They've a neurogenic heart, which has rhythmic depolarization that is answerable for initiating heartbeats.[24]: 653 Heartbeats originate in anxious tissue; innervated muscle cells trigger the heart to contract when stimulated by nerve impulses. The cardiac ganglion, which is made of 9 neurons, attaches towards the dorsal wall of the guts. https://stephenr998nev9.wikissl.com/user