Do jellyfish feel pain?

If jellyfish have no heart and no brain, are they still alive and are they suitable for vegetarians, see below

• and can people "live" like jellyfish do? and does it mean jellyfish don't feel the pain and killing and eating them is not a sin?

• Answer:

  Yes, jellyfish are alive. They sense their surroundings. They breathe (require oxygen). They are capable of movement. They grow. They require food. They have to expel waste. They reproduce. These are the seven characteristics of life, taught in 1st year secondary school science. Jellyfish have nerves, so they would feel pain. They are considered animals, because they have to ingest their food. Therefore, killing and eating one would negate vegetarianism. And no, people cannot live like jellyfish, because our bodies are not adapted that way.