Missing Heads on Coco Worm

[Vayder1]

I have a coco worm in my tank I got from Will back in November. I woke up one morning to find that one of the heads had been "lopped off" :( and just floating in the tank. A couple weeks later and now the second head is now floating at the bottom of the tank. :mad:
Questions: Do they have predators? (I have 2 emerald crabs)
I feed my Tank DT's a few times a week is this enough or do they require something extra?

Here is my water perameters
Nitrates: 0
Calcium 370
Salt .23
PH 8.4

[GoTakuF1]

I've had an angel fish that would trie to nip at the crown but the worm is usually quick to retract before any damage can be done. So I don't think your crabs can do any better (unless they're small enough to fall inside the tube!). Coco worms usually release their crowns due to poor water quality or sudden changes in water chemistry. If you keep your water quality stable, it should grow the crown back within a couple of weeks.

[Vayder1]

Hmm, I kinda thought that any predator might have a hard time getting to it. Occasionaly my PH gets low and I double dose with B-Ionic. Could that be the problem?

[GoTakuF1]

That could very well be the problem. Perhaps you can dose the same amount of B-ionic over a longer period of time to reduce the pH shock.