My local place found a Crinoid feather star as a hitchhiker in one of their shipments. Since I have a non-photosynthetic aquarium and dose phytoplankton, they decided my tank would be the best (local) home for it. I also think it will be interesting to see the behavior of my Crinoid squat lobster Allogalathea elegans with this Crinoid feather star. (My Galathea inflata is in the other tank to prevent squat lobster disputes...)
I've had the star for a few days now, and it is very cryptic. It hangs upside down under some of my branch rock in the exact spot where I placed it after acclimation (near the squat lobster). I'm considering getting a small lunar light so I can view it when it is most active at night. I've seen a couple arms come out during feeding time, but that's all I've seen of it. My squat lobster usually hangs out in a Gorgonian, but I haven't seen it since I put the feather star in. Maybe it's under there with the Crinoid.
To prepare for the addition of this sea star, I made sure to cover my pump intakes with fine mesh bags. I wouldn't want it getting the tips of its arms chopped off when it finds a cozy spot too close to the pump's impeller.
The other non-photosynthetic tank inhabitants are doing very well (as far as I know.) My hard tube coco worm Protula bispiralis has grown about two full inches since I got it a couple months ago! My sea cucumber Pentacta anceps still extends and "licks" its feeding arms when I dose phytoplankton. And of course, the seahorses are doing well.
I will let you all know how the Crinoid feather star does. They are notoriously impossible to keep in home aquariums and usually starve to death slowly. If you've had success with this species and kept it alive longer than 6 months, please give me some advice. Otherwise, just wish me luck.
Also, check out Echinoblog's new post about Crinoid locomotion and Charles Messing's blog about The Crinoid Feeding Mechanism.