Jellyfish return to Budapest Zoo after 50 years

After 50 years, jellyfish are living again in a pool in the Budapest Zoo, reports ma.hu.

The body of a jellyfish is 95 percent water, making it very vulnerable, and extremely difficult to keep. Even rising air bubbles can kill them by tearing their tissues, while being stuck in a corner of the aquarium can be fatal. The water therefore cannot contain any dangerous objects, and cannot have any corners that result in stagnation of the water. The aquarium also has to be equipped with a special machine which keeps the water in constant rotation allowing the jellyfish to flow with the water passively. This artificial flow is stopped from time to time to allow younger specimens swim actively to train their muscles and toughen their fragile bodies.

The other difficulty of keeping jellyfish is that they consume live plankton, small crabs and similar tiny organisms which are abundant in their natural environment but cannot be kept so densely in a pool tank, so the animals have to be fed one by one. They also need very good water quality, low temperature and lighting. Their reproduction is interesting as well as they have both sexual and asexual reproductive stages.

The jellyfish type kept in the Budapest Zoo is the Aurelia aurita or Moon Jellyfish.

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