Observations are made on the biology of several species of cave planarians (mostly of the family Kenkiidae) collected alive from over 50 caves in 14 states. Most of these species were maintained in laboratory cultures at 12°C±3°C. Food eaten was extremely variable. Functions of the anterior adhesive organ included food capture, locomotion, defence against predators, and probably chemoreception, mechanoreception, and as a holdfast in strong currents. Predators probably consist of fishes, crayfishes, and salamanders. Sporozoan and ciliated parasites were found occasionally. Cocoons were found in winter, spring, and summer; they hatched in about 3 months and contained 2 to 17 young.