Spinners are the dying form the dun(the adult mayfly). They have done their duty to mayflies and nature and are on their way out(dying) in the 24-48hours that they are out of the water. (remember 363 days to develop from egg to an adult)..Adult mayflies don't even have mouth parts.

A SPENT spinner (seriously) is a dead, lifeless form of the mayfly that has spent the past two days in life's activities that perpetuate the species and keeps us in a constant state of craziness for a month consentrating on "the hatch"......It is generally an easy lifeform to recognize on the water as a small cigarette can seen in one of the claws on the spent spinners! HA! If I need to explain anything more in detail, go ask your parents!

Cripples are as previously described. Those mayflies that for some reason don't make it out of the shuck (nymphal exoskeleton) or their wings don't develop for some unknown reason. The crippple and the emergers are the easiest life stages for the trout to eat during a hatch. Normally a sip rise instead of a big splashing(better hurry and eat this one) rise.