A brain is needed to keep living, right? Well, not necessarily! Some animals have no brain, yet manage to survive just fine.
Instead of a brain, some creatures have clusters of nerve cells called ganglia that help direct traffic in their bodies. But surprisingly, most of the animals we'll be looking at don’t even have ganglia to help them out.
1. Sea Star
Although they're without a brain or ganglia, sea stars do have some sense of smell, touch and sight. Each of the arms can sense the world around it.
If one of the arms smells something good to eat, it cuts off power to the other arms and begins pulling the whole creature towards the food.