Based on the provided information, sea urchins are animals that don't sleep.
Sea Urchins and Sleep
Sea urchins lack a brain and eyes, which are typically associated with sleep. Instead of a centralized brain, they possess a nerve ring that surrounds their mouth. This nerve ring connects to their tube feet, which are small appendages used for movement and sensing the environment.
Here's a summary of their unique characteristics:
- No Brain or Eyes: This absence suggests a different mode of existence compared to animals that require sleep for cognitive function.
- Nerve Ring: Functions as a decentralized nervous system, allowing them to respond to stimuli.
- Tube Feet: Used for movement and sensory perception.
- Camouflage: Sea urchins can change color and shape to blend in with their surroundings, providing protection from predators.
| Feature | Description |
|---|---|
| Brain | Absent |
| Eyes | Absent |
| Nervous System | Nerve ring around the mouth, connected to tube feet |
| Movement & Sense | Tube feet |
| Defense | Camouflage (changing color and shape) |
