Interesting. My father bred living tubifex in the garage refrigerator for our aquariums. The manner in which you collect them at feeding time is slightly unnerving - you feel hundreds of individual worms brush gently as you grasp within their mass, and what better way to trigger xenophobia than to exacerbate any existing paranoia. The more alarming part is that you dip your naked fingers into cold water, then down into the perceptibly moving mass, transparent as the balling worms retract from your heat and taste. It doesn't really help to remind yourself that these are entirely harmless animals and probably a good source of disgusting protein. It will never again help because I've only recently gotten over the ancient Korean silkworm snack food industry's existence, let alone entire possible culinary adventures inducing second-servings of maggot souffle or wolf spider casserole. The effort we had to go through to keep their water oxygenated at intervals was obviously something they regulate in the wild by forming a stiff colony sac seen in the video. It's perhaps one of the most disgusting things I've ever thought about sticking my hand into, next to Vernon, of course. (Btw, thanks for the adobo recipe - delicious cold sandwiched). I imagine that the sac is composed of their own dead colonists and the permeability may effect oxygenation, reproduction rates and timing. They do not like light. Refrigerated life is a strange thing..