Help ID. Bivalve?

[CieloRojos]

OK, I have been seeing this "thing" in my LR for awhile. at first I didn't think anything of it. I didn't even think it was alive. I have highlighted the pic with two red circles to help. The thing is transparent and mostly embeded in rock, so it was a BOOGER to get a pic.

The bottom red circle is the larger visible part of the creature. It appears to be a diaphinous jelly-like funnel. It disapears into the rock and reappears about 1.25" up as a tube made of the same material. It projects no more than 1/3" out of the rock.

At first I thought it was just some see-through dead stuff that would eventually dissolve, but it has grown. Today when I fed the tank the tube flexed. Suprised the heck outa me. Any idea?

OK, new info on this weird, weird critter....it is part of the LR. Maybe it is perfectly camoflouged, or more likely the LR gunk has encrusted it's shell. I was watching the tank today as I fed and the whole section of LR around the critter swung open about a 1/4 inch and it sprayed a bunch of dust from the top orifice. Then it closed back to normal. weirdweirdweird.



Click on the pic to get the big version.

http://img1.glowfoto.com/images/2005/07/08-1547418534T.jpg (http://www.glowfoto.com/viewimage.php?img=08-154741L&y=2005&m=07&t=jpg&rand=8534&srv=img1):confused:

[rshimek]

Hi,

The circled portions of the image appear to be the siphons of a bivalve that is largely imbedded or buried in the rock. This is a pretty common thing. There are a lot of rock-burrowing bivalves found in tropical waters. The larger "funnel" appears to be the incurrent siphon (I think I can see some small projecting tentacles around it, and such structures are typically found on the incurrent siphon). The other structure should be the excurrent siphon. If you wish to test this, mix a bit of milk with sea water and carefully introduce it into the water near the lower siphon. If the animal is feeding the milk will be sucked into the lower opening and a short time later be ejected from the upper one.

[CieloRojos]

Thanks. So this guy is harmless? He is certainly interesting.

[rshimek]

Hi,

Yes, they are harmless. Most rock-boring clams die after a while in marine tanks. They generally don't get enough phytoplankton or small particulate organic matter to persist for any extended period.