Giant flatworm? ID please

[ACBlinky]

It never ceases to amaze me the amount of life that we bring into our tanks with live rock. It has been nearly a year since I added any rock to my 30g, but tonight I saw this guy for the first time. I got the best picture I could using a flash since it's nearly 3am and the tank was in darkness (I was peering in with a flashlight when I found him). I imagine it's some sort of flatworm, but much bigger than the tiny ones I've seen before. It measures about 1.5" long - you can see my 1" clown goby just behind it for reference. It's tan, with white in the centre and a white edge all the way around its body. TIA to anyone who can ID it for me

 

[LeslieH]

That's a nice picture of a polyclad flatworm underside. Unfortunately it's the topside that's needed for id..... but in general all polyclads are predators.

 

[ACBlinky]

Oh no! Thanks so much for the ID, if I manage to see him again I'll try to remove him and get a picture of his topside so we can narrow it down further. I'm going to see if I can find some information on these guys - I haven't seen anything damaged or missing, I wonder what he's been eating...

 

[sugartooth]

Yes, if anyone can give tips how to get rid of them....or at least some natural predators that we can buy.
I would like to get rid of mine....I saw one and then a few days later I saw about 6.
Thanks!

 

[LeslieH]

molluscs, worms, small crustaceans, tunicates, sponges are some dinner items. Some flatworms have very specific diets (like bivalves only) while others are generalists.

Others will have to tell you what eats flatworms. In the field I capture them using a pipette (= miniature turkey baster) by first blowing them off the substrate then sucking them up or picking them up with a brush.

 

[ACBlinky]

Hmm... I had some white lattice sponge (Clathrina coriacea as far as I could tell) appear out of the rockwork in this tank, and it was either eaten or disintigrated over a period of weeks. There was no smell or ammonia spike, so I imagine something ate it. I blamed my angel, though I never saw him in the act - I wonder if it was the flatworm! I've lost tunicates and pineapple sponges as well, but there is also a type of green sponge that I can't ID, it seems untouched.

You know, until now I wondered how someone could specialize in worms... now I think I get it. I'm always interested in learning about new hitchhikers, but this little guy has me FASCINATED; I'm trying to do some research (if you can call surfing research) and learn what I can about these creatures, they're pretty amazing.

 

[ACBlinky]

Well I saw it again this morning and managed to get a decent shot from the top. This was taken through 2' water from one side of the tank to the other, but the colour's pretty accurate. He's nearly the same colour all the way through, the top is more pinkish/purplish and bottom side is just a little paler. He's nothing like the pictures I've been seeing - when I google 'polyclad flatworm' I see creatures that are much more extravagant!

 

[LeslieH]

True, it's not one of the more colorful ones which also means no one can identify it from just a photo. Sorry! But they are fascinating creatures. I hope in your web search that you also found out about the bizarre way some of them mate?