Modeling experiments on pacemaker interactions in scyphomedusae

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Rodney T. Hayward (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/
Advisor
Richard Satterlie

Abstract: 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 found in the marginal rhopalia, which are 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 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 artificial pacemaker networks created from pacemaker ablation experiments. In all species, with increasing pacemaker number, the frequency and regularity of swimming increased. Integrate and fire pacemaker models were used to determine if the pacemaker networks of three species of scyphomedusae were resetting, independent, or semi-independent. It is concluded that Chrysaora quinquecirrha and Stomolophus meleagris have a resetting pacemaker networks. In contrast, Aurelia aurita has a semi-independent pacemaker network and the ephyra of Aurelia aurita has resetting pacemaker network.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Science
Language: English
Date: 2009
Keywords
Invertebrates--Research, Scyphozoa--Research, Jellyfishes--Research
Subjects
Jellyfishes -- Research
Invertebrates -- Research
Scyphozoa -- Research