemerteans). Synaptids are commonly translucent. I don't know anything about tropical ones but would bet dollars to donuts that Leslie is right on the money.

--Jon

I was right originally? With that head?

I'm glad that this photo prompted so much interest, didn't expect it...

Since we're at it, after Leslie's first reply, I felt a bit curious. Being no expert in sea cucumber or marine biology, I'd always thought that sea cucumbers were members of the echinoderms, and had a penta-symmetry. So a flat sea cucumber sounded unusual. But then again, my knowledge on this is very limited...

Any clarification, even succinct, would be appreciated.

Thanks,

Mathieu

You're right about the penta (5-sided) symmetry. That doesn't have anything to do with diameter or shape however. Some sea cucumbers have fairly rigid exteriors & appear round or rounded on top & flat on bottom. Others are very soft & quickly go from a circle in cross section to completely flat by expelling their internal water.

OIC. Thanks for the explanation. Guess I'll have to get myself one more book on marine life and get more dives in to observe critters

More diving is always a good option!

Leslie's uncertainty has me wondering. It definitely is not a nemertean. There are not many translucent options among benthic critters, especially at 1 m long. It's not a benthic ctenophore and I am almost certain there are no marine flatworms this long. We may be looking at the hind end of whatever it is. If we are seeing sediment in the gut, it almost has to be a synaptid; they certainly get that long. If we are seeing sediment through the entire thing, I would guess that we are looking through the tentacle of the world's biggest terebellid polychaete, which would tally with the probing behavior. A scary thought. Leslie, could there be such a large terebellid? Or maybe the hind of one?

Certainly not a polychaete tentacle! And I don't know of any terebellids that come out of their tubes. Maybe the world's largest echiuroid proboscis?

Matt - you're just going to have to keep diving until you find & rephotograph this thing for us. Now get back in the water!!

Actually, I do have a couple more pictures of that critter, whatever it may be!

I'm not sure whether they provide more insight on what it is, though... <_<

This shot's horrible artistically speaking, but gives an idea of its length...