10 Animals That Do Not Have A Brain

 Here’s a list of 10 animals that do not have a brain:

1. Jellyfish

   
   
   Jellyfish rely on a simple nerve net to sense their surroundings and coordinate movement.

2. Sea Star (Starfish)

   
   
   Starfish use a decentralized nerve ring and radial nerves for movement and sensory input.

3. Sea Urchins

   
   
   Similar to starfish, sea urchins have a nerve ring and no centralized brain.

4. Sponges

   
   
   Sponges lack a nervous system entirely and rely on water flow and specialized cells for function.

5. Corals

   
   
   Corals are similar to sponges in lacking a nervous system and instead rely on a simple network of nerves to detect changes.

6. Sea Cucumbers

   
   
   Sea cucumbers have a nerve ring near the mouth but no brain.

7. Tunicates (Sea Squirts)

   
   
   While their larvae have a brain-like structure, adult tunicates lose it as they mature.

8. Portuguese Man O’ War

   
   
   This is a siphonophore, not a single organism, but a colony of specialized individuals. It lacks a central brain and operates through a simple nerve net.

9. Hydra

   
   
   Hydra use a nerve net to respond to stimuli but have no brain.

10. Planarians (Flatworms)

    
    
    While some flatworms have basic clusters of nerve cells (ganglia), certain species lack a centralized brain structure.

These animals rely on decentralized systems, nerve nets, or other biological mechanisms to sense and respond to their environments.