MARE 394 – Dogfish Dissection #1 – External Anatomy, Musculature, & Digestive
System
You will be responsible for all systems listed in the lab whether there is a specific figure
to represent each in your dissection guide. You are asked to draw each of the tissues as
they appear in your animal - not as they appear in the dissection guide.
1. External Anatomy
Orient yourself to the shark by identifying the following external features:
a. Lateral line
b. Anterior dorsal fin
c. Posterior dorsal fin
d. Pectoral fin
e. Caudal fin
f. Pelvic fin
g. Spiracle
h. Lateral line
i. Eye
j. Gill slits
k. Nostrils
l. Cloacal opening
m. Ampullae of Lorenzini
n. Clasper (♂)
o. Endolymphatic pore
2. Musculature
Using a scalpel and forceps, carefully remove the skin covering the muscles illustrated
below from the mouth to the anterior dorsal fin that appear in Fig. 5 (p.10).
Identify the following features:
3. Dorsal longitudinal bundles
4. Dorsal superficial constrictor
6. Extensor of fin
10. Lateral longitudinal bundle
13. Quadratomandibularis
17. Ventral longitudinal bundle
3. Digestive and Respiratory Systems
Using scissors, make a cut from the corner of the jaw through the five gill arches. Just
posterior to the fifth gill arch, make a cut across the throat just between the heart
(anterior) and the abdominal cavity (posterior).
Identify the following features from the mouth and pharynx in Fig 8 (p.15).
3. Esophagus
9. Gill rakers
17. Pharynx
18. Spiracle
20. Tongue
Using the scalpel, make a shallow incision in the middle of the abdominal cavity halfway
between the cloaca and the pharyngeal cavity. Once the incision has been made,
carefully insert forceps to pull the abdominal wall away from the internal organs so that
the incision can be extended to the pharynx (anteriorly). Cut transversely across the
abdominal wall at the pharynx and just above the cloacal opening so that the wall
sections can be folded open to expose the internal organs. Pin the abdominal walls to the
dissection pad to hold them in place; you may need to score the internal abdominal wall
to relieve the tension.
Identify the following features of the digestive system from Fig. 11 (p.19).
3. Bile duct
4. Body of stomach
5. Cardiac region of stomach
9. Colon
13. Dorsal lobe of pancreas
14. Duodenum
15. Falciform ligament
16. Gall bladder
22. Left lobe of liver
25. Median lobe of liver
33. Pyloric region of stomach
34. Rectal gland
35. Right lobe of liver
37. Spleen
39. Valvular intestine
41. Ventral lobe of pancreas
Using scissors or scalpel, cut open portions of the esophagus to expose the papillae, the
stomach to expose the rugae, and the intestine to expose the spiral valve following the
figure on page 22. Examine the gut contents of the stomach and compare with other
students.