Hitchhiker Nudibranch,Serpent Star?

[black_majik]

I bought a sponge two weeks ago and I noticed two things on it.

1) A pencil-tipped size starfish that was all white and looked like a serpent star.

2) A weird growth( hard to tell) at the time

Well, about 10 minutes ago I saw that growth MOVING on my glass and it took me only two seconds to realize it was a nudibranch.

So my questions are these:

1) What are the chances of the serpent star being alive? How long does it took for them to grow noticeable?

2) Can this nudibranch be harmful?

 

[reef_researcher]

I've had many of the little white serpent stars in my tank for over a year now and I've never noticed a increase in size, I think they might just be a small variety

 

[greenbean36191]

There are lots of serpent stars that are commensals on sponges or just common hitchhikers. The growth rate and adult size will vary between species. Many will stay small.

If the nudibranch came in on a sponge, that's probably its food. It won't be a predator on anything else. The only worry in that case is the unlikely case that you got one of the phyllidiids, which can poison fish if they're unhappy. Otherwise it will be completely harmless and an interesting addition to the tank.

 

[black_majik]

The nudibranch is never around the sponge and it has a green plant growing on it. I think its an algae eater

 

[greenbean36191]

All nudibranchs are carnivores, so it's either not an algae eater or it's not a nudibranch. A picture would really help.

 

[Pea-brain]

Yep, all nudibranches eat corals, anenomes, or sponges. Might be a sea hare. Lots of nudibranches have colorful feathery appendages on their backs.

Danh

 

[rnmahler]

if the nudibranch is green it could be a lettuce nudibranch which does not eat corals but is an algee eater