I know this post is really old, but people keep reading it and there aren't that many responses... so to all future readers, here goes nothing.
Chocolate Chip starfish (and any other healthy starfish) are VERY active. I personally watched a chocolate chip star detach from a glass tank wall, fall onto a FISH, wrap its apendages (very quickly) around the fish (which was healthy and part of my collection!) and procede to ingest the entire fish in less than 36 hours!
Sand Sifter Stars are also very cool to watch, they will dissapear underneath the sandy substrate and reappear minutes, hours, or days later on the other side of the tank!
Starfish are amazing creatures. Color, Activity, and Feeding patterns are all tell-tale signs of their health. There are as many kinds of starfish as there are inverts in the
SW arena... in my option they are a must for any SW tank, no matter how big or small!
Hope you enjoy the info, have a great day!