Zenuwstelsels en gedrag in het dierenrijk - Chptr 7: Mechanism of Behaviour

Question

What is the nerve net and how does it work?

Answer 1

A net of nerves that are nonpolarized and conduct impulses in all directions. There is also no centralized processing of information, however simpel behaviours are still observed amoung the Cnidaria (sea anemones, hydra and jellyfish).

Peristaltic contraction in the gut wall of vertabrates is a nerve net. (& starfish back pincers)

Answer 2

The Echinodermata (starfish, sea urchin..) have a radially symmetrical nervous system. The nervous ring centered in the body leads out into nerve tracts extending into each arm. coodinated movements are partially controlled by impulses that travel through sensory neurons and interneurons, through the central ring, to motor neurons. Specialized types of receptors are found for receiving contact, taste, and general chemical signals.

Answer 3

Found in animals with directional movement (worms, molluscs, arthropods (insects and crustaceans), and chordates. Associated with the evolution of a distinct head (cephalization). These animals became more specialized for movement, giving the ventral part of the body the side that was used for moving.