42.7 Thursday, Jan. 5 Swim pacemaker response to bath applied neurotransmitters in the box jellyfish Tripedalia cystophora rhopalium. BIELECKI, Jan*; GARM, Anders; University of Copenhagen; University of Copenhagen firstname.lastname@example.org
Here we present the first physiological evidence of neurotransmitters used in box jellyfish visual processing. Bath applied RFamides have a proven positive effect on photo tactic behavior in cnidarians but until now there has been no physiological evidence of the effect of any types of neurotransmitters. Extracellular electrophysiology was performed on the rhopalial swimming pacemaker of the box jellyfish Tripedalia cystophora and showed a marked decrease in pacemaker output in the presence of bath applied FMRFamide and serotonin-like neurotransmitters. Other neurotransmitter species commonly associated with cnidarians (taurine, GABA, acetylcholine, glycine and glutamate) had no detectable effect. The inhibitory effect on swim pacemaker cells observed in this work is seemingly in direct contradiction to the positive photo taxis behavioral studies performed on other cnidarians, however, a decrease in pacemaker frequency is not directly correlated to negative photo taxis, but is rather an indication of swimming strategy in the box jellyfish; turning around the passive side of the bell. An inhibitory signal on one side of the bell would thus cause the animal to turn around that axis. This effect can be correlated to new biomechanical research on box jellyfish bell contractions to explain the positive photo taxis observed in previous studies.