WTH is my brittle star doing?

[c est ma]

So, I was messing around, looking for things close to the front glass of the tank to take pics of through my loupe, when I found this brittle star wedged under a rock outcrop that nearly touches the front glass (thus all the diatoms--can't get a Nimble Nano in here). Here are a few shots of it (sorry about the quality--not much depth of field through the loupe):

 

 

 

Then I noticed that it was periodically pulsing!--inflating its central disc and puffing out dorsally, in one spot or another, rapidly. It is rather hard to see in stills, but here's an image that captures the puffing out of one part of the disc:

 

 

Followed by a return to normal a few seconds later:

 

 

And another still that shows some puffing:

 

 

And the subsequent normal state a few seconds later:

 

 

I was actually able to get some vids through my loupe that show the phenomenon much better. Below the following links, I've noted where in the 40-seconds the action happens. Afterward there's not much to see, except the occasional twitch of a tube foot. I'd crop these if I had the right program!

 

http://video.google.com/videoplay?docid=-5...81363&hl=en

( action in 1st 5 seconds)

 

http://video.google.com/videoplay?docid=-4880223194332132290

(action @ 13 seconds)

 

http://video.google.com/videoplay?docid=5625037100401991682

(action about 4 seconds into vid)

 

Anybody ever observe this before? Any idea what's going on?

 

--Diane

[Mudfish]

Fantastic, as always. Your work is a real asset here, Diane - I really appreciate it!

 

Are these shots of one of the same tiny brittle stars as before, or of a larger one?

[Ryanhdd]

that is crazy weird looking. I wonder why it does this.

[mascencerro]

maybe its gotta poop?

[yardboy]

Cool Diane. I've never been able to observe my brittle stars that close up. Usually all I can see are their legs flailing around in the current. Could that behavior be associated with them spawning?

[c est ma]

Fantastic, as always. Your work is a real asset here, Diane - I really appreciate it!

 

Are these shots of one of the same tiny brittle stars as before, or of a larger one?

 

Thank you! This is one of same species that I've posted spawning threads about. While not as small as the teeny white hitcher brittles, these do not get too big...I'd say an average adult might have a central disc ~ 0.5cm in diameter, and legs ~ 2-3 cm long (thus, a max. legspan of 6.5cm or so...). (Good nano size!)

 

 

maybe its gotta poop?

 

Maybe. For all my observation, I have never seen one poop. Many times, however, I have seen them pass little lumps of poop out of their crevices in the rock, all the way down the length of one leg, conveyor belt-style, until it reaches the tip and falls of...They produce copious feces--like some snails do...

 

I watched this particular star for quite a while. It remained in the same place, only shifting slightly back and forth. And, seeing as how I usually got one (and only one) "inflation event" for each little 40 second vid I took, I guess I could say that these events were happening about once every 40 seconds or so...I did not see any feces emerge...

 

Personally, I was surprised to see how flexible the aboral disc surface appears to be!

 

Cool Diane. I've never been able to observe my brittle stars that close up. Usually all I can see are their legs flailing around in the current. Could that behavior be associated with them spawning?

 

Well, it resembles nothing I've seen in my two times witnessing spawning events. But since I can't watch the tank 24 hrs a day, I can't say that they didn't proceed to spawn after I went to bed...

 

For the moment I don't tend to associate this behavior with either spawning or defecating, but I can't be sure and will have to hope for future, more telling observations, I guess. (Guess I should try a little research, too!)

 

Thanks for the comments, everybody.

 

--Diane

[CONSTANTNE]

Thats interesting. I would say maybe spawning but who knows. Maybe someone else would know