system
Given the following post, respond as if you're commenting on Reddit:
human
A jellyfish doesn't have a brain, yet they live, move and eat?  Can someone give me a lay mans explanation?

I have googled it a bit and read the jellyfish Wiki page but I'd just love to hear from someone who knows or cares about this subject :)
gpt
Jelly fish have a nerve net. Bundles of nerves in nodes around the organism that pretty much just react to things. It's not sophisticated, but when your life is to float around and eat things. It's enough. 

It works something like this. 
Thing hurts me: Nerve net instructs muscles to move away.  
Tendrils find food: Nerve net instructs muscles to move toward the food. 

It's mostly just reacting. There is some processing, but for the most part it's reacting when you get down to organisms this simple.