The fattest one's I've found (and almost always on the pale pink side) are in the middle of some just finished food area, which makes sense I guess heh.

Any worms I've found in the older VC which has less food and moisture can be long, sometimes very long, but always much slimmer and darker red.

Ok. Remember for all I know I am raising baby snakes in Southern New England.

I think I do not have earthworms because those are longer and fatter and are found when I spade the earth. They also appear dryer.

I think I do not have nightcrawlers because those are huge, and scary and lay upon the surface at night and need to be caught by flashlight.

I think I do have some type of redwiggler because I got them from a compost heap. The compost heap may of been seeded with a tiny amount of dying worms from a library vermicompost workship for school children. They seemed to exhibit yellow tail tips.

Some live inside two 4 gallon skimpy bottom pails. At some point I crushed up a bunch of biochar as much as I could without risk of breathing any dust. This was put into the bin. It was fun to do. I hoped the biochar would get dirty or charged with organic life. It should also provide surface area for weebeasties to multiply to feed the worms.

The worms did seem to take on a color change, primarily a black line down the middle. Presumabley this was the food pathway. It was not clear. Strangely, even though the biochar has all passed through the system one would think a generation of worms ago the worms still seem to retain this darkness. The biochar and the darkness line, not a deeper red, seemed to match just when the biochar was added.

Additionaly, your mention of worm sizes and changes in relation to the enviornment reminds me of some old online information or maybe misinformation. The story went something like a college student in a dorm room grew worms but because he raised them in such a confined? space they remained small. Whenever he needed to fill an order to sell he gave the needed miniture sized worms more food and space and he quickly could fill the orders he had. Reading the days worth of material about this on the web could no doubt lead one to insanity. To save time I described it just above. I think what you are acurately describing happening in your bins is similar to what the college student had also observed and had as his "business plan". I'm just going for the "big, fat, juicy ones" and trying to avoid the long, skinny ones that sometimes fall apart when picked up. I'm guessing you do too.

"When I first collected my red wigglers from a neighbor's leaf compost bin they were less than two inches long and a dark red color. Today the mature worms are typically twice that size, and more of a pinkish cream color, especially in the outdoor manure compost bins, where I have seen some nearly three times the size of the original strain." It is like the pink ones are living in nirvana or worm heaven. They have the perfect food and enviornment and have no need to toughen up and forage in the dark forest. They are sheltered, fast growing, the 1920's flappers of their day, no hardtimes. As opposed to us old, wrinkled travelers.