Im so sorry about your spider... death is never easy. When one of my beloved pets dies, i always feel like a part of me dies with them. Its sounds dramatic but thats how it feels. My animals are everything to me and they mean more than most of the people in my life.
I do very much think you should send Apollo in to figure out the cause of death, then maybe you can save the other befores its too late...
Again im sorry for your loss, my thoughts are with you