Hi,
There is no scientific or biological difference between brittle and serpent stars. This distinction is made in the aquarium trade only. Indeed, fairly closely related species may be separated by this distinction, while completely unrelated forms may be grouped.
The only problems I have heard about stem from the green 'serpent' brittlestar
Ophiarachna incrassata which is sold as a scavenger. Brittlestars are large animals and will not allow themselves to starve to death, so it is unwise to let them simply scavenge for their food. If hungry, a brittlestar can and will catch something to eat. When feeding shrimp (or shrimp pellets) or fish to your other inhabitants, you should spot feed the brittlestar as well. This *should* keep them out of trouble, but they have their own personalities and will sometimes prefer one of your other tank inhabitants. Still, I believe that the number of people who have had brittles eat something in their tank is low when compared to those who have kept these animals without any trouble. If you are going to avoid one, avoid the green serpent (a nice green with white spots on the disk). There is also a greenish one with bands on the arm...this is most likely an
Ophioderma spp.. I have not heard anything bad about them. Others that don't seem to have a bad rap include the mini-brittles in the sand bed or live rock, red serpents, black brittles and a few other grayish/greenish/reddish serpents (generally with banded arms).
IMO, and others agree, the brittlestar is one of the most interesting animals in a home aquarium!
You can find a lot of information about these animals at my site, link below!
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Brittlestars!!
http://home.att.net/~ophiuroid
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