Shark Dissection Lab



**INTRODUCTION AND PURPOSE:
-The fish that we disected was a dogfish shark. The dogfish shark belongs to the phylum Chordata and subphylum Vertebrata, and kingdom animalia. The dogfish resembles the characteristics of a regular fish, but doesn't classify as one. The sharks skeletal structures differ from fishes because they are made of cartilage and not bone. Fish have gas filled swim bladders that allow them to float if they stop swimming. Sharks, however, don't have swim bladders. If a shark stops swimming at deeper depths, they could die from the pressure. We observed the External and Internal features, and Urogenital System and the Brain. It took us three days to observe all of these.

First Day:
  • Lateral Line: pores attached to nerves that dectect water disturbances.
  • Ampullae's of Lorenzini: pores that sense the living organisms electromagnetic fields.
  • Placoid Scales or Denticles: shark's spiny skin
  • Countershading: shading of upper half and lower half of the shark.
  • Spiracles: allows the shark to breathe with a closed mouth.
  • Cloaca: receives all products from the intestines, urinary, and genital ducts.
  • Claspers:male's copulatory organs which allows fertilization
  • 5 fins: Caudal, Pectoral, Pelvic, and Dorsal also gills Second Day:
    • Observed Musculatory, Circulatory, Digestive, and Respiratory systems.
    • Deep Fasia: the film like skin that holds the muscle
    • Superficial Fasia: the film like skin that holds muscles to skin
    • Coelum or Body Cavity:made up of two chambers 1) pleuroperitoneal cavity 2) pericardial cavity
    • Liver: largest organ in the sharks body
    • Stomach, Duodenum, Pancreas, Spleen, Intestines, Colon, and Cloaca.
    Third Day:
    • Urogenital System and the Brain.
    • Urogenital System:kidneys, testes, epididymis, seminal vesicles, sperm sac, cloaca, and claspers.Female:ovaries, shell gland, and uterus.
    • Brain:cerebellum, superficial ophthalimic nerve, cerebral hemisphere, and the medulla oblongata.
    Conclusion:
    At the end of this lab, we had learned a lot of facts about the shark. We learned about external features such as the lateral line and countershading of the skin, the Ampullae of Lorenzini and how it's used to detect electrical fields, the gills and that there are five to seven gills on a shark. On the second day of our dissection, we looked at the musculatory and circulatory systems. This included the flexors and extensors of the fins, the myotomes which run from the trunk to the tail, the branchial and head region which is around the gills and the mouth. We also looked at the appendicular muscles which are the fin muscles. We discovered that two of our sharks were males, and one was a female. The claspers on the males were thin and located at the end of the pelvic fins.
    THE END
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