Chaotic or periodic variation? Looking at Crustacea hearts.

A simple relationship between the burst length of the trigger neurons of the Crustacea cardiac ganglion and the length of the heartbeat, is shown to lead to chaotic heart rate. Interestingly, the same type of relationship is also capable of generating complex periodic deviations from steady heart rhythm. Real Crustacea hearts are not likely to follow strictly either suite. The general procedure of analysis, however, is applicable to various biological rhythms, and explains how variation around the mean value can occasionally show up as intricate patterns which repeat themselves with accuracy.