My brittle star got large enough to wrap its tentacles around a new baby Luther goby, twice, and I removed the goby, took it back to LFS. They were kind enough to put it into a seven gallon tank and awaited the brittle star to be brought in. They do not injure or eat corals, Just weakened and maybe not even weakened fish which are small enough. The goby was very active two days after the fact in the seven gallon.
As to the reasons the earths reefs are in jeopardy are numerous;: from the dusts carrying molds from the African farm lands{their wild animal areas are being turned into farmlands due to the ever increasing need to feed their people} to a rise in the earths temperature to pollutants directly put there by mankind, and there are many more reasons, basically we are to blame for the damage of much of it. Global warming is not a myth. I think of all the lotions to prevent sunburn and incur suntanning. Think what millions of bottles of that goes into the oceans every year. Just keep thinking and you will be very saddened. Maybe some one with more knowledge than me will write in something positive that is benefitting the reef systems worldwide! Vote wisely!!!!