Echinodermata
Important information
- The nervous system is complex.
- A nerve plexus lies within and underneath the skin.
- The esophagus is surrounded by nerve rings.
- Ring and radial rings coordinate activity.
- They are sensitive to touch, light, temperature, and water.
Sea urchin (Echinus)
The nervous system of the echinus contains a ring of nerve fibers and brain cells which start from the mouth and end at the posterior. The brain is used to send nerve frequencies to send information to the body to help recognize the sensitivity. The lack of eyespots also affects the echinus as it cannot see. The use of the hairs that extend are used to sense other surfaces.
Starfish (Asteria)
The asteria (starfish) has a nervous system that consists of a radial nerve runnign the length of each ray and around the mouth.The nerve ring does not equip any kind of processing information. Many different radial nerves are used in order to move the starfish. They are sensitive to light, touch, and stenches.
Sea Cucumber (Holothurion)
The holothurion (sea cucumber) has a nervous system that consists of s ring of neural tissue that surrounds the mouth. Also five major nerves run from the nerve ring to the other end of the body. Many sea cucumbers do not have distinct sensory organs but they are sensitive to light and touch.