dissect out provided animal (pila/unio/prawn) so as to expose it's nervous system draw the labelled diagram of nervous system
Answers
(1.) DISSECTION OF PILA
Pila shows a well-developed nervous system. This nervous system will show 5 pairs of ganglia, the connectives and commisures and nerves.
NERVE GANGLIC
Cerebral ganglia
Pedal ganglia
Visceral ganglia
Pleural ganglia
Supra and infra intestinal ganglia.
On the dorso-lateral sides of the buccal mass cerebral ganglia are present. They are connected by cerebral commisures.
On the ventrolateral sides of the buccal mass a pair pleural and a pair pedal ganglia are present. The cerebral ganglia and pleural ganglia are connected by cerebro-pleural connectives. The cerebral and pedal ganglia are connected by cerebro-pedal connectives.
The two pedal ganglia are connected by pedal commisure. All these structures will form a nerve ring which looks like a square.
At the junction of buccal mass and oesophagus two buccal ganglia are present. They are connected in the cerebral ganglia with connectives
In the visceral mass two visceral ganglia are present. The pleural ganglia and visceral ganglia are connected by right and left pleuro-visceral connectives. From the right pleural ganglion a supra intestinal nerve will arise. It will travel over the oesophagus and is connected to the left pleuro-visceral connective. At this point, it form a supra intestinal ganglion.
Left pleural ganglion gives a nerve which connects with right pleuro-visceral connective and a infra intestinal ganglion is formed. Thus these nerves will give '8' shaped structure.
From cerebral nerve ganglia a number of small nerves will arise. They travel to tentacles, eyes, statocysts etc.
From pleural tjerve ganglia nerves will arise and will innervate mantle.
From visceral ganglia nerves will go to excretory organs, reproductive organs,
and to stomach.
Thus a well-developed nervous system is seen in the pila.
(2.) DISSECTION OF UNIO
(1.) The nervous system of Unio is symmetrically arranged on two sides of the body.
2. The ganglia are widely separated by long connectives in Unio.
Cerebral ganglia are two in number. These ganglia are to be called cerebropleural ganglia. Each ganglion is formed by the fusion of cerebral and pleural ganglia of the side. The ganglia are roughly triangular in outline and situated on the antero-dorsal corners of the mouth at the base of labial palps. These ganglia are connected by the cerebral commissure.
4. Pedal ganglia is a bilobed ganglionic mass formed by the fusion of two separate pedal ganglia. It is located at the junction of the visceral mass with the foot.
5. Pleural ganglia have no separate existence and become fused with cerebral ganglia.
6. Visceral ganglia is a large bilobed ganglion formed by the fusion of two visceral ganglia. It is situated posteriorly on the ventral side of the posterior adductor muscles.
7. Buccal ganglia is absent in Unio.
8. Intestinal gang-lion is absent in Unio.
9. Pedal commissure is absent in Unio.
10. Connections between cerebral pleural and pedal ganglia:
A pair of cerebropedal connectives connects the cerebropleural ganglia with the pedal.
11. Chiastoneury is absent in Unio.
(3.) DISSECTION OF PRAWN
Put the specimen (Fig. 4.1) on the dissecting tray. Lift the carapace from the lateral sides and cut it loose at the anterior end. Cut the inner lining membrane and the carapace is separated. Remove the abdominal terga with the pleura by making two parallel cuts along the ventrolateral lines of the abdomen starting from the anterior end and running up to telson. The dorsal surface of the animal is completely exposed.
Macrobrachium Rosenbergii
Put clear water in the dissecting tray and pin down the specimen properly. The organs lodged beneath the dorsal wall of the cephalothorax from dorsal to ventral surface in succession are, the pericardial sinus containing the heart, the gonads-testes or ovaries, the renal sac, the cardiac and pyloric stomach and the ventral thoracic ganglionic mass. The hepatopancreas is a large orange-yellow mass in which some of the above organs are embedded.
Dissection of Alimentary System:
Remove the dorsal wall of the cephalothorax, pericardial sinus, gonads and the renal sac. The major part of the cardiac stomach, the pyloric stomach and the anterior part of the mid gut (intestine) are embedded in the hepatopancreas (Figs. 4.2, 4.3).
Alimentary Canal. Dorsal View
Alimentary System. Lateral View
Give a superficial incision with a pair of fine scissors along the mid-dorsal line of the abdomen up to its posterior end. A narrow groove is exposed in which lies the intestine. The intestine blends with the surrounding muscles in colour but very often it stands out prominently due to its contents (Fig. 4.2). The muscles of one side at the base of the telson should be cut to expose the rectum .
Dissection of Prawn
Explanation:
Prawn: The prawn relates to the phylum Arthropoda and group Crustacea. lt is common as a nutritious and delicious food. There are several varieties of aquatic and freshwater prawns in Bangladesh. Galda prawn in a freshwater variety. There are relationships among all the varieties of prawn in their inner and outer compositions. Bagda is a kind of aquatic prawn.
Prawn is an invertebrate animal. So it is divided on the dorsal side. The digestive system of prawn is composed of two parts, specifically: 1. Alimentary Canal 2. Gastric Gland
To learn more:
i)Dissection of mammalian heart experiment - Brainly.in
https://brainly.in/question/14795371
ii)Dissection of frog is done from ventral side because [BHU 1982] A ...
https://brainly.in/question/2174337