Yellow Thing

[Steven]

There are two of these yellow things in my tank. They stick on either the glass or the rocks. I haven't seen them move, but each time I look at the tank they appear in different places. I've had them in my tank for several weeks. Today I found pieces of one scattered around my magnetic algae scraper. I suspect that someone killed it while using the algae scraper. Luckily, I took this picture awhile ago.

[Steven]

Here is the picture of the other one.

[tinyreef]

could be a roaming sponge. some sponges move around and extend "tentacles". i've never heard of one moving around so fast tho (from what your description sounds like).

 

it could also be a spaghetti worm but with a lot of it's tentacles retracted. the 2nd picture doesn't make me think so tho, 1st one does.

 

little bits also make me think sponge. i would assume you'd know guts if you saw it, i.e. if someone smooshed the "worm" with the scraper.

 

it's just the significant movement you related that doesn't seem to support "sponge" as the answer/guess. maybe there is a fast moving yellow sponge afterall.

 

but i thought they usually reside in a pineapple under the sea...

[Steven]

My description was somewhat misleading. I don't look at my tank very often. I'm pretty sure it moves very slowly.

 

Do you have a scientific name for the sponge you mentioned?

[tinyreef]

hell, off the top of my head? you're kidding, right? you'd be lucky if i remembered my home address.

 

i thought i saw it on tyree's book (Porifera) but i don't remember him noting it was motile, the yellow sponge. i believe he had it spreading/encrusting altho it looked very similar. then again, there's probably hundreds of different species and morphology changes to the environment too.

 

there's a couple of others he notes as moving/crawling. they're pretty obvious "movers" though as they reach and pull(?) with little sponge arms, almost like a octopus. i might be able to dig up the book when i get home (no promises) but the books a good read if you get it. www.dynamicecomorphology.com

[Steven]

Thanks. Its too bad, this sponge was killed, as I can't find the other one in the tank anymore. I'm wondering if the pieces of the sponge could regenerate into new sponges.