Structure and function of the locomotory system of the Scyphomedusa Cyanea capillata

The structure and function of the locomotory system of the jellyfish Cyanea capillata L. were studied by dissection, histology, photography and cinematography. The swimming muscle consists of a highly-folded subeptithelial-stratum of striated fibrils arranged on larger mesogleal folds. A proximal coronal muscle divided into 16 fields is anchored to the umbrella proper along the radial septa separating the fields. Sixteen distal couples of radial muscles are anchored to peripheral mesogleal buttresses. On the lower surface of the umbrellar mesoglea is a series of 16 deep radial grooves confluent with a coronal groove. These grooves (joints) are anchored to the exumbrellar surface of the umbrella by rows of large branching mesogleal fibers. During contraction, the muscles cause a folding of the umbrella around the system of joints. Sequences of swimming and turning were analyzed, and it was concluded that this swimming mechanism is much less refined than the hydrozoan mechanism.