Answer:
A blood donor is a person who donates blood and a blood recipient is a person who receives donated blood.
Explanation:
Jellyfish are forever but fish ain't.
Plus, jellyfish have those tentacle like things attached to thier body and you might confuse em for octopus for that very reason..
but you should really evade confusing em as an octopus cuz octopus might take it as an insult and the next thing you know will be a Kraken taking your house down.. which is pretty tragic :'(