Brittle Sea Star baby?

[keltharos]

I tried doing some research on this topic, but was unable to find any real information.

I decided to check out my reef tank on Friday night, and saw that my bubble tip brittle sea star was out and about. I took out the good old flashlight and started looking for bristleworms, when I noticed that the sea star had a baby hanging on it's back. I've only seen the one so far.

Do these commonly reproduce in aquariums? Are they egg layers, or do they reproduce via fission? I've had the sea star for about 4 months or so, and just noticed this for the first time. Any special considerations I should take to keep this new guy happy and healthy? It seems to just drape it's arms over the parent and grab food bits as they are going towards the mouth, so it looks like feeding isn't a problem.

Thanks for the help!

 

[captbunzo]

I'd say that care will be identical to that of the parent. And that you are very lucky indeed! I do not believe that brittle star reproduction is common at all in captive systems.

Pics, man! We need pics!!!

 

[keltharos]

I meant to add to my original post that pictures will be on the way shortly! I don't currently have a digital camera (shame on me..) but I am borrowing one tonight.

Thanks for the info! I'm excited.

 

[Guy]

More than likely the "baby" Brittle Star is an adult of a small species of Starfish. They are very common hitchhikers and will reproduce when conditions are good.

 

[keltharos]

I have seen many of the smaller, white star fish that climb the glass and rockwork, but this one is definitely different. It is basically identical to the larger brittle sea star, except it doesn't appear to have the "bubble tips." I actually almost missed it, because it sits on the larger one's back and is the same coloration (red-brown with the "cross pattern"). It has the long, serpent-like arms as well.

I will get pictures tonight though hopefully, and that may clear things up.

 

[captbunzo]

Keep us updated over the next several months!

 

[keltharos]

Just an update: I snapped a few photos last night, but I'm not satisfied with the results so I'm going to try again tonight. Hopefully I'll have some nice pics tomorrow!

Also, I looked a little closer and it appears the "baby" may have the beginnings of bubble-tips after all. I can't tell for sure though because it constantly sits on the back of the larger one, and there are a lot of "hairy" appendages moving around. I estimate it is approximately the diameter of a soda can, with arms stretched out. The larger one is enormous, so its hard to say how big that one is.

 

[ophiuroid]

It is not uncommon in this genus - most likely and Ophiomastix (probably Ophiomastix annulosa but note that many online pictures will be wrong). It is a species that we have fairly recently learned is a brooder and growth may be relatively slow...prior to emerging the juvenile may like in the genital bursae of the parent. How long have you had this animal? It is possible that it, well, for lack of a better term "became pregnant" in the wild and has been brooding the juvenile for some time.

Also notable is that there are some juveniles that are effectively "brood parasites" meaning they appear in this area, hanging onto an adult of another species. They are probably doing little harm all in all.

That being said the very common small white hitch hiker Amphipholis squamata is a simulatenous hermaphrodite and also a brooding species.

In general brittlestars are broadcast spawners with separate sexes. Very few reproduce by fission or splitting, though again, another common hitch hiker in our tanks does...the six armed Ophiactis.

 

[keltharos]

After many nights of diligently standing watch over my tank, I was finally able to snap a somewhat decent picture of the adult sea star with the juvenile. (Please forgive my amateur photo, this was my first attempt at taking pics of my tank and I had to drastically reduce the image sizes to be able to upload them to the Photo Gallery). The sea star is camera shy, but obviously the crab is not (as you can see from the first photo.)

This picture was taken during a 5 day period, approximately the week of 1/8/2006. The close-up is a magnified version of the same photo, focusing on the juvenile sea star.

Feedback welcome! I will monitor it's growth over the next several months, and will track it's progress with upcoming photos.

 

[ophiuroid]

That is an outstanding photo! Both creatures are Ophiomastix annulosa as suspected. Very very nice picture! Thanks for sharing!

How long have you had this animal?

 

[captbunzo]

Thank you for posting the pictures. They are wonderful!

 

[keltharos]

Thanks for the comments! I thought the pictures didn't really do it justice, but they must not have been that bad after all. I will be sure to continue checking back in periodically, and hopefully I have even better pictures next time (I've had opportunities when it fully emerged from the rockwork, but didn't have a camera handy at the time).

I just called my friend who owns the store I bought it from, and I purchased it on 8/15/05.

It sounds like the development stage is slow, but do you know approx. how long they stay attached to the host "parent" before detaching themselves? I know in my particular case it will be difficult at best to figure out how long it's been growing in it's current stage of life, but as I said before, I didn't notice the juvenile when I purchased the adult so it must have been very small.

Thanks again for your feedback! I have found this whole discovery to be very fascinating and enlightening!

 

[ophiuroid]

I wish I could tell you how long it will stay there. I suspect no one really knows so I would MUCH appreciate you letting us know! The juvenile at the time you purchased it may very well have been inside what are called the genital bursae of the adults. If you ever see them "on their back" there are two slits in each interradius (area between each arms). These are the genital bursae, though they are also used in respiration. It is a typical place for some of these guys to brood, almost like a baby kangaroo