Bug-like thing with horns on its behind

[Kurt_Nelson]

What the heck is this???

It's maybe about 3/16" long, and seems to really like it on my sponge covering my powerhead. The top of the picture - where the "horns" are - is the things behind. It seems to be really happy cleaning gunk from the sponge, so I'm thinking it's probably a good thing to have around. But it's kinda scary. This is the biggest one - I've seen a smaller one crawling around on my rock.

I tried to grab it with some forceps the other day, and it just kind of flung itself off the sponge and drifted in the current. Don't think it actually swims. It eventually hid itself in the sand when I came after it again.

Any ideas? Good or bad? Should I name it or get rid of it?!

 

[Devilishturtles]

Kinda looks like a species or Dorid or nudibranch. Any chance for a better picture?

http://www.julianrocks.net/nudibranchs/nudibranchs.htm

Dorids are noted for the little horns by their butts.

 

[Kurt_Nelson]

Kinda looks like a species or Dorid or nudibranch. Any chance for a better picture?

http://www.julianrocks.net/nudibranchs/nudibranchs.htm

Dorids are noted for the little horns by their butts.

Nope... not a nudibranch. I forgot to mention that it has a hard shell. When I tried to grab it with the forceps, it was definitely hard. I just now noticed that I've got three of them, in various sizes, hanging out on the powerhead sponge.

Here's a different picture, not zoomed in and cropped so much so you can get a feel for the size of the thing...

I'd describe it more like a potato bug, but that always seems to make people think isopod, and it sure doesn't look like the ones I've seen pictures of.

 

[Devilishturtles]

Ah. Well in that case, I would guess some species of limpet. There are thousands, but for most of them, they are harmless algae grazers. Some may also eat up sponges and soft corals, so keep an eye out.

 

[roka64]

I agree w/DT. My only other guess is a sea hare, but I'm not sure if they have a shell. If you notice it expelling purple dye, it is probably a sea hare.

 

[Fluff]

Looks like Pan (Arcadian God) or am I the only one seeing the face? lol Ok, my eyes are still screwy but I think you have a type of isopod. No idea what species but keep an eye on it. If you see it latched onto your fish at night, you need to remove it. Some are parasitic, some are not but it warrents watching.

 

[Kurt_Nelson]

Looks like Pan (Arcadian God) or am I the only one seeing the face?

Nope... you're not the only one seeing it!

I guess when I said it had a hard shell, I didn't mean hard hard, just crunchy hard. (Does that make sense? It does in my head!) I'm new to this stuff, but I have seen limpets before, and I'm pretty sure this isn't one.

I think you're right Fluff. I did some more research, and while it doesn't look like the dreaded hand/fish eating isopod, it seems to share enough similarities. I snagged one Saturday night with the forceps and examined it. Those "horns" on its back end look more like fish hooks when you look at it up close. Knowing how these things have evolved themselves with equipment to help them stay alive, I'm thinking that things that have fish hooks as part of their bodies might not be the best thing in the world to have in the tank.

After reading up on isopods in general, I decided I really didn't want this thing getting a foothold, so I went on an eradication campaign last night. They're quick, but don't seem to have too good of peripherial vision - lucky for me. Got all but one last night. The last one departed us tonight. (My new favorite toy are my 12" long forcep/tweezers!) I also swapped out my powerhead sponges for their spares... it was time for them to get cleaned anyway.

Thanks for the input all. If I can ever find a picture of one online, I'll post back.

 

[Devilishturtles]

Nice ID Fluff!

 

[Kurt_Nelson]

Think I found it...

The "horns" on this one don't look as pronounced, but the coloration sure matches. Looking at http://www.mov.vic.gov.au/crust/pillbugs.html they comment that the males are more "highly ornamented" so I guess I've been knocking off all the guys.

 

[Fluff]

Wow, the face on this one does look a bit more femanine. lol
Good job on the detective work.