Comb Jellies might get to 6 inches. The Lion's Mane Jellyfish is the largest reaching maximum lengths of 24 inches. What you don't see The aquarium's jellyfish have a special diet of brine shrimp, which keepers must hatch. Each day they open enough cans of shrimp eggs to feed the jellyfish and place the eggs in water. Within 18 to 24 hours the eggs hatch.
Keepers add a special vitamin food, which is eaten by the shrimp.
One day later they're ready to be fed to the jellyfish, and the process begins all over again. Sea Nettles are known to eat Comb Jellyfishes, which eat oyster larvae in large quantities. Thus, those in the oyster industry appreciate Sea Nettles. It is also known to be cannibalistic and eat oyster larvae. The Elegant Jelly uses rapid pulsing and slow drifting motions to swim at depths of 200-300 feet.