for the same reason we do , a brain to move and think, nevres so that if you scuff your knee or hurt yourself your nervous system delivers a message to your brain telling you you have hurt yourself
This may be a transposition of the plural noun "nerves" (sensory cells).
no animals have a brain even dinosaurs do
brain brain brain
Both animals and humans do have reward centers in the brain. Both humans and animals feel happy or pleasure when the reward centers of the brain are stimulated.
cockroaches
no
My brain lets me speak and form sentences.
Some animals, such as those in the genus Hydra, don't actually have a brain per se, making it difficult to answer.
No, not every animal needs a brain. A jellyfish does not have a brain, it barely has any organs.
Microscopic animals
No.
A jellyfish & a starfish A Jellyfish has no brain & no heart A starfish has no brain & no blood