Meeting Abstract

P3.69  Jan. 6  Modeling Experiments on Pacemaker Interactions in Scyphomedusae HAYWARD, R.T.*; SATTERLIE, R.A.; NOLAN, T.G.; University of North Carolina Wilmington; University of North Carolina Wilmington; State University of New York rth2850@uncw.edu

Scyphozoan jellyfish are free-swimming gelatinous organisms whose nervous system includes a motor nerve net that controls swimming. Swim contractions originate in a network of distributed pacemakers. Swim pacemakers are found in the rhopalia located around the margin of the bell. Many scyphozoan jellyfish have eight rhopalia, while others have sixteen or more. At any one time, the fastest pacemaker controls the motor output of the swim system. The activity of a single pacemaker is irregular, however, by linking multiple irregular pacemakers the swim system exhibits regular contractions. Thus, multiple pacemakers are believed to increase the frequency and regularity of swim contractions. Pacemaker interactions in Chrysaora quinquecirrha, Stomolophus meleagris, Aurelia aurita, and the ephyra of Aurelia aurita were investigated, using an artificial neural network created from pacemaker ablation experiments. In all species, with increasing pacemaker number, the frequency and regularity of swimming increased. The model is being used to determine if the pacemaker networks of three species of scyphomedusae are independent, semi-independent, or resetting.