Question: If jellyfish have no brain how do they know how to swim?

Anna Middleton answered on 19 Mar 2014:

Hi littleewok
This is a really good question. Jellyfish aren’t actually fish, they are ‘plankton’. They have nerves that respond to their needs – the nerves pick up when food is around and they eat it. It’s a bit like the plants that can eat flies, they don’t have a brain either, but they are a set of reflexes that respond automatically to things. It’s all an automatic process there is no ‘thinking’ involved.