I know this has been discussed before but I have several questions.

I have a few compost heaps now and the very first one I introduced some
worms.

An old schoolmate has only just started composting and he has worms already
without introducing. How can that be?

I tipped my dalek type compost bin over in Nov. and spreaded the compost on
top of the soil where my spuds are going to be 2012 with thousands of
stripey worms. I have huge earthworms even now when I dig down. I am
wondering what happened to the stripeys(origional worms), have they been
eaten? Have they transformed into earthworms?

Baz