Subject: Starfish brain

Caroline Margaret Delong (delong@hawaii.edu)
Sun, 25 Apr 1999 21:07:24 -1000

On Wed, 21 Apr 1999, Mike D. Stewart wrote:

> how can a starfish move with no brain to controll it's nervouse system?
> 
Hi Mike,

The starfish has no central nervous system.  The starfish's movements and
behaviors are controlled by a nerve net: a system of functionally
connected nerve cells and fibers anatomically dispersed throughout most of
the animal. More than one nerve net can be present- each responding to
different kinds of stimuli and eliciting different forms of response.
Nerve nets, having no centralized system, are efficient in terms of
resistance to injuries and the mediation of local response. The behavioral
repertoire of starfish is such that a nerve net is sufficient to control
movements (i.e., it doesn't take a big brain to move a starfish).

If you are interested, check out these texts.  My undergraduate class on
Brain, Behavior, and Evolution used them.
 
Shepherd, 1983, _Neurobiology_.
Bullock et al., 1977, _Introduction to Nervous Systems_.

Aloha,
Caroline