How do jellyfish know to eat if they have no brain?

Jellyfish do have a nervous system, but it is very simple and does not include a brain. Instead, they have a network of nerves that are spread throughout their body. These nerves sense changes in the environment, such as the presence of food or danger. When the nerves sense food, they send a signal to the jellyfish's muscles, which then contract and move the jellyfish towards the food.

As they lack a centralized brain, jellyfish cannot make decisions or learn from experience. Instead, they rely on simple reflexes to respond to their environment.