Swimming control in a cubomedusan jellyfish

Abstract

Although it has been established that swimming in scyphozoans is under control of rhopalial pacemakers and an associated subumbrellar nerve-net^1–3, little is known about this control at the cellular level. There is some doubt whether scyphozoan neurones have all-or-none action potentials^3–6. Here we show that subumbrellar neurones of the sea wasp Carybdea rastonii Haacke (Class Scyphozoa, Order Cubomedusae) propagate such action potentials, and that activity in these neurones originates in the rhopalial pacemakers and produces a contraction of the swimming musculature. The neurophysiology of swimming has not previously been studied in this order.