nervous system of mollusk cephalopod (cuttlefish)

this will help to understand nervous system of cuttlefish

1. CUTTLEFISH-NERVOUS SYSTEM

2. DEPARTMENT OF ZOOLOGY SEMINAR TOPIC:- NERVOUS SYSTEM - CEPHALOPOD REPRESENTED BY – n. r. Sharma

3. CONTENTS INTRODUCTION CLASS- CEPHALOPOD EXAMPLE- SEPIA(CUTTLEFISH) CUTTLEFISH- NERVOUS SYSTEM FEATURES OF NERVOUS SYSTEM

4. Phylum Mollusca, Class Cephalopod Cephalopods (Class Cephalopoda) are a group of molluscs that include squid, nautilus, cuttlefish and octopus Cephalopods (which means “head-footed”) have heads surrounded by a foot modified into arms and tentacles, usually equipped with suckers that are used to capture prey Cephalopod nervous system has been extensively studied as a comparative model to vertebrates.

5. Cuttlefish: Order Sepiida Sepia is commonly known as cuttle fish Cuttlefish are among the most intelligent invertebrates Body is bilaterally symmetrical, dorsoventrally flattened and is divisible into head, collar and trunk. Called “chameleons of the sea” for their astonishing ability to change skin color at will Sepia is cosmopolitan in distribution. It is commonly found in India, Europe and Mediterranean region.

6. Nervous system in sepia:- Nervous system consists of paired ganglia, connectives and nerve Central nervous system(CNS) Peripheral nervous system(PNS) Sympathetic nervous system Central nervous system - central nervous system contain brain enclosed in a cartilaginous capsule Brain consists of four typical molluscan ganglionic masses Cerebral or supra-esophagus ganglia Superior-buccal ganglia Sub-esophageal ganglia Pleura-visceral ganglia

7. Central nervous system Sub-esophageal ganglionic mass, lying beneath the esophagus is partly divided into two lobes they are: Anterior lobe: anterior lobe which is also known as the branchial ganglion Posterior lobe: posterior lobe which is also known as the pedal ganglion. Pleura-visceral ganglia :- they give off two pairs of main nerves Visceral nerves Pallial nerves

8. Peripheral nervous system peripheral nervous system composed of stellate ganglia, nervous cords of the arms/tentacles and several sparse ganglia. PNS constitutes 2/3 of the total nervous system. pallial nerve divide into two branches – outer branch and inner branch outer branch immediately terminates into a large, roughly triangular structure known as stellate ganglia, which can be seen without dissection. inner branch is connected to the stellate ganglion by two commissured and innervates the fin.

9. Sympathetic nervous system a pair sympathetic nerves, arising from the inferior buccal ganglion, runs posteriorly along the esophagus to join gastric ganglion Gastric ganglion sends nerves to the liver, stomach, caecum and intestine.

10. Some important features of nervous system The cuttlefish has the most complex nervous system among invertebrates with highly developed neural organs that allow them to learn and remember. Transformation from one color to another, which can take less than a second, is controlled by the nervous system. The nervous system includes a variety of senses including sight, smell, and even sound (in the form of pressure waves).