The spectacle of thousands of jellyfish at Hobart's waterfront dock may be breathtaking, but a leading scientist has warned their presence indicates something in the environment is out of balance.

The life cycle of jellyfish can seem almost otherworldly ... The medusa stage varies in duration among species. For example, the moon jellyfish has a relatively short lifespan, living for about ...

Moon jellies, which are found in shallow ... The juvenile then starts the jellyfish’s life cycle all over again. It’s as if a frog, say, were to revert to a tadpole or a butterfly to a ...