How Much Nervous System Does an Echinoderm Have? Sea Stars

question 77

Multiple Choice

How much nervous system does an echinoderm have? Sea stars have

• A)a complex of nerve ganglia in each ray.
• B)a central nervous system including a brain.
• C)a simple nerve ring and radial nerves leading to simple sensory cells scattered over the epidermis.
• D)no genuine nerve cells are found in echinoderms;they operate completely by a hydraulic system.

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Definitions:

Reticular Formation

A network of nerves in the brainstem that plays a key role in controlling arousal and alertness.

Afferent Neurons

Neurons that transmit messages from sensory receptors to the spinal cord and brain; also called sensory neurons.

Efferent Neurons

Neurons that transmit messages from the brain or spinal cord to muscles and glands; also called motor neurons.

Glial Cells

Non-neuronal cells in the central and peripheral nervous systems that support and protect neurons.