Subject: How do you tell poisonous jellyfish from the non-poisonous variety?

We see a lot of jellyfish on our shores and I have been asked by numerous 
children if all jellyfish sting?, how do you tell a poisonous one from a 
non-poisonous one?, Can dead jellyfish hurt you?(which you already 
answered), Is there a significance to the colors found in the middle (Pink 
or red flower shape in middle)?

Re: How do you tell poisonous jellyfish from the non-poisonous variety?