Nudist Snail?

[sapphiredonna]

There's something crawling around my tank that looks like a snail who decided to leave his shell behind. I'm assuming this is not that case and that it is, in fact, a hitch-hiker sea slug. He looks like an Astrea but with slightly longer antennae and, again, no shell. His back looks kinda bumpy and he blends in really well with the coraline algae in the tank (mostly purple, a little green). I've seen him on the glass and on rocks. I just want to make sure he's reef safe; as far as I'm concerned, so long as he doesn't annoy my corals, the more inverts the merrier. Any idea what he might be?
And if it is a snail who decided he doesn't want his shell anymore, it must be either a Cerith.

 

[chrisstie]

If it is shell less completely it isn't a snail unless its a Stomatella.. their shells are sort of halved and hidden.

if his back is bumpy look up "nudibranch". there are billions of him but it would at least give you an idea on where to start an iD.

a picture would be great too!

 

[pagojoe]

It sounds like it might be a Stomatella. They have reduced shells, covering about one third of the body (unless they've dropped the back half of the foot recently, in which case the shell covers a larger percentage of the snail). They have the ability to extend the mantle so that it covers the entire shell, which is what keeps the shell clean and shiny, but when the mantle is completely extended the animal just looks like a slug with branches or bumps on the dorsum. If it is a Stomatella, and you poke it, it will withdraw the mantle so that you can see the shell.

Cheers,



Don