Question

is there any animal without brain​

Answer 1

Answer:

Scientists have shown that animals as simple as the roundworm C. elegans, with a brain of just 302 neurons, need sleep to survive. Cassiopea has no brain to speak of—just a diffuse “net” of nerve cells distributed across their small, squishy bodies. These jellyfish barely even behave like animals.

Answer 2

Answer:

yes, the answer is jellyfish