Newb question: Urchins and shrimp

[sharuq1]

I have one of those urchins that looks like a green/orange/white pincushion (I don't know the name-same as the one here: http://www.canreef.com/vbulletin/showthread.php?t=33789
Anyway, I ordered a fire shrimp from hidden reef and I am not sure whether to put him in my bc or in the new 8g, which is currently the home for the urchin.

Concerns:

**Will the urchin eat him/grab him??

**BC 14-have been noticing some disapearing hermit crabs in the tank and wondering if it is due to a hitchiker crab that I can't find but have seen sheddings of.....

**On the other hand the 14g tank has been running since April, the 8g tank has only been up a month.

I really love fire shrimps and I don't want my new one to be eaten