THE EFFECTS OF COOLING CONDITIONS ON THE BEHAVIOR OF OXYTRICHA-BIFARIA (CILIOPHORA HYPOTRICHIDA)

The new analytic approach to the behavior of ciliates represented by t he ethogram was used to study the locomotion of Oxytricha bifaria at d ifferent temperatures, isotropically applied according to a new protoc ol. It was shown that under these experimental conditions as the tempe rature dropped in stages from 24 degrees C to 19 degrees C to 14 degre es C to 9 degrees C, the general mobility of experimental populations decreased, as indicated by 1) the decreasing percentage of mobile orga nisms, 2) their decreasing velocity, 3) their prolonged backward creep ing, and 4) the increasing length of their immobilization periods. The ethogram more particularly revealed that decreasing temperatures indu ced 1) the appearance of rightward arcs (several of them being travell ed by specimens sliding on the substrate), 2) the reduction of both th e radius and the velocity along the normal leftward arcs (A(-)) and th e segments (S), and 3) the symmetric increase of both the central angl e and the duration of the A and S. These changes were reversibly induc ed: they disappeared when the temperature returned to 24 degrees C. Mo reover, a new behavioral pattern, the prolonged Side Stepping Reaction , was found. Helicoidal swimming, occurring only at 14 degrees C, was analyzed. Among all of the behavioral parameters, nine were shown to c hange dramatically between 14 degrees C and 9 degrees C, demonstrating that the linear cooling of the populations induced clear non-linear e ffects.