Since we implemented our new cleaning/maintenance protocols, our juvenile moon jellyfish (in small tanks) have shown significant improvements in their structure and development. The diameter of the bells increased, and curvature has decreased (signs of better health). Previously, there was little activity in these individuals, but now 87% of the jellyfish have resumed pulsation and at great frequency. We are carefully monitoring and feeding them more frequently to encourage faster growth until they are big enough to be moved to the large Kreisel tank.
As with previous months, there have been recent challenges with the jellyfish. Two of the juvenile medusae detached their oral arms from their bells; we thought this was irreversible, but we were pleased to see that one of the individuals regrew its oral arms and completed perfect symmetry again, one month later. This coincides with current literature and scientific observations that Aurelia aurita can regenerate to full capacity, given optimum conditions and presence of vital organs.
Whilst the Aurelia medusae in the main aquarium appear healthy and are growing at a good rate, the increased competition for Artemia food means the Marbled jellyfish individual has actually shrunk in size (we have now removed it, for closer observation and direct feeding).
After relocating the juvenile medusae from the Fish Lab tanks to our large Kreisel tank, we attempted to run on an open system (with filtered water pumped in from the ocean). However, the jellyfish started to display signs of stress (increased bell concavity, retracted oral arms) and therefore the tank was retreated to a closed system, with daily flushing and water renewal. Growth of Aurelia aurita is not always linear, and they are able to reverse their lifecycle if the environment proves unsuitable for sustained positive growth. They do not appear to adapt well and environmental conditioning has not proven an easy feat, however, these individuals precede dinosaurs and therefore this unique method of adaptation and sustaining life has no doubt proven efficient in their longevity and persistence in the dynamic ocean environment.
During July, the Aurelia grew an average of 60mm around the margin, whereas during August this reduced to just an 8mm increase. We currently have a total of 20 good-sized jellyfish featured in the Kriesel aquarium, and a further 11 individuals are being grown on in the Fish Lab until they reach the required size.