I find sea jellies mesmerizing to watch - from a safe distance!   

Can you imagine drifting along in an ocean current like a sea jelly?

Your tentacles trail along behind you. Your body pulses like a heartbeat, flattening and then rounding again into a bell shape. The warm saltwater envelopes you, muffling the cries of gulls and the laughter of beach-goers.

If you can imagine all that, you're one up on the jellies. They don't have brains - at least not the kind most animals do. Jellies have a network of nerve cells that let them feel the warmth of the sun or the touch of an animal.

They also don't have hearts - just ask anyone who's been stung by one!