The organization of motor systems in crayfish has been the subject of multiple studies beginning in the last century, giving as a result a rather accurate picture of the elements and relations conforming this complex structure. However, no such picture is available about the organization responsible of the circadian motor activity after 60 years of studies. We are approaching this problem through the study of the ontogeny of the main characteristics of this rhythm, by both experimental and mathematical techniques. We outline the main features of this study and we formulate the biological hypotheses that we propose as conclusions of this work.