Molpadiodemas villosus - armoured sea cucumber anyone have advice on keep or remove?

[AstroMelly]

Hi all

I just saw this guy for the second time at the top water margin. From underneath it looked a bit more like a nudi this time so I removed for a closer look. I thought it was a stoma previously but there’s no shell. The body goes rigid when touched so I figured an echinoderm. Size is about 1cm.

Google search of the image turned up this link.

Any ideas on whether it’s reef safe?
I’m putting him back for now as I first saw it a couple of days ago so should be easy enough to remove if needed.

Pretty cool hitchhiker I thought!

 

[Reefing102]

To my knowledge, most if not all sea cucumbers are generally reef safe, the mainly thing is toxicity if/when they die or get stressed (sea apples for example can release a toxin).

Here’s some great info from @ISpeakForTheSeas in post 10

Dead sea cucumber toxin

Hello tankmates! I recently had a sea cucumber die in a small 10 gallon tank. I have read they can possibly release a toxin when they die. I did an ammonia test and 0 ppm. Should I do a 100% water change or should I even worry about it? The only other things in the tank were live rock and 2...

www.reef2reef.com

 

[AstroMelly]

Hey thanks for your reply. Yes I am of the same opinion that this is probably safe to leave in. It’s such a tiny critter I’m not worried about toxins. The tank is a 6ft so the net effect would be negligible.

He lives!!!

 

[taricha]

I'm gonna say this is a starfish arm. The underside pic is pretty persuasive.

 

[bradleym]

I'm gonna say this is a starfish arm. The underside pic is pretty persuasive.

Oh man! I can totally see it now. Great observation!

 

[AstroMelly]

Really? That’s an interesting proposition. If I see it again I will try and grab some more pics to see if it is growing. It does look strikingly similar to the image in the link though.

 

[AstroMelly]

Can a starfish arm survive without the central mouth? This thing was quite happy and moving around.

 

[taricha]

Can a starfish arm survive without the central mouth? This thing was quite happy and moving around.

some can indeed regrow/become healthy individuals from a single arm.

 

[AstroMelly]

some can indeed regrow/become healthy individuals from a single arm.

I’ll be sure to keep an eye out - if I see it again and it appears to have changed I’ll try and grab a few pics!

Thanks for your input!

 

[ISpeakForTheSeas]

Just to add, yeah, that looks like an Aquilonastra (known in the hobby as Asterina) starfish leg; the reproduce through fission, sometimes just from a single leg. In your pic, the red part is the central disk piece still attached to the leg, and the other end is the tip of the leg.

 

[AstroMelly]

Just to add, yeah, that looks like an Aquilonastra (known in the hobby as Asterina) starfish leg; the reproduce through fission, sometimes just from a single leg. In your pic, the red part is the central disk piece still attached to the leg, and the other end is the tip of the leg.

Hi @ISpeakForTheSeas

We have a load of asterina stars, in fact we got a harlequin shrimp to try and keep the numbers down but I’ve never seen one as big as this - especially not a single leg as big as this so I’m stunned by that news! I know there are many species of asterina and I’ve seen at least two seemingly distinct colour variants but size wise they are usually half the size of this guy at most.

We did have a sand sifting star for about 6 months but sadly he faded away but that was probably about 2 years since. The patterning on the top of this creature did remind me of that starfish. I was wondering if maybe part of it could have survived.

Still an interesting thing to see in the tank I think and thanks for your info!

 

[ISpeakForTheSeas]

Edit: Wrong place *Facepalm*

Yeah, Aquilonastra sizes can vary drastically, with some species getting quite large.
Edit 2 (now that I'm not rushing to correct my mistake post, haha): Yeah, definitely not the sand-sifting starfish unfortunately. With regards to Aquilonastra size:

It depends on the species - some of them can get up to almost 4" (~10cm). Most common ones in the hobby are tiny, but there are actually a number of Aquilonastra species that get larger than 2cm.