green star brittle

[kjswift]

Does anyone have a green star brittle? If so, just wondering about food and behavior. Thanks

[DeletedAccount]

Will eat anything and everything - small fish, other stars - any food that is for carnivores he will readily take. They are EXCELLENT trappers! Beware of these guys!

[Markster]

I have had one for a few weeks now and he doesn't do much. Stays in front of the tank and tangles underneath the brain I have on a rock. Hasn't move around the tank a whole lot, especially at night when the moonlights are on. I drop down shrimp pellets and he eats them right up.

[matt]

I'm pretty sure they're ravenous sand bed predators. I'm not sure of the behavior of specific species (is that a redundant redundancy) but most stars of any size will wipe out a deep sand bed, so I've read. If you're trying to keep a DSB probably you should not keep this animal.

[prof]

I have one. Looks really cool but I understand that they are ravenous carnivores. Any one have a good trigger tank that could use a cool star?

Dave

[GaryP]

I've always heard that they will catch fish but have kept one for years and never had one catch a fish, at least that I know of. I've always dropped a table shrip to mine about twice a week. They do grow quickly. I like having them in a tank because I know they do a good job at cleaning up left over food or any fish that die and are not recoverable. They do grow very quickly.

[JimD]

Keep an eye out for the ambush stature, the main body elevated above the sandbed, thats how they catch food in the wild, if left unfed in the aquarium, they can and will predate on whatever they can catch in their trap. The key to keeping one of these is regular direct feeding.

[GaryP]

Jim, the only time I ever see my brittle star is when I feed him. He'll stick out an arm to lasso whatever I feed him and then drag it back it into the live rock. I rarely see his central disk, just an arm or two sticking out.

[kaiser]

I got a rid of mine after he ate 2 cleaner shrimp.

[brewercm]

Only thing I've seen mine eat that ticked me off was he got hold of a small frag of xenia that he ripped off the rock it was banded too. Not sure if he ate it and kept it or not. Other than that he comes out at feeding time, also have had it for about 4 years now. I believe mine is the green serpent though, could be a brittle but I've seen them listed as both on some pages I've looked at.

[JimD]

Gary,
What you decribe is what Im talking about concerning these things, well fed is the key, try not feeding it for a couple of weeks and get back to me. lol NOT! BTW, Ive not heard of many problems concerning the browns, as Josh noted, its the green brittle star that could wreak havok, green serpants dont have spines but should still be concidered "opportunistic"

[matt]

I think the real concern is if you have a deep sand bed with lots of critters to process organic wastes. The stars will decimate this population, rendering your sand bed basically non functioning. At least that's what I've read. In a system with a DSB, it's the animals that live in it that make it work. Most of these animals are never, or rarely, seen. Worms, micro fauna, etc...

[GaryP]

Correct me if I'm wrong here but what makes a DSB work is the bacterial populations that exist at decreasing oxygen levels as you progress downwards through the bed. What you may be referring to are the critters that keep the DSB stirred up and alllow for water to migrate through the DSB.

[matt]

Actually, that's part of what makes a sand bed work, but it's the critters in the sand bed that keep the bacterial population stable. They do this by A) cleaning the surfaces of the sand and providing habitat for the bacteria, B) eating a lot of bacteria; this seems counter intuitive, but it's the constant growth and reproduction of bacteria that processes nitrogen compounds. They also do facilitate water movement through the sand. They also consume all sorts of organic waste products, and produce larvae which is food for many tank inhabitants. Basically, it's the micro fauna which allows the sand bed to act as a live habitat for waste processing in general. So when you have an animal that's predatory on these critters, the bacteria can't function as needed.

At least that's the gist of what I've read by Shimek, who seems to be a real authority on deep sand beds. I know that since I removed most of the hermits and the coral banded shrimp from my tank, there was a pretty strong reduction in cyano- in fact, I haven't noticed any cyano at all in my current system, despite a relatively low ph (calcium reactor) and LOTS of feeding. In my previous tank, which had lots of hermits and the shrimp in question, I had constant battles with cyano, despite a very high ph (KW) and very strong water movement. (about 2000gph+ in a 45 breeder) I do notice a huge population of worms and such; this also may be partially due to using bio-assay salt, which apparently has lower heavy metal content and supports a higher larval survival than IO. That was another Shimek study.

[rocketeer]

My green brittle star doesn't seem interested in the sand at all. He's about 10 inches across. Are we confusing sand sifting stars with green brittle stars? Is there really a difference?

Also, concerning hermits, will they keep populations of copepods and amphipods low? This concernes me because I would like to keep mandarins. And how do you know if you need more hermits?

Jack

[matt]

I may very well be confusing different types of stars; I've basically avoided adding any stars except for the "micro" brittles that IPSF sells, so I don't know much about specific ones. My guess is that the larger ones would also eat small sand bed animals given the opportunity, but that's just a guess. I think hermits might adversely affect copepods and amphipods, but I'm not sure if this would be mostly do to consuming them, their larvae, or their food supply. I'd think about using this bio-assay salt (okay flamers, start your torches) for keeping a mandarin, because I have really noticed an increase in population of amphipods in my new tank. There are other factors, though, like the absence of hermits.

[GaryP]

Matt,

Thanks for your info. I definitely agree with some of it. A rapidly reproducing bacterial population (log phase growth) will always be more metabolically active than a mature non-dividing population. Can you give me the reference to Shimek's book?

I guess my point is that I have never had my tank threatned by an uncontrolled outbreak of hermit crabs. I can't say the same for hair algae though. Maybe its a matter of the lesser of two evils.

[matt]

Gary;

Most of what I've read by Shimek is his series of articles in reefkeeping magazine (online at reefcentral) and his online articles that are referenced at the top of his "Ask Dr. Ron" board at reefcentral. He has a book out "sand bed secrets" that I've been meaning to buy for a while; but I think there are excerpts from it in some of his online articles. FWIW, I don't think that some hermits will completely destroy a sand bed, particularly if it's fairly deep. It's the sand sifting stars and gobies that are supposedly the most destructive, but I have not kept either of these animals so I'm not too familiar. I'm a big fan of the diadema urchins for algae control, as they are completely algal grazers, to my knowledge.