Ready for this jelly?

NO BRAINER: Jellyfish are simple creatures.

- Here, MEG JORSH

They're made up of 95% water, with no brains, hearts or (often) eyes to complicate matters.

They do have a mouth, though - it doubles as an anus - and a basic nervous system that lets them smell, detect light and respond to danger.

ENDLESS POSSIBILITIES: Your average jellyfish is here for a good time, not for a long time. Some only live for a few hours, while larger species can stick around more than a year.

Then there's the Turritopsis dohrnii, known as the "immortal jellyfish", which can technically live forever by reverting to a juvenile form.

WHAT'S IN A NAME? Jellyfish... are not fish. They're members of the snappily named cnidarian family, along with corals and sea anemones. They come trailing tentacles used to sting prey via cells called cnidocytes, which explode when stimulated.